From 02446fc99abb06d3117d65c0b1f5fba4f906db2e Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Mon, 4 Jan 2010 07:37:31 +0000 Subject: [PATCH] split instcombine of compares (visit[FI]Cmp) out to a new InstCombineCompares.cpp file. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@92467 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Transforms/InstCombine/CMakeLists.txt | 1 + lib/Transforms/InstCombine/InstCombine.h | 18 +- .../InstCombine/InstCombineCompares.cpp | 2443 ++++++++++++++++ .../InstCombine/InstructionCombining.cpp | 2450 +---------------- 4 files changed, 2477 insertions(+), 2435 deletions(-) create mode 100644 lib/Transforms/InstCombine/InstCombineCompares.cpp diff --git a/lib/Transforms/InstCombine/CMakeLists.txt b/lib/Transforms/InstCombine/CMakeLists.txt index 665903064a5..96b016650e2 100644 --- a/lib/Transforms/InstCombine/CMakeLists.txt +++ b/lib/Transforms/InstCombine/CMakeLists.txt @@ -1,5 +1,6 @@ add_llvm_library(LLVMInstCombine InstructionCombining.cpp + InstCombineCompares.cpp InstCombineSimplifyDemanded.cpp ) diff --git a/lib/Transforms/InstCombine/InstCombine.h b/lib/Transforms/InstCombine/InstCombine.h index d4d26f8e348..a1e9f2ffe31 100644 --- a/lib/Transforms/InstCombine/InstCombine.h +++ b/lib/Transforms/InstCombine/InstCombine.h @@ -32,6 +32,20 @@ enum SelectPatternFlavor { SPF_SMAX, SPF_UMAX //SPF_ABS - TODO. }; + +/// getComplexity: Assign a complexity or rank value to LLVM Values... +/// 0 -> undef, 1 -> Const, 2 -> Other, 3 -> Arg, 3 -> Unary, 4 -> OtherInst +static inline unsigned getComplexity(Value *V) { + if (isa(V)) { + if (BinaryOperator::isNeg(V) || + BinaryOperator::isFNeg(V) || + BinaryOperator::isNot(V)) + return 3; + return 4; + } + if (isa(V)) return 3; + return isa(V) ? (isa(V) ? 0 : 1) : 2; +} /// InstCombineIRInserter - This is an IRBuilder insertion helper that works @@ -179,6 +193,8 @@ public: Instruction *visitInstruction(Instruction &I) { return 0; } private: + Value *dyn_castNegVal(Value *V) const; + Instruction *visitCallSite(CallSite CS); bool transformConstExprCastCall(CallSite CS); Instruction *transformCallThroughTrampoline(CallSite CS); @@ -186,7 +202,7 @@ private: bool DoXform = true); bool WillNotOverflowSignedAdd(Value *LHS, Value *RHS); DbgDeclareInst *hasOneUsePlusDeclare(Value *V); - + Value *EmitGEPOffset(User *GEP); public: // InsertNewInstBefore - insert an instruction New before instruction Old diff --git a/lib/Transforms/InstCombine/InstCombineCompares.cpp b/lib/Transforms/InstCombine/InstCombineCompares.cpp new file mode 100644 index 00000000000..005f1a0bc4f --- /dev/null +++ b/lib/Transforms/InstCombine/InstCombineCompares.cpp @@ -0,0 +1,2443 @@ +//===- InstCombineCompares.cpp --------------------------------------------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This file implements the visitICmp and visitFCmp functions. +// +//===----------------------------------------------------------------------===// + +#include "InstCombine.h" +#include "llvm/IntrinsicInst.h" +#include "llvm/Analysis/InstructionSimplify.h" +#include "llvm/Analysis/MemoryBuiltins.h" +#include "llvm/Target/TargetData.h" +#include "llvm/Support/ConstantRange.h" +#include "llvm/Support/GetElementPtrTypeIterator.h" +#include "llvm/Support/PatternMatch.h" +using namespace llvm; +using namespace PatternMatch; + +/// AddOne - Add one to a ConstantInt +static Constant *AddOne(Constant *C) { + return ConstantExpr::getAdd(C, ConstantInt::get(C->getType(), 1)); +} +/// SubOne - Subtract one from a ConstantInt +static Constant *SubOne(ConstantInt *C) { + return ConstantExpr::getSub(C, ConstantInt::get(C->getType(), 1)); +} + +static ConstantInt *ExtractElement(Constant *V, Constant *Idx) { + return cast(ConstantExpr::getExtractElement(V, Idx)); +} + +static bool HasAddOverflow(ConstantInt *Result, + ConstantInt *In1, ConstantInt *In2, + bool IsSigned) { + if (IsSigned) + if (In2->getValue().isNegative()) + return Result->getValue().sgt(In1->getValue()); + else + return Result->getValue().slt(In1->getValue()); + else + return Result->getValue().ult(In1->getValue()); +} + +/// AddWithOverflow - Compute Result = In1+In2, returning true if the result +/// overflowed for this type. +static bool AddWithOverflow(Constant *&Result, Constant *In1, + Constant *In2, bool IsSigned = false) { + Result = ConstantExpr::getAdd(In1, In2); + + if (const VectorType *VTy = dyn_cast(In1->getType())) { + for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) { + Constant *Idx = ConstantInt::get(Type::getInt32Ty(In1->getContext()), i); + if (HasAddOverflow(ExtractElement(Result, Idx), + ExtractElement(In1, Idx), + ExtractElement(In2, Idx), + IsSigned)) + return true; + } + return false; + } + + return HasAddOverflow(cast(Result), + cast(In1), cast(In2), + IsSigned); +} + +static bool HasSubOverflow(ConstantInt *Result, + ConstantInt *In1, ConstantInt *In2, + bool IsSigned) { + if (IsSigned) + if (In2->getValue().isNegative()) + return Result->getValue().slt(In1->getValue()); + else + return Result->getValue().sgt(In1->getValue()); + else + return Result->getValue().ugt(In1->getValue()); +} + +/// SubWithOverflow - Compute Result = In1-In2, returning true if the result +/// overflowed for this type. +static bool SubWithOverflow(Constant *&Result, Constant *In1, + Constant *In2, bool IsSigned = false) { + Result = ConstantExpr::getSub(In1, In2); + + if (const VectorType *VTy = dyn_cast(In1->getType())) { + for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) { + Constant *Idx = ConstantInt::get(Type::getInt32Ty(In1->getContext()), i); + if (HasSubOverflow(ExtractElement(Result, Idx), + ExtractElement(In1, Idx), + ExtractElement(In2, Idx), + IsSigned)) + return true; + } + return false; + } + + return HasSubOverflow(cast(Result), + cast(In1), cast(In2), + IsSigned); +} + +/// isSignBitCheck - Given an exploded icmp instruction, return true if the +/// comparison only checks the sign bit. If it only checks the sign bit, set +/// TrueIfSigned if the result of the comparison is true when the input value is +/// signed. +static bool isSignBitCheck(ICmpInst::Predicate pred, ConstantInt *RHS, + bool &TrueIfSigned) { + switch (pred) { + case ICmpInst::ICMP_SLT: // True if LHS s< 0 + TrueIfSigned = true; + return RHS->isZero(); + case ICmpInst::ICMP_SLE: // True if LHS s<= RHS and RHS == -1 + TrueIfSigned = true; + return RHS->isAllOnesValue(); + case ICmpInst::ICMP_SGT: // True if LHS s> -1 + TrueIfSigned = false; + return RHS->isAllOnesValue(); + case ICmpInst::ICMP_UGT: + // True if LHS u> RHS and RHS == high-bit-mask - 1 + TrueIfSigned = true; + return RHS->getValue() == + APInt::getSignedMaxValue(RHS->getType()->getPrimitiveSizeInBits()); + case ICmpInst::ICMP_UGE: + // True if LHS u>= RHS and RHS == high-bit-mask (2^7, 2^15, 2^31, etc) + TrueIfSigned = true; + return RHS->getValue().isSignBit(); + default: + return false; + } +} + +// isHighOnes - Return true if the constant is of the form 1+0+. +// This is the same as lowones(~X). +static bool isHighOnes(const ConstantInt *CI) { + return (~CI->getValue() + 1).isPowerOf2(); +} + +/// ComputeSignedMinMaxValuesFromKnownBits - Given a signed integer type and a +/// set of known zero and one bits, compute the maximum and minimum values that +/// could have the specified known zero and known one bits, returning them in +/// min/max. +static void ComputeSignedMinMaxValuesFromKnownBits(const APInt& KnownZero, + const APInt& KnownOne, + APInt& Min, APInt& Max) { + assert(KnownZero.getBitWidth() == KnownOne.getBitWidth() && + KnownZero.getBitWidth() == Min.getBitWidth() && + KnownZero.getBitWidth() == Max.getBitWidth() && + "KnownZero, KnownOne and Min, Max must have equal bitwidth."); + APInt UnknownBits = ~(KnownZero|KnownOne); + + // The minimum value is when all unknown bits are zeros, EXCEPT for the sign + // bit if it is unknown. + Min = KnownOne; + Max = KnownOne|UnknownBits; + + if (UnknownBits.isNegative()) { // Sign bit is unknown + Min.set(Min.getBitWidth()-1); + Max.clear(Max.getBitWidth()-1); + } +} + +// ComputeUnsignedMinMaxValuesFromKnownBits - Given an unsigned integer type and +// a set of known zero and one bits, compute the maximum and minimum values that +// could have the specified known zero and known one bits, returning them in +// min/max. +static void ComputeUnsignedMinMaxValuesFromKnownBits(const APInt &KnownZero, + const APInt &KnownOne, + APInt &Min, APInt &Max) { + assert(KnownZero.getBitWidth() == KnownOne.getBitWidth() && + KnownZero.getBitWidth() == Min.getBitWidth() && + KnownZero.getBitWidth() == Max.getBitWidth() && + "Ty, KnownZero, KnownOne and Min, Max must have equal bitwidth."); + APInt UnknownBits = ~(KnownZero|KnownOne); + + // The minimum value is when the unknown bits are all zeros. + Min = KnownOne; + // The maximum value is when the unknown bits are all ones. + Max = KnownOne|UnknownBits; +} + + + +/// FoldCmpLoadFromIndexedGlobal - Called we see this pattern: +/// cmp pred (load (gep GV, ...)), cmpcst +/// where GV is a global variable with a constant initializer. Try to simplify +/// this into some simple computation that does not need the load. For example +/// we can optimize "icmp eq (load (gep "foo", 0, i)), 0" into "icmp eq i, 3". +/// +/// If AndCst is non-null, then the loaded value is masked with that constant +/// before doing the comparison. This handles cases like "A[i]&4 == 0". +Instruction *InstCombiner:: +FoldCmpLoadFromIndexedGlobal(GetElementPtrInst *GEP, GlobalVariable *GV, + CmpInst &ICI, ConstantInt *AndCst) { + ConstantArray *Init = dyn_cast(GV->getInitializer()); + if (Init == 0 || Init->getNumOperands() > 1024) return 0; + + // There are many forms of this optimization we can handle, for now, just do + // the simple index into a single-dimensional array. + // + // Require: GEP GV, 0, i {{, constant indices}} + if (GEP->getNumOperands() < 3 || + !isa(GEP->getOperand(1)) || + !cast(GEP->getOperand(1))->isZero() || + isa(GEP->getOperand(2))) + return 0; + + // Check that indices after the variable are constants and in-range for the + // type they index. Collect the indices. This is typically for arrays of + // structs. + SmallVector LaterIndices; + + const Type *EltTy = cast(Init->getType())->getElementType(); + for (unsigned i = 3, e = GEP->getNumOperands(); i != e; ++i) { + ConstantInt *Idx = dyn_cast(GEP->getOperand(i)); + if (Idx == 0) return 0; // Variable index. + + uint64_t IdxVal = Idx->getZExtValue(); + if ((unsigned)IdxVal != IdxVal) return 0; // Too large array index. + + if (const StructType *STy = dyn_cast(EltTy)) + EltTy = STy->getElementType(IdxVal); + else if (const ArrayType *ATy = dyn_cast(EltTy)) { + if (IdxVal >= ATy->getNumElements()) return 0; + EltTy = ATy->getElementType(); + } else { + return 0; // Unknown type. + } + + LaterIndices.push_back(IdxVal); + } + + enum { Overdefined = -3, Undefined = -2 }; + + // Variables for our state machines. + + // FirstTrueElement/SecondTrueElement - Used to emit a comparison of the form + // "i == 47 | i == 87", where 47 is the first index the condition is true for, + // and 87 is the second (and last) index. FirstTrueElement is -2 when + // undefined, otherwise set to the first true element. SecondTrueElement is + // -2 when undefined, -3 when overdefined and >= 0 when that index is true. + int FirstTrueElement = Undefined, SecondTrueElement = Undefined; + + // FirstFalseElement/SecondFalseElement - Used to emit a comparison of the + // form "i != 47 & i != 87". Same state transitions as for true elements. + int FirstFalseElement = Undefined, SecondFalseElement = Undefined; + + /// TrueRangeEnd/FalseRangeEnd - In conjunction with First*Element, these + /// define a state machine that triggers for ranges of values that the index + /// is true or false for. This triggers on things like "abbbbc"[i] == 'b'. + /// This is -2 when undefined, -3 when overdefined, and otherwise the last + /// index in the range (inclusive). We use -2 for undefined here because we + /// use relative comparisons and don't want 0-1 to match -1. + int TrueRangeEnd = Undefined, FalseRangeEnd = Undefined; + + // MagicBitvector - This is a magic bitvector where we set a bit if the + // comparison is true for element 'i'. If there are 64 elements or less in + // the array, this will fully represent all the comparison results. + uint64_t MagicBitvector = 0; + + + // Scan the array and see if one of our patterns matches. + Constant *CompareRHS = cast(ICI.getOperand(1)); + for (unsigned i = 0, e = Init->getNumOperands(); i != e; ++i) { + Constant *Elt = Init->getOperand(i); + + // If this is indexing an array of structures, get the structure element. + if (!LaterIndices.empty()) + Elt = ConstantExpr::getExtractValue(Elt, LaterIndices.data(), + LaterIndices.size()); + + // If the element is masked, handle it. + if (AndCst) Elt = ConstantExpr::getAnd(Elt, AndCst); + + // Find out if the comparison would be true or false for the i'th element. + Constant *C = ConstantFoldCompareInstOperands(ICI.getPredicate(), Elt, + CompareRHS, TD); + // If the result is undef for this element, ignore it. + if (isa(C)) { + // Extend range state machines to cover this element in case there is an + // undef in the middle of the range. + if (TrueRangeEnd == (int)i-1) + TrueRangeEnd = i; + if (FalseRangeEnd == (int)i-1) + FalseRangeEnd = i; + continue; + } + + // If we can't compute the result for any of the elements, we have to give + // up evaluating the entire conditional. + if (!isa(C)) return 0; + + // Otherwise, we know if the comparison is true or false for this element, + // update our state machines. + bool IsTrueForElt = !cast(C)->isZero(); + + // State machine for single/double/range index comparison. + if (IsTrueForElt) { + // Update the TrueElement state machine. + if (FirstTrueElement == Undefined) + FirstTrueElement = TrueRangeEnd = i; // First true element. + else { + // Update double-compare state machine. + if (SecondTrueElement == Undefined) + SecondTrueElement = i; + else + SecondTrueElement = Overdefined; + + // Update range state machine. + if (TrueRangeEnd == (int)i-1) + TrueRangeEnd = i; + else + TrueRangeEnd = Overdefined; + } + } else { + // Update the FalseElement state machine. + if (FirstFalseElement == Undefined) + FirstFalseElement = FalseRangeEnd = i; // First false element. + else { + // Update double-compare state machine. + if (SecondFalseElement == Undefined) + SecondFalseElement = i; + else + SecondFalseElement = Overdefined; + + // Update range state machine. + if (FalseRangeEnd == (int)i-1) + FalseRangeEnd = i; + else + FalseRangeEnd = Overdefined; + } + } + + + // If this element is in range, update our magic bitvector. + if (i < 64 && IsTrueForElt) + MagicBitvector |= 1ULL << i; + + // If all of our states become overdefined, bail out early. Since the + // predicate is expensive, only check it every 8 elements. This is only + // really useful for really huge arrays. + if ((i & 8) == 0 && i >= 64 && SecondTrueElement == Overdefined && + SecondFalseElement == Overdefined && TrueRangeEnd == Overdefined && + FalseRangeEnd == Overdefined) + return 0; + } + + // Now that we've scanned the entire array, emit our new comparison(s). We + // order the state machines in complexity of the generated code. + Value *Idx = GEP->getOperand(2); + + + // If the comparison is only true for one or two elements, emit direct + // comparisons. + if (SecondTrueElement != Overdefined) { + // None true -> false. + if (FirstTrueElement == Undefined) + return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(GEP->getContext())); + + Value *FirstTrueIdx = ConstantInt::get(Idx->getType(), FirstTrueElement); + + // True for one element -> 'i == 47'. + if (SecondTrueElement == Undefined) + return new ICmpInst(ICmpInst::ICMP_EQ, Idx, FirstTrueIdx); + + // True for two elements -> 'i == 47 | i == 72'. + Value *C1 = Builder->CreateICmpEQ(Idx, FirstTrueIdx); + Value *SecondTrueIdx = ConstantInt::get(Idx->getType(), SecondTrueElement); + Value *C2 = Builder->CreateICmpEQ(Idx, SecondTrueIdx); + return BinaryOperator::CreateOr(C1, C2); + } + + // If the comparison is only false for one or two elements, emit direct + // comparisons. + if (SecondFalseElement != Overdefined) { + // None false -> true. + if (FirstFalseElement == Undefined) + return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(GEP->getContext())); + + Value *FirstFalseIdx = ConstantInt::get(Idx->getType(), FirstFalseElement); + + // False for one element -> 'i != 47'. + if (SecondFalseElement == Undefined) + return new ICmpInst(ICmpInst::ICMP_NE, Idx, FirstFalseIdx); + + // False for two elements -> 'i != 47 & i != 72'. + Value *C1 = Builder->CreateICmpNE(Idx, FirstFalseIdx); + Value *SecondFalseIdx = ConstantInt::get(Idx->getType(),SecondFalseElement); + Value *C2 = Builder->CreateICmpNE(Idx, SecondFalseIdx); + return BinaryOperator::CreateAnd(C1, C2); + } + + // If the comparison can be replaced with a range comparison for the elements + // where it is true, emit the range check. + if (TrueRangeEnd != Overdefined) { + assert(TrueRangeEnd != FirstTrueElement && "Should emit single compare"); + + // Generate (i-FirstTrue) getType(), -FirstTrueElement); + Idx = Builder->CreateAdd(Idx, Offs); + } + + Value *End = ConstantInt::get(Idx->getType(), + TrueRangeEnd-FirstTrueElement+1); + return new ICmpInst(ICmpInst::ICMP_ULT, Idx, End); + } + + // False range check. + if (FalseRangeEnd != Overdefined) { + assert(FalseRangeEnd != FirstFalseElement && "Should emit single compare"); + // Generate (i-FirstFalse) >u (FalseRangeEnd-FirstFalse). + if (FirstFalseElement) { + Value *Offs = ConstantInt::get(Idx->getType(), -FirstFalseElement); + Idx = Builder->CreateAdd(Idx, Offs); + } + + Value *End = ConstantInt::get(Idx->getType(), + FalseRangeEnd-FirstFalseElement); + return new ICmpInst(ICmpInst::ICMP_UGT, Idx, End); + } + + + // If a 32-bit or 64-bit magic bitvector captures the entire comparison state + // of this load, replace it with computation that does: + // ((magic_cst >> i) & 1) != 0 + if (Init->getNumOperands() <= 32 || + (TD && Init->getNumOperands() <= 64 && TD->isLegalInteger(64))) { + const Type *Ty; + if (Init->getNumOperands() <= 32) + Ty = Type::getInt32Ty(Init->getContext()); + else + Ty = Type::getInt64Ty(Init->getContext()); + Value *V = Builder->CreateIntCast(Idx, Ty, false); + V = Builder->CreateLShr(ConstantInt::get(Ty, MagicBitvector), V); + V = Builder->CreateAnd(ConstantInt::get(Ty, 1), V); + return new ICmpInst(ICmpInst::ICMP_NE, V, ConstantInt::get(Ty, 0)); + } + + return 0; +} + + +/// EvaluateGEPOffsetExpression - Return a value that can be used to compare +/// the *offset* implied by a GEP to zero. For example, if we have &A[i], we +/// want to return 'i' for "icmp ne i, 0". Note that, in general, indices can +/// be complex, and scales are involved. The above expression would also be +/// legal to codegen as "icmp ne (i*4), 0" (assuming A is a pointer to i32). +/// This later form is less amenable to optimization though, and we are allowed +/// to generate the first by knowing that pointer arithmetic doesn't overflow. +/// +/// If we can't emit an optimized form for this expression, this returns null. +/// +static Value *EvaluateGEPOffsetExpression(User *GEP, Instruction &I, + InstCombiner &IC) { + TargetData &TD = *IC.getTargetData(); + gep_type_iterator GTI = gep_type_begin(GEP); + + // Check to see if this gep only has a single variable index. If so, and if + // any constant indices are a multiple of its scale, then we can compute this + // in terms of the scale of the variable index. For example, if the GEP + // implies an offset of "12 + i*4", then we can codegen this as "3 + i", + // because the expression will cross zero at the same point. + unsigned i, e = GEP->getNumOperands(); + int64_t Offset = 0; + for (i = 1; i != e; ++i, ++GTI) { + if (ConstantInt *CI = dyn_cast(GEP->getOperand(i))) { + // Compute the aggregate offset of constant indices. + if (CI->isZero()) continue; + + // Handle a struct index, which adds its field offset to the pointer. + if (const StructType *STy = dyn_cast(*GTI)) { + Offset += TD.getStructLayout(STy)->getElementOffset(CI->getZExtValue()); + } else { + uint64_t Size = TD.getTypeAllocSize(GTI.getIndexedType()); + Offset += Size*CI->getSExtValue(); + } + } else { + // Found our variable index. + break; + } + } + + // If there are no variable indices, we must have a constant offset, just + // evaluate it the general way. + if (i == e) return 0; + + Value *VariableIdx = GEP->getOperand(i); + // Determine the scale factor of the variable element. For example, this is + // 4 if the variable index is into an array of i32. + uint64_t VariableScale = TD.getTypeAllocSize(GTI.getIndexedType()); + + // Verify that there are no other variable indices. If so, emit the hard way. + for (++i, ++GTI; i != e; ++i, ++GTI) { + ConstantInt *CI = dyn_cast(GEP->getOperand(i)); + if (!CI) return 0; + + // Compute the aggregate offset of constant indices. + if (CI->isZero()) continue; + + // Handle a struct index, which adds its field offset to the pointer. + if (const StructType *STy = dyn_cast(*GTI)) { + Offset += TD.getStructLayout(STy)->getElementOffset(CI->getZExtValue()); + } else { + uint64_t Size = TD.getTypeAllocSize(GTI.getIndexedType()); + Offset += Size*CI->getSExtValue(); + } + } + + // Okay, we know we have a single variable index, which must be a + // pointer/array/vector index. If there is no offset, life is simple, return + // the index. + unsigned IntPtrWidth = TD.getPointerSizeInBits(); + if (Offset == 0) { + // Cast to intptrty in case a truncation occurs. If an extension is needed, + // we don't need to bother extending: the extension won't affect where the + // computation crosses zero. + if (VariableIdx->getType()->getPrimitiveSizeInBits() > IntPtrWidth) + VariableIdx = new TruncInst(VariableIdx, + TD.getIntPtrType(VariableIdx->getContext()), + VariableIdx->getName(), &I); + return VariableIdx; + } + + // Otherwise, there is an index. The computation we will do will be modulo + // the pointer size, so get it. + uint64_t PtrSizeMask = ~0ULL >> (64-IntPtrWidth); + + Offset &= PtrSizeMask; + VariableScale &= PtrSizeMask; + + // To do this transformation, any constant index must be a multiple of the + // variable scale factor. For example, we can evaluate "12 + 4*i" as "3 + i", + // but we can't evaluate "10 + 3*i" in terms of i. Check that the offset is a + // multiple of the variable scale. + int64_t NewOffs = Offset / (int64_t)VariableScale; + if (Offset != NewOffs*(int64_t)VariableScale) + return 0; + + // Okay, we can do this evaluation. Start by converting the index to intptr. + const Type *IntPtrTy = TD.getIntPtrType(VariableIdx->getContext()); + if (VariableIdx->getType() != IntPtrTy) + VariableIdx = CastInst::CreateIntegerCast(VariableIdx, IntPtrTy, + true /*SExt*/, + VariableIdx->getName(), &I); + Constant *OffsetVal = ConstantInt::get(IntPtrTy, NewOffs); + return BinaryOperator::CreateAdd(VariableIdx, OffsetVal, "offset", &I); +} + +/// FoldGEPICmp - Fold comparisons between a GEP instruction and something +/// else. At this point we know that the GEP is on the LHS of the comparison. +Instruction *InstCombiner::FoldGEPICmp(GEPOperator *GEPLHS, Value *RHS, + ICmpInst::Predicate Cond, + Instruction &I) { + // Look through bitcasts. + if (BitCastInst *BCI = dyn_cast(RHS)) + RHS = BCI->getOperand(0); + + Value *PtrBase = GEPLHS->getOperand(0); + if (TD && PtrBase == RHS && GEPLHS->isInBounds()) { + // ((gep Ptr, OFFSET) cmp Ptr) ---> (OFFSET cmp 0). + // This transformation (ignoring the base and scales) is valid because we + // know pointers can't overflow since the gep is inbounds. See if we can + // output an optimized form. + Value *Offset = EvaluateGEPOffsetExpression(GEPLHS, I, *this); + + // If not, synthesize the offset the hard way. + if (Offset == 0) + Offset = EmitGEPOffset(GEPLHS); + return new ICmpInst(ICmpInst::getSignedPredicate(Cond), Offset, + Constant::getNullValue(Offset->getType())); + } else if (GEPOperator *GEPRHS = dyn_cast(RHS)) { + // If the base pointers are different, but the indices are the same, just + // compare the base pointer. + if (PtrBase != GEPRHS->getOperand(0)) { + bool IndicesTheSame = GEPLHS->getNumOperands()==GEPRHS->getNumOperands(); + IndicesTheSame &= GEPLHS->getOperand(0)->getType() == + GEPRHS->getOperand(0)->getType(); + if (IndicesTheSame) + for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i) + if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) { + IndicesTheSame = false; + break; + } + + // If all indices are the same, just compare the base pointers. + if (IndicesTheSame) + return new ICmpInst(ICmpInst::getSignedPredicate(Cond), + GEPLHS->getOperand(0), GEPRHS->getOperand(0)); + + // Otherwise, the base pointers are different and the indices are + // different, bail out. + return 0; + } + + // If one of the GEPs has all zero indices, recurse. + bool AllZeros = true; + for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i) + if (!isa(GEPLHS->getOperand(i)) || + !cast(GEPLHS->getOperand(i))->isNullValue()) { + AllZeros = false; + break; + } + if (AllZeros) + return FoldGEPICmp(GEPRHS, GEPLHS->getOperand(0), + ICmpInst::getSwappedPredicate(Cond), I); + + // If the other GEP has all zero indices, recurse. + AllZeros = true; + for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i) + if (!isa(GEPRHS->getOperand(i)) || + !cast(GEPRHS->getOperand(i))->isNullValue()) { + AllZeros = false; + break; + } + if (AllZeros) + return FoldGEPICmp(GEPLHS, GEPRHS->getOperand(0), Cond, I); + + if (GEPLHS->getNumOperands() == GEPRHS->getNumOperands()) { + // If the GEPs only differ by one index, compare it. + unsigned NumDifferences = 0; // Keep track of # differences. + unsigned DiffOperand = 0; // The operand that differs. + for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i) + if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) { + if (GEPLHS->getOperand(i)->getType()->getPrimitiveSizeInBits() != + GEPRHS->getOperand(i)->getType()->getPrimitiveSizeInBits()) { + // Irreconcilable differences. + NumDifferences = 2; + break; + } else { + if (NumDifferences++) break; + DiffOperand = i; + } + } + + if (NumDifferences == 0) // SAME GEP? + return ReplaceInstUsesWith(I, // No comparison is needed here. + ConstantInt::get(Type::getInt1Ty(I.getContext()), + ICmpInst::isTrueWhenEqual(Cond))); + + else if (NumDifferences == 1) { + Value *LHSV = GEPLHS->getOperand(DiffOperand); + Value *RHSV = GEPRHS->getOperand(DiffOperand); + // Make sure we do a signed comparison here. + return new ICmpInst(ICmpInst::getSignedPredicate(Cond), LHSV, RHSV); + } + } + + // Only lower this if the icmp is the only user of the GEP or if we expect + // the result to fold to a constant! + if (TD && + (isa(GEPLHS) || GEPLHS->hasOneUse()) && + (isa(GEPRHS) || GEPRHS->hasOneUse())) { + // ((gep Ptr, OFFSET1) cmp (gep Ptr, OFFSET2) ---> (OFFSET1 cmp OFFSET2) + Value *L = EmitGEPOffset(GEPLHS); + Value *R = EmitGEPOffset(GEPRHS); + return new ICmpInst(ICmpInst::getSignedPredicate(Cond), L, R); + } + } + return 0; +} + +/// FoldICmpAddOpCst - Fold "icmp pred (X+CI), X". +Instruction *InstCombiner::FoldICmpAddOpCst(ICmpInst &ICI, + Value *X, ConstantInt *CI, + ICmpInst::Predicate Pred, + Value *TheAdd) { + // If we have X+0, exit early (simplifying logic below) and let it get folded + // elsewhere. icmp X+0, X -> icmp X, X + if (CI->isZero()) { + bool isTrue = ICmpInst::isTrueWhenEqual(Pred); + return ReplaceInstUsesWith(ICI, ConstantInt::get(ICI.getType(), isTrue)); + } + + // (X+4) == X -> false. + if (Pred == ICmpInst::ICMP_EQ) + return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(X->getContext())); + + // (X+4) != X -> true. + if (Pred == ICmpInst::ICMP_NE) + return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(X->getContext())); + + // If this is an instruction (as opposed to constantexpr) get NUW/NSW info. + bool isNUW = false, isNSW = false; + if (BinaryOperator *Add = dyn_cast(TheAdd)) { + isNUW = Add->hasNoUnsignedWrap(); + isNSW = Add->hasNoSignedWrap(); + } + + // From this point on, we know that (X+C <= X) --> (X+C < X) because C != 0, + // so the values can never be equal. Similiarly for all other "or equals" + // operators. + + // (X+1) X >u (MAXUINT-1) --> X != 255 + // (X+2) X >u (MAXUINT-2) --> X > 253 + // (X+MAXUINT) X >u (MAXUINT-MAXUINT) --> X != 0 + if (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_ULE) { + // If this is an NUW add, then this is always false. + if (isNUW) + return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(X->getContext())); + + Value *R = ConstantExpr::getSub(ConstantInt::get(CI->getType(), -1ULL), CI); + return new ICmpInst(ICmpInst::ICMP_UGT, X, R); + } + + // (X+1) >u X --> X X != 255 + // (X+2) >u X --> X X u X --> X X X == 0 + if (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_UGE) { + // If this is an NUW add, then this is always true. + if (isNUW) + return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(X->getContext())); + return new ICmpInst(ICmpInst::ICMP_ULT, X, ConstantExpr::getNeg(CI)); + } + + unsigned BitWidth = CI->getType()->getPrimitiveSizeInBits(); + ConstantInt *SMax = ConstantInt::get(X->getContext(), + APInt::getSignedMaxValue(BitWidth)); + + // (X+ 1) X >s (MAXSINT-1) --> X == 127 + // (X+ 2) X >s (MAXSINT-2) --> X >s 125 + // (X+MAXSINT) X >s (MAXSINT-MAXSINT) --> X >s 0 + // (X+MINSINT) X >s (MAXSINT-MINSINT) --> X >s -1 + // (X+ -2) X >s (MAXSINT- -2) --> X >s 126 + // (X+ -1) X >s (MAXSINT- -1) --> X != 127 + if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SLE) { + // If this is an NSW add, then we have two cases: if the constant is + // positive, then this is always false, if negative, this is always true. + if (isNSW) { + bool isTrue = CI->getValue().isNegative(); + return ReplaceInstUsesWith(ICI, ConstantInt::get(ICI.getType(), isTrue)); + } + + return new ICmpInst(ICmpInst::ICMP_SGT, X, ConstantExpr::getSub(SMax, CI)); + } + + // (X+ 1) >s X --> X X != 127 + // (X+ 2) >s X --> X X s X --> X X s X --> X X s X --> X X s X --> X X == -128 + + // If this is an NSW add, then we have two cases: if the constant is + // positive, then this is always true, if negative, this is always false. + if (isNSW) { + bool isTrue = !CI->getValue().isNegative(); + return ReplaceInstUsesWith(ICI, ConstantInt::get(ICI.getType(), isTrue)); + } + + assert(Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SGE); + Constant *C = ConstantInt::get(X->getContext(), CI->getValue()-1); + return new ICmpInst(ICmpInst::ICMP_SLT, X, ConstantExpr::getSub(SMax, C)); +} + +/// FoldICmpDivCst - Fold "icmp pred, ([su]div X, DivRHS), CmpRHS" where DivRHS +/// and CmpRHS are both known to be integer constants. +Instruction *InstCombiner::FoldICmpDivCst(ICmpInst &ICI, BinaryOperator *DivI, + ConstantInt *DivRHS) { + ConstantInt *CmpRHS = cast(ICI.getOperand(1)); + const APInt &CmpRHSV = CmpRHS->getValue(); + + // FIXME: If the operand types don't match the type of the divide + // then don't attempt this transform. The code below doesn't have the + // logic to deal with a signed divide and an unsigned compare (and + // vice versa). This is because (x /s C1) getOpcode() == Instruction::SDiv; + if (!ICI.isEquality() && DivIsSigned != ICI.isSigned()) + return 0; + if (DivRHS->isZero()) + return 0; // The ProdOV computation fails on divide by zero. + if (DivIsSigned && DivRHS->isAllOnesValue()) + return 0; // The overflow computation also screws up here + if (DivRHS->isOne()) + return 0; // Not worth bothering, and eliminates some funny cases + // with INT_MIN. + + // Compute Prod = CI * DivRHS. We are essentially solving an equation + // of form X/C1=C2. We solve for X by multiplying C1 (DivRHS) and + // C2 (CI). By solving for X we can turn this into a range check + // instead of computing a divide. + Constant *Prod = ConstantExpr::getMul(CmpRHS, DivRHS); + + // Determine if the product overflows by seeing if the product is + // not equal to the divide. Make sure we do the same kind of divide + // as in the LHS instruction that we're folding. + bool ProdOV = (DivIsSigned ? ConstantExpr::getSDiv(Prod, DivRHS) : + ConstantExpr::getUDiv(Prod, DivRHS)) != CmpRHS; + + // Get the ICmp opcode + ICmpInst::Predicate Pred = ICI.getPredicate(); + + // Figure out the interval that is being checked. For example, a comparison + // like "X /u 5 == 0" is really checking that X is in the interval [0, 5). + // Compute this interval based on the constants involved and the signedness of + // the compare/divide. This computes a half-open interval, keeping track of + // whether either value in the interval overflows. After analysis each + // overflow variable is set to 0 if it's corresponding bound variable is valid + // -1 if overflowed off the bottom end, or +1 if overflowed off the top end. + int LoOverflow = 0, HiOverflow = 0; + Constant *LoBound = 0, *HiBound = 0; + + if (!DivIsSigned) { // udiv + // e.g. X/5 op 3 --> [15, 20) + LoBound = Prod; + HiOverflow = LoOverflow = ProdOV; + if (!HiOverflow) + HiOverflow = AddWithOverflow(HiBound, LoBound, DivRHS, false); + } else if (DivRHS->getValue().isStrictlyPositive()) { // Divisor is > 0. + if (CmpRHSV == 0) { // (X / pos) op 0 + // Can't overflow. e.g. X/2 op 0 --> [-1, 2) + LoBound = cast(ConstantExpr::getNeg(SubOne(DivRHS))); + HiBound = DivRHS; + } else if (CmpRHSV.isStrictlyPositive()) { // (X / pos) op pos + LoBound = Prod; // e.g. X/5 op 3 --> [15, 20) + HiOverflow = LoOverflow = ProdOV; + if (!HiOverflow) + HiOverflow = AddWithOverflow(HiBound, Prod, DivRHS, true); + } else { // (X / pos) op neg + // e.g. X/5 op -3 --> [-15-4, -15+1) --> [-19, -14) + HiBound = AddOne(Prod); + LoOverflow = HiOverflow = ProdOV ? -1 : 0; + if (!LoOverflow) { + ConstantInt* DivNeg = + cast(ConstantExpr::getNeg(DivRHS)); + LoOverflow = AddWithOverflow(LoBound, HiBound, DivNeg, true) ? -1 : 0; + } + } + } else if (DivRHS->getValue().isNegative()) { // Divisor is < 0. + if (CmpRHSV == 0) { // (X / neg) op 0 + // e.g. X/-5 op 0 --> [-4, 5) + LoBound = AddOne(DivRHS); + HiBound = cast(ConstantExpr::getNeg(DivRHS)); + if (HiBound == DivRHS) { // -INTMIN = INTMIN + HiOverflow = 1; // [INTMIN+1, overflow) + HiBound = 0; // e.g. X/INTMIN = 0 --> X > INTMIN + } + } else if (CmpRHSV.isStrictlyPositive()) { // (X / neg) op pos + // e.g. X/-5 op 3 --> [-19, -14) + HiBound = AddOne(Prod); + HiOverflow = LoOverflow = ProdOV ? -1 : 0; + if (!LoOverflow) + LoOverflow = AddWithOverflow(LoBound, HiBound, DivRHS, true) ? -1 : 0; + } else { // (X / neg) op neg + LoBound = Prod; // e.g. X/-5 op -3 --> [15, 20) + LoOverflow = HiOverflow = ProdOV; + if (!HiOverflow) + HiOverflow = SubWithOverflow(HiBound, Prod, DivRHS, true); + } + + // Dividing by a negative swaps the condition. LT <-> GT + Pred = ICmpInst::getSwappedPredicate(Pred); + } + + Value *X = DivI->getOperand(0); + switch (Pred) { + default: llvm_unreachable("Unhandled icmp opcode!"); + case ICmpInst::ICMP_EQ: + if (LoOverflow && HiOverflow) + return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(ICI.getContext())); + else if (HiOverflow) + return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SGE : + ICmpInst::ICMP_UGE, X, LoBound); + else if (LoOverflow) + return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SLT : + ICmpInst::ICMP_ULT, X, HiBound); + else + return InsertRangeTest(X, LoBound, HiBound, DivIsSigned, true, ICI); + case ICmpInst::ICMP_NE: + if (LoOverflow && HiOverflow) + return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(ICI.getContext())); + else if (HiOverflow) + return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SLT : + ICmpInst::ICMP_ULT, X, LoBound); + else if (LoOverflow) + return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SGE : + ICmpInst::ICMP_UGE, X, HiBound); + else + return InsertRangeTest(X, LoBound, HiBound, DivIsSigned, false, ICI); + case ICmpInst::ICMP_ULT: + case ICmpInst::ICMP_SLT: + if (LoOverflow == +1) // Low bound is greater than input range. + return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(ICI.getContext())); + if (LoOverflow == -1) // Low bound is less than input range. + return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(ICI.getContext())); + return new ICmpInst(Pred, X, LoBound); + case ICmpInst::ICMP_UGT: + case ICmpInst::ICMP_SGT: + if (HiOverflow == +1) // High bound greater than input range. + return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(ICI.getContext())); + else if (HiOverflow == -1) // High bound less than input range. + return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(ICI.getContext())); + if (Pred == ICmpInst::ICMP_UGT) + return new ICmpInst(ICmpInst::ICMP_UGE, X, HiBound); + else + return new ICmpInst(ICmpInst::ICMP_SGE, X, HiBound); + } +} + + +/// visitICmpInstWithInstAndIntCst - Handle "icmp (instr, intcst)". +/// +Instruction *InstCombiner::visitICmpInstWithInstAndIntCst(ICmpInst &ICI, + Instruction *LHSI, + ConstantInt *RHS) { + const APInt &RHSV = RHS->getValue(); + + switch (LHSI->getOpcode()) { + case Instruction::Trunc: + if (ICI.isEquality() && LHSI->hasOneUse()) { + // Simplify icmp eq (trunc x to i8), 42 -> icmp eq x, 42|highbits if all + // of the high bits truncated out of x are known. + unsigned DstBits = LHSI->getType()->getPrimitiveSizeInBits(), + SrcBits = LHSI->getOperand(0)->getType()->getPrimitiveSizeInBits(); + APInt Mask(APInt::getHighBitsSet(SrcBits, SrcBits-DstBits)); + APInt KnownZero(SrcBits, 0), KnownOne(SrcBits, 0); + ComputeMaskedBits(LHSI->getOperand(0), Mask, KnownZero, KnownOne); + + // If all the high bits are known, we can do this xform. + if ((KnownZero|KnownOne).countLeadingOnes() >= SrcBits-DstBits) { + // Pull in the high bits from known-ones set. + APInt NewRHS(RHS->getValue()); + NewRHS.zext(SrcBits); + NewRHS |= KnownOne; + return new ICmpInst(ICI.getPredicate(), LHSI->getOperand(0), + ConstantInt::get(ICI.getContext(), NewRHS)); + } + } + break; + + case Instruction::Xor: // (icmp pred (xor X, XorCST), CI) + if (ConstantInt *XorCST = dyn_cast(LHSI->getOperand(1))) { + // If this is a comparison that tests the signbit (X < 0) or (x > -1), + // fold the xor. + if ((ICI.getPredicate() == ICmpInst::ICMP_SLT && RHSV == 0) || + (ICI.getPredicate() == ICmpInst::ICMP_SGT && RHSV.isAllOnesValue())) { + Value *CompareVal = LHSI->getOperand(0); + + // If the sign bit of the XorCST is not set, there is no change to + // the operation, just stop using the Xor. + if (!XorCST->getValue().isNegative()) { + ICI.setOperand(0, CompareVal); + Worklist.Add(LHSI); + return &ICI; + } + + // Was the old condition true if the operand is positive? + bool isTrueIfPositive = ICI.getPredicate() == ICmpInst::ICMP_SGT; + + // If so, the new one isn't. + isTrueIfPositive ^= true; + + if (isTrueIfPositive) + return new ICmpInst(ICmpInst::ICMP_SGT, CompareVal, + SubOne(RHS)); + else + return new ICmpInst(ICmpInst::ICMP_SLT, CompareVal, + AddOne(RHS)); + } + + if (LHSI->hasOneUse()) { + // (icmp u/s (xor A SignBit), C) -> (icmp s/u A, (xor C SignBit)) + if (!ICI.isEquality() && XorCST->getValue().isSignBit()) { + const APInt &SignBit = XorCST->getValue(); + ICmpInst::Predicate Pred = ICI.isSigned() + ? ICI.getUnsignedPredicate() + : ICI.getSignedPredicate(); + return new ICmpInst(Pred, LHSI->getOperand(0), + ConstantInt::get(ICI.getContext(), + RHSV ^ SignBit)); + } + + // (icmp u/s (xor A ~SignBit), C) -> (icmp s/u (xor C ~SignBit), A) + if (!ICI.isEquality() && XorCST->getValue().isMaxSignedValue()) { + const APInt &NotSignBit = XorCST->getValue(); + ICmpInst::Predicate Pred = ICI.isSigned() + ? ICI.getUnsignedPredicate() + : ICI.getSignedPredicate(); + Pred = ICI.getSwappedPredicate(Pred); + return new ICmpInst(Pred, LHSI->getOperand(0), + ConstantInt::get(ICI.getContext(), + RHSV ^ NotSignBit)); + } + } + } + break; + case Instruction::And: // (icmp pred (and X, AndCST), RHS) + if (LHSI->hasOneUse() && isa(LHSI->getOperand(1)) && + LHSI->getOperand(0)->hasOneUse()) { + ConstantInt *AndCST = cast(LHSI->getOperand(1)); + + // If the LHS is an AND of a truncating cast, we can widen the + // and/compare to be the input width without changing the value + // produced, eliminating a cast. + if (TruncInst *Cast = dyn_cast(LHSI->getOperand(0))) { + // We can do this transformation if either the AND constant does not + // have its sign bit set or if it is an equality comparison. + // Extending a relational comparison when we're checking the sign + // bit would not work. + if (Cast->hasOneUse() && + (ICI.isEquality() || + (AndCST->getValue().isNonNegative() && RHSV.isNonNegative()))) { + uint32_t BitWidth = + cast(Cast->getOperand(0)->getType())->getBitWidth(); + APInt NewCST = AndCST->getValue(); + NewCST.zext(BitWidth); + APInt NewCI = RHSV; + NewCI.zext(BitWidth); + Value *NewAnd = + Builder->CreateAnd(Cast->getOperand(0), + ConstantInt::get(ICI.getContext(), NewCST), + LHSI->getName()); + return new ICmpInst(ICI.getPredicate(), NewAnd, + ConstantInt::get(ICI.getContext(), NewCI)); + } + } + + // If this is: (X >> C1) & C2 != C3 (where any shift and any compare + // could exist), turn it into (X & (C2 << C1)) != (C3 << C1). This + // happens a LOT in code produced by the C front-end, for bitfield + // access. + BinaryOperator *Shift = dyn_cast(LHSI->getOperand(0)); + if (Shift && !Shift->isShift()) + Shift = 0; + + ConstantInt *ShAmt; + ShAmt = Shift ? dyn_cast(Shift->getOperand(1)) : 0; + const Type *Ty = Shift ? Shift->getType() : 0; // Type of the shift. + const Type *AndTy = AndCST->getType(); // Type of the and. + + // We can fold this as long as we can't shift unknown bits + // into the mask. This can only happen with signed shift + // rights, as they sign-extend. + if (ShAmt) { + bool CanFold = Shift->isLogicalShift(); + if (!CanFold) { + // To test for the bad case of the signed shr, see if any + // of the bits shifted in could be tested after the mask. + uint32_t TyBits = Ty->getPrimitiveSizeInBits(); + int ShAmtVal = TyBits - ShAmt->getLimitedValue(TyBits); + + uint32_t BitWidth = AndTy->getPrimitiveSizeInBits(); + if ((APInt::getHighBitsSet(BitWidth, BitWidth-ShAmtVal) & + AndCST->getValue()) == 0) + CanFold = true; + } + + if (CanFold) { + Constant *NewCst; + if (Shift->getOpcode() == Instruction::Shl) + NewCst = ConstantExpr::getLShr(RHS, ShAmt); + else + NewCst = ConstantExpr::getShl(RHS, ShAmt); + + // Check to see if we are shifting out any of the bits being + // compared. + if (ConstantExpr::get(Shift->getOpcode(), + NewCst, ShAmt) != RHS) { + // If we shifted bits out, the fold is not going to work out. + // As a special case, check to see if this means that the + // result is always true or false now. + if (ICI.getPredicate() == ICmpInst::ICMP_EQ) + return ReplaceInstUsesWith(ICI, + ConstantInt::getFalse(ICI.getContext())); + if (ICI.getPredicate() == ICmpInst::ICMP_NE) + return ReplaceInstUsesWith(ICI, + ConstantInt::getTrue(ICI.getContext())); + } else { + ICI.setOperand(1, NewCst); + Constant *NewAndCST; + if (Shift->getOpcode() == Instruction::Shl) + NewAndCST = ConstantExpr::getLShr(AndCST, ShAmt); + else + NewAndCST = ConstantExpr::getShl(AndCST, ShAmt); + LHSI->setOperand(1, NewAndCST); + LHSI->setOperand(0, Shift->getOperand(0)); + Worklist.Add(Shift); // Shift is dead. + return &ICI; + } + } + } + + // Turn ((X >> Y) & C) == 0 into (X & (C << Y)) == 0. The later is + // preferable because it allows the C<hasOneUse() && RHSV == 0 && + ICI.isEquality() && !Shift->isArithmeticShift() && + !isa(Shift->getOperand(0))) { + // Compute C << Y. + Value *NS; + if (Shift->getOpcode() == Instruction::LShr) { + NS = Builder->CreateShl(AndCST, Shift->getOperand(1), "tmp"); + } else { + // Insert a logical shift. + NS = Builder->CreateLShr(AndCST, Shift->getOperand(1), "tmp"); + } + + // Compute X & (C << Y). + Value *NewAnd = + Builder->CreateAnd(Shift->getOperand(0), NS, LHSI->getName()); + + ICI.setOperand(0, NewAnd); + return &ICI; + } + } + + // Try to optimize things like "A[i]&42 == 0" to index computations. + if (LoadInst *LI = dyn_cast(LHSI->getOperand(0))) { + if (GetElementPtrInst *GEP = + dyn_cast(LI->getOperand(0))) + if (GlobalVariable *GV = dyn_cast(GEP->getOperand(0))) + if (GV->isConstant() && GV->hasDefinitiveInitializer() && + !LI->isVolatile() && isa(LHSI->getOperand(1))) { + ConstantInt *C = cast(LHSI->getOperand(1)); + if (Instruction *Res = FoldCmpLoadFromIndexedGlobal(GEP, GV,ICI, C)) + return Res; + } + } + break; + + case Instruction::Or: { + if (!ICI.isEquality() || !RHS->isNullValue() || !LHSI->hasOneUse()) + break; + Value *P, *Q; + if (match(LHSI, m_Or(m_PtrToInt(m_Value(P)), m_PtrToInt(m_Value(Q))))) { + // Simplify icmp eq (or (ptrtoint P), (ptrtoint Q)), 0 + // -> and (icmp eq P, null), (icmp eq Q, null). + + Value *ICIP = Builder->CreateICmp(ICI.getPredicate(), P, + Constant::getNullValue(P->getType())); + Value *ICIQ = Builder->CreateICmp(ICI.getPredicate(), Q, + Constant::getNullValue(Q->getType())); + Instruction *Op; + if (ICI.getPredicate() == ICmpInst::ICMP_EQ) + Op = BinaryOperator::CreateAnd(ICIP, ICIQ); + else + Op = BinaryOperator::CreateOr(ICIP, ICIQ); + return Op; + } + break; + } + + case Instruction::Shl: { // (icmp pred (shl X, ShAmt), CI) + ConstantInt *ShAmt = dyn_cast(LHSI->getOperand(1)); + if (!ShAmt) break; + + uint32_t TypeBits = RHSV.getBitWidth(); + + // Check that the shift amount is in range. If not, don't perform + // undefined shifts. When the shift is visited it will be + // simplified. + if (ShAmt->uge(TypeBits)) + break; + + if (ICI.isEquality()) { + // If we are comparing against bits always shifted out, the + // comparison cannot succeed. + Constant *Comp = + ConstantExpr::getShl(ConstantExpr::getLShr(RHS, ShAmt), + ShAmt); + if (Comp != RHS) {// Comparing against a bit that we know is zero. + bool IsICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE; + Constant *Cst = + ConstantInt::get(Type::getInt1Ty(ICI.getContext()), IsICMP_NE); + return ReplaceInstUsesWith(ICI, Cst); + } + + if (LHSI->hasOneUse()) { + // Otherwise strength reduce the shift into an and. + uint32_t ShAmtVal = (uint32_t)ShAmt->getLimitedValue(TypeBits); + Constant *Mask = + ConstantInt::get(ICI.getContext(), APInt::getLowBitsSet(TypeBits, + TypeBits-ShAmtVal)); + + Value *And = + Builder->CreateAnd(LHSI->getOperand(0),Mask, LHSI->getName()+".mask"); + return new ICmpInst(ICI.getPredicate(), And, + ConstantInt::get(ICI.getContext(), + RHSV.lshr(ShAmtVal))); + } + } + + // Otherwise, if this is a comparison of the sign bit, simplify to and/test. + bool TrueIfSigned = false; + if (LHSI->hasOneUse() && + isSignBitCheck(ICI.getPredicate(), RHS, TrueIfSigned)) { + // (X << 31) (X&1) != 0 + Constant *Mask = ConstantInt::get(ICI.getContext(), APInt(TypeBits, 1) << + (TypeBits-ShAmt->getZExtValue()-1)); + Value *And = + Builder->CreateAnd(LHSI->getOperand(0), Mask, LHSI->getName()+".mask"); + return new ICmpInst(TrueIfSigned ? ICmpInst::ICMP_NE : ICmpInst::ICMP_EQ, + And, Constant::getNullValue(And->getType())); + } + break; + } + + case Instruction::LShr: // (icmp pred (shr X, ShAmt), CI) + case Instruction::AShr: { + // Only handle equality comparisons of shift-by-constant. + ConstantInt *ShAmt = dyn_cast(LHSI->getOperand(1)); + if (!ShAmt || !ICI.isEquality()) break; + + // Check that the shift amount is in range. If not, don't perform + // undefined shifts. When the shift is visited it will be + // simplified. + uint32_t TypeBits = RHSV.getBitWidth(); + if (ShAmt->uge(TypeBits)) + break; + + uint32_t ShAmtVal = (uint32_t)ShAmt->getLimitedValue(TypeBits); + + // If we are comparing against bits always shifted out, the + // comparison cannot succeed. + APInt Comp = RHSV << ShAmtVal; + if (LHSI->getOpcode() == Instruction::LShr) + Comp = Comp.lshr(ShAmtVal); + else + Comp = Comp.ashr(ShAmtVal); + + if (Comp != RHSV) { // Comparing against a bit that we know is zero. + bool IsICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE; + Constant *Cst = ConstantInt::get(Type::getInt1Ty(ICI.getContext()), + IsICMP_NE); + return ReplaceInstUsesWith(ICI, Cst); + } + + // Otherwise, check to see if the bits shifted out are known to be zero. + // If so, we can compare against the unshifted value: + // (X & 4) >> 1 == 2 --> (X & 4) == 4. + if (LHSI->hasOneUse() && + MaskedValueIsZero(LHSI->getOperand(0), + APInt::getLowBitsSet(Comp.getBitWidth(), ShAmtVal))) { + return new ICmpInst(ICI.getPredicate(), LHSI->getOperand(0), + ConstantExpr::getShl(RHS, ShAmt)); + } + + if (LHSI->hasOneUse()) { + // Otherwise strength reduce the shift into an and. + APInt Val(APInt::getHighBitsSet(TypeBits, TypeBits - ShAmtVal)); + Constant *Mask = ConstantInt::get(ICI.getContext(), Val); + + Value *And = Builder->CreateAnd(LHSI->getOperand(0), + Mask, LHSI->getName()+".mask"); + return new ICmpInst(ICI.getPredicate(), And, + ConstantExpr::getShl(RHS, ShAmt)); + } + break; + } + + case Instruction::SDiv: + case Instruction::UDiv: + // Fold: icmp pred ([us]div X, C1), C2 -> range test + // Fold this div into the comparison, producing a range check. + // Determine, based on the divide type, what the range is being + // checked. If there is an overflow on the low or high side, remember + // it, otherwise compute the range [low, hi) bounding the new value. + // See: InsertRangeTest above for the kinds of replacements possible. + if (ConstantInt *DivRHS = dyn_cast(LHSI->getOperand(1))) + if (Instruction *R = FoldICmpDivCst(ICI, cast(LHSI), + DivRHS)) + return R; + break; + + case Instruction::Add: + // Fold: icmp pred (add X, C1), C2 + if (!ICI.isEquality()) { + ConstantInt *LHSC = dyn_cast(LHSI->getOperand(1)); + if (!LHSC) break; + const APInt &LHSV = LHSC->getValue(); + + ConstantRange CR = ICI.makeConstantRange(ICI.getPredicate(), RHSV) + .subtract(LHSV); + + if (ICI.isSigned()) { + if (CR.getLower().isSignBit()) { + return new ICmpInst(ICmpInst::ICMP_SLT, LHSI->getOperand(0), + ConstantInt::get(ICI.getContext(),CR.getUpper())); + } else if (CR.getUpper().isSignBit()) { + return new ICmpInst(ICmpInst::ICMP_SGE, LHSI->getOperand(0), + ConstantInt::get(ICI.getContext(),CR.getLower())); + } + } else { + if (CR.getLower().isMinValue()) { + return new ICmpInst(ICmpInst::ICMP_ULT, LHSI->getOperand(0), + ConstantInt::get(ICI.getContext(),CR.getUpper())); + } else if (CR.getUpper().isMinValue()) { + return new ICmpInst(ICmpInst::ICMP_UGE, LHSI->getOperand(0), + ConstantInt::get(ICI.getContext(),CR.getLower())); + } + } + } + break; + } + + // Simplify icmp_eq and icmp_ne instructions with integer constant RHS. + if (ICI.isEquality()) { + bool isICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE; + + // If the first operand is (add|sub|and|or|xor|rem) with a constant, and + // the second operand is a constant, simplify a bit. + if (BinaryOperator *BO = dyn_cast(LHSI)) { + switch (BO->getOpcode()) { + case Instruction::SRem: + // If we have a signed (X % (2^c)) == 0, turn it into an unsigned one. + if (RHSV == 0 && isa(BO->getOperand(1)) &&BO->hasOneUse()){ + const APInt &V = cast(BO->getOperand(1))->getValue(); + if (V.sgt(APInt(V.getBitWidth(), 1)) && V.isPowerOf2()) { + Value *NewRem = + Builder->CreateURem(BO->getOperand(0), BO->getOperand(1), + BO->getName()); + return new ICmpInst(ICI.getPredicate(), NewRem, + Constant::getNullValue(BO->getType())); + } + } + break; + case Instruction::Add: + // Replace ((add A, B) != C) with (A != C-B) if B & C are constants. + if (ConstantInt *BOp1C = dyn_cast(BO->getOperand(1))) { + if (BO->hasOneUse()) + return new ICmpInst(ICI.getPredicate(), BO->getOperand(0), + ConstantExpr::getSub(RHS, BOp1C)); + } else if (RHSV == 0) { + // Replace ((add A, B) != 0) with (A != -B) if A or B is + // efficiently invertible, or if the add has just this one use. + Value *BOp0 = BO->getOperand(0), *BOp1 = BO->getOperand(1); + + if (Value *NegVal = dyn_castNegVal(BOp1)) + return new ICmpInst(ICI.getPredicate(), BOp0, NegVal); + else if (Value *NegVal = dyn_castNegVal(BOp0)) + return new ICmpInst(ICI.getPredicate(), NegVal, BOp1); + else if (BO->hasOneUse()) { + Value *Neg = Builder->CreateNeg(BOp1); + Neg->takeName(BO); + return new ICmpInst(ICI.getPredicate(), BOp0, Neg); + } + } + break; + case Instruction::Xor: + // For the xor case, we can xor two constants together, eliminating + // the explicit xor. + if (Constant *BOC = dyn_cast(BO->getOperand(1))) + return new ICmpInst(ICI.getPredicate(), BO->getOperand(0), + ConstantExpr::getXor(RHS, BOC)); + + // FALLTHROUGH + case Instruction::Sub: + // Replace (([sub|xor] A, B) != 0) with (A != B) + if (RHSV == 0) + return new ICmpInst(ICI.getPredicate(), BO->getOperand(0), + BO->getOperand(1)); + break; + + case Instruction::Or: + // If bits are being or'd in that are not present in the constant we + // are comparing against, then the comparison could never succeed! + if (Constant *BOC = dyn_cast(BO->getOperand(1))) { + Constant *NotCI = ConstantExpr::getNot(RHS); + if (!ConstantExpr::getAnd(BOC, NotCI)->isNullValue()) + return ReplaceInstUsesWith(ICI, + ConstantInt::get(Type::getInt1Ty(ICI.getContext()), + isICMP_NE)); + } + break; + + case Instruction::And: + if (ConstantInt *BOC = dyn_cast(BO->getOperand(1))) { + // If bits are being compared against that are and'd out, then the + // comparison can never succeed! + if ((RHSV & ~BOC->getValue()) != 0) + return ReplaceInstUsesWith(ICI, + ConstantInt::get(Type::getInt1Ty(ICI.getContext()), + isICMP_NE)); + + // If we have ((X & C) == C), turn it into ((X & C) != 0). + if (RHS == BOC && RHSV.isPowerOf2()) + return new ICmpInst(isICMP_NE ? ICmpInst::ICMP_EQ : + ICmpInst::ICMP_NE, LHSI, + Constant::getNullValue(RHS->getType())); + + // Replace (and X, (1 << size(X)-1) != 0) with x s< 0 + if (BOC->getValue().isSignBit()) { + Value *X = BO->getOperand(0); + Constant *Zero = Constant::getNullValue(X->getType()); + ICmpInst::Predicate pred = isICMP_NE ? + ICmpInst::ICMP_SLT : ICmpInst::ICMP_SGE; + return new ICmpInst(pred, X, Zero); + } + + // ((X & ~7) == 0) --> X < 8 + if (RHSV == 0 && isHighOnes(BOC)) { + Value *X = BO->getOperand(0); + Constant *NegX = ConstantExpr::getNeg(BOC); + ICmpInst::Predicate pred = isICMP_NE ? + ICmpInst::ICMP_UGE : ICmpInst::ICMP_ULT; + return new ICmpInst(pred, X, NegX); + } + } + default: break; + } + } else if (IntrinsicInst *II = dyn_cast(LHSI)) { + // Handle icmp {eq|ne} , intcst. + if (II->getIntrinsicID() == Intrinsic::bswap) { + Worklist.Add(II); + ICI.setOperand(0, II->getOperand(1)); + ICI.setOperand(1, ConstantInt::get(II->getContext(), RHSV.byteSwap())); + return &ICI; + } + } + } + return 0; +} + +/// visitICmpInstWithCastAndCast - Handle icmp (cast x to y), (cast/cst). +/// We only handle extending casts so far. +/// +Instruction *InstCombiner::visitICmpInstWithCastAndCast(ICmpInst &ICI) { + const CastInst *LHSCI = cast(ICI.getOperand(0)); + Value *LHSCIOp = LHSCI->getOperand(0); + const Type *SrcTy = LHSCIOp->getType(); + const Type *DestTy = LHSCI->getType(); + Value *RHSCIOp; + + // Turn icmp (ptrtoint x), (ptrtoint/c) into a compare of the input if the + // integer type is the same size as the pointer type. + if (TD && LHSCI->getOpcode() == Instruction::PtrToInt && + TD->getPointerSizeInBits() == + cast(DestTy)->getBitWidth()) { + Value *RHSOp = 0; + if (Constant *RHSC = dyn_cast(ICI.getOperand(1))) { + RHSOp = ConstantExpr::getIntToPtr(RHSC, SrcTy); + } else if (PtrToIntInst *RHSC = dyn_cast(ICI.getOperand(1))) { + RHSOp = RHSC->getOperand(0); + // If the pointer types don't match, insert a bitcast. + if (LHSCIOp->getType() != RHSOp->getType()) + RHSOp = Builder->CreateBitCast(RHSOp, LHSCIOp->getType()); + } + + if (RHSOp) + return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSOp); + } + + // The code below only handles extension cast instructions, so far. + // Enforce this. + if (LHSCI->getOpcode() != Instruction::ZExt && + LHSCI->getOpcode() != Instruction::SExt) + return 0; + + bool isSignedExt = LHSCI->getOpcode() == Instruction::SExt; + bool isSignedCmp = ICI.isSigned(); + + if (CastInst *CI = dyn_cast(ICI.getOperand(1))) { + // Not an extension from the same type? + RHSCIOp = CI->getOperand(0); + if (RHSCIOp->getType() != LHSCIOp->getType()) + return 0; + + // If the signedness of the two casts doesn't agree (i.e. one is a sext + // and the other is a zext), then we can't handle this. + if (CI->getOpcode() != LHSCI->getOpcode()) + return 0; + + // Deal with equality cases early. + if (ICI.isEquality()) + return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSCIOp); + + // A signed comparison of sign extended values simplifies into a + // signed comparison. + if (isSignedCmp && isSignedExt) + return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSCIOp); + + // The other three cases all fold into an unsigned comparison. + return new ICmpInst(ICI.getUnsignedPredicate(), LHSCIOp, RHSCIOp); + } + + // If we aren't dealing with a constant on the RHS, exit early + ConstantInt *CI = dyn_cast(ICI.getOperand(1)); + if (!CI) + return 0; + + // Compute the constant that would happen if we truncated to SrcTy then + // reextended to DestTy. + Constant *Res1 = ConstantExpr::getTrunc(CI, SrcTy); + Constant *Res2 = ConstantExpr::getCast(LHSCI->getOpcode(), + Res1, DestTy); + + // If the re-extended constant didn't change... + if (Res2 == CI) { + // Deal with equality cases early. + if (ICI.isEquality()) + return new ICmpInst(ICI.getPredicate(), LHSCIOp, Res1); + + // A signed comparison of sign extended values simplifies into a + // signed comparison. + if (isSignedExt && isSignedCmp) + return new ICmpInst(ICI.getPredicate(), LHSCIOp, Res1); + + // The other three cases all fold into an unsigned comparison. + return new ICmpInst(ICI.getUnsignedPredicate(), LHSCIOp, Res1); + } + + // The re-extended constant changed so the constant cannot be represented + // in the shorter type. Consequently, we cannot emit a simple comparison. + + // First, handle some easy cases. We know the result cannot be equal at this + // point so handle the ICI.isEquality() cases + if (ICI.getPredicate() == ICmpInst::ICMP_EQ) + return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(ICI.getContext())); + if (ICI.getPredicate() == ICmpInst::ICMP_NE) + return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(ICI.getContext())); + + // Evaluate the comparison for LT (we invert for GT below). LE and GE cases + // should have been folded away previously and not enter in here. + Value *Result; + if (isSignedCmp) { + // We're performing a signed comparison. + if (cast(CI)->getValue().isNegative()) + Result = ConstantInt::getFalse(ICI.getContext()); // X < (small) --> false + else + Result = ConstantInt::getTrue(ICI.getContext()); // X < (large) --> true + } else { + // We're performing an unsigned comparison. + if (isSignedExt) { + // We're performing an unsigned comp with a sign extended value. + // This is true if the input is >= 0. [aka >s -1] + Constant *NegOne = Constant::getAllOnesValue(SrcTy); + Result = Builder->CreateICmpSGT(LHSCIOp, NegOne, ICI.getName()); + } else { + // Unsigned extend & unsigned compare -> always true. + Result = ConstantInt::getTrue(ICI.getContext()); + } + } + + // Finally, return the value computed. + if (ICI.getPredicate() == ICmpInst::ICMP_ULT || + ICI.getPredicate() == ICmpInst::ICMP_SLT) + return ReplaceInstUsesWith(ICI, Result); + + assert((ICI.getPredicate()==ICmpInst::ICMP_UGT || + ICI.getPredicate()==ICmpInst::ICMP_SGT) && + "ICmp should be folded!"); + if (Constant *CI = dyn_cast(Result)) + return ReplaceInstUsesWith(ICI, ConstantExpr::getNot(CI)); + return BinaryOperator::CreateNot(Result); +} + + + +Instruction *InstCombiner::visitICmpInst(ICmpInst &I) { + bool Changed = false; + + /// Orders the operands of the compare so that they are listed from most + /// complex to least complex. This puts constants before unary operators, + /// before binary operators. + if (getComplexity(I.getOperand(0)) < getComplexity(I.getOperand(1))) { + I.swapOperands(); + Changed = true; + } + + Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); + + if (Value *V = SimplifyICmpInst(I.getPredicate(), Op0, Op1, TD)) + return ReplaceInstUsesWith(I, V); + + const Type *Ty = Op0->getType(); + + // icmp's with boolean values can always be turned into bitwise operations + if (Ty == Type::getInt1Ty(I.getContext())) { + switch (I.getPredicate()) { + default: llvm_unreachable("Invalid icmp instruction!"); + case ICmpInst::ICMP_EQ: { // icmp eq i1 A, B -> ~(A^B) + Value *Xor = Builder->CreateXor(Op0, Op1, I.getName()+"tmp"); + return BinaryOperator::CreateNot(Xor); + } + case ICmpInst::ICMP_NE: // icmp eq i1 A, B -> A^B + return BinaryOperator::CreateXor(Op0, Op1); + + case ICmpInst::ICMP_UGT: + std::swap(Op0, Op1); // Change icmp ugt -> icmp ult + // FALL THROUGH + case ICmpInst::ICMP_ULT:{ // icmp ult i1 A, B -> ~A & B + Value *Not = Builder->CreateNot(Op0, I.getName()+"tmp"); + return BinaryOperator::CreateAnd(Not, Op1); + } + case ICmpInst::ICMP_SGT: + std::swap(Op0, Op1); // Change icmp sgt -> icmp slt + // FALL THROUGH + case ICmpInst::ICMP_SLT: { // icmp slt i1 A, B -> A & ~B + Value *Not = Builder->CreateNot(Op1, I.getName()+"tmp"); + return BinaryOperator::CreateAnd(Not, Op0); + } + case ICmpInst::ICMP_UGE: + std::swap(Op0, Op1); // Change icmp uge -> icmp ule + // FALL THROUGH + case ICmpInst::ICMP_ULE: { // icmp ule i1 A, B -> ~A | B + Value *Not = Builder->CreateNot(Op0, I.getName()+"tmp"); + return BinaryOperator::CreateOr(Not, Op1); + } + case ICmpInst::ICMP_SGE: + std::swap(Op0, Op1); // Change icmp sge -> icmp sle + // FALL THROUGH + case ICmpInst::ICMP_SLE: { // icmp sle i1 A, B -> A | ~B + Value *Not = Builder->CreateNot(Op1, I.getName()+"tmp"); + return BinaryOperator::CreateOr(Not, Op0); + } + } + } + + unsigned BitWidth = 0; + if (TD) + BitWidth = TD->getTypeSizeInBits(Ty->getScalarType()); + else if (Ty->isIntOrIntVector()) + BitWidth = Ty->getScalarSizeInBits(); + + bool isSignBit = false; + + // See if we are doing a comparison with a constant. + if (ConstantInt *CI = dyn_cast(Op1)) { + Value *A = 0, *B = 0; + + // (icmp ne/eq (sub A B) 0) -> (icmp ne/eq A, B) + if (I.isEquality() && CI->isZero() && + match(Op0, m_Sub(m_Value(A), m_Value(B)))) { + // (icmp cond A B) if cond is equality + return new ICmpInst(I.getPredicate(), A, B); + } + + // If we have an icmp le or icmp ge instruction, turn it into the + // appropriate icmp lt or icmp gt instruction. This allows us to rely on + // them being folded in the code below. The SimplifyICmpInst code has + // already handled the edge cases for us, so we just assert on them. + switch (I.getPredicate()) { + default: break; + case ICmpInst::ICMP_ULE: + assert(!CI->isMaxValue(false)); // A <=u MAX -> TRUE + return new ICmpInst(ICmpInst::ICMP_ULT, Op0, + ConstantInt::get(CI->getContext(), CI->getValue()+1)); + case ICmpInst::ICMP_SLE: + assert(!CI->isMaxValue(true)); // A <=s MAX -> TRUE + return new ICmpInst(ICmpInst::ICMP_SLT, Op0, + ConstantInt::get(CI->getContext(), CI->getValue()+1)); + case ICmpInst::ICMP_UGE: + assert(!CI->isMinValue(false)); // A >=u MIN -> TRUE + return new ICmpInst(ICmpInst::ICMP_UGT, Op0, + ConstantInt::get(CI->getContext(), CI->getValue()-1)); + case ICmpInst::ICMP_SGE: + assert(!CI->isMinValue(true)); // A >=s MIN -> TRUE + return new ICmpInst(ICmpInst::ICMP_SGT, Op0, + ConstantInt::get(CI->getContext(), CI->getValue()-1)); + } + + // If this comparison is a normal comparison, it demands all + // bits, if it is a sign bit comparison, it only demands the sign bit. + bool UnusedBit; + isSignBit = isSignBitCheck(I.getPredicate(), CI, UnusedBit); + } + + // See if we can fold the comparison based on range information we can get + // by checking whether bits are known to be zero or one in the input. + if (BitWidth != 0) { + APInt Op0KnownZero(BitWidth, 0), Op0KnownOne(BitWidth, 0); + APInt Op1KnownZero(BitWidth, 0), Op1KnownOne(BitWidth, 0); + + if (SimplifyDemandedBits(I.getOperandUse(0), + isSignBit ? APInt::getSignBit(BitWidth) + : APInt::getAllOnesValue(BitWidth), + Op0KnownZero, Op0KnownOne, 0)) + return &I; + if (SimplifyDemandedBits(I.getOperandUse(1), + APInt::getAllOnesValue(BitWidth), + Op1KnownZero, Op1KnownOne, 0)) + return &I; + + // Given the known and unknown bits, compute a range that the LHS could be + // in. Compute the Min, Max and RHS values based on the known bits. For the + // EQ and NE we use unsigned values. + APInt Op0Min(BitWidth, 0), Op0Max(BitWidth, 0); + APInt Op1Min(BitWidth, 0), Op1Max(BitWidth, 0); + if (I.isSigned()) { + ComputeSignedMinMaxValuesFromKnownBits(Op0KnownZero, Op0KnownOne, + Op0Min, Op0Max); + ComputeSignedMinMaxValuesFromKnownBits(Op1KnownZero, Op1KnownOne, + Op1Min, Op1Max); + } else { + ComputeUnsignedMinMaxValuesFromKnownBits(Op0KnownZero, Op0KnownOne, + Op0Min, Op0Max); + ComputeUnsignedMinMaxValuesFromKnownBits(Op1KnownZero, Op1KnownOne, + Op1Min, Op1Max); + } + + // If Min and Max are known to be the same, then SimplifyDemandedBits + // figured out that the LHS is a constant. Just constant fold this now so + // that code below can assume that Min != Max. + if (!isa(Op0) && Op0Min == Op0Max) + return new ICmpInst(I.getPredicate(), + ConstantInt::get(I.getContext(), Op0Min), Op1); + if (!isa(Op1) && Op1Min == Op1Max) + return new ICmpInst(I.getPredicate(), Op0, + ConstantInt::get(I.getContext(), Op1Min)); + + // Based on the range information we know about the LHS, see if we can + // simplify this comparison. For example, (x&4) < 8 is always true. + switch (I.getPredicate()) { + default: llvm_unreachable("Unknown icmp opcode!"); + case ICmpInst::ICMP_EQ: + if (Op0Max.ult(Op1Min) || Op0Min.ugt(Op1Max)) + return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext())); + break; + case ICmpInst::ICMP_NE: + if (Op0Max.ult(Op1Min) || Op0Min.ugt(Op1Max)) + return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext())); + break; + case ICmpInst::ICMP_ULT: + if (Op0Max.ult(Op1Min)) // A true if max(A) < min(B) + return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext())); + if (Op0Min.uge(Op1Max)) // A false if min(A) >= max(B) + return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext())); + if (Op1Min == Op0Max) // A A != B if max(A) == min(B) + return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1); + if (ConstantInt *CI = dyn_cast(Op1)) { + if (Op1Max == Op0Min+1) // A A == C-1 if min(A)+1 == C + return new ICmpInst(ICmpInst::ICMP_EQ, Op0, + ConstantInt::get(CI->getContext(), CI->getValue()-1)); + + // (x (x >s -1) -> true if sign bit clear + if (CI->isMinValue(true)) + return new ICmpInst(ICmpInst::ICMP_SGT, Op0, + Constant::getAllOnesValue(Op0->getType())); + } + break; + case ICmpInst::ICMP_UGT: + if (Op0Min.ugt(Op1Max)) // A >u B -> true if min(A) > max(B) + return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext())); + if (Op0Max.ule(Op1Min)) // A >u B -> false if max(A) <= max(B) + return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext())); + + if (Op1Max == Op0Min) // A >u B -> A != B if min(A) == max(B) + return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1); + if (ConstantInt *CI = dyn_cast(Op1)) { + if (Op1Min == Op0Max-1) // A >u C -> A == C+1 if max(a)-1 == C + return new ICmpInst(ICmpInst::ICMP_EQ, Op0, + ConstantInt::get(CI->getContext(), CI->getValue()+1)); + + // (x >u 2147483647) -> (x true if sign bit set + if (CI->isMaxValue(true)) + return new ICmpInst(ICmpInst::ICMP_SLT, Op0, + Constant::getNullValue(Op0->getType())); + } + break; + case ICmpInst::ICMP_SLT: + if (Op0Max.slt(Op1Min)) // A true if max(A) < min(C) + return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext())); + if (Op0Min.sge(Op1Max)) // A false if min(A) >= max(C) + return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext())); + if (Op1Min == Op0Max) // A A != B if max(A) == min(B) + return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1); + if (ConstantInt *CI = dyn_cast(Op1)) { + if (Op1Max == Op0Min+1) // A A == C-1 if min(A)+1 == C + return new ICmpInst(ICmpInst::ICMP_EQ, Op0, + ConstantInt::get(CI->getContext(), CI->getValue()-1)); + } + break; + case ICmpInst::ICMP_SGT: + if (Op0Min.sgt(Op1Max)) // A >s B -> true if min(A) > max(B) + return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext())); + if (Op0Max.sle(Op1Min)) // A >s B -> false if max(A) <= min(B) + return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext())); + + if (Op1Max == Op0Min) // A >s B -> A != B if min(A) == max(B) + return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1); + if (ConstantInt *CI = dyn_cast(Op1)) { + if (Op1Min == Op0Max-1) // A >s C -> A == C+1 if max(A)-1 == C + return new ICmpInst(ICmpInst::ICMP_EQ, Op0, + ConstantInt::get(CI->getContext(), CI->getValue()+1)); + } + break; + case ICmpInst::ICMP_SGE: + assert(!isa(Op1) && "ICMP_SGE with ConstantInt not folded!"); + if (Op0Min.sge(Op1Max)) // A >=s B -> true if min(A) >= max(B) + return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext())); + if (Op0Max.slt(Op1Min)) // A >=s B -> false if max(A) < min(B) + return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext())); + break; + case ICmpInst::ICMP_SLE: + assert(!isa(Op1) && "ICMP_SLE with ConstantInt not folded!"); + if (Op0Max.sle(Op1Min)) // A <=s B -> true if max(A) <= min(B) + return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext())); + if (Op0Min.sgt(Op1Max)) // A <=s B -> false if min(A) > max(B) + return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext())); + break; + case ICmpInst::ICMP_UGE: + assert(!isa(Op1) && "ICMP_UGE with ConstantInt not folded!"); + if (Op0Min.uge(Op1Max)) // A >=u B -> true if min(A) >= max(B) + return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext())); + if (Op0Max.ult(Op1Min)) // A >=u B -> false if max(A) < min(B) + return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext())); + break; + case ICmpInst::ICMP_ULE: + assert(!isa(Op1) && "ICMP_ULE with ConstantInt not folded!"); + if (Op0Max.ule(Op1Min)) // A <=u B -> true if max(A) <= min(B) + return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext())); + if (Op0Min.ugt(Op1Max)) // A <=u B -> false if min(A) > max(B) + return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext())); + break; + } + + // Turn a signed comparison into an unsigned one if both operands + // are known to have the same sign. + if (I.isSigned() && + ((Op0KnownZero.isNegative() && Op1KnownZero.isNegative()) || + (Op0KnownOne.isNegative() && Op1KnownOne.isNegative()))) + return new ICmpInst(I.getUnsignedPredicate(), Op0, Op1); + } + + // Test if the ICmpInst instruction is used exclusively by a select as + // part of a minimum or maximum operation. If so, refrain from doing + // any other folding. This helps out other analyses which understand + // non-obfuscated minimum and maximum idioms, such as ScalarEvolution + // and CodeGen. And in this case, at least one of the comparison + // operands has at least one user besides the compare (the select), + // which would often largely negate the benefit of folding anyway. + if (I.hasOneUse()) + if (SelectInst *SI = dyn_cast(*I.use_begin())) + if ((SI->getOperand(1) == Op0 && SI->getOperand(2) == Op1) || + (SI->getOperand(2) == Op0 && SI->getOperand(1) == Op1)) + return 0; + + // See if we are doing a comparison between a constant and an instruction that + // can be folded into the comparison. + if (ConstantInt *CI = dyn_cast(Op1)) { + // Since the RHS is a ConstantInt (CI), if the left hand side is an + // instruction, see if that instruction also has constants so that the + // instruction can be folded into the icmp + if (Instruction *LHSI = dyn_cast(Op0)) + if (Instruction *Res = visitICmpInstWithInstAndIntCst(I, LHSI, CI)) + return Res; + } + + // Handle icmp with constant (but not simple integer constant) RHS + if (Constant *RHSC = dyn_cast(Op1)) { + if (Instruction *LHSI = dyn_cast(Op0)) + switch (LHSI->getOpcode()) { + case Instruction::GetElementPtr: + // icmp pred GEP (P, int 0, int 0, int 0), null -> icmp pred P, null + if (RHSC->isNullValue() && + cast(LHSI)->hasAllZeroIndices()) + return new ICmpInst(I.getPredicate(), LHSI->getOperand(0), + Constant::getNullValue(LHSI->getOperand(0)->getType())); + break; + case Instruction::PHI: + // Only fold icmp into the PHI if the phi and icmp are in the same + // block. If in the same block, we're encouraging jump threading. If + // not, we are just pessimizing the code by making an i1 phi. + if (LHSI->getParent() == I.getParent()) + if (Instruction *NV = FoldOpIntoPhi(I, true)) + return NV; + break; + case Instruction::Select: { + // If either operand of the select is a constant, we can fold the + // comparison into the select arms, which will cause one to be + // constant folded and the select turned into a bitwise or. + Value *Op1 = 0, *Op2 = 0; + if (Constant *C = dyn_cast(LHSI->getOperand(1))) + Op1 = ConstantExpr::getICmp(I.getPredicate(), C, RHSC); + if (Constant *C = dyn_cast(LHSI->getOperand(2))) + Op2 = ConstantExpr::getICmp(I.getPredicate(), C, RHSC); + + // We only want to perform this transformation if it will not lead to + // additional code. This is true if either both sides of the select + // fold to a constant (in which case the icmp is replaced with a select + // which will usually simplify) or this is the only user of the + // select (in which case we are trading a select+icmp for a simpler + // select+icmp). + if ((Op1 && Op2) || (LHSI->hasOneUse() && (Op1 || Op2))) { + if (!Op1) + Op1 = Builder->CreateICmp(I.getPredicate(), LHSI->getOperand(1), + RHSC, I.getName()); + if (!Op2) + Op2 = Builder->CreateICmp(I.getPredicate(), LHSI->getOperand(2), + RHSC, I.getName()); + return SelectInst::Create(LHSI->getOperand(0), Op1, Op2); + } + break; + } + case Instruction::Call: + // If we have (malloc != null), and if the malloc has a single use, we + // can assume it is successful and remove the malloc. + if (isMalloc(LHSI) && LHSI->hasOneUse() && + isa(RHSC)) { + // Need to explicitly erase malloc call here, instead of adding it to + // Worklist, because it won't get DCE'd from the Worklist since + // isInstructionTriviallyDead() returns false for function calls. + // It is OK to replace LHSI/MallocCall with Undef because the + // instruction that uses it will be erased via Worklist. + if (extractMallocCall(LHSI)) { + LHSI->replaceAllUsesWith(UndefValue::get(LHSI->getType())); + EraseInstFromFunction(*LHSI); + return ReplaceInstUsesWith(I, + ConstantInt::get(Type::getInt1Ty(I.getContext()), + !I.isTrueWhenEqual())); + } + if (CallInst* MallocCall = extractMallocCallFromBitCast(LHSI)) + if (MallocCall->hasOneUse()) { + MallocCall->replaceAllUsesWith( + UndefValue::get(MallocCall->getType())); + EraseInstFromFunction(*MallocCall); + Worklist.Add(LHSI); // The malloc's bitcast use. + return ReplaceInstUsesWith(I, + ConstantInt::get(Type::getInt1Ty(I.getContext()), + !I.isTrueWhenEqual())); + } + } + break; + case Instruction::IntToPtr: + // icmp pred inttoptr(X), null -> icmp pred X, 0 + if (RHSC->isNullValue() && TD && + TD->getIntPtrType(RHSC->getContext()) == + LHSI->getOperand(0)->getType()) + return new ICmpInst(I.getPredicate(), LHSI->getOperand(0), + Constant::getNullValue(LHSI->getOperand(0)->getType())); + break; + + case Instruction::Load: + // Try to optimize things like "A[i] > 4" to index computations. + if (GetElementPtrInst *GEP = + dyn_cast(LHSI->getOperand(0))) { + if (GlobalVariable *GV = dyn_cast(GEP->getOperand(0))) + if (GV->isConstant() && GV->hasDefinitiveInitializer() && + !cast(LHSI)->isVolatile()) + if (Instruction *Res = FoldCmpLoadFromIndexedGlobal(GEP, GV, I)) + return Res; + } + break; + } + } + + // If we can optimize a 'icmp GEP, P' or 'icmp P, GEP', do so now. + if (GEPOperator *GEP = dyn_cast(Op0)) + if (Instruction *NI = FoldGEPICmp(GEP, Op1, I.getPredicate(), I)) + return NI; + if (GEPOperator *GEP = dyn_cast(Op1)) + if (Instruction *NI = FoldGEPICmp(GEP, Op0, + ICmpInst::getSwappedPredicate(I.getPredicate()), I)) + return NI; + + // Test to see if the operands of the icmp are casted versions of other + // values. If the ptr->ptr cast can be stripped off both arguments, we do so + // now. + if (BitCastInst *CI = dyn_cast(Op0)) { + if (isa(Op0->getType()) && + (isa(Op1) || isa(Op1))) { + // We keep moving the cast from the left operand over to the right + // operand, where it can often be eliminated completely. + Op0 = CI->getOperand(0); + + // If operand #1 is a bitcast instruction, it must also be a ptr->ptr cast + // so eliminate it as well. + if (BitCastInst *CI2 = dyn_cast(Op1)) + Op1 = CI2->getOperand(0); + + // If Op1 is a constant, we can fold the cast into the constant. + if (Op0->getType() != Op1->getType()) { + if (Constant *Op1C = dyn_cast(Op1)) { + Op1 = ConstantExpr::getBitCast(Op1C, Op0->getType()); + } else { + // Otherwise, cast the RHS right before the icmp + Op1 = Builder->CreateBitCast(Op1, Op0->getType()); + } + } + return new ICmpInst(I.getPredicate(), Op0, Op1); + } + } + + if (isa(Op0)) { + // Handle the special case of: icmp (cast bool to X), + // This comes up when you have code like + // int X = A < B; + // if (X) ... + // For generality, we handle any zero-extension of any operand comparison + // with a constant or another cast from the same type. + if (isa(Op1) || isa(Op1)) + if (Instruction *R = visitICmpInstWithCastAndCast(I)) + return R; + } + + // See if it's the same type of instruction on the left and right. + if (BinaryOperator *Op0I = dyn_cast(Op0)) { + if (BinaryOperator *Op1I = dyn_cast(Op1)) { + if (Op0I->getOpcode() == Op1I->getOpcode() && Op0I->hasOneUse() && + Op1I->hasOneUse() && Op0I->getOperand(1) == Op1I->getOperand(1)) { + switch (Op0I->getOpcode()) { + default: break; + case Instruction::Add: + case Instruction::Sub: + case Instruction::Xor: + if (I.isEquality()) // a+x icmp eq/ne b+x --> a icmp b + return new ICmpInst(I.getPredicate(), Op0I->getOperand(0), + Op1I->getOperand(0)); + // icmp u/s (a ^ signbit), (b ^ signbit) --> icmp s/u a, b + if (ConstantInt *CI = dyn_cast(Op0I->getOperand(1))) { + if (CI->getValue().isSignBit()) { + ICmpInst::Predicate Pred = I.isSigned() + ? I.getUnsignedPredicate() + : I.getSignedPredicate(); + return new ICmpInst(Pred, Op0I->getOperand(0), + Op1I->getOperand(0)); + } + + if (CI->getValue().isMaxSignedValue()) { + ICmpInst::Predicate Pred = I.isSigned() + ? I.getUnsignedPredicate() + : I.getSignedPredicate(); + Pred = I.getSwappedPredicate(Pred); + return new ICmpInst(Pred, Op0I->getOperand(0), + Op1I->getOperand(0)); + } + } + break; + case Instruction::Mul: + if (!I.isEquality()) + break; + + if (ConstantInt *CI = dyn_cast(Op0I->getOperand(1))) { + // a * Cst icmp eq/ne b * Cst --> a & Mask icmp b & Mask + // Mask = -1 >> count-trailing-zeros(Cst). + if (!CI->isZero() && !CI->isOne()) { + const APInt &AP = CI->getValue(); + ConstantInt *Mask = ConstantInt::get(I.getContext(), + APInt::getLowBitsSet(AP.getBitWidth(), + AP.getBitWidth() - + AP.countTrailingZeros())); + Value *And1 = Builder->CreateAnd(Op0I->getOperand(0), Mask); + Value *And2 = Builder->CreateAnd(Op1I->getOperand(0), Mask); + return new ICmpInst(I.getPredicate(), And1, And2); + } + } + break; + } + } + } + } + + // ~x < ~y --> y < x + { Value *A, *B; + if (match(Op0, m_Not(m_Value(A))) && + match(Op1, m_Not(m_Value(B)))) + return new ICmpInst(I.getPredicate(), B, A); + } + + if (I.isEquality()) { + Value *A, *B, *C, *D; + + // -x == -y --> x == y + if (match(Op0, m_Neg(m_Value(A))) && + match(Op1, m_Neg(m_Value(B)))) + return new ICmpInst(I.getPredicate(), A, B); + + if (match(Op0, m_Xor(m_Value(A), m_Value(B)))) { + if (A == Op1 || B == Op1) { // (A^B) == A -> B == 0 + Value *OtherVal = A == Op1 ? B : A; + return new ICmpInst(I.getPredicate(), OtherVal, + Constant::getNullValue(A->getType())); + } + + if (match(Op1, m_Xor(m_Value(C), m_Value(D)))) { + // A^c1 == C^c2 --> A == C^(c1^c2) + ConstantInt *C1, *C2; + if (match(B, m_ConstantInt(C1)) && + match(D, m_ConstantInt(C2)) && Op1->hasOneUse()) { + Constant *NC = ConstantInt::get(I.getContext(), + C1->getValue() ^ C2->getValue()); + Value *Xor = Builder->CreateXor(C, NC, "tmp"); + return new ICmpInst(I.getPredicate(), A, Xor); + } + + // A^B == A^D -> B == D + if (A == C) return new ICmpInst(I.getPredicate(), B, D); + if (A == D) return new ICmpInst(I.getPredicate(), B, C); + if (B == C) return new ICmpInst(I.getPredicate(), A, D); + if (B == D) return new ICmpInst(I.getPredicate(), A, C); + } + } + + if (match(Op1, m_Xor(m_Value(A), m_Value(B))) && + (A == Op0 || B == Op0)) { + // A == (A^B) -> B == 0 + Value *OtherVal = A == Op0 ? B : A; + return new ICmpInst(I.getPredicate(), OtherVal, + Constant::getNullValue(A->getType())); + } + + // (A-B) == A -> B == 0 + if (match(Op0, m_Sub(m_Specific(Op1), m_Value(B)))) + return new ICmpInst(I.getPredicate(), B, + Constant::getNullValue(B->getType())); + + // A == (A-B) -> B == 0 + if (match(Op1, m_Sub(m_Specific(Op0), m_Value(B)))) + return new ICmpInst(I.getPredicate(), B, + Constant::getNullValue(B->getType())); + + // (X&Z) == (Y&Z) -> (X^Y) & Z == 0 + if (Op0->hasOneUse() && Op1->hasOneUse() && + match(Op0, m_And(m_Value(A), m_Value(B))) && + match(Op1, m_And(m_Value(C), m_Value(D)))) { + Value *X = 0, *Y = 0, *Z = 0; + + if (A == C) { + X = B; Y = D; Z = A; + } else if (A == D) { + X = B; Y = C; Z = A; + } else if (B == C) { + X = A; Y = D; Z = B; + } else if (B == D) { + X = A; Y = C; Z = B; + } + + if (X) { // Build (X^Y) & Z + Op1 = Builder->CreateXor(X, Y, "tmp"); + Op1 = Builder->CreateAnd(Op1, Z, "tmp"); + I.setOperand(0, Op1); + I.setOperand(1, Constant::getNullValue(Op1->getType())); + return &I; + } + } + } + + { + Value *X; ConstantInt *Cst; + // icmp X+Cst, X + if (match(Op0, m_Add(m_Value(X), m_ConstantInt(Cst))) && Op1 == X) + return FoldICmpAddOpCst(I, X, Cst, I.getPredicate(), Op0); + + // icmp X, X+Cst + if (match(Op1, m_Add(m_Value(X), m_ConstantInt(Cst))) && Op0 == X) + return FoldICmpAddOpCst(I, X, Cst, I.getSwappedPredicate(), Op1); + } + return Changed ? &I : 0; +} + + + + + + +/// FoldFCmp_IntToFP_Cst - Fold fcmp ([us]itofp x, cst) if possible. +/// +Instruction *InstCombiner::FoldFCmp_IntToFP_Cst(FCmpInst &I, + Instruction *LHSI, + Constant *RHSC) { + if (!isa(RHSC)) return 0; + const APFloat &RHS = cast(RHSC)->getValueAPF(); + + // Get the width of the mantissa. We don't want to hack on conversions that + // might lose information from the integer, e.g. "i64 -> float" + int MantissaWidth = LHSI->getType()->getFPMantissaWidth(); + if (MantissaWidth == -1) return 0; // Unknown. + + // Check to see that the input is converted from an integer type that is small + // enough that preserves all bits. TODO: check here for "known" sign bits. + // This would allow us to handle (fptosi (x >>s 62) to float) if x is i64 f.e. + unsigned InputSize = LHSI->getOperand(0)->getType()->getScalarSizeInBits(); + + // If this is a uitofp instruction, we need an extra bit to hold the sign. + bool LHSUnsigned = isa(LHSI); + if (LHSUnsigned) + ++InputSize; + + // If the conversion would lose info, don't hack on this. + if ((int)InputSize > MantissaWidth) + return 0; + + // Otherwise, we can potentially simplify the comparison. We know that it + // will always come through as an integer value and we know the constant is + // not a NAN (it would have been previously simplified). + assert(!RHS.isNaN() && "NaN comparison not already folded!"); + + ICmpInst::Predicate Pred; + switch (I.getPredicate()) { + default: llvm_unreachable("Unexpected predicate!"); + case FCmpInst::FCMP_UEQ: + case FCmpInst::FCMP_OEQ: + Pred = ICmpInst::ICMP_EQ; + break; + case FCmpInst::FCMP_UGT: + case FCmpInst::FCMP_OGT: + Pred = LHSUnsigned ? ICmpInst::ICMP_UGT : ICmpInst::ICMP_SGT; + break; + case FCmpInst::FCMP_UGE: + case FCmpInst::FCMP_OGE: + Pred = LHSUnsigned ? ICmpInst::ICMP_UGE : ICmpInst::ICMP_SGE; + break; + case FCmpInst::FCMP_ULT: + case FCmpInst::FCMP_OLT: + Pred = LHSUnsigned ? ICmpInst::ICMP_ULT : ICmpInst::ICMP_SLT; + break; + case FCmpInst::FCMP_ULE: + case FCmpInst::FCMP_OLE: + Pred = LHSUnsigned ? ICmpInst::ICMP_ULE : ICmpInst::ICMP_SLE; + break; + case FCmpInst::FCMP_UNE: + case FCmpInst::FCMP_ONE: + Pred = ICmpInst::ICMP_NE; + break; + case FCmpInst::FCMP_ORD: + return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext())); + case FCmpInst::FCMP_UNO: + return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext())); + } + + const IntegerType *IntTy = cast(LHSI->getOperand(0)->getType()); + + // Now we know that the APFloat is a normal number, zero or inf. + + // See if the FP constant is too large for the integer. For example, + // comparing an i8 to 300.0. + unsigned IntWidth = IntTy->getScalarSizeInBits(); + + if (!LHSUnsigned) { + // If the RHS value is > SignedMax, fold the comparison. This handles +INF + // and large values. + APFloat SMax(RHS.getSemantics(), APFloat::fcZero, false); + SMax.convertFromAPInt(APInt::getSignedMaxValue(IntWidth), true, + APFloat::rmNearestTiesToEven); + if (SMax.compare(RHS) == APFloat::cmpLessThan) { // smax < 13123.0 + if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_SLT || + Pred == ICmpInst::ICMP_SLE) + return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext())); + return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext())); + } + } else { + // If the RHS value is > UnsignedMax, fold the comparison. This handles + // +INF and large values. + APFloat UMax(RHS.getSemantics(), APFloat::fcZero, false); + UMax.convertFromAPInt(APInt::getMaxValue(IntWidth), false, + APFloat::rmNearestTiesToEven); + if (UMax.compare(RHS) == APFloat::cmpLessThan) { // umax < 13123.0 + if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_ULT || + Pred == ICmpInst::ICMP_ULE) + return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext())); + return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext())); + } + } + + if (!LHSUnsigned) { + // See if the RHS value is < SignedMin. + APFloat SMin(RHS.getSemantics(), APFloat::fcZero, false); + SMin.convertFromAPInt(APInt::getSignedMinValue(IntWidth), true, + APFloat::rmNearestTiesToEven); + if (SMin.compare(RHS) == APFloat::cmpGreaterThan) { // smin > 12312.0 + if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_SGT || + Pred == ICmpInst::ICMP_SGE) + return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext())); + return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext())); + } + } + + // Okay, now we know that the FP constant fits in the range [SMIN, SMAX] or + // [0, UMAX], but it may still be fractional. See if it is fractional by + // casting the FP value to the integer value and back, checking for equality. + // Don't do this for zero, because -0.0 is not fractional. + Constant *RHSInt = LHSUnsigned + ? ConstantExpr::getFPToUI(RHSC, IntTy) + : ConstantExpr::getFPToSI(RHSC, IntTy); + if (!RHS.isZero()) { + bool Equal = LHSUnsigned + ? ConstantExpr::getUIToFP(RHSInt, RHSC->getType()) == RHSC + : ConstantExpr::getSIToFP(RHSInt, RHSC->getType()) == RHSC; + if (!Equal) { + // If we had a comparison against a fractional value, we have to adjust + // the compare predicate and sometimes the value. RHSC is rounded towards + // zero at this point. + switch (Pred) { + default: llvm_unreachable("Unexpected integer comparison!"); + case ICmpInst::ICMP_NE: // (float)int != 4.4 --> true + return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext())); + case ICmpInst::ICMP_EQ: // (float)int == 4.4 --> false + return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext())); + case ICmpInst::ICMP_ULE: + // (float)int <= 4.4 --> int <= 4 + // (float)int <= -4.4 --> false + if (RHS.isNegative()) + return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext())); + break; + case ICmpInst::ICMP_SLE: + // (float)int <= 4.4 --> int <= 4 + // (float)int <= -4.4 --> int < -4 + if (RHS.isNegative()) + Pred = ICmpInst::ICMP_SLT; + break; + case ICmpInst::ICMP_ULT: + // (float)int < -4.4 --> false + // (float)int < 4.4 --> int <= 4 + if (RHS.isNegative()) + return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext())); + Pred = ICmpInst::ICMP_ULE; + break; + case ICmpInst::ICMP_SLT: + // (float)int < -4.4 --> int < -4 + // (float)int < 4.4 --> int <= 4 + if (!RHS.isNegative()) + Pred = ICmpInst::ICMP_SLE; + break; + case ICmpInst::ICMP_UGT: + // (float)int > 4.4 --> int > 4 + // (float)int > -4.4 --> true + if (RHS.isNegative()) + return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext())); + break; + case ICmpInst::ICMP_SGT: + // (float)int > 4.4 --> int > 4 + // (float)int > -4.4 --> int >= -4 + if (RHS.isNegative()) + Pred = ICmpInst::ICMP_SGE; + break; + case ICmpInst::ICMP_UGE: + // (float)int >= -4.4 --> true + // (float)int >= 4.4 --> int > 4 + if (!RHS.isNegative()) + return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext())); + Pred = ICmpInst::ICMP_UGT; + break; + case ICmpInst::ICMP_SGE: + // (float)int >= -4.4 --> int >= -4 + // (float)int >= 4.4 --> int > 4 + if (!RHS.isNegative()) + Pred = ICmpInst::ICMP_SGT; + break; + } + } + } + + // Lower this FP comparison into an appropriate integer version of the + // comparison. + return new ICmpInst(Pred, LHSI->getOperand(0), RHSInt); +} + +Instruction *InstCombiner::visitFCmpInst(FCmpInst &I) { + bool Changed = false; + + /// Orders the operands of the compare so that they are listed from most + /// complex to least complex. This puts constants before unary operators, + /// before binary operators. + if (getComplexity(I.getOperand(0)) < getComplexity(I.getOperand(1))) { + I.swapOperands(); + Changed = true; + } + + Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); + + if (Value *V = SimplifyFCmpInst(I.getPredicate(), Op0, Op1, TD)) + return ReplaceInstUsesWith(I, V); + + // Simplify 'fcmp pred X, X' + if (Op0 == Op1) { + switch (I.getPredicate()) { + default: llvm_unreachable("Unknown predicate!"); + case FCmpInst::FCMP_UNO: // True if unordered: isnan(X) | isnan(Y) + case FCmpInst::FCMP_ULT: // True if unordered or less than + case FCmpInst::FCMP_UGT: // True if unordered or greater than + case FCmpInst::FCMP_UNE: // True if unordered or not equal + // Canonicalize these to be 'fcmp uno %X, 0.0'. + I.setPredicate(FCmpInst::FCMP_UNO); + I.setOperand(1, Constant::getNullValue(Op0->getType())); + return &I; + + case FCmpInst::FCMP_ORD: // True if ordered (no nans) + case FCmpInst::FCMP_OEQ: // True if ordered and equal + case FCmpInst::FCMP_OGE: // True if ordered and greater than or equal + case FCmpInst::FCMP_OLE: // True if ordered and less than or equal + // Canonicalize these to be 'fcmp ord %X, 0.0'. + I.setPredicate(FCmpInst::FCMP_ORD); + I.setOperand(1, Constant::getNullValue(Op0->getType())); + return &I; + } + } + + // Handle fcmp with constant RHS + if (Constant *RHSC = dyn_cast(Op1)) { + if (Instruction *LHSI = dyn_cast(Op0)) + switch (LHSI->getOpcode()) { + case Instruction::PHI: + // Only fold fcmp into the PHI if the phi and fcmp are in the same + // block. If in the same block, we're encouraging jump threading. If + // not, we are just pessimizing the code by making an i1 phi. + if (LHSI->getParent() == I.getParent()) + if (Instruction *NV = FoldOpIntoPhi(I, true)) + return NV; + break; + case Instruction::SIToFP: + case Instruction::UIToFP: + if (Instruction *NV = FoldFCmp_IntToFP_Cst(I, LHSI, RHSC)) + return NV; + break; + case Instruction::Select: { + // If either operand of the select is a constant, we can fold the + // comparison into the select arms, which will cause one to be + // constant folded and the select turned into a bitwise or. + Value *Op1 = 0, *Op2 = 0; + if (LHSI->hasOneUse()) { + if (Constant *C = dyn_cast(LHSI->getOperand(1))) { + // Fold the known value into the constant operand. + Op1 = ConstantExpr::getCompare(I.getPredicate(), C, RHSC); + // Insert a new FCmp of the other select operand. + Op2 = Builder->CreateFCmp(I.getPredicate(), + LHSI->getOperand(2), RHSC, I.getName()); + } else if (Constant *C = dyn_cast(LHSI->getOperand(2))) { + // Fold the known value into the constant operand. + Op2 = ConstantExpr::getCompare(I.getPredicate(), C, RHSC); + // Insert a new FCmp of the other select operand. + Op1 = Builder->CreateFCmp(I.getPredicate(), LHSI->getOperand(1), + RHSC, I.getName()); + } + } + + if (Op1) + return SelectInst::Create(LHSI->getOperand(0), Op1, Op2); + break; + } + case Instruction::Load: + if (GetElementPtrInst *GEP = + dyn_cast(LHSI->getOperand(0))) { + if (GlobalVariable *GV = dyn_cast(GEP->getOperand(0))) + if (GV->isConstant() && GV->hasDefinitiveInitializer() && + !cast(LHSI)->isVolatile()) + if (Instruction *Res = FoldCmpLoadFromIndexedGlobal(GEP, GV, I)) + return Res; + } + break; + } + } + + return Changed ? &I : 0; +} diff --git a/lib/Transforms/InstCombine/InstructionCombining.cpp b/lib/Transforms/InstCombine/InstructionCombining.cpp index 82cc9ebac18..a0bd43ab701 100644 --- a/lib/Transforms/InstCombine/InstructionCombining.cpp +++ b/lib/Transforms/InstCombine/InstructionCombining.cpp @@ -48,7 +48,6 @@ #include "llvm/Transforms/Utils/BasicBlockUtils.h" #include "llvm/Transforms/Utils/Local.h" #include "llvm/Support/CallSite.h" -#include "llvm/Support/ConstantRange.h" #include "llvm/Support/Debug.h" #include "llvm/Support/ErrorHandling.h" #include "llvm/Support/GetElementPtrTypeIterator.h" @@ -79,20 +78,6 @@ void InstCombiner::getAnalysisUsage(AnalysisUsage &AU) const { } -// getComplexity: Assign a complexity or rank value to LLVM Values... -// 0 -> undef, 1 -> Const, 2 -> Other, 3 -> Arg, 3 -> Unary, 4 -> OtherInst -static unsigned getComplexity(Value *V) { - if (isa(V)) { - if (BinaryOperator::isNeg(V) || - BinaryOperator::isFNeg(V) || - BinaryOperator::isNot(V)) - return 3; - return 4; - } - if (isa(V)) return 3; - return isa(V) ? (isa(V) ? 0 : 1) : 2; -} - // isOnlyUse - Return true if this instruction will be deleted if we stop using // it. static bool isOnlyUse(Value *V) { @@ -246,7 +231,7 @@ bool InstCombiner::SimplifyCommutative(BinaryOperator &I) { // dyn_castNegVal - Given a 'sub' instruction, return the RHS of the instruction // if the LHS is a constant zero (which is the 'negate' form). // -static inline Value *dyn_castNegVal(Value *V) { +Value *InstCombiner::dyn_castNegVal(Value *V) const { if (BinaryOperator::isNeg(V)) return BinaryOperator::getNegArgument(V); @@ -392,13 +377,11 @@ static inline Value *dyn_castFoldableMul(Value *V, ConstantInt *&CST) { /// AddOne - Add one to a ConstantInt static Constant *AddOne(Constant *C) { - return ConstantExpr::getAdd(C, - ConstantInt::get(C->getType(), 1)); + return ConstantExpr::getAdd(C, ConstantInt::get(C->getType(), 1)); } /// SubOne - Subtract one from a ConstantInt static Constant *SubOne(ConstantInt *C) { - return ConstantExpr::getSub(C, - ConstantInt::get(C->getType(), 1)); + return ConstantExpr::getSub(C, ConstantInt::get(C->getType(), 1)); } /// MultiplyOverflows - True if the multiply can not be expressed in an int /// this size. @@ -424,49 +407,6 @@ static bool MultiplyOverflows(ConstantInt *C1, ConstantInt *C2, bool sign) { } -// ComputeSignedMinMaxValuesFromKnownBits - Given a signed integer type and a -// set of known zero and one bits, compute the maximum and minimum values that -// could have the specified known zero and known one bits, returning them in -// min/max. -static void ComputeSignedMinMaxValuesFromKnownBits(const APInt& KnownZero, - const APInt& KnownOne, - APInt& Min, APInt& Max) { - assert(KnownZero.getBitWidth() == KnownOne.getBitWidth() && - KnownZero.getBitWidth() == Min.getBitWidth() && - KnownZero.getBitWidth() == Max.getBitWidth() && - "KnownZero, KnownOne and Min, Max must have equal bitwidth."); - APInt UnknownBits = ~(KnownZero|KnownOne); - - // The minimum value is when all unknown bits are zeros, EXCEPT for the sign - // bit if it is unknown. - Min = KnownOne; - Max = KnownOne|UnknownBits; - - if (UnknownBits.isNegative()) { // Sign bit is unknown - Min.set(Min.getBitWidth()-1); - Max.clear(Max.getBitWidth()-1); - } -} - -// ComputeUnsignedMinMaxValuesFromKnownBits - Given an unsigned integer type and -// a set of known zero and one bits, compute the maximum and minimum values that -// could have the specified known zero and known one bits, returning them in -// min/max. -static void ComputeUnsignedMinMaxValuesFromKnownBits(const APInt &KnownZero, - const APInt &KnownOne, - APInt &Min, APInt &Max) { - assert(KnownZero.getBitWidth() == KnownOne.getBitWidth() && - KnownZero.getBitWidth() == Min.getBitWidth() && - KnownZero.getBitWidth() == Max.getBitWidth() && - "Ty, KnownZero, KnownOne and Min, Max must have equal bitwidth."); - APInt UnknownBits = ~(KnownZero|KnownOne); - - // The minimum value is when the unknown bits are all zeros. - Min = KnownOne; - // The maximum value is when the unknown bits are all ones. - Max = KnownOne|UnknownBits; -} - /// AssociativeOpt - Perform an optimization on an associative operator. This /// function is designed to check a chain of associative operators for a @@ -1138,8 +1078,8 @@ Instruction *InstCombiner::visitFAdd(BinaryOperator &I) { /// EmitGEPOffset - Given a getelementptr instruction/constantexpr, emit the /// code necessary to compute the offset from the base pointer (without adding /// in the base pointer). Return the result as a signed integer of intptr size. -static Value *EmitGEPOffset(User *GEP, InstCombiner &IC) { - TargetData &TD = *IC.getTargetData(); +Value *InstCombiner::EmitGEPOffset(User *GEP) { + TargetData &TD = *getTargetData(); gep_type_iterator GTI = gep_type_begin(GEP); const Type *IntPtrTy = TD.getIntPtrType(GEP->getContext()); Value *Result = Constant::getNullValue(IntPtrTy); @@ -1159,9 +1099,9 @@ static Value *EmitGEPOffset(User *GEP, InstCombiner &IC) { if (const StructType *STy = dyn_cast(*GTI)) { Size = TD.getStructLayout(STy)->getElementOffset(OpC->getZExtValue()); - Result = IC.Builder->CreateAdd(Result, - ConstantInt::get(IntPtrTy, Size), - GEP->getName()+".offs"); + Result = Builder->CreateAdd(Result, + ConstantInt::get(IntPtrTy, Size), + GEP->getName()+".offs"); continue; } @@ -1170,130 +1110,25 @@ static Value *EmitGEPOffset(User *GEP, InstCombiner &IC) { ConstantExpr::getIntegerCast(OpC, IntPtrTy, true /*SExt*/); Scale = ConstantExpr::getMul(OC, Scale); // Emit an add instruction. - Result = IC.Builder->CreateAdd(Result, Scale, GEP->getName()+".offs"); + Result = Builder->CreateAdd(Result, Scale, GEP->getName()+".offs"); continue; } // Convert to correct type. if (Op->getType() != IntPtrTy) - Op = IC.Builder->CreateIntCast(Op, IntPtrTy, true, Op->getName()+".c"); + Op = Builder->CreateIntCast(Op, IntPtrTy, true, Op->getName()+".c"); if (Size != 1) { Constant *Scale = ConstantInt::get(IntPtrTy, Size); // We'll let instcombine(mul) convert this to a shl if possible. - Op = IC.Builder->CreateMul(Op, Scale, GEP->getName()+".idx"); + Op = Builder->CreateMul(Op, Scale, GEP->getName()+".idx"); } // Emit an add instruction. - Result = IC.Builder->CreateAdd(Op, Result, GEP->getName()+".offs"); + Result = Builder->CreateAdd(Op, Result, GEP->getName()+".offs"); } return Result; } -/// EvaluateGEPOffsetExpression - Return a value that can be used to compare -/// the *offset* implied by a GEP to zero. For example, if we have &A[i], we -/// want to return 'i' for "icmp ne i, 0". Note that, in general, indices can -/// be complex, and scales are involved. The above expression would also be -/// legal to codegen as "icmp ne (i*4), 0" (assuming A is a pointer to i32). -/// This later form is less amenable to optimization though, and we are allowed -/// to generate the first by knowing that pointer arithmetic doesn't overflow. -/// -/// If we can't emit an optimized form for this expression, this returns null. -/// -static Value *EvaluateGEPOffsetExpression(User *GEP, Instruction &I, - InstCombiner &IC) { - TargetData &TD = *IC.getTargetData(); - gep_type_iterator GTI = gep_type_begin(GEP); - - // Check to see if this gep only has a single variable index. If so, and if - // any constant indices are a multiple of its scale, then we can compute this - // in terms of the scale of the variable index. For example, if the GEP - // implies an offset of "12 + i*4", then we can codegen this as "3 + i", - // because the expression will cross zero at the same point. - unsigned i, e = GEP->getNumOperands(); - int64_t Offset = 0; - for (i = 1; i != e; ++i, ++GTI) { - if (ConstantInt *CI = dyn_cast(GEP->getOperand(i))) { - // Compute the aggregate offset of constant indices. - if (CI->isZero()) continue; - - // Handle a struct index, which adds its field offset to the pointer. - if (const StructType *STy = dyn_cast(*GTI)) { - Offset += TD.getStructLayout(STy)->getElementOffset(CI->getZExtValue()); - } else { - uint64_t Size = TD.getTypeAllocSize(GTI.getIndexedType()); - Offset += Size*CI->getSExtValue(); - } - } else { - // Found our variable index. - break; - } - } - - // If there are no variable indices, we must have a constant offset, just - // evaluate it the general way. - if (i == e) return 0; - - Value *VariableIdx = GEP->getOperand(i); - // Determine the scale factor of the variable element. For example, this is - // 4 if the variable index is into an array of i32. - uint64_t VariableScale = TD.getTypeAllocSize(GTI.getIndexedType()); - - // Verify that there are no other variable indices. If so, emit the hard way. - for (++i, ++GTI; i != e; ++i, ++GTI) { - ConstantInt *CI = dyn_cast(GEP->getOperand(i)); - if (!CI) return 0; - - // Compute the aggregate offset of constant indices. - if (CI->isZero()) continue; - - // Handle a struct index, which adds its field offset to the pointer. - if (const StructType *STy = dyn_cast(*GTI)) { - Offset += TD.getStructLayout(STy)->getElementOffset(CI->getZExtValue()); - } else { - uint64_t Size = TD.getTypeAllocSize(GTI.getIndexedType()); - Offset += Size*CI->getSExtValue(); - } - } - - // Okay, we know we have a single variable index, which must be a - // pointer/array/vector index. If there is no offset, life is simple, return - // the index. - unsigned IntPtrWidth = TD.getPointerSizeInBits(); - if (Offset == 0) { - // Cast to intptrty in case a truncation occurs. If an extension is needed, - // we don't need to bother extending: the extension won't affect where the - // computation crosses zero. - if (VariableIdx->getType()->getPrimitiveSizeInBits() > IntPtrWidth) - VariableIdx = new TruncInst(VariableIdx, - TD.getIntPtrType(VariableIdx->getContext()), - VariableIdx->getName(), &I); - return VariableIdx; - } - - // Otherwise, there is an index. The computation we will do will be modulo - // the pointer size, so get it. - uint64_t PtrSizeMask = ~0ULL >> (64-IntPtrWidth); - - Offset &= PtrSizeMask; - VariableScale &= PtrSizeMask; - - // To do this transformation, any constant index must be a multiple of the - // variable scale factor. For example, we can evaluate "12 + 4*i" as "3 + i", - // but we can't evaluate "10 + 3*i" in terms of i. Check that the offset is a - // multiple of the variable scale. - int64_t NewOffs = Offset / (int64_t)VariableScale; - if (Offset != NewOffs*(int64_t)VariableScale) - return 0; - - // Okay, we can do this evaluation. Start by converting the index to intptr. - const Type *IntPtrTy = TD.getIntPtrType(VariableIdx->getContext()); - if (VariableIdx->getType() != IntPtrTy) - VariableIdx = CastInst::CreateIntegerCast(VariableIdx, IntPtrTy, - true /*SExt*/, - VariableIdx->getName(), &I); - Constant *OffsetVal = ConstantInt::get(IntPtrTy, NewOffs); - return BinaryOperator::CreateAdd(VariableIdx, OffsetVal, "offset", &I); -} /// Optimize pointer differences into the same array into a size. Consider: @@ -1349,12 +1184,12 @@ Value *InstCombiner::OptimizePointerDifference(Value *LHS, Value *RHS, return 0; // Emit the offset of the GEP and an intptr_t. - Value *Result = EmitGEPOffset(GEP, *this); + Value *Result = EmitGEPOffset(GEP); // If we had a constant expression GEP on the other side offsetting the // pointer, subtract it from the offset we have. if (CstGEP) { - Value *CstOffset = EmitGEPOffset(CstGEP, *this); + Value *CstOffset = EmitGEPOffset(CstGEP); Result = Builder->CreateSub(Result, CstOffset); } @@ -1559,36 +1394,6 @@ Instruction *InstCombiner::visitFSub(BinaryOperator &I) { return 0; } -/// isSignBitCheck - Given an exploded icmp instruction, return true if the -/// comparison only checks the sign bit. If it only checks the sign bit, set -/// TrueIfSigned if the result of the comparison is true when the input value is -/// signed. -static bool isSignBitCheck(ICmpInst::Predicate pred, ConstantInt *RHS, - bool &TrueIfSigned) { - switch (pred) { - case ICmpInst::ICMP_SLT: // True if LHS s< 0 - TrueIfSigned = true; - return RHS->isZero(); - case ICmpInst::ICMP_SLE: // True if LHS s<= RHS and RHS == -1 - TrueIfSigned = true; - return RHS->isAllOnesValue(); - case ICmpInst::ICMP_SGT: // True if LHS s> -1 - TrueIfSigned = false; - return RHS->isAllOnesValue(); - case ICmpInst::ICMP_UGT: - // True if LHS u> RHS and RHS == high-bit-mask - 1 - TrueIfSigned = true; - return RHS->getValue() == - APInt::getSignedMaxValue(RHS->getType()->getPrimitiveSizeInBits()); - case ICmpInst::ICMP_UGE: - // True if LHS u>= RHS and RHS == high-bit-mask (2^7, 2^15, 2^31, etc) - TrueIfSigned = true; - return RHS->getValue().isSignBit(); - default: - return false; - } -} - Instruction *InstCombiner::visitMul(BinaryOperator &I) { bool Changed = SimplifyCommutative(I); Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); @@ -2242,12 +2047,6 @@ static bool isOneBitSet(const ConstantInt *CI) { return CI->getValue().isPowerOf2(); } -// isHighOnes - Return true if the constant is of the form 1+0+. -// This is the same as lowones(~X). -static bool isHighOnes(const ConstantInt *CI) { - return (~CI->getValue() + 1).isPowerOf2(); -} - /// getICmpCode - Encode a icmp predicate into a three bit mask. These bits /// are carefully arranged to allow folding of expressions such as: /// @@ -4186,2223 +3985,6 @@ Instruction *InstCombiner::visitXor(BinaryOperator &I) { return Changed ? &I : 0; } -static ConstantInt *ExtractElement(Constant *V, Constant *Idx) { - return cast(ConstantExpr::getExtractElement(V, Idx)); -} - -static bool HasAddOverflow(ConstantInt *Result, - ConstantInt *In1, ConstantInt *In2, - bool IsSigned) { - if (IsSigned) - if (In2->getValue().isNegative()) - return Result->getValue().sgt(In1->getValue()); - else - return Result->getValue().slt(In1->getValue()); - else - return Result->getValue().ult(In1->getValue()); -} - -/// AddWithOverflow - Compute Result = In1+In2, returning true if the result -/// overflowed for this type. -static bool AddWithOverflow(Constant *&Result, Constant *In1, - Constant *In2, bool IsSigned = false) { - Result = ConstantExpr::getAdd(In1, In2); - - if (const VectorType *VTy = dyn_cast(In1->getType())) { - for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) { - Constant *Idx = ConstantInt::get(Type::getInt32Ty(In1->getContext()), i); - if (HasAddOverflow(ExtractElement(Result, Idx), - ExtractElement(In1, Idx), - ExtractElement(In2, Idx), - IsSigned)) - return true; - } - return false; - } - - return HasAddOverflow(cast(Result), - cast(In1), cast(In2), - IsSigned); -} - -static bool HasSubOverflow(ConstantInt *Result, - ConstantInt *In1, ConstantInt *In2, - bool IsSigned) { - if (IsSigned) - if (In2->getValue().isNegative()) - return Result->getValue().slt(In1->getValue()); - else - return Result->getValue().sgt(In1->getValue()); - else - return Result->getValue().ugt(In1->getValue()); -} - -/// SubWithOverflow - Compute Result = In1-In2, returning true if the result -/// overflowed for this type. -static bool SubWithOverflow(Constant *&Result, Constant *In1, - Constant *In2, bool IsSigned = false) { - Result = ConstantExpr::getSub(In1, In2); - - if (const VectorType *VTy = dyn_cast(In1->getType())) { - for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) { - Constant *Idx = ConstantInt::get(Type::getInt32Ty(In1->getContext()), i); - if (HasSubOverflow(ExtractElement(Result, Idx), - ExtractElement(In1, Idx), - ExtractElement(In2, Idx), - IsSigned)) - return true; - } - return false; - } - - return HasSubOverflow(cast(Result), - cast(In1), cast(In2), - IsSigned); -} - - -/// FoldGEPICmp - Fold comparisons between a GEP instruction and something -/// else. At this point we know that the GEP is on the LHS of the comparison. -Instruction *InstCombiner::FoldGEPICmp(GEPOperator *GEPLHS, Value *RHS, - ICmpInst::Predicate Cond, - Instruction &I) { - // Look through bitcasts. - if (BitCastInst *BCI = dyn_cast(RHS)) - RHS = BCI->getOperand(0); - - Value *PtrBase = GEPLHS->getOperand(0); - if (TD && PtrBase == RHS && GEPLHS->isInBounds()) { - // ((gep Ptr, OFFSET) cmp Ptr) ---> (OFFSET cmp 0). - // This transformation (ignoring the base and scales) is valid because we - // know pointers can't overflow since the gep is inbounds. See if we can - // output an optimized form. - Value *Offset = EvaluateGEPOffsetExpression(GEPLHS, I, *this); - - // If not, synthesize the offset the hard way. - if (Offset == 0) - Offset = EmitGEPOffset(GEPLHS, *this); - return new ICmpInst(ICmpInst::getSignedPredicate(Cond), Offset, - Constant::getNullValue(Offset->getType())); - } else if (GEPOperator *GEPRHS = dyn_cast(RHS)) { - // If the base pointers are different, but the indices are the same, just - // compare the base pointer. - if (PtrBase != GEPRHS->getOperand(0)) { - bool IndicesTheSame = GEPLHS->getNumOperands()==GEPRHS->getNumOperands(); - IndicesTheSame &= GEPLHS->getOperand(0)->getType() == - GEPRHS->getOperand(0)->getType(); - if (IndicesTheSame) - for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i) - if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) { - IndicesTheSame = false; - break; - } - - // If all indices are the same, just compare the base pointers. - if (IndicesTheSame) - return new ICmpInst(ICmpInst::getSignedPredicate(Cond), - GEPLHS->getOperand(0), GEPRHS->getOperand(0)); - - // Otherwise, the base pointers are different and the indices are - // different, bail out. - return 0; - } - - // If one of the GEPs has all zero indices, recurse. - bool AllZeros = true; - for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i) - if (!isa(GEPLHS->getOperand(i)) || - !cast(GEPLHS->getOperand(i))->isNullValue()) { - AllZeros = false; - break; - } - if (AllZeros) - return FoldGEPICmp(GEPRHS, GEPLHS->getOperand(0), - ICmpInst::getSwappedPredicate(Cond), I); - - // If the other GEP has all zero indices, recurse. - AllZeros = true; - for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i) - if (!isa(GEPRHS->getOperand(i)) || - !cast(GEPRHS->getOperand(i))->isNullValue()) { - AllZeros = false; - break; - } - if (AllZeros) - return FoldGEPICmp(GEPLHS, GEPRHS->getOperand(0), Cond, I); - - if (GEPLHS->getNumOperands() == GEPRHS->getNumOperands()) { - // If the GEPs only differ by one index, compare it. - unsigned NumDifferences = 0; // Keep track of # differences. - unsigned DiffOperand = 0; // The operand that differs. - for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i) - if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) { - if (GEPLHS->getOperand(i)->getType()->getPrimitiveSizeInBits() != - GEPRHS->getOperand(i)->getType()->getPrimitiveSizeInBits()) { - // Irreconcilable differences. - NumDifferences = 2; - break; - } else { - if (NumDifferences++) break; - DiffOperand = i; - } - } - - if (NumDifferences == 0) // SAME GEP? - return ReplaceInstUsesWith(I, // No comparison is needed here. - ConstantInt::get(Type::getInt1Ty(I.getContext()), - ICmpInst::isTrueWhenEqual(Cond))); - - else if (NumDifferences == 1) { - Value *LHSV = GEPLHS->getOperand(DiffOperand); - Value *RHSV = GEPRHS->getOperand(DiffOperand); - // Make sure we do a signed comparison here. - return new ICmpInst(ICmpInst::getSignedPredicate(Cond), LHSV, RHSV); - } - } - - // Only lower this if the icmp is the only user of the GEP or if we expect - // the result to fold to a constant! - if (TD && - (isa(GEPLHS) || GEPLHS->hasOneUse()) && - (isa(GEPRHS) || GEPRHS->hasOneUse())) { - // ((gep Ptr, OFFSET1) cmp (gep Ptr, OFFSET2) ---> (OFFSET1 cmp OFFSET2) - Value *L = EmitGEPOffset(GEPLHS, *this); - Value *R = EmitGEPOffset(GEPRHS, *this); - return new ICmpInst(ICmpInst::getSignedPredicate(Cond), L, R); - } - } - return 0; -} - -/// FoldFCmp_IntToFP_Cst - Fold fcmp ([us]itofp x, cst) if possible. -/// -Instruction *InstCombiner::FoldFCmp_IntToFP_Cst(FCmpInst &I, - Instruction *LHSI, - Constant *RHSC) { - if (!isa(RHSC)) return 0; - const APFloat &RHS = cast(RHSC)->getValueAPF(); - - // Get the width of the mantissa. We don't want to hack on conversions that - // might lose information from the integer, e.g. "i64 -> float" - int MantissaWidth = LHSI->getType()->getFPMantissaWidth(); - if (MantissaWidth == -1) return 0; // Unknown. - - // Check to see that the input is converted from an integer type that is small - // enough that preserves all bits. TODO: check here for "known" sign bits. - // This would allow us to handle (fptosi (x >>s 62) to float) if x is i64 f.e. - unsigned InputSize = LHSI->getOperand(0)->getType()->getScalarSizeInBits(); - - // If this is a uitofp instruction, we need an extra bit to hold the sign. - bool LHSUnsigned = isa(LHSI); - if (LHSUnsigned) - ++InputSize; - - // If the conversion would lose info, don't hack on this. - if ((int)InputSize > MantissaWidth) - return 0; - - // Otherwise, we can potentially simplify the comparison. We know that it - // will always come through as an integer value and we know the constant is - // not a NAN (it would have been previously simplified). - assert(!RHS.isNaN() && "NaN comparison not already folded!"); - - ICmpInst::Predicate Pred; - switch (I.getPredicate()) { - default: llvm_unreachable("Unexpected predicate!"); - case FCmpInst::FCMP_UEQ: - case FCmpInst::FCMP_OEQ: - Pred = ICmpInst::ICMP_EQ; - break; - case FCmpInst::FCMP_UGT: - case FCmpInst::FCMP_OGT: - Pred = LHSUnsigned ? ICmpInst::ICMP_UGT : ICmpInst::ICMP_SGT; - break; - case FCmpInst::FCMP_UGE: - case FCmpInst::FCMP_OGE: - Pred = LHSUnsigned ? ICmpInst::ICMP_UGE : ICmpInst::ICMP_SGE; - break; - case FCmpInst::FCMP_ULT: - case FCmpInst::FCMP_OLT: - Pred = LHSUnsigned ? ICmpInst::ICMP_ULT : ICmpInst::ICMP_SLT; - break; - case FCmpInst::FCMP_ULE: - case FCmpInst::FCMP_OLE: - Pred = LHSUnsigned ? ICmpInst::ICMP_ULE : ICmpInst::ICMP_SLE; - break; - case FCmpInst::FCMP_UNE: - case FCmpInst::FCMP_ONE: - Pred = ICmpInst::ICMP_NE; - break; - case FCmpInst::FCMP_ORD: - return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext())); - case FCmpInst::FCMP_UNO: - return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext())); - } - - const IntegerType *IntTy = cast(LHSI->getOperand(0)->getType()); - - // Now we know that the APFloat is a normal number, zero or inf. - - // See if the FP constant is too large for the integer. For example, - // comparing an i8 to 300.0. - unsigned IntWidth = IntTy->getScalarSizeInBits(); - - if (!LHSUnsigned) { - // If the RHS value is > SignedMax, fold the comparison. This handles +INF - // and large values. - APFloat SMax(RHS.getSemantics(), APFloat::fcZero, false); - SMax.convertFromAPInt(APInt::getSignedMaxValue(IntWidth), true, - APFloat::rmNearestTiesToEven); - if (SMax.compare(RHS) == APFloat::cmpLessThan) { // smax < 13123.0 - if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_SLT || - Pred == ICmpInst::ICMP_SLE) - return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext())); - return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext())); - } - } else { - // If the RHS value is > UnsignedMax, fold the comparison. This handles - // +INF and large values. - APFloat UMax(RHS.getSemantics(), APFloat::fcZero, false); - UMax.convertFromAPInt(APInt::getMaxValue(IntWidth), false, - APFloat::rmNearestTiesToEven); - if (UMax.compare(RHS) == APFloat::cmpLessThan) { // umax < 13123.0 - if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_ULT || - Pred == ICmpInst::ICMP_ULE) - return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext())); - return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext())); - } - } - - if (!LHSUnsigned) { - // See if the RHS value is < SignedMin. - APFloat SMin(RHS.getSemantics(), APFloat::fcZero, false); - SMin.convertFromAPInt(APInt::getSignedMinValue(IntWidth), true, - APFloat::rmNearestTiesToEven); - if (SMin.compare(RHS) == APFloat::cmpGreaterThan) { // smin > 12312.0 - if (Pred == ICmpInst::ICMP_NE || Pred == ICmpInst::ICMP_SGT || - Pred == ICmpInst::ICMP_SGE) - return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext())); - return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext())); - } - } - - // Okay, now we know that the FP constant fits in the range [SMIN, SMAX] or - // [0, UMAX], but it may still be fractional. See if it is fractional by - // casting the FP value to the integer value and back, checking for equality. - // Don't do this for zero, because -0.0 is not fractional. - Constant *RHSInt = LHSUnsigned - ? ConstantExpr::getFPToUI(RHSC, IntTy) - : ConstantExpr::getFPToSI(RHSC, IntTy); - if (!RHS.isZero()) { - bool Equal = LHSUnsigned - ? ConstantExpr::getUIToFP(RHSInt, RHSC->getType()) == RHSC - : ConstantExpr::getSIToFP(RHSInt, RHSC->getType()) == RHSC; - if (!Equal) { - // If we had a comparison against a fractional value, we have to adjust - // the compare predicate and sometimes the value. RHSC is rounded towards - // zero at this point. - switch (Pred) { - default: llvm_unreachable("Unexpected integer comparison!"); - case ICmpInst::ICMP_NE: // (float)int != 4.4 --> true - return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext())); - case ICmpInst::ICMP_EQ: // (float)int == 4.4 --> false - return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext())); - case ICmpInst::ICMP_ULE: - // (float)int <= 4.4 --> int <= 4 - // (float)int <= -4.4 --> false - if (RHS.isNegative()) - return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext())); - break; - case ICmpInst::ICMP_SLE: - // (float)int <= 4.4 --> int <= 4 - // (float)int <= -4.4 --> int < -4 - if (RHS.isNegative()) - Pred = ICmpInst::ICMP_SLT; - break; - case ICmpInst::ICMP_ULT: - // (float)int < -4.4 --> false - // (float)int < 4.4 --> int <= 4 - if (RHS.isNegative()) - return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext())); - Pred = ICmpInst::ICMP_ULE; - break; - case ICmpInst::ICMP_SLT: - // (float)int < -4.4 --> int < -4 - // (float)int < 4.4 --> int <= 4 - if (!RHS.isNegative()) - Pred = ICmpInst::ICMP_SLE; - break; - case ICmpInst::ICMP_UGT: - // (float)int > 4.4 --> int > 4 - // (float)int > -4.4 --> true - if (RHS.isNegative()) - return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext())); - break; - case ICmpInst::ICMP_SGT: - // (float)int > 4.4 --> int > 4 - // (float)int > -4.4 --> int >= -4 - if (RHS.isNegative()) - Pred = ICmpInst::ICMP_SGE; - break; - case ICmpInst::ICMP_UGE: - // (float)int >= -4.4 --> true - // (float)int >= 4.4 --> int > 4 - if (!RHS.isNegative()) - return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext())); - Pred = ICmpInst::ICMP_UGT; - break; - case ICmpInst::ICMP_SGE: - // (float)int >= -4.4 --> int >= -4 - // (float)int >= 4.4 --> int > 4 - if (!RHS.isNegative()) - Pred = ICmpInst::ICMP_SGT; - break; - } - } - } - - // Lower this FP comparison into an appropriate integer version of the - // comparison. - return new ICmpInst(Pred, LHSI->getOperand(0), RHSInt); -} - -/// FoldCmpLoadFromIndexedGlobal - Called we see this pattern: -/// cmp pred (load (gep GV, ...)), cmpcst -/// where GV is a global variable with a constant initializer. Try to simplify -/// this into some simple computation that does not need the load. For example -/// we can optimize "icmp eq (load (gep "foo", 0, i)), 0" into "icmp eq i, 3". -/// -/// If AndCst is non-null, then the loaded value is masked with that constant -/// before doing the comparison. This handles cases like "A[i]&4 == 0". -Instruction *InstCombiner:: -FoldCmpLoadFromIndexedGlobal(GetElementPtrInst *GEP, GlobalVariable *GV, - CmpInst &ICI, ConstantInt *AndCst) { - ConstantArray *Init = dyn_cast(GV->getInitializer()); - if (Init == 0 || Init->getNumOperands() > 1024) return 0; - - // There are many forms of this optimization we can handle, for now, just do - // the simple index into a single-dimensional array. - // - // Require: GEP GV, 0, i {{, constant indices}} - if (GEP->getNumOperands() < 3 || - !isa(GEP->getOperand(1)) || - !cast(GEP->getOperand(1))->isZero() || - isa(GEP->getOperand(2))) - return 0; - - // Check that indices after the variable are constants and in-range for the - // type they index. Collect the indices. This is typically for arrays of - // structs. - SmallVector LaterIndices; - - const Type *EltTy = cast(Init->getType())->getElementType(); - for (unsigned i = 3, e = GEP->getNumOperands(); i != e; ++i) { - ConstantInt *Idx = dyn_cast(GEP->getOperand(i)); - if (Idx == 0) return 0; // Variable index. - - uint64_t IdxVal = Idx->getZExtValue(); - if ((unsigned)IdxVal != IdxVal) return 0; // Too large array index. - - if (const StructType *STy = dyn_cast(EltTy)) - EltTy = STy->getElementType(IdxVal); - else if (const ArrayType *ATy = dyn_cast(EltTy)) { - if (IdxVal >= ATy->getNumElements()) return 0; - EltTy = ATy->getElementType(); - } else { - return 0; // Unknown type. - } - - LaterIndices.push_back(IdxVal); - } - - enum { Overdefined = -3, Undefined = -2 }; - - // Variables for our state machines. - - // FirstTrueElement/SecondTrueElement - Used to emit a comparison of the form - // "i == 47 | i == 87", where 47 is the first index the condition is true for, - // and 87 is the second (and last) index. FirstTrueElement is -2 when - // undefined, otherwise set to the first true element. SecondTrueElement is - // -2 when undefined, -3 when overdefined and >= 0 when that index is true. - int FirstTrueElement = Undefined, SecondTrueElement = Undefined; - - // FirstFalseElement/SecondFalseElement - Used to emit a comparison of the - // form "i != 47 & i != 87". Same state transitions as for true elements. - int FirstFalseElement = Undefined, SecondFalseElement = Undefined; - - /// TrueRangeEnd/FalseRangeEnd - In conjunction with First*Element, these - /// define a state machine that triggers for ranges of values that the index - /// is true or false for. This triggers on things like "abbbbc"[i] == 'b'. - /// This is -2 when undefined, -3 when overdefined, and otherwise the last - /// index in the range (inclusive). We use -2 for undefined here because we - /// use relative comparisons and don't want 0-1 to match -1. - int TrueRangeEnd = Undefined, FalseRangeEnd = Undefined; - - // MagicBitvector - This is a magic bitvector where we set a bit if the - // comparison is true for element 'i'. If there are 64 elements or less in - // the array, this will fully represent all the comparison results. - uint64_t MagicBitvector = 0; - - - // Scan the array and see if one of our patterns matches. - Constant *CompareRHS = cast(ICI.getOperand(1)); - for (unsigned i = 0, e = Init->getNumOperands(); i != e; ++i) { - Constant *Elt = Init->getOperand(i); - - // If this is indexing an array of structures, get the structure element. - if (!LaterIndices.empty()) - Elt = ConstantExpr::getExtractValue(Elt, LaterIndices.data(), - LaterIndices.size()); - - // If the element is masked, handle it. - if (AndCst) Elt = ConstantExpr::getAnd(Elt, AndCst); - - // Find out if the comparison would be true or false for the i'th element. - Constant *C = ConstantFoldCompareInstOperands(ICI.getPredicate(), Elt, - CompareRHS, TD); - // If the result is undef for this element, ignore it. - if (isa(C)) { - // Extend range state machines to cover this element in case there is an - // undef in the middle of the range. - if (TrueRangeEnd == (int)i-1) - TrueRangeEnd = i; - if (FalseRangeEnd == (int)i-1) - FalseRangeEnd = i; - continue; - } - - // If we can't compute the result for any of the elements, we have to give - // up evaluating the entire conditional. - if (!isa(C)) return 0; - - // Otherwise, we know if the comparison is true or false for this element, - // update our state machines. - bool IsTrueForElt = !cast(C)->isZero(); - - // State machine for single/double/range index comparison. - if (IsTrueForElt) { - // Update the TrueElement state machine. - if (FirstTrueElement == Undefined) - FirstTrueElement = TrueRangeEnd = i; // First true element. - else { - // Update double-compare state machine. - if (SecondTrueElement == Undefined) - SecondTrueElement = i; - else - SecondTrueElement = Overdefined; - - // Update range state machine. - if (TrueRangeEnd == (int)i-1) - TrueRangeEnd = i; - else - TrueRangeEnd = Overdefined; - } - } else { - // Update the FalseElement state machine. - if (FirstFalseElement == Undefined) - FirstFalseElement = FalseRangeEnd = i; // First false element. - else { - // Update double-compare state machine. - if (SecondFalseElement == Undefined) - SecondFalseElement = i; - else - SecondFalseElement = Overdefined; - - // Update range state machine. - if (FalseRangeEnd == (int)i-1) - FalseRangeEnd = i; - else - FalseRangeEnd = Overdefined; - } - } - - - // If this element is in range, update our magic bitvector. - if (i < 64 && IsTrueForElt) - MagicBitvector |= 1ULL << i; - - // If all of our states become overdefined, bail out early. Since the - // predicate is expensive, only check it every 8 elements. This is only - // really useful for really huge arrays. - if ((i & 8) == 0 && i >= 64 && SecondTrueElement == Overdefined && - SecondFalseElement == Overdefined && TrueRangeEnd == Overdefined && - FalseRangeEnd == Overdefined) - return 0; - } - - // Now that we've scanned the entire array, emit our new comparison(s). We - // order the state machines in complexity of the generated code. - Value *Idx = GEP->getOperand(2); - - - // If the comparison is only true for one or two elements, emit direct - // comparisons. - if (SecondTrueElement != Overdefined) { - // None true -> false. - if (FirstTrueElement == Undefined) - return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(GEP->getContext())); - - Value *FirstTrueIdx = ConstantInt::get(Idx->getType(), FirstTrueElement); - - // True for one element -> 'i == 47'. - if (SecondTrueElement == Undefined) - return new ICmpInst(ICmpInst::ICMP_EQ, Idx, FirstTrueIdx); - - // True for two elements -> 'i == 47 | i == 72'. - Value *C1 = Builder->CreateICmpEQ(Idx, FirstTrueIdx); - Value *SecondTrueIdx = ConstantInt::get(Idx->getType(), SecondTrueElement); - Value *C2 = Builder->CreateICmpEQ(Idx, SecondTrueIdx); - return BinaryOperator::CreateOr(C1, C2); - } - - // If the comparison is only false for one or two elements, emit direct - // comparisons. - if (SecondFalseElement != Overdefined) { - // None false -> true. - if (FirstFalseElement == Undefined) - return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(GEP->getContext())); - - Value *FirstFalseIdx = ConstantInt::get(Idx->getType(), FirstFalseElement); - - // False for one element -> 'i != 47'. - if (SecondFalseElement == Undefined) - return new ICmpInst(ICmpInst::ICMP_NE, Idx, FirstFalseIdx); - - // False for two elements -> 'i != 47 & i != 72'. - Value *C1 = Builder->CreateICmpNE(Idx, FirstFalseIdx); - Value *SecondFalseIdx = ConstantInt::get(Idx->getType(),SecondFalseElement); - Value *C2 = Builder->CreateICmpNE(Idx, SecondFalseIdx); - return BinaryOperator::CreateAnd(C1, C2); - } - - // If the comparison can be replaced with a range comparison for the elements - // where it is true, emit the range check. - if (TrueRangeEnd != Overdefined) { - assert(TrueRangeEnd != FirstTrueElement && "Should emit single compare"); - - // Generate (i-FirstTrue) getType(), -FirstTrueElement); - Idx = Builder->CreateAdd(Idx, Offs); - } - - Value *End = ConstantInt::get(Idx->getType(), - TrueRangeEnd-FirstTrueElement+1); - return new ICmpInst(ICmpInst::ICMP_ULT, Idx, End); - } - - // False range check. - if (FalseRangeEnd != Overdefined) { - assert(FalseRangeEnd != FirstFalseElement && "Should emit single compare"); - // Generate (i-FirstFalse) >u (FalseRangeEnd-FirstFalse). - if (FirstFalseElement) { - Value *Offs = ConstantInt::get(Idx->getType(), -FirstFalseElement); - Idx = Builder->CreateAdd(Idx, Offs); - } - - Value *End = ConstantInt::get(Idx->getType(), - FalseRangeEnd-FirstFalseElement); - return new ICmpInst(ICmpInst::ICMP_UGT, Idx, End); - } - - - // If a 32-bit or 64-bit magic bitvector captures the entire comparison state - // of this load, replace it with computation that does: - // ((magic_cst >> i) & 1) != 0 - if (Init->getNumOperands() <= 32 || - (TD && Init->getNumOperands() <= 64 && TD->isLegalInteger(64))) { - const Type *Ty; - if (Init->getNumOperands() <= 32) - Ty = Type::getInt32Ty(Init->getContext()); - else - Ty = Type::getInt64Ty(Init->getContext()); - Value *V = Builder->CreateIntCast(Idx, Ty, false); - V = Builder->CreateLShr(ConstantInt::get(Ty, MagicBitvector), V); - V = Builder->CreateAnd(ConstantInt::get(Ty, 1), V); - return new ICmpInst(ICmpInst::ICMP_NE, V, ConstantInt::get(Ty, 0)); - } - - return 0; -} - - -Instruction *InstCombiner::visitFCmpInst(FCmpInst &I) { - bool Changed = false; - - /// Orders the operands of the compare so that they are listed from most - /// complex to least complex. This puts constants before unary operators, - /// before binary operators. - if (getComplexity(I.getOperand(0)) < getComplexity(I.getOperand(1))) { - I.swapOperands(); - Changed = true; - } - - Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); - - if (Value *V = SimplifyFCmpInst(I.getPredicate(), Op0, Op1, TD)) - return ReplaceInstUsesWith(I, V); - - // Simplify 'fcmp pred X, X' - if (Op0 == Op1) { - switch (I.getPredicate()) { - default: llvm_unreachable("Unknown predicate!"); - case FCmpInst::FCMP_UNO: // True if unordered: isnan(X) | isnan(Y) - case FCmpInst::FCMP_ULT: // True if unordered or less than - case FCmpInst::FCMP_UGT: // True if unordered or greater than - case FCmpInst::FCMP_UNE: // True if unordered or not equal - // Canonicalize these to be 'fcmp uno %X, 0.0'. - I.setPredicate(FCmpInst::FCMP_UNO); - I.setOperand(1, Constant::getNullValue(Op0->getType())); - return &I; - - case FCmpInst::FCMP_ORD: // True if ordered (no nans) - case FCmpInst::FCMP_OEQ: // True if ordered and equal - case FCmpInst::FCMP_OGE: // True if ordered and greater than or equal - case FCmpInst::FCMP_OLE: // True if ordered and less than or equal - // Canonicalize these to be 'fcmp ord %X, 0.0'. - I.setPredicate(FCmpInst::FCMP_ORD); - I.setOperand(1, Constant::getNullValue(Op0->getType())); - return &I; - } - } - - // Handle fcmp with constant RHS - if (Constant *RHSC = dyn_cast(Op1)) { - if (Instruction *LHSI = dyn_cast(Op0)) - switch (LHSI->getOpcode()) { - case Instruction::PHI: - // Only fold fcmp into the PHI if the phi and fcmp are in the same - // block. If in the same block, we're encouraging jump threading. If - // not, we are just pessimizing the code by making an i1 phi. - if (LHSI->getParent() == I.getParent()) - if (Instruction *NV = FoldOpIntoPhi(I, true)) - return NV; - break; - case Instruction::SIToFP: - case Instruction::UIToFP: - if (Instruction *NV = FoldFCmp_IntToFP_Cst(I, LHSI, RHSC)) - return NV; - break; - case Instruction::Select: { - // If either operand of the select is a constant, we can fold the - // comparison into the select arms, which will cause one to be - // constant folded and the select turned into a bitwise or. - Value *Op1 = 0, *Op2 = 0; - if (LHSI->hasOneUse()) { - if (Constant *C = dyn_cast(LHSI->getOperand(1))) { - // Fold the known value into the constant operand. - Op1 = ConstantExpr::getCompare(I.getPredicate(), C, RHSC); - // Insert a new FCmp of the other select operand. - Op2 = Builder->CreateFCmp(I.getPredicate(), - LHSI->getOperand(2), RHSC, I.getName()); - } else if (Constant *C = dyn_cast(LHSI->getOperand(2))) { - // Fold the known value into the constant operand. - Op2 = ConstantExpr::getCompare(I.getPredicate(), C, RHSC); - // Insert a new FCmp of the other select operand. - Op1 = Builder->CreateFCmp(I.getPredicate(), LHSI->getOperand(1), - RHSC, I.getName()); - } - } - - if (Op1) - return SelectInst::Create(LHSI->getOperand(0), Op1, Op2); - break; - } - case Instruction::Load: - if (GetElementPtrInst *GEP = - dyn_cast(LHSI->getOperand(0))) { - if (GlobalVariable *GV = dyn_cast(GEP->getOperand(0))) - if (GV->isConstant() && GV->hasDefinitiveInitializer() && - !cast(LHSI)->isVolatile()) - if (Instruction *Res = FoldCmpLoadFromIndexedGlobal(GEP, GV, I)) - return Res; - } - break; - } - } - - return Changed ? &I : 0; -} - -Instruction *InstCombiner::visitICmpInst(ICmpInst &I) { - bool Changed = false; - - /// Orders the operands of the compare so that they are listed from most - /// complex to least complex. This puts constants before unary operators, - /// before binary operators. - if (getComplexity(I.getOperand(0)) < getComplexity(I.getOperand(1))) { - I.swapOperands(); - Changed = true; - } - - Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); - - if (Value *V = SimplifyICmpInst(I.getPredicate(), Op0, Op1, TD)) - return ReplaceInstUsesWith(I, V); - - const Type *Ty = Op0->getType(); - - // icmp's with boolean values can always be turned into bitwise operations - if (Ty == Type::getInt1Ty(I.getContext())) { - switch (I.getPredicate()) { - default: llvm_unreachable("Invalid icmp instruction!"); - case ICmpInst::ICMP_EQ: { // icmp eq i1 A, B -> ~(A^B) - Value *Xor = Builder->CreateXor(Op0, Op1, I.getName()+"tmp"); - return BinaryOperator::CreateNot(Xor); - } - case ICmpInst::ICMP_NE: // icmp eq i1 A, B -> A^B - return BinaryOperator::CreateXor(Op0, Op1); - - case ICmpInst::ICMP_UGT: - std::swap(Op0, Op1); // Change icmp ugt -> icmp ult - // FALL THROUGH - case ICmpInst::ICMP_ULT:{ // icmp ult i1 A, B -> ~A & B - Value *Not = Builder->CreateNot(Op0, I.getName()+"tmp"); - return BinaryOperator::CreateAnd(Not, Op1); - } - case ICmpInst::ICMP_SGT: - std::swap(Op0, Op1); // Change icmp sgt -> icmp slt - // FALL THROUGH - case ICmpInst::ICMP_SLT: { // icmp slt i1 A, B -> A & ~B - Value *Not = Builder->CreateNot(Op1, I.getName()+"tmp"); - return BinaryOperator::CreateAnd(Not, Op0); - } - case ICmpInst::ICMP_UGE: - std::swap(Op0, Op1); // Change icmp uge -> icmp ule - // FALL THROUGH - case ICmpInst::ICMP_ULE: { // icmp ule i1 A, B -> ~A | B - Value *Not = Builder->CreateNot(Op0, I.getName()+"tmp"); - return BinaryOperator::CreateOr(Not, Op1); - } - case ICmpInst::ICMP_SGE: - std::swap(Op0, Op1); // Change icmp sge -> icmp sle - // FALL THROUGH - case ICmpInst::ICMP_SLE: { // icmp sle i1 A, B -> A | ~B - Value *Not = Builder->CreateNot(Op1, I.getName()+"tmp"); - return BinaryOperator::CreateOr(Not, Op0); - } - } - } - - unsigned BitWidth = 0; - if (TD) - BitWidth = TD->getTypeSizeInBits(Ty->getScalarType()); - else if (Ty->isIntOrIntVector()) - BitWidth = Ty->getScalarSizeInBits(); - - bool isSignBit = false; - - // See if we are doing a comparison with a constant. - if (ConstantInt *CI = dyn_cast(Op1)) { - Value *A = 0, *B = 0; - - // (icmp ne/eq (sub A B) 0) -> (icmp ne/eq A, B) - if (I.isEquality() && CI->isZero() && - match(Op0, m_Sub(m_Value(A), m_Value(B)))) { - // (icmp cond A B) if cond is equality - return new ICmpInst(I.getPredicate(), A, B); - } - - // If we have an icmp le or icmp ge instruction, turn it into the - // appropriate icmp lt or icmp gt instruction. This allows us to rely on - // them being folded in the code below. The SimplifyICmpInst code has - // already handled the edge cases for us, so we just assert on them. - switch (I.getPredicate()) { - default: break; - case ICmpInst::ICMP_ULE: - assert(!CI->isMaxValue(false)); // A <=u MAX -> TRUE - return new ICmpInst(ICmpInst::ICMP_ULT, Op0, - AddOne(CI)); - case ICmpInst::ICMP_SLE: - assert(!CI->isMaxValue(true)); // A <=s MAX -> TRUE - return new ICmpInst(ICmpInst::ICMP_SLT, Op0, - AddOne(CI)); - case ICmpInst::ICMP_UGE: - assert(!CI->isMinValue(false)); // A >=u MIN -> TRUE - return new ICmpInst(ICmpInst::ICMP_UGT, Op0, - SubOne(CI)); - case ICmpInst::ICMP_SGE: - assert(!CI->isMinValue(true)); // A >=s MIN -> TRUE - return new ICmpInst(ICmpInst::ICMP_SGT, Op0, - SubOne(CI)); - } - - // If this comparison is a normal comparison, it demands all - // bits, if it is a sign bit comparison, it only demands the sign bit. - bool UnusedBit; - isSignBit = isSignBitCheck(I.getPredicate(), CI, UnusedBit); - } - - // See if we can fold the comparison based on range information we can get - // by checking whether bits are known to be zero or one in the input. - if (BitWidth != 0) { - APInt Op0KnownZero(BitWidth, 0), Op0KnownOne(BitWidth, 0); - APInt Op1KnownZero(BitWidth, 0), Op1KnownOne(BitWidth, 0); - - if (SimplifyDemandedBits(I.getOperandUse(0), - isSignBit ? APInt::getSignBit(BitWidth) - : APInt::getAllOnesValue(BitWidth), - Op0KnownZero, Op0KnownOne, 0)) - return &I; - if (SimplifyDemandedBits(I.getOperandUse(1), - APInt::getAllOnesValue(BitWidth), - Op1KnownZero, Op1KnownOne, 0)) - return &I; - - // Given the known and unknown bits, compute a range that the LHS could be - // in. Compute the Min, Max and RHS values based on the known bits. For the - // EQ and NE we use unsigned values. - APInt Op0Min(BitWidth, 0), Op0Max(BitWidth, 0); - APInt Op1Min(BitWidth, 0), Op1Max(BitWidth, 0); - if (I.isSigned()) { - ComputeSignedMinMaxValuesFromKnownBits(Op0KnownZero, Op0KnownOne, - Op0Min, Op0Max); - ComputeSignedMinMaxValuesFromKnownBits(Op1KnownZero, Op1KnownOne, - Op1Min, Op1Max); - } else { - ComputeUnsignedMinMaxValuesFromKnownBits(Op0KnownZero, Op0KnownOne, - Op0Min, Op0Max); - ComputeUnsignedMinMaxValuesFromKnownBits(Op1KnownZero, Op1KnownOne, - Op1Min, Op1Max); - } - - // If Min and Max are known to be the same, then SimplifyDemandedBits - // figured out that the LHS is a constant. Just constant fold this now so - // that code below can assume that Min != Max. - if (!isa(Op0) && Op0Min == Op0Max) - return new ICmpInst(I.getPredicate(), - ConstantInt::get(I.getContext(), Op0Min), Op1); - if (!isa(Op1) && Op1Min == Op1Max) - return new ICmpInst(I.getPredicate(), Op0, - ConstantInt::get(I.getContext(), Op1Min)); - - // Based on the range information we know about the LHS, see if we can - // simplify this comparison. For example, (x&4) < 8 is always true. - switch (I.getPredicate()) { - default: llvm_unreachable("Unknown icmp opcode!"); - case ICmpInst::ICMP_EQ: - if (Op0Max.ult(Op1Min) || Op0Min.ugt(Op1Max)) - return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext())); - break; - case ICmpInst::ICMP_NE: - if (Op0Max.ult(Op1Min) || Op0Min.ugt(Op1Max)) - return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext())); - break; - case ICmpInst::ICMP_ULT: - if (Op0Max.ult(Op1Min)) // A true if max(A) < min(B) - return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext())); - if (Op0Min.uge(Op1Max)) // A false if min(A) >= max(B) - return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext())); - if (Op1Min == Op0Max) // A A != B if max(A) == min(B) - return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1); - if (ConstantInt *CI = dyn_cast(Op1)) { - if (Op1Max == Op0Min+1) // A A == C-1 if min(A)+1 == C - return new ICmpInst(ICmpInst::ICMP_EQ, Op0, - SubOne(CI)); - - // (x (x >s -1) -> true if sign bit clear - if (CI->isMinValue(true)) - return new ICmpInst(ICmpInst::ICMP_SGT, Op0, - Constant::getAllOnesValue(Op0->getType())); - } - break; - case ICmpInst::ICMP_UGT: - if (Op0Min.ugt(Op1Max)) // A >u B -> true if min(A) > max(B) - return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext())); - if (Op0Max.ule(Op1Min)) // A >u B -> false if max(A) <= max(B) - return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext())); - - if (Op1Max == Op0Min) // A >u B -> A != B if min(A) == max(B) - return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1); - if (ConstantInt *CI = dyn_cast(Op1)) { - if (Op1Min == Op0Max-1) // A >u C -> A == C+1 if max(a)-1 == C - return new ICmpInst(ICmpInst::ICMP_EQ, Op0, - AddOne(CI)); - - // (x >u 2147483647) -> (x true if sign bit set - if (CI->isMaxValue(true)) - return new ICmpInst(ICmpInst::ICMP_SLT, Op0, - Constant::getNullValue(Op0->getType())); - } - break; - case ICmpInst::ICMP_SLT: - if (Op0Max.slt(Op1Min)) // A true if max(A) < min(C) - return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext())); - if (Op0Min.sge(Op1Max)) // A false if min(A) >= max(C) - return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext())); - if (Op1Min == Op0Max) // A A != B if max(A) == min(B) - return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1); - if (ConstantInt *CI = dyn_cast(Op1)) { - if (Op1Max == Op0Min+1) // A A == C-1 if min(A)+1 == C - return new ICmpInst(ICmpInst::ICMP_EQ, Op0, - SubOne(CI)); - } - break; - case ICmpInst::ICMP_SGT: - if (Op0Min.sgt(Op1Max)) // A >s B -> true if min(A) > max(B) - return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext())); - if (Op0Max.sle(Op1Min)) // A >s B -> false if max(A) <= min(B) - return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext())); - - if (Op1Max == Op0Min) // A >s B -> A != B if min(A) == max(B) - return new ICmpInst(ICmpInst::ICMP_NE, Op0, Op1); - if (ConstantInt *CI = dyn_cast(Op1)) { - if (Op1Min == Op0Max-1) // A >s C -> A == C+1 if max(A)-1 == C - return new ICmpInst(ICmpInst::ICMP_EQ, Op0, - AddOne(CI)); - } - break; - case ICmpInst::ICMP_SGE: - assert(!isa(Op1) && "ICMP_SGE with ConstantInt not folded!"); - if (Op0Min.sge(Op1Max)) // A >=s B -> true if min(A) >= max(B) - return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext())); - if (Op0Max.slt(Op1Min)) // A >=s B -> false if max(A) < min(B) - return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext())); - break; - case ICmpInst::ICMP_SLE: - assert(!isa(Op1) && "ICMP_SLE with ConstantInt not folded!"); - if (Op0Max.sle(Op1Min)) // A <=s B -> true if max(A) <= min(B) - return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext())); - if (Op0Min.sgt(Op1Max)) // A <=s B -> false if min(A) > max(B) - return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext())); - break; - case ICmpInst::ICMP_UGE: - assert(!isa(Op1) && "ICMP_UGE with ConstantInt not folded!"); - if (Op0Min.uge(Op1Max)) // A >=u B -> true if min(A) >= max(B) - return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext())); - if (Op0Max.ult(Op1Min)) // A >=u B -> false if max(A) < min(B) - return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext())); - break; - case ICmpInst::ICMP_ULE: - assert(!isa(Op1) && "ICMP_ULE with ConstantInt not folded!"); - if (Op0Max.ule(Op1Min)) // A <=u B -> true if max(A) <= min(B) - return ReplaceInstUsesWith(I, ConstantInt::getTrue(I.getContext())); - if (Op0Min.ugt(Op1Max)) // A <=u B -> false if min(A) > max(B) - return ReplaceInstUsesWith(I, ConstantInt::getFalse(I.getContext())); - break; - } - - // Turn a signed comparison into an unsigned one if both operands - // are known to have the same sign. - if (I.isSigned() && - ((Op0KnownZero.isNegative() && Op1KnownZero.isNegative()) || - (Op0KnownOne.isNegative() && Op1KnownOne.isNegative()))) - return new ICmpInst(I.getUnsignedPredicate(), Op0, Op1); - } - - // Test if the ICmpInst instruction is used exclusively by a select as - // part of a minimum or maximum operation. If so, refrain from doing - // any other folding. This helps out other analyses which understand - // non-obfuscated minimum and maximum idioms, such as ScalarEvolution - // and CodeGen. And in this case, at least one of the comparison - // operands has at least one user besides the compare (the select), - // which would often largely negate the benefit of folding anyway. - if (I.hasOneUse()) - if (SelectInst *SI = dyn_cast(*I.use_begin())) - if ((SI->getOperand(1) == Op0 && SI->getOperand(2) == Op1) || - (SI->getOperand(2) == Op0 && SI->getOperand(1) == Op1)) - return 0; - - // See if we are doing a comparison between a constant and an instruction that - // can be folded into the comparison. - if (ConstantInt *CI = dyn_cast(Op1)) { - // Since the RHS is a ConstantInt (CI), if the left hand side is an - // instruction, see if that instruction also has constants so that the - // instruction can be folded into the icmp - if (Instruction *LHSI = dyn_cast(Op0)) - if (Instruction *Res = visitICmpInstWithInstAndIntCst(I, LHSI, CI)) - return Res; - } - - // Handle icmp with constant (but not simple integer constant) RHS - if (Constant *RHSC = dyn_cast(Op1)) { - if (Instruction *LHSI = dyn_cast(Op0)) - switch (LHSI->getOpcode()) { - case Instruction::GetElementPtr: - // icmp pred GEP (P, int 0, int 0, int 0), null -> icmp pred P, null - if (RHSC->isNullValue() && - cast(LHSI)->hasAllZeroIndices()) - return new ICmpInst(I.getPredicate(), LHSI->getOperand(0), - Constant::getNullValue(LHSI->getOperand(0)->getType())); - break; - case Instruction::PHI: - // Only fold icmp into the PHI if the phi and icmp are in the same - // block. If in the same block, we're encouraging jump threading. If - // not, we are just pessimizing the code by making an i1 phi. - if (LHSI->getParent() == I.getParent()) - if (Instruction *NV = FoldOpIntoPhi(I, true)) - return NV; - break; - case Instruction::Select: { - // If either operand of the select is a constant, we can fold the - // comparison into the select arms, which will cause one to be - // constant folded and the select turned into a bitwise or. - Value *Op1 = 0, *Op2 = 0; - if (Constant *C = dyn_cast(LHSI->getOperand(1))) - Op1 = ConstantExpr::getICmp(I.getPredicate(), C, RHSC); - if (Constant *C = dyn_cast(LHSI->getOperand(2))) - Op2 = ConstantExpr::getICmp(I.getPredicate(), C, RHSC); - - // We only want to perform this transformation if it will not lead to - // additional code. This is true if either both sides of the select - // fold to a constant (in which case the icmp is replaced with a select - // which will usually simplify) or this is the only user of the - // select (in which case we are trading a select+icmp for a simpler - // select+icmp). - if ((Op1 && Op2) || (LHSI->hasOneUse() && (Op1 || Op2))) { - if (!Op1) - Op1 = Builder->CreateICmp(I.getPredicate(), LHSI->getOperand(1), - RHSC, I.getName()); - if (!Op2) - Op2 = Builder->CreateICmp(I.getPredicate(), LHSI->getOperand(2), - RHSC, I.getName()); - return SelectInst::Create(LHSI->getOperand(0), Op1, Op2); - } - break; - } - case Instruction::Call: - // If we have (malloc != null), and if the malloc has a single use, we - // can assume it is successful and remove the malloc. - if (isMalloc(LHSI) && LHSI->hasOneUse() && - isa(RHSC)) { - // Need to explicitly erase malloc call here, instead of adding it to - // Worklist, because it won't get DCE'd from the Worklist since - // isInstructionTriviallyDead() returns false for function calls. - // It is OK to replace LHSI/MallocCall with Undef because the - // instruction that uses it will be erased via Worklist. - if (extractMallocCall(LHSI)) { - LHSI->replaceAllUsesWith(UndefValue::get(LHSI->getType())); - EraseInstFromFunction(*LHSI); - return ReplaceInstUsesWith(I, - ConstantInt::get(Type::getInt1Ty(I.getContext()), - !I.isTrueWhenEqual())); - } - if (CallInst* MallocCall = extractMallocCallFromBitCast(LHSI)) - if (MallocCall->hasOneUse()) { - MallocCall->replaceAllUsesWith( - UndefValue::get(MallocCall->getType())); - EraseInstFromFunction(*MallocCall); - Worklist.Add(LHSI); // The malloc's bitcast use. - return ReplaceInstUsesWith(I, - ConstantInt::get(Type::getInt1Ty(I.getContext()), - !I.isTrueWhenEqual())); - } - } - break; - case Instruction::IntToPtr: - // icmp pred inttoptr(X), null -> icmp pred X, 0 - if (RHSC->isNullValue() && TD && - TD->getIntPtrType(RHSC->getContext()) == - LHSI->getOperand(0)->getType()) - return new ICmpInst(I.getPredicate(), LHSI->getOperand(0), - Constant::getNullValue(LHSI->getOperand(0)->getType())); - break; - - case Instruction::Load: - // Try to optimize things like "A[i] > 4" to index computations. - if (GetElementPtrInst *GEP = - dyn_cast(LHSI->getOperand(0))) { - if (GlobalVariable *GV = dyn_cast(GEP->getOperand(0))) - if (GV->isConstant() && GV->hasDefinitiveInitializer() && - !cast(LHSI)->isVolatile()) - if (Instruction *Res = FoldCmpLoadFromIndexedGlobal(GEP, GV, I)) - return Res; - } - break; - } - } - - // If we can optimize a 'icmp GEP, P' or 'icmp P, GEP', do so now. - if (GEPOperator *GEP = dyn_cast(Op0)) - if (Instruction *NI = FoldGEPICmp(GEP, Op1, I.getPredicate(), I)) - return NI; - if (GEPOperator *GEP = dyn_cast(Op1)) - if (Instruction *NI = FoldGEPICmp(GEP, Op0, - ICmpInst::getSwappedPredicate(I.getPredicate()), I)) - return NI; - - // Test to see if the operands of the icmp are casted versions of other - // values. If the ptr->ptr cast can be stripped off both arguments, we do so - // now. - if (BitCastInst *CI = dyn_cast(Op0)) { - if (isa(Op0->getType()) && - (isa(Op1) || isa(Op1))) { - // We keep moving the cast from the left operand over to the right - // operand, where it can often be eliminated completely. - Op0 = CI->getOperand(0); - - // If operand #1 is a bitcast instruction, it must also be a ptr->ptr cast - // so eliminate it as well. - if (BitCastInst *CI2 = dyn_cast(Op1)) - Op1 = CI2->getOperand(0); - - // If Op1 is a constant, we can fold the cast into the constant. - if (Op0->getType() != Op1->getType()) { - if (Constant *Op1C = dyn_cast(Op1)) { - Op1 = ConstantExpr::getBitCast(Op1C, Op0->getType()); - } else { - // Otherwise, cast the RHS right before the icmp - Op1 = Builder->CreateBitCast(Op1, Op0->getType()); - } - } - return new ICmpInst(I.getPredicate(), Op0, Op1); - } - } - - if (isa(Op0)) { - // Handle the special case of: icmp (cast bool to X), - // This comes up when you have code like - // int X = A < B; - // if (X) ... - // For generality, we handle any zero-extension of any operand comparison - // with a constant or another cast from the same type. - if (isa(Op1) || isa(Op1)) - if (Instruction *R = visitICmpInstWithCastAndCast(I)) - return R; - } - - // See if it's the same type of instruction on the left and right. - if (BinaryOperator *Op0I = dyn_cast(Op0)) { - if (BinaryOperator *Op1I = dyn_cast(Op1)) { - if (Op0I->getOpcode() == Op1I->getOpcode() && Op0I->hasOneUse() && - Op1I->hasOneUse() && Op0I->getOperand(1) == Op1I->getOperand(1)) { - switch (Op0I->getOpcode()) { - default: break; - case Instruction::Add: - case Instruction::Sub: - case Instruction::Xor: - if (I.isEquality()) // a+x icmp eq/ne b+x --> a icmp b - return new ICmpInst(I.getPredicate(), Op0I->getOperand(0), - Op1I->getOperand(0)); - // icmp u/s (a ^ signbit), (b ^ signbit) --> icmp s/u a, b - if (ConstantInt *CI = dyn_cast(Op0I->getOperand(1))) { - if (CI->getValue().isSignBit()) { - ICmpInst::Predicate Pred = I.isSigned() - ? I.getUnsignedPredicate() - : I.getSignedPredicate(); - return new ICmpInst(Pred, Op0I->getOperand(0), - Op1I->getOperand(0)); - } - - if (CI->getValue().isMaxSignedValue()) { - ICmpInst::Predicate Pred = I.isSigned() - ? I.getUnsignedPredicate() - : I.getSignedPredicate(); - Pred = I.getSwappedPredicate(Pred); - return new ICmpInst(Pred, Op0I->getOperand(0), - Op1I->getOperand(0)); - } - } - break; - case Instruction::Mul: - if (!I.isEquality()) - break; - - if (ConstantInt *CI = dyn_cast(Op0I->getOperand(1))) { - // a * Cst icmp eq/ne b * Cst --> a & Mask icmp b & Mask - // Mask = -1 >> count-trailing-zeros(Cst). - if (!CI->isZero() && !CI->isOne()) { - const APInt &AP = CI->getValue(); - ConstantInt *Mask = ConstantInt::get(I.getContext(), - APInt::getLowBitsSet(AP.getBitWidth(), - AP.getBitWidth() - - AP.countTrailingZeros())); - Value *And1 = Builder->CreateAnd(Op0I->getOperand(0), Mask); - Value *And2 = Builder->CreateAnd(Op1I->getOperand(0), Mask); - return new ICmpInst(I.getPredicate(), And1, And2); - } - } - break; - } - } - } - } - - // ~x < ~y --> y < x - { Value *A, *B; - if (match(Op0, m_Not(m_Value(A))) && - match(Op1, m_Not(m_Value(B)))) - return new ICmpInst(I.getPredicate(), B, A); - } - - if (I.isEquality()) { - Value *A, *B, *C, *D; - - // -x == -y --> x == y - if (match(Op0, m_Neg(m_Value(A))) && - match(Op1, m_Neg(m_Value(B)))) - return new ICmpInst(I.getPredicate(), A, B); - - if (match(Op0, m_Xor(m_Value(A), m_Value(B)))) { - if (A == Op1 || B == Op1) { // (A^B) == A -> B == 0 - Value *OtherVal = A == Op1 ? B : A; - return new ICmpInst(I.getPredicate(), OtherVal, - Constant::getNullValue(A->getType())); - } - - if (match(Op1, m_Xor(m_Value(C), m_Value(D)))) { - // A^c1 == C^c2 --> A == C^(c1^c2) - ConstantInt *C1, *C2; - if (match(B, m_ConstantInt(C1)) && - match(D, m_ConstantInt(C2)) && Op1->hasOneUse()) { - Constant *NC = ConstantInt::get(I.getContext(), - C1->getValue() ^ C2->getValue()); - Value *Xor = Builder->CreateXor(C, NC, "tmp"); - return new ICmpInst(I.getPredicate(), A, Xor); - } - - // A^B == A^D -> B == D - if (A == C) return new ICmpInst(I.getPredicate(), B, D); - if (A == D) return new ICmpInst(I.getPredicate(), B, C); - if (B == C) return new ICmpInst(I.getPredicate(), A, D); - if (B == D) return new ICmpInst(I.getPredicate(), A, C); - } - } - - if (match(Op1, m_Xor(m_Value(A), m_Value(B))) && - (A == Op0 || B == Op0)) { - // A == (A^B) -> B == 0 - Value *OtherVal = A == Op0 ? B : A; - return new ICmpInst(I.getPredicate(), OtherVal, - Constant::getNullValue(A->getType())); - } - - // (A-B) == A -> B == 0 - if (match(Op0, m_Sub(m_Specific(Op1), m_Value(B)))) - return new ICmpInst(I.getPredicate(), B, - Constant::getNullValue(B->getType())); - - // A == (A-B) -> B == 0 - if (match(Op1, m_Sub(m_Specific(Op0), m_Value(B)))) - return new ICmpInst(I.getPredicate(), B, - Constant::getNullValue(B->getType())); - - // (X&Z) == (Y&Z) -> (X^Y) & Z == 0 - if (Op0->hasOneUse() && Op1->hasOneUse() && - match(Op0, m_And(m_Value(A), m_Value(B))) && - match(Op1, m_And(m_Value(C), m_Value(D)))) { - Value *X = 0, *Y = 0, *Z = 0; - - if (A == C) { - X = B; Y = D; Z = A; - } else if (A == D) { - X = B; Y = C; Z = A; - } else if (B == C) { - X = A; Y = D; Z = B; - } else if (B == D) { - X = A; Y = C; Z = B; - } - - if (X) { // Build (X^Y) & Z - Op1 = Builder->CreateXor(X, Y, "tmp"); - Op1 = Builder->CreateAnd(Op1, Z, "tmp"); - I.setOperand(0, Op1); - I.setOperand(1, Constant::getNullValue(Op1->getType())); - return &I; - } - } - } - - { - Value *X; ConstantInt *Cst; - // icmp X+Cst, X - if (match(Op0, m_Add(m_Value(X), m_ConstantInt(Cst))) && Op1 == X) - return FoldICmpAddOpCst(I, X, Cst, I.getPredicate(), Op0); - - // icmp X, X+Cst - if (match(Op1, m_Add(m_Value(X), m_ConstantInt(Cst))) && Op0 == X) - return FoldICmpAddOpCst(I, X, Cst, I.getSwappedPredicate(), Op1); - } - return Changed ? &I : 0; -} - -/// FoldICmpAddOpCst - Fold "icmp pred (X+CI), X". -Instruction *InstCombiner::FoldICmpAddOpCst(ICmpInst &ICI, - Value *X, ConstantInt *CI, - ICmpInst::Predicate Pred, - Value *TheAdd) { - // If we have X+0, exit early (simplifying logic below) and let it get folded - // elsewhere. icmp X+0, X -> icmp X, X - if (CI->isZero()) { - bool isTrue = ICmpInst::isTrueWhenEqual(Pred); - return ReplaceInstUsesWith(ICI, ConstantInt::get(ICI.getType(), isTrue)); - } - - // (X+4) == X -> false. - if (Pred == ICmpInst::ICMP_EQ) - return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(X->getContext())); - - // (X+4) != X -> true. - if (Pred == ICmpInst::ICMP_NE) - return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(X->getContext())); - - // If this is an instruction (as opposed to constantexpr) get NUW/NSW info. - bool isNUW = false, isNSW = false; - if (BinaryOperator *Add = dyn_cast(TheAdd)) { - isNUW = Add->hasNoUnsignedWrap(); - isNSW = Add->hasNoSignedWrap(); - } - - // From this point on, we know that (X+C <= X) --> (X+C < X) because C != 0, - // so the values can never be equal. Similiarly for all other "or equals" - // operators. - - // (X+1) X >u (MAXUINT-1) --> X != 255 - // (X+2) X >u (MAXUINT-2) --> X > 253 - // (X+MAXUINT) X >u (MAXUINT-MAXUINT) --> X != 0 - if (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_ULE) { - // If this is an NUW add, then this is always false. - if (isNUW) - return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(X->getContext())); - - Value *R = ConstantExpr::getSub(ConstantInt::get(CI->getType(), -1ULL), CI); - return new ICmpInst(ICmpInst::ICMP_UGT, X, R); - } - - // (X+1) >u X --> X X != 255 - // (X+2) >u X --> X X u X --> X X X == 0 - if (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_UGE) { - // If this is an NUW add, then this is always true. - if (isNUW) - return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(X->getContext())); - return new ICmpInst(ICmpInst::ICMP_ULT, X, ConstantExpr::getNeg(CI)); - } - - unsigned BitWidth = CI->getType()->getPrimitiveSizeInBits(); - ConstantInt *SMax = ConstantInt::get(X->getContext(), - APInt::getSignedMaxValue(BitWidth)); - - // (X+ 1) X >s (MAXSINT-1) --> X == 127 - // (X+ 2) X >s (MAXSINT-2) --> X >s 125 - // (X+MAXSINT) X >s (MAXSINT-MAXSINT) --> X >s 0 - // (X+MINSINT) X >s (MAXSINT-MINSINT) --> X >s -1 - // (X+ -2) X >s (MAXSINT- -2) --> X >s 126 - // (X+ -1) X >s (MAXSINT- -1) --> X != 127 - if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SLE) { - // If this is an NSW add, then we have two cases: if the constant is - // positive, then this is always false, if negative, this is always true. - if (isNSW) { - bool isTrue = CI->getValue().isNegative(); - return ReplaceInstUsesWith(ICI, ConstantInt::get(ICI.getType(), isTrue)); - } - - return new ICmpInst(ICmpInst::ICMP_SGT, X, ConstantExpr::getSub(SMax, CI)); - } - - // (X+ 1) >s X --> X X != 127 - // (X+ 2) >s X --> X X s X --> X X s X --> X X s X --> X X s X --> X X == -128 - - // If this is an NSW add, then we have two cases: if the constant is - // positive, then this is always true, if negative, this is always false. - if (isNSW) { - bool isTrue = !CI->getValue().isNegative(); - return ReplaceInstUsesWith(ICI, ConstantInt::get(ICI.getType(), isTrue)); - } - - assert(Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SGE); - Constant *C = ConstantInt::get(X->getContext(), CI->getValue()-1); - return new ICmpInst(ICmpInst::ICMP_SLT, X, ConstantExpr::getSub(SMax, C)); -} - -/// FoldICmpDivCst - Fold "icmp pred, ([su]div X, DivRHS), CmpRHS" where DivRHS -/// and CmpRHS are both known to be integer constants. -Instruction *InstCombiner::FoldICmpDivCst(ICmpInst &ICI, BinaryOperator *DivI, - ConstantInt *DivRHS) { - ConstantInt *CmpRHS = cast(ICI.getOperand(1)); - const APInt &CmpRHSV = CmpRHS->getValue(); - - // FIXME: If the operand types don't match the type of the divide - // then don't attempt this transform. The code below doesn't have the - // logic to deal with a signed divide and an unsigned compare (and - // vice versa). This is because (x /s C1) getOpcode() == Instruction::SDiv; - if (!ICI.isEquality() && DivIsSigned != ICI.isSigned()) - return 0; - if (DivRHS->isZero()) - return 0; // The ProdOV computation fails on divide by zero. - if (DivIsSigned && DivRHS->isAllOnesValue()) - return 0; // The overflow computation also screws up here - if (DivRHS->isOne()) - return 0; // Not worth bothering, and eliminates some funny cases - // with INT_MIN. - - // Compute Prod = CI * DivRHS. We are essentially solving an equation - // of form X/C1=C2. We solve for X by multiplying C1 (DivRHS) and - // C2 (CI). By solving for X we can turn this into a range check - // instead of computing a divide. - Constant *Prod = ConstantExpr::getMul(CmpRHS, DivRHS); - - // Determine if the product overflows by seeing if the product is - // not equal to the divide. Make sure we do the same kind of divide - // as in the LHS instruction that we're folding. - bool ProdOV = (DivIsSigned ? ConstantExpr::getSDiv(Prod, DivRHS) : - ConstantExpr::getUDiv(Prod, DivRHS)) != CmpRHS; - - // Get the ICmp opcode - ICmpInst::Predicate Pred = ICI.getPredicate(); - - // Figure out the interval that is being checked. For example, a comparison - // like "X /u 5 == 0" is really checking that X is in the interval [0, 5). - // Compute this interval based on the constants involved and the signedness of - // the compare/divide. This computes a half-open interval, keeping track of - // whether either value in the interval overflows. After analysis each - // overflow variable is set to 0 if it's corresponding bound variable is valid - // -1 if overflowed off the bottom end, or +1 if overflowed off the top end. - int LoOverflow = 0, HiOverflow = 0; - Constant *LoBound = 0, *HiBound = 0; - - if (!DivIsSigned) { // udiv - // e.g. X/5 op 3 --> [15, 20) - LoBound = Prod; - HiOverflow = LoOverflow = ProdOV; - if (!HiOverflow) - HiOverflow = AddWithOverflow(HiBound, LoBound, DivRHS, false); - } else if (DivRHS->getValue().isStrictlyPositive()) { // Divisor is > 0. - if (CmpRHSV == 0) { // (X / pos) op 0 - // Can't overflow. e.g. X/2 op 0 --> [-1, 2) - LoBound = cast(ConstantExpr::getNeg(SubOne(DivRHS))); - HiBound = DivRHS; - } else if (CmpRHSV.isStrictlyPositive()) { // (X / pos) op pos - LoBound = Prod; // e.g. X/5 op 3 --> [15, 20) - HiOverflow = LoOverflow = ProdOV; - if (!HiOverflow) - HiOverflow = AddWithOverflow(HiBound, Prod, DivRHS, true); - } else { // (X / pos) op neg - // e.g. X/5 op -3 --> [-15-4, -15+1) --> [-19, -14) - HiBound = AddOne(Prod); - LoOverflow = HiOverflow = ProdOV ? -1 : 0; - if (!LoOverflow) { - ConstantInt* DivNeg = - cast(ConstantExpr::getNeg(DivRHS)); - LoOverflow = AddWithOverflow(LoBound, HiBound, DivNeg, true) ? -1 : 0; - } - } - } else if (DivRHS->getValue().isNegative()) { // Divisor is < 0. - if (CmpRHSV == 0) { // (X / neg) op 0 - // e.g. X/-5 op 0 --> [-4, 5) - LoBound = AddOne(DivRHS); - HiBound = cast(ConstantExpr::getNeg(DivRHS)); - if (HiBound == DivRHS) { // -INTMIN = INTMIN - HiOverflow = 1; // [INTMIN+1, overflow) - HiBound = 0; // e.g. X/INTMIN = 0 --> X > INTMIN - } - } else if (CmpRHSV.isStrictlyPositive()) { // (X / neg) op pos - // e.g. X/-5 op 3 --> [-19, -14) - HiBound = AddOne(Prod); - HiOverflow = LoOverflow = ProdOV ? -1 : 0; - if (!LoOverflow) - LoOverflow = AddWithOverflow(LoBound, HiBound, DivRHS, true) ? -1 : 0; - } else { // (X / neg) op neg - LoBound = Prod; // e.g. X/-5 op -3 --> [15, 20) - LoOverflow = HiOverflow = ProdOV; - if (!HiOverflow) - HiOverflow = SubWithOverflow(HiBound, Prod, DivRHS, true); - } - - // Dividing by a negative swaps the condition. LT <-> GT - Pred = ICmpInst::getSwappedPredicate(Pred); - } - - Value *X = DivI->getOperand(0); - switch (Pred) { - default: llvm_unreachable("Unhandled icmp opcode!"); - case ICmpInst::ICMP_EQ: - if (LoOverflow && HiOverflow) - return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(ICI.getContext())); - else if (HiOverflow) - return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SGE : - ICmpInst::ICMP_UGE, X, LoBound); - else if (LoOverflow) - return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SLT : - ICmpInst::ICMP_ULT, X, HiBound); - else - return InsertRangeTest(X, LoBound, HiBound, DivIsSigned, true, ICI); - case ICmpInst::ICMP_NE: - if (LoOverflow && HiOverflow) - return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(ICI.getContext())); - else if (HiOverflow) - return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SLT : - ICmpInst::ICMP_ULT, X, LoBound); - else if (LoOverflow) - return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SGE : - ICmpInst::ICMP_UGE, X, HiBound); - else - return InsertRangeTest(X, LoBound, HiBound, DivIsSigned, false, ICI); - case ICmpInst::ICMP_ULT: - case ICmpInst::ICMP_SLT: - if (LoOverflow == +1) // Low bound is greater than input range. - return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(ICI.getContext())); - if (LoOverflow == -1) // Low bound is less than input range. - return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(ICI.getContext())); - return new ICmpInst(Pred, X, LoBound); - case ICmpInst::ICMP_UGT: - case ICmpInst::ICMP_SGT: - if (HiOverflow == +1) // High bound greater than input range. - return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(ICI.getContext())); - else if (HiOverflow == -1) // High bound less than input range. - return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(ICI.getContext())); - if (Pred == ICmpInst::ICMP_UGT) - return new ICmpInst(ICmpInst::ICMP_UGE, X, HiBound); - else - return new ICmpInst(ICmpInst::ICMP_SGE, X, HiBound); - } -} - - -/// visitICmpInstWithInstAndIntCst - Handle "icmp (instr, intcst)". -/// -Instruction *InstCombiner::visitICmpInstWithInstAndIntCst(ICmpInst &ICI, - Instruction *LHSI, - ConstantInt *RHS) { - const APInt &RHSV = RHS->getValue(); - - switch (LHSI->getOpcode()) { - case Instruction::Trunc: - if (ICI.isEquality() && LHSI->hasOneUse()) { - // Simplify icmp eq (trunc x to i8), 42 -> icmp eq x, 42|highbits if all - // of the high bits truncated out of x are known. - unsigned DstBits = LHSI->getType()->getPrimitiveSizeInBits(), - SrcBits = LHSI->getOperand(0)->getType()->getPrimitiveSizeInBits(); - APInt Mask(APInt::getHighBitsSet(SrcBits, SrcBits-DstBits)); - APInt KnownZero(SrcBits, 0), KnownOne(SrcBits, 0); - ComputeMaskedBits(LHSI->getOperand(0), Mask, KnownZero, KnownOne); - - // If all the high bits are known, we can do this xform. - if ((KnownZero|KnownOne).countLeadingOnes() >= SrcBits-DstBits) { - // Pull in the high bits from known-ones set. - APInt NewRHS(RHS->getValue()); - NewRHS.zext(SrcBits); - NewRHS |= KnownOne; - return new ICmpInst(ICI.getPredicate(), LHSI->getOperand(0), - ConstantInt::get(ICI.getContext(), NewRHS)); - } - } - break; - - case Instruction::Xor: // (icmp pred (xor X, XorCST), CI) - if (ConstantInt *XorCST = dyn_cast(LHSI->getOperand(1))) { - // If this is a comparison that tests the signbit (X < 0) or (x > -1), - // fold the xor. - if ((ICI.getPredicate() == ICmpInst::ICMP_SLT && RHSV == 0) || - (ICI.getPredicate() == ICmpInst::ICMP_SGT && RHSV.isAllOnesValue())) { - Value *CompareVal = LHSI->getOperand(0); - - // If the sign bit of the XorCST is not set, there is no change to - // the operation, just stop using the Xor. - if (!XorCST->getValue().isNegative()) { - ICI.setOperand(0, CompareVal); - Worklist.Add(LHSI); - return &ICI; - } - - // Was the old condition true if the operand is positive? - bool isTrueIfPositive = ICI.getPredicate() == ICmpInst::ICMP_SGT; - - // If so, the new one isn't. - isTrueIfPositive ^= true; - - if (isTrueIfPositive) - return new ICmpInst(ICmpInst::ICMP_SGT, CompareVal, - SubOne(RHS)); - else - return new ICmpInst(ICmpInst::ICMP_SLT, CompareVal, - AddOne(RHS)); - } - - if (LHSI->hasOneUse()) { - // (icmp u/s (xor A SignBit), C) -> (icmp s/u A, (xor C SignBit)) - if (!ICI.isEquality() && XorCST->getValue().isSignBit()) { - const APInt &SignBit = XorCST->getValue(); - ICmpInst::Predicate Pred = ICI.isSigned() - ? ICI.getUnsignedPredicate() - : ICI.getSignedPredicate(); - return new ICmpInst(Pred, LHSI->getOperand(0), - ConstantInt::get(ICI.getContext(), - RHSV ^ SignBit)); - } - - // (icmp u/s (xor A ~SignBit), C) -> (icmp s/u (xor C ~SignBit), A) - if (!ICI.isEquality() && XorCST->getValue().isMaxSignedValue()) { - const APInt &NotSignBit = XorCST->getValue(); - ICmpInst::Predicate Pred = ICI.isSigned() - ? ICI.getUnsignedPredicate() - : ICI.getSignedPredicate(); - Pred = ICI.getSwappedPredicate(Pred); - return new ICmpInst(Pred, LHSI->getOperand(0), - ConstantInt::get(ICI.getContext(), - RHSV ^ NotSignBit)); - } - } - } - break; - case Instruction::And: // (icmp pred (and X, AndCST), RHS) - if (LHSI->hasOneUse() && isa(LHSI->getOperand(1)) && - LHSI->getOperand(0)->hasOneUse()) { - ConstantInt *AndCST = cast(LHSI->getOperand(1)); - - // If the LHS is an AND of a truncating cast, we can widen the - // and/compare to be the input width without changing the value - // produced, eliminating a cast. - if (TruncInst *Cast = dyn_cast(LHSI->getOperand(0))) { - // We can do this transformation if either the AND constant does not - // have its sign bit set or if it is an equality comparison. - // Extending a relational comparison when we're checking the sign - // bit would not work. - if (Cast->hasOneUse() && - (ICI.isEquality() || - (AndCST->getValue().isNonNegative() && RHSV.isNonNegative()))) { - uint32_t BitWidth = - cast(Cast->getOperand(0)->getType())->getBitWidth(); - APInt NewCST = AndCST->getValue(); - NewCST.zext(BitWidth); - APInt NewCI = RHSV; - NewCI.zext(BitWidth); - Value *NewAnd = - Builder->CreateAnd(Cast->getOperand(0), - ConstantInt::get(ICI.getContext(), NewCST), - LHSI->getName()); - return new ICmpInst(ICI.getPredicate(), NewAnd, - ConstantInt::get(ICI.getContext(), NewCI)); - } - } - - // If this is: (X >> C1) & C2 != C3 (where any shift and any compare - // could exist), turn it into (X & (C2 << C1)) != (C3 << C1). This - // happens a LOT in code produced by the C front-end, for bitfield - // access. - BinaryOperator *Shift = dyn_cast(LHSI->getOperand(0)); - if (Shift && !Shift->isShift()) - Shift = 0; - - ConstantInt *ShAmt; - ShAmt = Shift ? dyn_cast(Shift->getOperand(1)) : 0; - const Type *Ty = Shift ? Shift->getType() : 0; // Type of the shift. - const Type *AndTy = AndCST->getType(); // Type of the and. - - // We can fold this as long as we can't shift unknown bits - // into the mask. This can only happen with signed shift - // rights, as they sign-extend. - if (ShAmt) { - bool CanFold = Shift->isLogicalShift(); - if (!CanFold) { - // To test for the bad case of the signed shr, see if any - // of the bits shifted in could be tested after the mask. - uint32_t TyBits = Ty->getPrimitiveSizeInBits(); - int ShAmtVal = TyBits - ShAmt->getLimitedValue(TyBits); - - uint32_t BitWidth = AndTy->getPrimitiveSizeInBits(); - if ((APInt::getHighBitsSet(BitWidth, BitWidth-ShAmtVal) & - AndCST->getValue()) == 0) - CanFold = true; - } - - if (CanFold) { - Constant *NewCst; - if (Shift->getOpcode() == Instruction::Shl) - NewCst = ConstantExpr::getLShr(RHS, ShAmt); - else - NewCst = ConstantExpr::getShl(RHS, ShAmt); - - // Check to see if we are shifting out any of the bits being - // compared. - if (ConstantExpr::get(Shift->getOpcode(), - NewCst, ShAmt) != RHS) { - // If we shifted bits out, the fold is not going to work out. - // As a special case, check to see if this means that the - // result is always true or false now. - if (ICI.getPredicate() == ICmpInst::ICMP_EQ) - return ReplaceInstUsesWith(ICI, - ConstantInt::getFalse(ICI.getContext())); - if (ICI.getPredicate() == ICmpInst::ICMP_NE) - return ReplaceInstUsesWith(ICI, - ConstantInt::getTrue(ICI.getContext())); - } else { - ICI.setOperand(1, NewCst); - Constant *NewAndCST; - if (Shift->getOpcode() == Instruction::Shl) - NewAndCST = ConstantExpr::getLShr(AndCST, ShAmt); - else - NewAndCST = ConstantExpr::getShl(AndCST, ShAmt); - LHSI->setOperand(1, NewAndCST); - LHSI->setOperand(0, Shift->getOperand(0)); - Worklist.Add(Shift); // Shift is dead. - return &ICI; - } - } - } - - // Turn ((X >> Y) & C) == 0 into (X & (C << Y)) == 0. The later is - // preferable because it allows the C<hasOneUse() && RHSV == 0 && - ICI.isEquality() && !Shift->isArithmeticShift() && - !isa(Shift->getOperand(0))) { - // Compute C << Y. - Value *NS; - if (Shift->getOpcode() == Instruction::LShr) { - NS = Builder->CreateShl(AndCST, Shift->getOperand(1), "tmp"); - } else { - // Insert a logical shift. - NS = Builder->CreateLShr(AndCST, Shift->getOperand(1), "tmp"); - } - - // Compute X & (C << Y). - Value *NewAnd = - Builder->CreateAnd(Shift->getOperand(0), NS, LHSI->getName()); - - ICI.setOperand(0, NewAnd); - return &ICI; - } - } - - // Try to optimize things like "A[i]&42 == 0" to index computations. - if (LoadInst *LI = dyn_cast(LHSI->getOperand(0))) { - if (GetElementPtrInst *GEP = - dyn_cast(LI->getOperand(0))) - if (GlobalVariable *GV = dyn_cast(GEP->getOperand(0))) - if (GV->isConstant() && GV->hasDefinitiveInitializer() && - !LI->isVolatile() && isa(LHSI->getOperand(1))) { - ConstantInt *C = cast(LHSI->getOperand(1)); - if (Instruction *Res = FoldCmpLoadFromIndexedGlobal(GEP, GV,ICI, C)) - return Res; - } - } - break; - - case Instruction::Or: { - if (!ICI.isEquality() || !RHS->isNullValue() || !LHSI->hasOneUse()) - break; - Value *P, *Q; - if (match(LHSI, m_Or(m_PtrToInt(m_Value(P)), m_PtrToInt(m_Value(Q))))) { - // Simplify icmp eq (or (ptrtoint P), (ptrtoint Q)), 0 - // -> and (icmp eq P, null), (icmp eq Q, null). - - Value *ICIP = Builder->CreateICmp(ICI.getPredicate(), P, - Constant::getNullValue(P->getType())); - Value *ICIQ = Builder->CreateICmp(ICI.getPredicate(), Q, - Constant::getNullValue(Q->getType())); - Instruction *Op; - if (ICI.getPredicate() == ICmpInst::ICMP_EQ) - Op = BinaryOperator::CreateAnd(ICIP, ICIQ); - else - Op = BinaryOperator::CreateOr(ICIP, ICIQ); - return Op; - } - break; - } - - case Instruction::Shl: { // (icmp pred (shl X, ShAmt), CI) - ConstantInt *ShAmt = dyn_cast(LHSI->getOperand(1)); - if (!ShAmt) break; - - uint32_t TypeBits = RHSV.getBitWidth(); - - // Check that the shift amount is in range. If not, don't perform - // undefined shifts. When the shift is visited it will be - // simplified. - if (ShAmt->uge(TypeBits)) - break; - - if (ICI.isEquality()) { - // If we are comparing against bits always shifted out, the - // comparison cannot succeed. - Constant *Comp = - ConstantExpr::getShl(ConstantExpr::getLShr(RHS, ShAmt), - ShAmt); - if (Comp != RHS) {// Comparing against a bit that we know is zero. - bool IsICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE; - Constant *Cst = - ConstantInt::get(Type::getInt1Ty(ICI.getContext()), IsICMP_NE); - return ReplaceInstUsesWith(ICI, Cst); - } - - if (LHSI->hasOneUse()) { - // Otherwise strength reduce the shift into an and. - uint32_t ShAmtVal = (uint32_t)ShAmt->getLimitedValue(TypeBits); - Constant *Mask = - ConstantInt::get(ICI.getContext(), APInt::getLowBitsSet(TypeBits, - TypeBits-ShAmtVal)); - - Value *And = - Builder->CreateAnd(LHSI->getOperand(0),Mask, LHSI->getName()+".mask"); - return new ICmpInst(ICI.getPredicate(), And, - ConstantInt::get(ICI.getContext(), - RHSV.lshr(ShAmtVal))); - } - } - - // Otherwise, if this is a comparison of the sign bit, simplify to and/test. - bool TrueIfSigned = false; - if (LHSI->hasOneUse() && - isSignBitCheck(ICI.getPredicate(), RHS, TrueIfSigned)) { - // (X << 31) (X&1) != 0 - Constant *Mask = ConstantInt::get(ICI.getContext(), APInt(TypeBits, 1) << - (TypeBits-ShAmt->getZExtValue()-1)); - Value *And = - Builder->CreateAnd(LHSI->getOperand(0), Mask, LHSI->getName()+".mask"); - return new ICmpInst(TrueIfSigned ? ICmpInst::ICMP_NE : ICmpInst::ICMP_EQ, - And, Constant::getNullValue(And->getType())); - } - break; - } - - case Instruction::LShr: // (icmp pred (shr X, ShAmt), CI) - case Instruction::AShr: { - // Only handle equality comparisons of shift-by-constant. - ConstantInt *ShAmt = dyn_cast(LHSI->getOperand(1)); - if (!ShAmt || !ICI.isEquality()) break; - - // Check that the shift amount is in range. If not, don't perform - // undefined shifts. When the shift is visited it will be - // simplified. - uint32_t TypeBits = RHSV.getBitWidth(); - if (ShAmt->uge(TypeBits)) - break; - - uint32_t ShAmtVal = (uint32_t)ShAmt->getLimitedValue(TypeBits); - - // If we are comparing against bits always shifted out, the - // comparison cannot succeed. - APInt Comp = RHSV << ShAmtVal; - if (LHSI->getOpcode() == Instruction::LShr) - Comp = Comp.lshr(ShAmtVal); - else - Comp = Comp.ashr(ShAmtVal); - - if (Comp != RHSV) { // Comparing against a bit that we know is zero. - bool IsICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE; - Constant *Cst = ConstantInt::get(Type::getInt1Ty(ICI.getContext()), - IsICMP_NE); - return ReplaceInstUsesWith(ICI, Cst); - } - - // Otherwise, check to see if the bits shifted out are known to be zero. - // If so, we can compare against the unshifted value: - // (X & 4) >> 1 == 2 --> (X & 4) == 4. - if (LHSI->hasOneUse() && - MaskedValueIsZero(LHSI->getOperand(0), - APInt::getLowBitsSet(Comp.getBitWidth(), ShAmtVal))) { - return new ICmpInst(ICI.getPredicate(), LHSI->getOperand(0), - ConstantExpr::getShl(RHS, ShAmt)); - } - - if (LHSI->hasOneUse()) { - // Otherwise strength reduce the shift into an and. - APInt Val(APInt::getHighBitsSet(TypeBits, TypeBits - ShAmtVal)); - Constant *Mask = ConstantInt::get(ICI.getContext(), Val); - - Value *And = Builder->CreateAnd(LHSI->getOperand(0), - Mask, LHSI->getName()+".mask"); - return new ICmpInst(ICI.getPredicate(), And, - ConstantExpr::getShl(RHS, ShAmt)); - } - break; - } - - case Instruction::SDiv: - case Instruction::UDiv: - // Fold: icmp pred ([us]div X, C1), C2 -> range test - // Fold this div into the comparison, producing a range check. - // Determine, based on the divide type, what the range is being - // checked. If there is an overflow on the low or high side, remember - // it, otherwise compute the range [low, hi) bounding the new value. - // See: InsertRangeTest above for the kinds of replacements possible. - if (ConstantInt *DivRHS = dyn_cast(LHSI->getOperand(1))) - if (Instruction *R = FoldICmpDivCst(ICI, cast(LHSI), - DivRHS)) - return R; - break; - - case Instruction::Add: - // Fold: icmp pred (add X, C1), C2 - if (!ICI.isEquality()) { - ConstantInt *LHSC = dyn_cast(LHSI->getOperand(1)); - if (!LHSC) break; - const APInt &LHSV = LHSC->getValue(); - - ConstantRange CR = ICI.makeConstantRange(ICI.getPredicate(), RHSV) - .subtract(LHSV); - - if (ICI.isSigned()) { - if (CR.getLower().isSignBit()) { - return new ICmpInst(ICmpInst::ICMP_SLT, LHSI->getOperand(0), - ConstantInt::get(ICI.getContext(),CR.getUpper())); - } else if (CR.getUpper().isSignBit()) { - return new ICmpInst(ICmpInst::ICMP_SGE, LHSI->getOperand(0), - ConstantInt::get(ICI.getContext(),CR.getLower())); - } - } else { - if (CR.getLower().isMinValue()) { - return new ICmpInst(ICmpInst::ICMP_ULT, LHSI->getOperand(0), - ConstantInt::get(ICI.getContext(),CR.getUpper())); - } else if (CR.getUpper().isMinValue()) { - return new ICmpInst(ICmpInst::ICMP_UGE, LHSI->getOperand(0), - ConstantInt::get(ICI.getContext(),CR.getLower())); - } - } - } - break; - } - - // Simplify icmp_eq and icmp_ne instructions with integer constant RHS. - if (ICI.isEquality()) { - bool isICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE; - - // If the first operand is (add|sub|and|or|xor|rem) with a constant, and - // the second operand is a constant, simplify a bit. - if (BinaryOperator *BO = dyn_cast(LHSI)) { - switch (BO->getOpcode()) { - case Instruction::SRem: - // If we have a signed (X % (2^c)) == 0, turn it into an unsigned one. - if (RHSV == 0 && isa(BO->getOperand(1)) &&BO->hasOneUse()){ - const APInt &V = cast(BO->getOperand(1))->getValue(); - if (V.sgt(APInt(V.getBitWidth(), 1)) && V.isPowerOf2()) { - Value *NewRem = - Builder->CreateURem(BO->getOperand(0), BO->getOperand(1), - BO->getName()); - return new ICmpInst(ICI.getPredicate(), NewRem, - Constant::getNullValue(BO->getType())); - } - } - break; - case Instruction::Add: - // Replace ((add A, B) != C) with (A != C-B) if B & C are constants. - if (ConstantInt *BOp1C = dyn_cast(BO->getOperand(1))) { - if (BO->hasOneUse()) - return new ICmpInst(ICI.getPredicate(), BO->getOperand(0), - ConstantExpr::getSub(RHS, BOp1C)); - } else if (RHSV == 0) { - // Replace ((add A, B) != 0) with (A != -B) if A or B is - // efficiently invertible, or if the add has just this one use. - Value *BOp0 = BO->getOperand(0), *BOp1 = BO->getOperand(1); - - if (Value *NegVal = dyn_castNegVal(BOp1)) - return new ICmpInst(ICI.getPredicate(), BOp0, NegVal); - else if (Value *NegVal = dyn_castNegVal(BOp0)) - return new ICmpInst(ICI.getPredicate(), NegVal, BOp1); - else if (BO->hasOneUse()) { - Value *Neg = Builder->CreateNeg(BOp1); - Neg->takeName(BO); - return new ICmpInst(ICI.getPredicate(), BOp0, Neg); - } - } - break; - case Instruction::Xor: - // For the xor case, we can xor two constants together, eliminating - // the explicit xor. - if (Constant *BOC = dyn_cast(BO->getOperand(1))) - return new ICmpInst(ICI.getPredicate(), BO->getOperand(0), - ConstantExpr::getXor(RHS, BOC)); - - // FALLTHROUGH - case Instruction::Sub: - // Replace (([sub|xor] A, B) != 0) with (A != B) - if (RHSV == 0) - return new ICmpInst(ICI.getPredicate(), BO->getOperand(0), - BO->getOperand(1)); - break; - - case Instruction::Or: - // If bits are being or'd in that are not present in the constant we - // are comparing against, then the comparison could never succeed! - if (Constant *BOC = dyn_cast(BO->getOperand(1))) { - Constant *NotCI = ConstantExpr::getNot(RHS); - if (!ConstantExpr::getAnd(BOC, NotCI)->isNullValue()) - return ReplaceInstUsesWith(ICI, - ConstantInt::get(Type::getInt1Ty(ICI.getContext()), - isICMP_NE)); - } - break; - - case Instruction::And: - if (ConstantInt *BOC = dyn_cast(BO->getOperand(1))) { - // If bits are being compared against that are and'd out, then the - // comparison can never succeed! - if ((RHSV & ~BOC->getValue()) != 0) - return ReplaceInstUsesWith(ICI, - ConstantInt::get(Type::getInt1Ty(ICI.getContext()), - isICMP_NE)); - - // If we have ((X & C) == C), turn it into ((X & C) != 0). - if (RHS == BOC && RHSV.isPowerOf2()) - return new ICmpInst(isICMP_NE ? ICmpInst::ICMP_EQ : - ICmpInst::ICMP_NE, LHSI, - Constant::getNullValue(RHS->getType())); - - // Replace (and X, (1 << size(X)-1) != 0) with x s< 0 - if (BOC->getValue().isSignBit()) { - Value *X = BO->getOperand(0); - Constant *Zero = Constant::getNullValue(X->getType()); - ICmpInst::Predicate pred = isICMP_NE ? - ICmpInst::ICMP_SLT : ICmpInst::ICMP_SGE; - return new ICmpInst(pred, X, Zero); - } - - // ((X & ~7) == 0) --> X < 8 - if (RHSV == 0 && isHighOnes(BOC)) { - Value *X = BO->getOperand(0); - Constant *NegX = ConstantExpr::getNeg(BOC); - ICmpInst::Predicate pred = isICMP_NE ? - ICmpInst::ICMP_UGE : ICmpInst::ICMP_ULT; - return new ICmpInst(pred, X, NegX); - } - } - default: break; - } - } else if (IntrinsicInst *II = dyn_cast(LHSI)) { - // Handle icmp {eq|ne} , intcst. - if (II->getIntrinsicID() == Intrinsic::bswap) { - Worklist.Add(II); - ICI.setOperand(0, II->getOperand(1)); - ICI.setOperand(1, ConstantInt::get(II->getContext(), RHSV.byteSwap())); - return &ICI; - } - } - } - return 0; -} - -/// visitICmpInstWithCastAndCast - Handle icmp (cast x to y), (cast/cst). -/// We only handle extending casts so far. -/// -Instruction *InstCombiner::visitICmpInstWithCastAndCast(ICmpInst &ICI) { - const CastInst *LHSCI = cast(ICI.getOperand(0)); - Value *LHSCIOp = LHSCI->getOperand(0); - const Type *SrcTy = LHSCIOp->getType(); - const Type *DestTy = LHSCI->getType(); - Value *RHSCIOp; - - // Turn icmp (ptrtoint x), (ptrtoint/c) into a compare of the input if the - // integer type is the same size as the pointer type. - if (TD && LHSCI->getOpcode() == Instruction::PtrToInt && - TD->getPointerSizeInBits() == - cast(DestTy)->getBitWidth()) { - Value *RHSOp = 0; - if (Constant *RHSC = dyn_cast(ICI.getOperand(1))) { - RHSOp = ConstantExpr::getIntToPtr(RHSC, SrcTy); - } else if (PtrToIntInst *RHSC = dyn_cast(ICI.getOperand(1))) { - RHSOp = RHSC->getOperand(0); - // If the pointer types don't match, insert a bitcast. - if (LHSCIOp->getType() != RHSOp->getType()) - RHSOp = Builder->CreateBitCast(RHSOp, LHSCIOp->getType()); - } - - if (RHSOp) - return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSOp); - } - - // The code below only handles extension cast instructions, so far. - // Enforce this. - if (LHSCI->getOpcode() != Instruction::ZExt && - LHSCI->getOpcode() != Instruction::SExt) - return 0; - - bool isSignedExt = LHSCI->getOpcode() == Instruction::SExt; - bool isSignedCmp = ICI.isSigned(); - - if (CastInst *CI = dyn_cast(ICI.getOperand(1))) { - // Not an extension from the same type? - RHSCIOp = CI->getOperand(0); - if (RHSCIOp->getType() != LHSCIOp->getType()) - return 0; - - // If the signedness of the two casts doesn't agree (i.e. one is a sext - // and the other is a zext), then we can't handle this. - if (CI->getOpcode() != LHSCI->getOpcode()) - return 0; - - // Deal with equality cases early. - if (ICI.isEquality()) - return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSCIOp); - - // A signed comparison of sign extended values simplifies into a - // signed comparison. - if (isSignedCmp && isSignedExt) - return new ICmpInst(ICI.getPredicate(), LHSCIOp, RHSCIOp); - - // The other three cases all fold into an unsigned comparison. - return new ICmpInst(ICI.getUnsignedPredicate(), LHSCIOp, RHSCIOp); - } - - // If we aren't dealing with a constant on the RHS, exit early - ConstantInt *CI = dyn_cast(ICI.getOperand(1)); - if (!CI) - return 0; - - // Compute the constant that would happen if we truncated to SrcTy then - // reextended to DestTy. - Constant *Res1 = ConstantExpr::getTrunc(CI, SrcTy); - Constant *Res2 = ConstantExpr::getCast(LHSCI->getOpcode(), - Res1, DestTy); - - // If the re-extended constant didn't change... - if (Res2 == CI) { - // Deal with equality cases early. - if (ICI.isEquality()) - return new ICmpInst(ICI.getPredicate(), LHSCIOp, Res1); - - // A signed comparison of sign extended values simplifies into a - // signed comparison. - if (isSignedExt && isSignedCmp) - return new ICmpInst(ICI.getPredicate(), LHSCIOp, Res1); - - // The other three cases all fold into an unsigned comparison. - return new ICmpInst(ICI.getUnsignedPredicate(), LHSCIOp, Res1); - } - - // The re-extended constant changed so the constant cannot be represented - // in the shorter type. Consequently, we cannot emit a simple comparison. - - // First, handle some easy cases. We know the result cannot be equal at this - // point so handle the ICI.isEquality() cases - if (ICI.getPredicate() == ICmpInst::ICMP_EQ) - return ReplaceInstUsesWith(ICI, ConstantInt::getFalse(ICI.getContext())); - if (ICI.getPredicate() == ICmpInst::ICMP_NE) - return ReplaceInstUsesWith(ICI, ConstantInt::getTrue(ICI.getContext())); - - // Evaluate the comparison for LT (we invert for GT below). LE and GE cases - // should have been folded away previously and not enter in here. - Value *Result; - if (isSignedCmp) { - // We're performing a signed comparison. - if (cast(CI)->getValue().isNegative()) - Result = ConstantInt::getFalse(ICI.getContext()); // X < (small) --> false - else - Result = ConstantInt::getTrue(ICI.getContext()); // X < (large) --> true - } else { - // We're performing an unsigned comparison. - if (isSignedExt) { - // We're performing an unsigned comp with a sign extended value. - // This is true if the input is >= 0. [aka >s -1] - Constant *NegOne = Constant::getAllOnesValue(SrcTy); - Result = Builder->CreateICmpSGT(LHSCIOp, NegOne, ICI.getName()); - } else { - // Unsigned extend & unsigned compare -> always true. - Result = ConstantInt::getTrue(ICI.getContext()); - } - } - - // Finally, return the value computed. - if (ICI.getPredicate() == ICmpInst::ICMP_ULT || - ICI.getPredicate() == ICmpInst::ICMP_SLT) - return ReplaceInstUsesWith(ICI, Result); - - assert((ICI.getPredicate()==ICmpInst::ICMP_UGT || - ICI.getPredicate()==ICmpInst::ICMP_SGT) && - "ICmp should be folded!"); - if (Constant *CI = dyn_cast(Result)) - return ReplaceInstUsesWith(ICI, ConstantExpr::getNot(CI)); - return BinaryOperator::CreateNot(Result); -} Instruction *InstCombiner::visitShl(BinaryOperator &I) { return commonShiftTransforms(I); @@ -7292,7 +4874,7 @@ Instruction *InstCombiner::commonPointerCastTransforms(CastInst &CI) { if (TD && GEP->hasOneUse() && isa(GEP->getOperand(0))) { if (GEP->hasAllConstantIndices()) { // We are guaranteed to get a constant from EmitGEPOffset. - ConstantInt *OffsetV = cast(EmitGEPOffset(GEP, *this)); + ConstantInt *OffsetV = cast(EmitGEPOffset(GEP)); int64_t Offset = OffsetV->getSExtValue(); // Get the base pointer input of the bitcast, and the type it points to. @@ -10874,7 +8456,7 @@ Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) { !isa(BCI->getOperand(0)) && GEP.hasAllConstantIndices()) { // Determine how much the GEP moves the pointer. We are guaranteed to get // a constant back from EmitGEPOffset. - ConstantInt *OffsetV = cast(EmitGEPOffset(&GEP, *this)); + ConstantInt *OffsetV = cast(EmitGEPOffset(&GEP)); int64_t Offset = OffsetV->getSExtValue(); // If this GEP instruction doesn't move the pointer, just replace the GEP -- 2.34.1