#include "llvm/Target/TargetData.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Local.h"
+#include "llvm/Support/CallSite.h"
+#include "llvm/Support/GetElementPtrTypeIterator.h"
#include "llvm/Support/InstIterator.h"
#include "llvm/Support/InstVisitor.h"
-#include "llvm/Support/CallSite.h"
#include "Support/Debug.h"
#include "Support/Statistic.h"
#include <algorithm>
AU.setPreservesCFG();
}
+ TargetData &getTargetData() const { return *TD; }
+
// Visitation implementation - Implement instruction combining for different
// instruction types. The semantics are as follows:
// Return Value:
Instruction *visitCallSite(CallSite CS);
bool transformConstExprCastCall(CallSite CS);
+ public:
// InsertNewInstBefore - insert an instruction New before instruction Old
// in the program. Add the new instruction to the worklist.
//
return New;
}
- public:
// ReplaceInstUsesWith - This method is to be used when an instruction is
// found to be dead, replacable with another preexisting expression. Here
// we add all uses of I to the worklist, replace all uses of I with the new
//
Instruction *ReplaceInstUsesWith(Instruction &I, Value *V) {
AddUsersToWorkList(I); // Add all modified instrs to worklist
- I.replaceAllUsesWith(V);
- return &I;
+ if (&I != V) {
+ I.replaceAllUsesWith(V);
+ return &I;
+ } else {
+ // If we are replacing the instruction with itself, this must be in a
+ // segment of unreachable code, so just clobber the instruction.
+ I.replaceAllUsesWith(Constant::getNullValue(I.getType()));
+ return &I;
+ }
}
// EraseInstFromFunction - When dealing with an instruction that has side
// Make what used to be the LHS of the root be the user of the root...
Value *ExtraOperand = TmpLHSI->getOperand(1);
- Root.replaceAllUsesWith(TmpLHSI); // Users now use TmpLHSI
+ if (&Root != TmpLHSI)
+ Root.replaceAllUsesWith(TmpLHSI); // Users now use TmpLHSI
+ else {
+ Root.replaceAllUsesWith(Constant::getNullValue(TmpLHSI->getType()));
+ return 0;
+ }
TmpLHSI->setOperand(1, &Root); // TmpLHSI now uses the root
BB->getInstList().remove(&Root); // Remove root from the BB
BB->getInstList().insert(TmpLHSI, &Root); // Insert root before TmpLHSI
if (ConstantInt *RHS = dyn_cast<ConstantInt>(I.getOperand(1))) {
if (RHS->equalsInt(1)) // X % 1 == 0
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
+ if (RHS->isAllOnesValue()) // X % -1 == 0
+ return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
// Check to see if this is an unsigned remainder with an exact power of 2,
// if so, convert to a bitwise and.
}
Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
- if (ConstantBool *C = dyn_cast<ConstantBool>(SI.getCondition()))
+ Value *CondVal = SI.getCondition();
+ Value *TrueVal = SI.getTrueValue();
+ Value *FalseVal = SI.getFalseValue();
+
+ // select true, X, Y -> X
+ // select false, X, Y -> Y
+ if (ConstantBool *C = dyn_cast<ConstantBool>(CondVal))
if (C == ConstantBool::True)
- return ReplaceInstUsesWith(SI, SI.getTrueValue());
+ return ReplaceInstUsesWith(SI, TrueVal);
else {
assert(C == ConstantBool::False);
- return ReplaceInstUsesWith(SI, SI.getFalseValue());
+ return ReplaceInstUsesWith(SI, FalseVal);
+ }
+
+ // select C, X, X -> X
+ if (TrueVal == FalseVal)
+ return ReplaceInstUsesWith(SI, TrueVal);
+
+ if (SI.getType() == Type::BoolTy)
+ if (ConstantBool *C = dyn_cast<ConstantBool>(TrueVal)) {
+ if (C == ConstantBool::True) {
+ // Change: A = select B, true, C --> A = or B, C
+ return BinaryOperator::create(Instruction::Or, CondVal, FalseVal);
+ } else {
+ // Change: A = select B, false, C --> A = and !B, C
+ Value *NotCond =
+ InsertNewInstBefore(BinaryOperator::createNot(CondVal,
+ "not."+CondVal->getName()), SI);
+ return BinaryOperator::create(Instruction::And, NotCond, FalseVal);
+ }
+ } else if (ConstantBool *C = dyn_cast<ConstantBool>(FalseVal)) {
+ if (C == ConstantBool::False) {
+ // Change: A = select B, C, false --> A = and B, C
+ return BinaryOperator::create(Instruction::And, CondVal, TrueVal);
+ } else {
+ // Change: A = select B, C, true --> A = or !B, C
+ Value *NotCond =
+ InsertNewInstBefore(BinaryOperator::createNot(CondVal,
+ "not."+CondVal->getName()), SI);
+ return BinaryOperator::create(Instruction::Or, NotCond, TrueVal);
+ }
}
- // Other transformations are possible!
+ // Selecting between two constants?
+ if (Constant *TrueValC = dyn_cast<Constant>(TrueVal))
+ if (Constant *FalseValC = dyn_cast<Constant>(FalseVal)) {
+ if (SI.getType()->isInteger()) {
+ // select C, 1, 0 -> cast C to int
+ if (FalseValC->isNullValue() && isa<ConstantInt>(TrueValC) &&
+ cast<ConstantInt>(TrueValC)->getRawValue() == 1) {
+ return new CastInst(CondVal, SI.getType());
+ } else if (TrueValC->isNullValue() && isa<ConstantInt>(FalseValC) &&
+ cast<ConstantInt>(FalseValC)->getRawValue() == 1) {
+ // select C, 0, 1 -> cast !C to int
+ Value *NotCond =
+ InsertNewInstBefore(BinaryOperator::createNot(CondVal,
+ "not."+CondVal->getName()), SI);
+ return new CastInst(NotCond, SI.getType());
+ }
+ }
+ }
+
return 0;
}
if ((*AI)->getType() == ParamTy) {
Args.push_back(*AI);
} else {
- Instruction *Cast = new CastInst(*AI, ParamTy, "tmp");
- InsertNewInstBefore(Cast, *Caller);
- Args.push_back(Cast);
+ Args.push_back(InsertNewInstBefore(new CastInst(*AI, ParamTy, "tmp"),
+ *Caller));
}
}
return 0;
}
+static Value *InsertSignExtendToPtrTy(Value *V, const Type *DTy,
+ Instruction *InsertPoint,
+ InstCombiner *IC) {
+ unsigned PS = IC->getTargetData().getPointerSize();
+ const Type *VTy = V->getType();
+ Instruction *Cast;
+ if (!VTy->isSigned() && VTy->getPrimitiveSize() < PS)
+ // We must insert a cast to ensure we sign-extend.
+ V = IC->InsertNewInstBefore(new CastInst(V, VTy->getSignedVersion(),
+ V->getName()), *InsertPoint);
+ return IC->InsertNewInstBefore(new CastInst(V, DTy, V->getName()),
+ *InsertPoint);
+}
+
Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
// Is it 'getelementptr %P, long 0' or 'getelementptr %P'
if (GEP.getNumOperands() == 2 && HasZeroPointerIndex)
return ReplaceInstUsesWith(GEP, GEP.getOperand(0));
+ // Eliminate unneeded casts for indices.
+ bool MadeChange = false;
+ gep_type_iterator GTI = gep_type_begin(GEP);
+ for (unsigned i = 1, e = GEP.getNumOperands(); i != e; ++i, ++GTI)
+ if (isa<SequentialType>(*GTI)) {
+ if (CastInst *CI = dyn_cast<CastInst>(GEP.getOperand(i))) {
+ Value *Src = CI->getOperand(0);
+ const Type *SrcTy = Src->getType();
+ const Type *DestTy = CI->getType();
+ if (Src->getType()->isInteger()) {
+ if (SrcTy->getPrimitiveSize() == DestTy->getPrimitiveSize()) {
+ // We can always eliminate a cast from ulong or long to the other.
+ // We can always eliminate a cast from uint to int or the other on
+ // 32-bit pointer platforms.
+ if (DestTy->getPrimitiveSize() >= TD->getPointerSize()) {
+ MadeChange = true;
+ GEP.setOperand(i, Src);
+ }
+ } else if (SrcTy->getPrimitiveSize() < DestTy->getPrimitiveSize() &&
+ SrcTy->getPrimitiveSize() == 4) {
+ // We can always eliminate a cast from int to [u]long. We can
+ // eliminate a cast from uint to [u]long iff the target is a 32-bit
+ // pointer target.
+ if (SrcTy->isSigned() ||
+ SrcTy->getPrimitiveSize() >= TD->getPointerSize()) {
+ MadeChange = true;
+ GEP.setOperand(i, Src);
+ }
+ }
+ }
+ }
+ // If we are using a wider index than needed for this platform, shrink it
+ // to what we need. If the incoming value needs a cast instruction,
+ // insert it. This explicit cast can make subsequent optimizations more
+ // obvious.
+ Value *Op = GEP.getOperand(i);
+ if (Op->getType()->getPrimitiveSize() > TD->getPointerSize())
+ if (!isa<Constant>(Op)) {
+ Op = InsertNewInstBefore(new CastInst(Op, TD->getIntPtrType(),
+ Op->getName()), GEP);
+ GEP.setOperand(i, Op);
+ MadeChange = true;
+ }
+ }
+ if (MadeChange) return &GEP;
+
// Combine Indices - If the source pointer to this getelementptr instruction
// is a getelementptr instruction, combine the indices of the two
// getelementptr instructions into a single instruction.
//
+ std::vector<Value*> SrcGEPOperands;
if (GetElementPtrInst *Src = dyn_cast<GetElementPtrInst>(GEP.getOperand(0))) {
+ SrcGEPOperands.assign(Src->op_begin(), Src->op_end());
+ } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(GEP.getOperand(0))) {
+ if (CE->getOpcode() == Instruction::GetElementPtr)
+ SrcGEPOperands.assign(CE->op_begin(), CE->op_end());
+ }
+
+ if (!SrcGEPOperands.empty()) {
std::vector<Value *> Indices;
// Can we combine the two pointer arithmetics offsets?
- if (Src->getNumOperands() == 2 && isa<Constant>(Src->getOperand(1)) &&
+ if (SrcGEPOperands.size() == 2 && isa<Constant>(SrcGEPOperands[1]) &&
isa<Constant>(GEP.getOperand(1))) {
+ Constant *SGC = cast<Constant>(SrcGEPOperands[1]);
+ Constant *GC = cast<Constant>(GEP.getOperand(1));
+ if (SGC->getType() != GC->getType()) {
+ SGC = ConstantExpr::getSignExtend(SGC, Type::LongTy);
+ GC = ConstantExpr::getSignExtend(GC, Type::LongTy);
+ }
+
// Replace: gep (gep %P, long C1), long C2, ...
// With: gep %P, long (C1+C2), ...
- Value *Sum = ConstantExpr::get(Instruction::Add,
- cast<Constant>(Src->getOperand(1)),
- cast<Constant>(GEP.getOperand(1)));
- assert(Sum && "Constant folding of longs failed!?");
- GEP.setOperand(0, Src->getOperand(0));
- GEP.setOperand(1, Sum);
- AddUsersToWorkList(*Src); // Reduce use count of Src
+ GEP.setOperand(0, SrcGEPOperands[0]);
+ GEP.setOperand(1, ConstantExpr::getAdd(SGC, GC));
+ if (Instruction *I = dyn_cast<Instruction>(GEP.getOperand(0)))
+ AddUsersToWorkList(*I); // Reduce use count of Src
return &GEP;
- } else if (Src->getNumOperands() == 2) {
+ } else if (SrcGEPOperands.size() == 2) {
// Replace: gep (gep %P, long B), long A, ...
// With: T = long A+B; gep %P, T, ...
//
// chain to be resolved before we perform this transformation. This
// avoids us creating a TON of code in some cases.
//
- if (isa<GetElementPtrInst>(Src->getOperand(0)) &&
- cast<Instruction>(Src->getOperand(0))->getNumOperands() == 2)
+ if (isa<GetElementPtrInst>(SrcGEPOperands[0]) &&
+ cast<Instruction>(SrcGEPOperands[0])->getNumOperands() == 2)
return 0; // Wait until our source is folded to completion.
- Value *Sum = BinaryOperator::create(Instruction::Add, Src->getOperand(1),
- GEP.getOperand(1),
- Src->getName()+".sum", &GEP);
- GEP.setOperand(0, Src->getOperand(0));
+ Value *Sum, *SO1 = SrcGEPOperands[1], *GO1 = GEP.getOperand(1);
+ if (SO1 == Constant::getNullValue(SO1->getType())) {
+ Sum = GO1;
+ } else if (GO1 == Constant::getNullValue(GO1->getType())) {
+ Sum = SO1;
+ } else {
+ // If they aren't the same type, convert both to an integer of the
+ // target's pointer size.
+ if (SO1->getType() != GO1->getType()) {
+ if (Constant *SO1C = dyn_cast<Constant>(SO1)) {
+ SO1 = ConstantExpr::getCast(SO1C, GO1->getType());
+ } else if (Constant *GO1C = dyn_cast<Constant>(GO1)) {
+ GO1 = ConstantExpr::getCast(GO1C, SO1->getType());
+ } else {
+ unsigned PS = TD->getPointerSize();
+ Instruction *Cast;
+ if (SO1->getType()->getPrimitiveSize() == PS) {
+ // Convert GO1 to SO1's type.
+ GO1 = InsertSignExtendToPtrTy(GO1, SO1->getType(), &GEP, this);
+
+ } else if (GO1->getType()->getPrimitiveSize() == PS) {
+ // Convert SO1 to GO1's type.
+ SO1 = InsertSignExtendToPtrTy(SO1, GO1->getType(), &GEP, this);
+ } else {
+ const Type *PT = TD->getIntPtrType();
+ SO1 = InsertSignExtendToPtrTy(SO1, PT, &GEP, this);
+ GO1 = InsertSignExtendToPtrTy(GO1, PT, &GEP, this);
+ }
+ }
+ }
+ Sum = BinaryOperator::create(Instruction::Add, SO1, GO1,
+ GEP.getOperand(0)->getName()+".sum", &GEP);
+ WorkList.push_back(cast<Instruction>(Sum));
+ }
+ GEP.setOperand(0, SrcGEPOperands[0]);
GEP.setOperand(1, Sum);
- WorkList.push_back(cast<Instruction>(Sum));
return &GEP;
- } else if (*GEP.idx_begin() == Constant::getNullValue(Type::LongTy) &&
- Src->getNumOperands() != 1) {
+ } else if (isa<Constant>(*GEP.idx_begin()) &&
+ cast<Constant>(*GEP.idx_begin())->isNullValue() &&
+ SrcGEPOperands.size() != 1) {
// Otherwise we can do the fold if the first index of the GEP is a zero
- Indices.insert(Indices.end(), Src->idx_begin(), Src->idx_end());
+ Indices.insert(Indices.end(), SrcGEPOperands.begin()+1,
+ SrcGEPOperands.end());
Indices.insert(Indices.end(), GEP.idx_begin()+1, GEP.idx_end());
- } else if (Src->getOperand(Src->getNumOperands()-1) ==
- Constant::getNullValue(Type::LongTy)) {
- // If the src gep ends with a constant array index, merge this get into
- // it, even if we have a non-zero array index.
- Indices.insert(Indices.end(), Src->idx_begin(), Src->idx_end()-1);
- Indices.insert(Indices.end(), GEP.idx_begin(), GEP.idx_end());
+ } else if (SrcGEPOperands.back() ==
+ Constant::getNullValue(SrcGEPOperands.back()->getType())) {
+ // We have to check to make sure this really is an ARRAY index we are
+ // ending up with, not a struct index.
+ generic_gep_type_iterator<std::vector<Value*>::iterator>
+ GTI = gep_type_begin(SrcGEPOperands[0]->getType(),
+ SrcGEPOperands.begin()+1, SrcGEPOperands.end());
+ std::advance(GTI, SrcGEPOperands.size()-2);
+ if (isa<SequentialType>(*GTI)) {
+ // If the src gep ends with a constant array index, merge this get into
+ // it, even if we have a non-zero array index.
+ Indices.insert(Indices.end(), SrcGEPOperands.begin()+1,
+ SrcGEPOperands.end()-1);
+ Indices.insert(Indices.end(), GEP.idx_begin(), GEP.idx_end());
+ }
}
if (!Indices.empty())
- return new GetElementPtrInst(Src->getOperand(0), Indices, GEP.getName());
+ return new GetElementPtrInst(SrcGEPOperands[0], Indices, GEP.getName());
} else if (GlobalValue *GV = dyn_cast<GlobalValue>(GEP.getOperand(0))) {
// GEP of global variable. If all of the indices for this GEP are
// Now that I is pointing to the first non-allocation-inst in the block,
// insert our getelementptr instruction...
//
- std::vector<Value*> Idx(2, Constant::getNullValue(Type::LongTy));
+ std::vector<Value*> Idx(2, Constant::getNullValue(Type::IntTy));
Value *V = new GetElementPtrInst(New, Idx, New->getName()+".sub", It);
// Now make everything use the getelementptr instead of the original
/// expression, or null if something is funny.
///
static Constant *GetGEPGlobalInitializer(Constant *C, ConstantExpr *CE) {
- if (CE->getOperand(1) != Constant::getNullValue(Type::LongTy))
+ if (CE->getOperand(1) != Constant::getNullValue(CE->getOperand(1)->getType()))
return 0; // Do not allow stepping over the value!
// Loop over all of the operands, tracking down which value we are
if (GV->isConstant() && !GV->isExternal())
if (Constant *V = GetGEPGlobalInitializer(GV->getInitializer(), CE))
return ReplaceInstUsesWith(LI, V);
+
+ // load (cast X) --> cast (load X) iff safe
+ if (CastInst *CI = dyn_cast<CastInst>(Op)) {
+ const Type *DestPTy = cast<PointerType>(CI->getType())->getElementType();
+ if (const PointerType *SrcTy =
+ dyn_cast<PointerType>(CI->getOperand(0)->getType())) {
+ const Type *SrcPTy = SrcTy->getElementType();
+ if (TD->getTypeSize(SrcPTy) == TD->getTypeSize(DestPTy) &&
+ (SrcPTy->isInteger() || isa<PointerType>(SrcPTy)) &&
+ (DestPTy->isInteger() || isa<PointerType>(DestPTy))) {
+ // Okay, we are casting from one integer or pointer type to another of
+ // the same size. Instead of casting the pointer before the load, cast
+ // the result of the loaded value.
+ Value *NewLoad = InsertNewInstBefore(new LoadInst(CI->getOperand(0),
+ CI->getName()), LI);
+ // Now cast the result of the load.
+ return new CastInst(NewLoad, LI.getType());
+ }
+ }
+ }
+
return 0;
}
continue;
}
+ // Check to see if any of the operands of this instruction are a
+ // ConstantPointerRef. Since they sneak in all over the place and inhibit
+ // optimization, we want to strip them out unconditionally!
+ for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
+ if (ConstantPointerRef *CPR =
+ dyn_cast<ConstantPointerRef>(I->getOperand(i))) {
+ I->setOperand(i, CPR->getValue());
+ Changed = true;
+ }
+
// Now that we have an instruction, try combining it to simplify it...
if (Instruction *Result = visit(*I)) {
++NumCombined;
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