#include "llvm/Analysis/ValueTracking.h"
#include "llvm/Constants.h"
#include "llvm/Instructions.h"
+#include "llvm/GlobalVariable.h"
#include "llvm/IntrinsicInst.h"
+#include "llvm/LLVMContext.h"
+#include "llvm/Operator.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Support/GetElementPtrTypeIterator.h"
#include "llvm/Support/MathExtras.h"
#include <cstring>
using namespace llvm;
-/// getOpcode - If this is an Instruction or a ConstantExpr, return the
-/// opcode value. Otherwise return UserOp1.
-static unsigned getOpcode(const Value *V) {
- if (const Instruction *I = dyn_cast<Instruction>(V))
- return I->getOpcode();
- if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
- return CE->getOpcode();
- // Use UserOp1 to mean there's no opcode.
- return Instruction::UserOp1;
-}
-
-
/// ComputeMaskedBits - Determine which of the bits specified in Mask are
/// known to be either zero or one and return them in the KnownZero/KnownOne
/// bit sets. This code only analyzes bits in Mask, in order to short-circuit
void llvm::ComputeMaskedBits(Value *V, const APInt &Mask,
APInt &KnownZero, APInt &KnownOne,
TargetData *TD, unsigned Depth) {
+ const unsigned MaxDepth = 6;
assert(V && "No Value?");
- assert(Depth <= 6 && "Limit Search Depth");
- uint32_t BitWidth = Mask.getBitWidth();
- assert((V->getType()->isInt
eger() || isa<PointerType>(V->getType())) &&
+ assert(Depth <= MaxDepth && "Limit Search Depth");
+ unsigned BitWidth = Mask.getBitWidth();
+ assert((V->getType()->isInt
OrIntVector() || isa<PointerType>(V->getType())) &&
"Not integer or pointer type!");
- assert((!TD || TD->getTypeSizeInBits(V->getType()) == BitWidth) &&
- (!isa<IntegerType>(V->getType()) ||
- V->getType()->getPrimitiveSizeInBits() == BitWidth) &&
+ assert((!TD ||
+ TD->getTypeSizeInBits(V->getType()->getScalarType()) == BitWidth) &&
+ (!V->getType()->isIntOrIntVector() ||
+ V->getType()->getScalarSizeInBits() == BitWidth) &&
KnownZero.getBitWidth() == BitWidth &&
KnownOne.getBitWidth() == BitWidth &&
"V, Mask, KnownOne and KnownZero should have same BitWidth");
KnownZero = ~KnownOne & Mask;
return;
}
- // Null is all-zeros.
- if (isa<ConstantPointerNull>(V)) {
+ // Null and aggregate-zero are all-zeros.
+ if (isa<ConstantPointerNull>(V) ||
+ isa<ConstantAggregateZero>(V)) {
KnownOne.clear();
KnownZero = Mask;
return;
}
+ // Handle a constant vector by taking the intersection of the known bits of
+ // each element.
+ if (ConstantVector *CV = dyn_cast<ConstantVector>(V)) {
+ KnownZero.set(); KnownOne.set();
+ for (unsigned i = 0, e = CV->getNumOperands(); i != e; ++i) {
+ APInt KnownZero2(BitWidth, 0), KnownOne2(BitWidth, 0);
+ ComputeMaskedBits(CV->getOperand(i), Mask, KnownZero2, KnownOne2,
+ TD, Depth);
+ KnownZero &= KnownZero2;
+ KnownOne &= KnownOne2;
+ }
+ return;
+ }
// The address of an aligned GlobalValue has trailing zeros.
if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) {
unsigned Align = GV->getAlignment();
- if (Align == 0 && TD && GV->getType()->getElementType()->isSized())
- Align = TD->getPrefTypeAlignment(GV->getType()->getElementType());
+ if (Align == 0 && TD && GV->getType()->getElementType()->isSized()) {
+ const Type *ObjectType = GV->getType()->getElementType();
+ // If the object is defined in the current Module, we'll be giving
+ // it the preferred alignment. Otherwise, we have to assume that it
+ // may only have the minimum ABI alignment.
+ if (!GV->isDeclaration() && !GV->mayBeOverridden())
+ Align = TD->getPrefTypeAlignment(ObjectType);
+ else
+ Align = TD->getABITypeAlignment(ObjectType);
+ }
if (Align > 0)
KnownZero = Mask & APInt::getLowBitsSet(BitWidth,
CountTrailingZeros_32(Align));
KnownZero.clear(); KnownOne.clear(); // Start out not knowing anything.
- if (Depth == 6 || Mask == 0)
+ if (Depth == MaxDepth || Mask == 0)
return; // Limit search depth.
- User *I = dyn_cast<User>(V);
+ Operator *I = dyn_cast<Operator>(V);
if (!I) return;
APInt KnownZero2(KnownZero), KnownOne2(KnownOne);
- switch (getOpcode(I)) {
+ switch (I->getOpcode()) {
default: break;
case Instruction::And: {
// If either the LHS or the RHS are Zero, the result is zero.
// Note that we handle pointer operands here because of inttoptr/ptrtoint
// which fall through here.
const Type *SrcTy = I->getOperand(0)->getType();
- uint32_t SrcBitWidth = TD ?
+ unsigned SrcBitWidth = TD ?
TD->getTypeSizeInBits(SrcTy) :
- SrcTy->getPrimitiveSizeInBits();
+ SrcTy->getScalarSizeInBits();
APInt MaskIn(Mask);
MaskIn.zextOrTrunc(SrcBitWidth);
KnownZero.zextOrTrunc(SrcBitWidth);
}
case Instruction::BitCast: {
const Type *SrcTy = I->getOperand(0)->getType();
- if (SrcTy->isInteger() || isa<PointerType>(SrcTy)) {
+ if ((SrcTy->isInteger() || isa<PointerType>(SrcTy)) &&
+ // TODO: For now, not handling conversions like:
+ // (bitcast i64 %x to <2 x i32>)
+ !isa<VectorType>(I->getType())) {
ComputeMaskedBits(I->getOperand(0), Mask, KnownZero, KnownOne, TD,
Depth+1);
return;
case Instruction::SExt: {
// Compute the bits in the result that are not present in the input.
const IntegerType *SrcTy = cast<IntegerType>(I->getOperand(0)->getType());
- uint32_t SrcBitWidth = SrcTy->getBitWidth();
+ unsigned SrcBitWidth = SrcTy->getBitWidth();
APInt MaskIn(Mask);
MaskIn.trunc(SrcBitWidth);
}
// fall through
case Instruction::Add: {
- // Output known-0 bits are known if clear or set in both the low clear bits
- // common to both LHS & RHS. For example, 8+(X<<3) is known to have the
- // low 3 bits clear.
- APInt Mask2 = APInt::getLowBitsSet(BitWidth, Mask.countTrailingOnes());
- ComputeMaskedBits(I->getOperand(0), Mask2, KnownZero2, KnownOne2, TD,
+ // If one of the operands has trailing zeros, than the bits that the
+ // other operand has in those bit positions will be preserved in the
+ // result. For an add, this works with either operand. For a subtract,
+ // this only works if the known zeros are in the right operand.
+ APInt LHSKnownZero(BitWidth, 0), LHSKnownOne(BitWidth, 0);
+ APInt Mask2 = APInt::getLowBitsSet(BitWidth,
+ BitWidth - Mask.countLeadingZeros());
+ ComputeMaskedBits(I->getOperand(0), Mask2, LHSKnownZero, LHSKnownOne, TD,
Depth+1);
- assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
- unsigned KnownZeroOut = KnownZero2.countTrailingOnes();
+ assert((LHSKnownZero & LHSKnownOne) == 0 &&
+ "Bits known to be one AND zero?");
+ unsigned LHSKnownZeroOut = LHSKnownZero.countTrailingOnes();
ComputeMaskedBits(I->getOperand(1), Mask2, KnownZero2, KnownOne2, TD,
Depth+1);
assert((KnownZero2 & KnownOne2) == 0 && "Bits known to be one AND zero?");
- KnownZeroOut = std::min(KnownZeroOut,
- KnownZero2.countTrailingOnes());
+ unsigned RHSKnownZeroOut = KnownZero2.countTrailingOnes();
- KnownZero |= APInt::getLowBitsSet(BitWidth, KnownZeroOut);
+ // Determine which operand has more trailing zeros, and use that
+ // many bits from the other operand.
+ if (LHSKnownZeroOut > RHSKnownZeroOut) {
+ if (I->getOpcode() == Instruction::Add) {
+ APInt Mask = APInt::getLowBitsSet(BitWidth, LHSKnownZeroOut);
+ KnownZero |= KnownZero2 & Mask;
+ KnownOne |= KnownOne2 & Mask;
+ } else {
+ // If the known zeros are in the left operand for a subtract,
+ // fall back to the minimum known zeros in both operands.
+ KnownZero |= APInt::getLowBitsSet(BitWidth,
+ std::min(LHSKnownZeroOut,
+ RHSKnownZeroOut));
+ }
+ } else if (RHSKnownZeroOut >= LHSKnownZeroOut) {
+ APInt Mask = APInt::getLowBitsSet(BitWidth, RHSKnownZeroOut);
+ KnownZero |= LHSKnownZero & Mask;
+ KnownOne |= LHSKnownOne & Mask;
+ }
return;
}
case Instruction::SRem:
ComputeMaskedBits(I->getOperand(0), Mask2, KnownZero2, KnownOne2, TD,
Depth+1);
- // The sign of a remainder is equal to the sign of the first
- // operand (zero being positive).
+ // If the sign bit of the first operand is zero, the sign bit of
+ // the result is zero. If the first operand has no one bits below
+ // the second operand's single 1 bit, its sign will be zero.
if (KnownZero2[BitWidth-1] || ((KnownZero2 & LowBits) == LowBits))
KnownZero2 |= ~LowBits;
- else if (KnownOne2[BitWidth-1])
- KnownOne2 |= ~LowBits;
KnownZero |= KnownZero2 & Mask;
- KnownOne |= KnownOne2 & Mask;
assert((KnownZero & KnownOne) == 0&&"Bits known to be one AND zero?");
}
ComputeMaskedBits(I->getOperand(1), AllOnes, KnownZero2, KnownOne2,
TD, Depth+1);
- uint32_t Leaders = std::max(KnownZero.countLeadingOnes(),
+ unsigned Leaders = std::max(KnownZero.countLeadingOnes(),
KnownZero2.countLeadingOnes());
KnownOne.clear();
KnownZero = APInt::getHighBitsSet(BitWidth, Leaders) & Mask;
unsigned Align = AI->getAlignment();
if (Align == 0 && TD) {
if (isa<AllocaInst>(AI))
- Align = TD->getPrefTypeAlignment(AI->getType()->getElementType());
+ Align = TD->getABITypeAlignment(AI->getType()->getElementType());
else if (isa<MallocInst>(AI)) {
// Malloc returns maximally aligned memory.
Align = TD->getABITypeAlignment(AI->getType()->getElementType());
Align =
std::max(Align,
- (unsigned)TD->getABITypeAlignment(Type::DoubleTy));
+ (unsigned)TD->getABITypeAlignment(
+ Type::getDoubleTy(V->getContext())));
Align =
std::max(Align,
- (unsigned)TD->getABITypeAlignment(Type::Int64Ty));
+ (unsigned)TD->getABITypeAlignment(
+ Type::getInt64Ty(V->getContext())));
}
}
// Handle array index arithmetic.
const Type *IndexedTy = GTI.getIndexedType();
if (!IndexedTy->isSized()) return;
- unsigned GEPOpiBits = Index->getType()->getPrimitiveSizeInBits();
- uint64_t TypeSize = TD ? TD->getABITypeSize(IndexedTy) : 1;
+ unsigned GEPOpiBits = Index->getType()->getScalarSizeInBits();
+ uint64_t TypeSize = TD ? TD->getTypeAllocSize(IndexedTy) : 1;
LocalMask = APInt::getAllOnesValue(GEPOpiBits);
LocalKnownZero = LocalKnownOne = APInt(GEPOpiBits, 0);
ComputeMaskedBits(Index, LocalMask,
LocalKnownZero, LocalKnownOne, TD, Depth+1);
TrailZ = std::min(TrailZ,
- CountTrailingZeros_64(TypeSize) +
- LocalKnownZero.countTrailingOnes());
+ unsigned(CountTrailingZeros_64(TypeSize) +
+ LocalKnownZero.countTrailingOnes()));
}
}
for (unsigned i = 0; i != 2; ++i) {
Value *L = P->getIncomingValue(i);
Value *R = P->getIncomingValue(!i);
- User *LU = dyn_cast<User>(L);
+ Operator *LU = dyn_cast<Operator>(L);
if (!LU)
continue;
- unsigned Opcode = getOpcode(LU);
+ unsigned Opcode = LU->getOpcode();
// Check for operations that have the property that if
// both their operands have low zero bits, the result
// will have low zero bits.
ComputeMaskedBits(R, Mask2, KnownZero2, KnownOne2, TD, Depth+1);
Mask2 = APInt::getLowBitsSet(BitWidth,
KnownZero2.countTrailingOnes());
- KnownOne2.clear();
- KnownZero2.clear();
- ComputeMaskedBits(L, Mask2, KnownZero2, KnownOne2, TD, Depth+1);
+
+ // We need to take the minimum number of known bits
+ APInt KnownZero3(KnownZero), KnownOne3(KnownOne);
+ ComputeMaskedBits(L, Mask2, KnownZero3, KnownOne3, TD, Depth+1);
+
KnownZero = Mask &
APInt::getLowBitsSet(BitWidth,
- KnownZero2.countTrailingOnes());
+ std::min(KnownZero2.countTrailingOnes(),
+ KnownZero3.countTrailingOnes()));
break;
}
}
}
+
+ // Otherwise take the unions of the known bit sets of the operands,
+ // taking conservative care to avoid excessive recursion.
+ if (Depth < MaxDepth - 1 && !KnownZero && !KnownOne) {
+ KnownZero = APInt::getAllOnesValue(BitWidth);
+ KnownOne = APInt::getAllOnesValue(BitWidth);
+ for (unsigned i = 0, e = P->getNumIncomingValues(); i != e; ++i) {
+ // Skip direct self references.
+ if (P->getIncomingValue(i) == P) continue;
+
+ KnownZero2 = APInt(BitWidth, 0);
+ KnownOne2 = APInt(BitWidth, 0);
+ // Recurse, but cap the recursion to one level, because we don't
+ // want to waste time spinning around in loops.
+ ComputeMaskedBits(P->getIncomingValue(i), KnownZero | KnownOne,
+ KnownZero2, KnownOne2, TD, MaxDepth-1);
+ KnownZero &= KnownZero2;
+ KnownOne &= KnownOne2;
+ // If all bits have been ruled out, there's no need to check
+ // more operands.
+ if (!KnownZero && !KnownOne)
+ break;
+ }
+ }
break;
}
case Instruction::Call:
/// 'Op' must have a scalar integer type.
///
unsigned llvm::ComputeNumSignBits(Value *V, TargetData *TD, unsigned Depth) {
- const IntegerType *Ty = cast<IntegerType>(V->getType());
- unsigned TyBits = Ty->getBitWidth();
+ assert((TD || V->getType()->isIntOrIntVector()) &&
+ "ComputeNumSignBits requires a TargetData object to operate "
+ "on non-integer values!");
+ const Type *Ty = V->getType();
+ unsigned TyBits = TD ? TD->getTypeSizeInBits(V->getType()->getScalarType()) :
+ Ty->getScalarSizeInBits();
unsigned Tmp, Tmp2;
unsigned FirstAnswer = 1;
if (Depth == 6)
return 1; // Limit search depth.
- User *U = dyn_cast<User>(V);
- switch (getOpcode(V)) {
+ Operator *U = dyn_cast<Operator>(V);
+ switch (Operator::getOpcode(V)) {
default: break;
case Instruction::SExt:
Tmp = TyBits-cast<IntegerType>(U->getOperand(0)->getType())->getBitWidth();
if (Tmp == 1) return 1; // Early out.
// Special case decrementing a value (ADD X, -1):
- if (ConstantInt *CRHS = dyn_cast<ConstantInt>(U->getOperand(0)))
+ if (ConstantInt *CRHS = dyn_cast<ConstantInt>(U->getOperand(1)))
if (CRHS->isAllOnesValue()) {
APInt KnownZero(TyBits, 0), KnownOne(TyBits, 0);
APInt Mask = APInt::getAllOnesValue(TyBits);
if (Depth == 6)
return 1; // Limit search depth.
- const Instruction *I = dyn_cast<Instruction>(V);
+ const Operator *I = dyn_cast<Operator>(V);
if (I == 0) return false;
// (add x, 0.0) is guaranteed to return +0.0, not -0.0.
- if (I->getOpcode() == Instruction::Add &&
+ if (I->getOpcode() == Instruction::FAdd &&
isa<ConstantFP>(I->getOperand(1)) &&
cast<ConstantFP>(I->getOperand(1))->isNullValue())
return true;
if (const CallInst *CI = dyn_cast<CallInst>(I))
if (const Function *F = CI->getCalledFunction()) {
if (F->isDeclaration()) {
- switch (F->getNameLen()) {
- case 3: // abs(x) != -0.0
- if (!strcmp(F->getNameStart(), "abs")) return true;
- break;
- case 4: // abs[lf](x) != -0.0
- if (!strcmp(F->getNameStart(), "absf")) return true;
- if (!strcmp(F->getNameStart(), "absl")) return true;
- break;
- }
+ // abs(x) != -0.0
+ if (F->getName() == "abs") return true;
+ // abs[lf](x) != -0.0
+ if (F->getName() == "absf") return true;
+ if (F->getName() == "absl") return true;
}
}
// indices from Idxs that should be left out when inserting into the resulting
// struct. To is the result struct built so far, new insertvalue instructions
// build on that.
-Value *BuildSubAggregate(Value *From, Value* To, const Type *IndexedType,
- SmallVector<unsigned, 10> &Idxs,
- unsigned IdxSkip,
- Instruction &InsertBefore) {
+static Value *BuildSubAggregate(Value *From, Value* To, const Type *IndexedType,
+ SmallVector<unsigned, 10> &Idxs,
+ unsigned IdxSkip,
+ LLVMContext &Context,
+ Instruction *InsertBefore) {
const llvm::StructType *STy = llvm::dyn_cast<llvm::StructType>(IndexedType);
if (STy) {
+ // Save the original To argument so we can modify it
+ Value *OrigTo = To;
// General case, the type indexed by Idxs is a struct
for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) {
// Process each struct element recursively
Idxs.push_back(i);
- To = BuildSubAggregate(From, To, STy->getElementType(i), Idxs, IdxSkip, InsertBefore);
+ Value *PrevTo = To;
+ To = BuildSubAggregate(From, To, STy->getElementType(i), Idxs, IdxSkip,
+ Context, InsertBefore);
Idxs.pop_back();
+ if (!To) {
+ // Couldn't find any inserted value for this index? Cleanup
+ while (PrevTo != OrigTo) {
+ InsertValueInst* Del = cast<InsertValueInst>(PrevTo);
+ PrevTo = Del->getAggregateOperand();
+ Del->eraseFromParent();
+ }
+ // Stop processing elements
+ break;
+ }
}
- return To;
- } else {
- // Base case, the type indexed by SourceIdxs is not a struct
- // Load the value from the nested struct into the sub struct (and skip
- // IdxSkip indices when indexing the sub struct).
- Instruction *V = llvm::ExtractValueInst::Create(From, Idxs.begin(), Idxs.end(), "tmp", &InsertBefore);
- Instruction *Ins = llvm::InsertValueInst::Create(To, V, Idxs.begin() + IdxSkip, Idxs.end(), "tmp", &InsertBefore);
- return Ins;
+ // If we succesfully found a value for each of our subaggregates
+ if (To)
+ return To;
}
+ // Base case, the type indexed by SourceIdxs is not a struct, or not all of
+ // the struct's elements had a value that was inserted directly. In the latter
+ // case, perhaps we can't determine each of the subelements individually, but
+ // we might be able to find the complete struct somewhere.
+
+ // Find the value that is at that particular spot
+ Value *V = FindInsertedValue(From, Idxs.begin(), Idxs.end(), Context);
+
+ if (!V)
+ return NULL;
+
+ // Insert the value in the new (sub) aggregrate
+ return llvm::InsertValueInst::Create(To, V, Idxs.begin() + IdxSkip,
+ Idxs.end(), "tmp", InsertBefore);
}
// This helper takes a nested struct and extracts a part of it (which is again a
// and the indices "1, 1" this returns
// { c, d }.
//
-// It does this by inserting an extractvalue and insertvalue for each element in
-// the resulting struct, as opposed to just inserting a single struct. This
-// allows for later folding of these individual extractvalue instructions with
-// insertvalue instructions that fill the nested struct.
+// It does this by inserting an insertvalue for each element in the resulting
+// struct, as opposed to just inserting a single struct. This will only work if
+// each of the elements of the substruct are known (ie, inserted into From by an
+// insertvalue instruction somewhere).
//
-// Any inserted instructions are inserted before InsertBefore
-Value *BuildSubAggregate(Value *From, const unsigned *idx_begin, const unsigned *idx_end, Instruction &InsertBefore) {
- const Type *IndexedType = ExtractValueInst::getIndexedType(From->getType(), idx_begin, idx_end);
+// All inserted insertvalue instructions are inserted before InsertBefore
+static Value *BuildSubAggregate(Value *From, const unsigned *idx_begin,
+ const unsigned *idx_end, LLVMContext &Context,
+ Instruction *InsertBefore) {
+ assert(InsertBefore && "Must have someplace to insert!");
+ const Type *IndexedType = ExtractValueInst::getIndexedType(From->getType(),
+ idx_begin,
+ idx_end);
Value *To = UndefValue::get(IndexedType);
SmallVector<unsigned, 10> Idxs(idx_begin, idx_end);
unsigned IdxSkip = Idxs.size();
- return BuildSubAggregate(From, To, IndexedType, Idxs, IdxSkip, InsertBefore);
+ return BuildSubAggregate(From, To, IndexedType, Idxs, IdxSkip,
+ Context, InsertBefore);
}
-/// FindInsertedValue - Given an aggregrate and an sequence of indices, see if the
-/// scalar value indexed is already around as a register, for example if it were
-/// inserted directly into the aggregrate.
+/// FindInsertedValue - Given an aggregrate and an sequence of indices, see if
+/// the scalar value indexed is already around as a register, for example if it
+/// were inserted directly into the aggregrate.
+///
+/// If InsertBefore is not null, this function will duplicate (modified)
+/// insertvalues when a part of a nested struct is extracted.
Value *llvm::FindInsertedValue(Value *V, const unsigned *idx_begin,
- const unsigned *idx_end, Instruction &InsertBefore) {
+ const unsigned *idx_end, LLVMContext &Context,
+ Instruction *InsertBefore) {
// Nothing to index? Just return V then (this is useful at the end of our
// recursion)
if (idx_begin == idx_end)
assert(ExtractValueInst::getIndexedType(V->getType(), idx_begin, idx_end)
&& "Invalid indices for type?");
const CompositeType *PTy = cast<CompositeType>(V->getType());
-
+
if (isa<UndefValue>(V))
return UndefValue::get(ExtractValueInst::getIndexedType(PTy,
idx_begin,
idx_end));
else if (isa<ConstantAggregateZero>(V))
return Constant::getNullValue(ExtractValueInst::getIndexedType(PTy,
- idx_begin,
- idx_end));
+ idx_begin,
+ idx_end));
else if (Constant *C = dyn_cast<Constant>(V)) {
if (isa<ConstantArray>(C) || isa<ConstantStruct>(C))
// Recursively process this constant
- return FindInsertedValue(C->getOperand(*idx_begin), ++idx_begin, idx_end, InsertBefore);
+ return FindInsertedValue(C->getOperand(*idx_begin), idx_begin + 1,
+ idx_end, Context, InsertBefore);
} else if (InsertValueInst *I = dyn_cast<InsertValueInst>(V)) {
// Loop the indices for the insertvalue instruction in parallel with the
// requested indices
const unsigned *req_idx = idx_begin;
- for (const unsigned *i = I->idx_begin(), *e = I->idx_end(); i != e; ++i, ++req_idx) {
- if (req_idx == idx_end)
- // The requested index is a part of a nested aggregate. Handle this
- // specially.
- return BuildSubAggregate(V, idx_begin, req_idx, InsertBefore);
+ for (const unsigned *i = I->idx_begin(), *e = I->idx_end();
+ i != e; ++i, ++req_idx) {
+ if (req_idx == idx_end) {
+ if (InsertBefore)
+ // The requested index identifies a part of a nested aggregate. Handle
+ // this specially. For example,
+ // %A = insertvalue { i32, {i32, i32 } } undef, i32 10, 1, 0
+ // %B = insertvalue { i32, {i32, i32 } } %A, i32 11, 1, 1
+ // %C = extractvalue {i32, { i32, i32 } } %B, 1
+ // This can be changed into
+ // %A = insertvalue {i32, i32 } undef, i32 10, 0
+ // %C = insertvalue {i32, i32 } %A, i32 11, 1
+ // which allows the unused 0,0 element from the nested struct to be
+ // removed.
+ return BuildSubAggregate(V, idx_begin, req_idx,
+ Context, InsertBefore);
+ else
+ // We can't handle this without inserting insertvalues
+ return 0;
+ }
// This insert value inserts something else than what we are looking for.
// See if the (aggregrate) value inserted into has the value we are
// looking for, then.
if (*req_idx != *i)
- return FindInsertedValue(I->getAggregateOperand(), idx_begin, idx_end, InsertBefore);
+ return FindInsertedValue(I->getAggregateOperand(), idx_begin, idx_end,
+ Context, InsertBefore);
}
// If we end up here, the indices of the insertvalue match with those
// requested (though possibly only partially). Now we recursively look at
// the inserted value, passing any remaining indices.
- return FindInsertedValue(I->getInsertedValueOperand(), req_idx, idx_end, InsertBefore);
+ return FindInsertedValue(I->getInsertedValueOperand(), req_idx, idx_end,
+ Context, InsertBefore);
} else if (ExtractValueInst *I = dyn_cast<ExtractValueInst>(V)) {
// If we're extracting a value from an aggregrate that was extracted from
// something else, we can extract from that something else directly instead.
// Calculate the number of indices required
unsigned size = I->getNumIndices() + (idx_end - idx_begin);
// Allocate some space to put the new indices in
- unsigned *new_begin = new unsigned[size];
- // Auto cleanup this array
- std::auto_ptr<unsigned> newptr(new_begin);
- // Start inserting at the beginning
- unsigned *new_end = new_begin;
+ SmallVector<unsigned, 5> Idxs;
+ Idxs.reserve(size);
// Add indices from the extract value instruction
- for (const unsigned *i = I->idx_begin(), *e = I->idx_end(); i != e; ++i, ++new_end)
- *new_end = *i;
+ for (const unsigned *i = I->idx_begin(), *e = I->idx_end();
+ i != e; ++i)
+ Idxs.push_back(*i);
// Add requested indices
- for (const unsigned *i = idx_begin, *e = idx_end; i != e; ++i, ++new_end)
- *new_end = *i;
+ for (const unsigned *i = idx_begin, *e = idx_end; i != e; ++i)
+ Idxs.push_back(*i);
- assert((unsigned)(new_end - new_begin) == size && "Number of indices added not correct?");
+ assert(Idxs.size() == size
+ && "Number of indices added not correct?");
- return FindInsertedValue(I->getAggregateOperand(), new_begin, new_end, InsertBefore);
+ return FindInsertedValue(I->getAggregateOperand(), Idxs.begin(), Idxs.end(),
+ Context, InsertBefore);
}
// Otherwise, we don't know (such as, extracting from a function return value
// or load instruction)
return 0;
}
+
+/// GetConstantStringInfo - This function computes the length of a
+/// null-terminated C string pointed to by V. If successful, it returns true
+/// and returns the string in Str. If unsuccessful, it returns false.
+bool llvm::GetConstantStringInfo(Value *V, std::string &Str, uint64_t Offset,
+ bool StopAtNul) {
+ // If V is NULL then return false;
+ if (V == NULL) return false;
+
+ // Look through bitcast instructions.
+ if (BitCastInst *BCI = dyn_cast<BitCastInst>(V))
+ return GetConstantStringInfo(BCI->getOperand(0), Str, Offset, StopAtNul);
+
+ // If the value is not a GEP instruction nor a constant expression with a
+ // GEP instruction, then return false because ConstantArray can't occur
+ // any other way
+ User *GEP = 0;
+ if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(V)) {
+ GEP = GEPI;
+ } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
+ if (CE->getOpcode() == Instruction::BitCast)
+ return GetConstantStringInfo(CE->getOperand(0), Str, Offset, StopAtNul);
+ if (CE->getOpcode() != Instruction::GetElementPtr)
+ return false;
+ GEP = CE;
+ }
+
+ if (GEP) {
+ // Make sure the GEP has exactly three arguments.
+ if (GEP->getNumOperands() != 3)
+ return false;
+
+ // Make sure the index-ee is a pointer to array of i8.
+ const PointerType *PT = cast<PointerType>(GEP->getOperand(0)->getType());
+ const ArrayType *AT = dyn_cast<ArrayType>(PT->getElementType());
+ if (AT == 0 || AT->getElementType() != Type::getInt8Ty(V->getContext()))
+ return false;
+
+ // Check to make sure that the first operand of the GEP is an integer and
+ // has value 0 so that we are sure we're indexing into the initializer.
+ ConstantInt *FirstIdx = dyn_cast<ConstantInt>(GEP->getOperand(1));
+ if (FirstIdx == 0 || !FirstIdx->isZero())
+ return false;
+
+ // If the second index isn't a ConstantInt, then this is a variable index
+ // into the array. If this occurs, we can't say anything meaningful about
+ // the string.
+ uint64_t StartIdx = 0;
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(2)))
+ StartIdx = CI->getZExtValue();
+ else
+ return false;
+ return GetConstantStringInfo(GEP->getOperand(0), Str, StartIdx+Offset,
+ StopAtNul);
+ }
+
+ // The GEP instruction, constant or instruction, must reference a global
+ // variable that is a constant and is initialized. The referenced constant
+ // initializer is the array that we'll use for optimization.
+ GlobalVariable* GV = dyn_cast<GlobalVariable>(V);
+ if (!GV || !GV->isConstant() || !GV->hasInitializer())
+ return false;
+ Constant *GlobalInit = GV->getInitializer();
+
+ // Handle the ConstantAggregateZero case
+ if (isa<ConstantAggregateZero>(GlobalInit)) {
+ // This is a degenerate case. The initializer is constant zero so the
+ // length of the string must be zero.
+ Str.clear();
+ return true;
+ }
+
+ // Must be a Constant Array
+ ConstantArray *Array = dyn_cast<ConstantArray>(GlobalInit);
+ if (Array == 0 ||
+ Array->getType()->getElementType() != Type::getInt8Ty(V->getContext()))
+ return false;
+
+ // Get the number of elements in the array
+ uint64_t NumElts = Array->getType()->getNumElements();
+
+ if (Offset > NumElts)
+ return false;
+
+ // Traverse the constant array from 'Offset' which is the place the GEP refers
+ // to in the array.
+ Str.reserve(NumElts-Offset);
+ for (unsigned i = Offset; i != NumElts; ++i) {
+ Constant *Elt = Array->getOperand(i);
+ ConstantInt *CI = dyn_cast<ConstantInt>(Elt);
+ if (!CI) // This array isn't suitable, non-int initializer.
+ return false;
+ if (StopAtNul && CI->isZero())
+ return true; // we found end of string, success!
+ Str += (char)CI->getZExtValue();
+ }
+
+ // The array isn't null terminated, but maybe this is a memcpy, not a strcpy.
+ return true;
+}
projects / oota-llvm.git / blobdiff