"Combine redundant instructions", false, false)
void InstCombiner::getAnalysisUsage(AnalysisUsage &AU) const {
- AU.addPreservedID(LCSSAID);
AU.setPreservesCFG();
}
// It simplifies to V. Form "A op V".
I.setOperand(0, A);
I.setOperand(1, V);
+ // Conservatively clear the optional flags, since they may not be
+ // preserved by the reassociation.
+ I.clearSubclassOptionalData();
Changed = true;
++NumReassoc;
continue;
// It simplifies to V. Form "V op C".
I.setOperand(0, V);
I.setOperand(1, C);
+ // Conservatively clear the optional flags, since they may not be
+ // preserved by the reassociation.
+ I.clearSubclassOptionalData();
Changed = true;
++NumReassoc;
continue;
// It simplifies to V. Form "V op B".
I.setOperand(0, V);
I.setOperand(1, B);
+ // Conservatively clear the optional flags, since they may not be
+ // preserved by the reassociation.
+ I.clearSubclassOptionalData();
Changed = true;
++NumReassoc;
continue;
// It simplifies to V. Form "B op V".
I.setOperand(0, B);
I.setOperand(1, V);
+ // Conservatively clear the optional flags, since they may not be
+ // preserved by the reassociation.
+ I.clearSubclassOptionalData();
Changed = true;
++NumReassoc;
continue;
Constant *C2 = cast<Constant>(Op1->getOperand(1));
Constant *Folded = ConstantExpr::get(Opcode, C1, C2);
- Instruction *New = BinaryOperator::Create(Opcode, A, B, Op1->getName(),
- &I);
- Worklist.Add(New);
+ Instruction *New = BinaryOperator::Create(Opcode, A, B);
+ InsertNewInstWith(New, I);
+ New->takeName(Op1);
I.setOperand(0, New);
I.setOperand(1, Folded);
+ // Conservatively clear the optional flags, since they may not be
+ // preserved by the reassociation.
+ I.clearSubclassOptionalData();
Changed = true;
continue;
}
static Value *FoldOperationIntoSelectOperand(Instruction &I, Value *SO,
InstCombiner *IC) {
- if (CastInst *CI = dyn_cast<CastInst>(&I))
+ if (CastInst *CI = dyn_cast<CastInst>(&I)) {
return IC->Builder->CreateCast(CI->getOpcode(), SO, I.getType());
+ }
// Figure out if the constant is the left or the right argument.
bool ConstIsRHS = isa<Constant>(I.getOperand(1));
// Bool selects with constant operands can be folded to logical ops.
if (SI->getType()->isIntegerTy(1)) return 0;
+ // If it's a bitcast involving vectors, make sure it has the same number of
+ // elements on both sides.
+ if (BitCastInst *BC = dyn_cast<BitCastInst>(&Op)) {
+ const VectorType *DestTy = dyn_cast<VectorType>(BC->getDestTy());
+ const VectorType *SrcTy = dyn_cast<VectorType>(BC->getSrcTy());
+
+ // Verify that either both or neither are vectors.
+ if ((SrcTy == NULL) != (DestTy == NULL)) return 0;
+ // If vectors, verify that they have the same number of elements.
+ if (SrcTy && SrcTy->getNumElements() != DestTy->getNumElements())
+ return 0;
+ }
+
Value *SelectTrueVal = FoldOperationIntoSelectOperand(Op, TV, this);
Value *SelectFalseVal = FoldOperationIntoSelectOperand(Op, FV, this);
- return SelectInst::Create(SI->getCondition(), SelectTrueVal,
- SelectFalseVal);
+ return SelectInst::Create(SI->getCondition(),
+ SelectTrueVal, SelectFalseVal);
}
return 0;
}
/// has a PHI node as operand #0, see if we can fold the instruction into the
/// PHI (which is only possible if all operands to the PHI are constants).
///
-/// If AllowAggressive is true, FoldOpIntoPhi will allow certain transforms
-/// that would normally be unprofitable because they strongly encourage jump
-/// threading.
-Instruction *InstCombiner::FoldOpIntoPhi(Instruction &I,
- bool AllowAggressive) {
- AllowAggressive = false;
+Instruction *InstCombiner::FoldOpIntoPhi(Instruction &I) {
PHINode *PN = cast<PHINode>(I.getOperand(0));
unsigned NumPHIValues = PN->getNumIncomingValues();
if (NumPHIValues == 0)
return 0;
- // We normally only transform phis with a single use, unless we're trying
- // hard to make jump threading happen.
- if (!PN->hasOneUse() && !AllowAggressive)
- return 0;
+ // We normally only transform phis with a single use. However, if a PHI has
+ // multiple uses and they are all the same operation, we can fold *all* of the
+ // uses into the PHI.
+ if (!PN->hasOneUse()) {
+ // Walk the use list for the instruction, comparing them to I.
+ for (Value::use_iterator UI = PN->use_begin(), E = PN->use_end();
+ UI != E; ++UI) {
+ Instruction *User = cast<Instruction>(*UI);
+ if (User != &I && !I.isIdenticalTo(User))
+ return 0;
+ }
+ // Otherwise, we can replace *all* users with the new PHI we form.
+ }
// Check to see if all of the operands of the PHI are simple constants
// (constantint/constantfp/undef). If there is one non-constant value,
if (NonConstBB) return 0; // More than one non-const value.
NonConstBB = PN->getIncomingBlock(i);
+
+ // If the InVal is an invoke at the end of the pred block, then we can't
+ // insert a computation after it without breaking the edge.
+ if (InvokeInst *II = dyn_cast<InvokeInst>(InVal))
+ if (II->getParent() == NonConstBB)
+ return 0;
- // If the incoming non-constant value is in I's block, we have an infinite
- // loop.
+ // If the incoming non-constant value is in I's block, we will remove one
+ // instruction, but insert another equivalent one, leading to infinite
+ // instcombine.
if (NonConstBB == I.getParent())
return 0;
}
// operation in that block. However, if this is a critical edge, we would be
// inserting the computation one some other paths (e.g. inside a loop). Only
// do this if the pred block is unconditionally branching into the phi block.
- if (NonConstBB != 0 && !AllowAggressive) {
+ if (NonConstBB != 0) {
BranchInst *BI = dyn_cast<BranchInst>(NonConstBB->getTerminator());
if (!BI || !BI->isUnconditional()) return 0;
}
// Okay, we can do the transformation: create the new PHI node.
- PHINode *NewPN = PHINode::Create(I.getType(), "");
- NewPN->reserveOperandSpace(PN->getNumOperands()/2);
+ PHINode *NewPN = PHINode::Create(I.getType(), PN->getNumIncomingValues());
InsertNewInstBefore(NewPN, *PN);
NewPN->takeName(PN);
-
+
+ // If we are going to have to insert a new computation, do so right before the
+ // predecessors terminator.
+ if (NonConstBB)
+ Builder->SetInsertPoint(NonConstBB->getTerminator());
+
// Next, add all of the operands to the PHI.
if (SelectInst *SI = dyn_cast<SelectInst>(&I)) {
// We only currently try to fold the condition of a select when it is a phi,
Value *TrueVInPred = TrueV->DoPHITranslation(PhiTransBB, ThisBB);
Value *FalseVInPred = FalseV->DoPHITranslation(PhiTransBB, ThisBB);
Value *InV = 0;
- if (Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i))) {
+ if (Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i)))
InV = InC->isNullValue() ? FalseVInPred : TrueVInPred;
- } else {
- assert(PN->getIncomingBlock(i) == NonConstBB);
- InV = SelectInst::Create(PN->getIncomingValue(i), TrueVInPred,
- FalseVInPred,
- "phitmp", NonConstBB->getTerminator());
- Worklist.Add(cast<Instruction>(InV));
- }
+ else
+ InV = Builder->CreateSelect(PN->getIncomingValue(i),
+ TrueVInPred, FalseVInPred, "phitmp");
NewPN->addIncoming(InV, ThisBB);
}
+ } else if (CmpInst *CI = dyn_cast<CmpInst>(&I)) {
+ Constant *C = cast<Constant>(I.getOperand(1));
+ for (unsigned i = 0; i != NumPHIValues; ++i) {
+ Value *InV = 0;
+ if (Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i)))
+ InV = ConstantExpr::getCompare(CI->getPredicate(), InC, C);
+ else if (isa<ICmpInst>(CI))
+ InV = Builder->CreateICmp(CI->getPredicate(), PN->getIncomingValue(i),
+ C, "phitmp");
+ else
+ InV = Builder->CreateFCmp(CI->getPredicate(), PN->getIncomingValue(i),
+ C, "phitmp");
+ NewPN->addIncoming(InV, PN->getIncomingBlock(i));
+ }
} else if (I.getNumOperands() == 2) {
Constant *C = cast<Constant>(I.getOperand(1));
for (unsigned i = 0; i != NumPHIValues; ++i) {
Value *InV = 0;
- if (Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i))) {
- if (CmpInst *CI = dyn_cast<CmpInst>(&I))
- InV = ConstantExpr::getCompare(CI->getPredicate(), InC, C);
- else
- InV = ConstantExpr::get(I.getOpcode(), InC, C);
- } else {
- assert(PN->getIncomingBlock(i) == NonConstBB);
- if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&I))
- InV = BinaryOperator::Create(BO->getOpcode(),
- PN->getIncomingValue(i), C, "phitmp",
- NonConstBB->getTerminator());
- else if (CmpInst *CI = dyn_cast<CmpInst>(&I))
- InV = CmpInst::Create(CI->getOpcode(),
- CI->getPredicate(),
- PN->getIncomingValue(i), C, "phitmp",
- NonConstBB->getTerminator());
- else
- llvm_unreachable("Unknown binop!");
-
- Worklist.Add(cast<Instruction>(InV));
- }
+ if (Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i)))
+ InV = ConstantExpr::get(I.getOpcode(), InC, C);
+ else
+ InV = Builder->CreateBinOp(cast<BinaryOperator>(I).getOpcode(),
+ PN->getIncomingValue(i), C, "phitmp");
NewPN->addIncoming(InV, PN->getIncomingBlock(i));
}
} else {
const Type *RetTy = CI->getType();
for (unsigned i = 0; i != NumPHIValues; ++i) {
Value *InV;
- if (Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i))) {
+ if (Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i)))
InV = ConstantExpr::getCast(CI->getOpcode(), InC, RetTy);
- } else {
- assert(PN->getIncomingBlock(i) == NonConstBB);
- InV = CastInst::Create(CI->getOpcode(), PN->getIncomingValue(i),
- I.getType(), "phitmp",
- NonConstBB->getTerminator());
- Worklist.Add(cast<Instruction>(InV));
- }
+ else
+ InV = Builder->CreateCast(CI->getOpcode(),
+ PN->getIncomingValue(i), I.getType(), "phitmp");
NewPN->addIncoming(InV, PN->getIncomingBlock(i));
}
}
+
+ for (Value::use_iterator UI = PN->use_begin(), E = PN->use_end();
+ UI != E; ) {
+ Instruction *User = cast<Instruction>(*UI++);
+ if (User == &I) continue;
+ ReplaceInstUsesWith(*User, NewPN);
+ EraseInstFromFunction(*User);
+ }
return ReplaceInstUsesWith(I, NewPN);
}
GetElementPtrInst::Create(Src->getOperand(0), Indices.begin(),
Indices.end(), GEP.getName());
}
-
+
// Handle gep(bitcast x) and gep(gep x, 0, 0, 0).
Value *StrippedPtr = PtrOp->stripPointerCasts();
- if (StrippedPtr != PtrOp) {
- const PointerType *StrippedPtrTy =cast<PointerType>(StrippedPtr->getType());
+ const PointerType *StrippedPtrTy =cast<PointerType>(StrippedPtr->getType());
+ if (StrippedPtr != PtrOp &&
+ StrippedPtrTy->getAddressSpace() == GEP.getPointerAddressSpace()) {
bool HasZeroPointerIndex = false;
if (ConstantInt *C = dyn_cast<ConstantInt>(GEP.getOperand(1)))
HasZeroPointerIndex = C->isZero();
-
+
// Transform: GEP (bitcast [10 x i8]* X to [0 x i8]*), i32 0, ...
// into : GEP [10 x i8]* X, i32 0, ...
//
// Likewise, transform: GEP (bitcast i8* X to [0 x i8]*), i32 0, ...
// into : GEP i8* X, ...
- //
+ //
// This occurs when the program declares an array extern like "int X[];"
if (HasZeroPointerIndex) {
const PointerType *CPTy = cast<PointerType>(PtrOp->getType());
}
}
}
-
+
/// See if we can simplify:
/// X = bitcast A* to B*
/// Y = gep X, <...constant indices...>
/// analysis of unions. If "A" is also a bitcast, wait for A/X to be merged.
if (BitCastInst *BCI = dyn_cast<BitCastInst>(PtrOp)) {
if (TD &&
- !isa<BitCastInst>(BCI->getOperand(0)) && GEP.hasAllConstantIndices()) {
+ !isa<BitCastInst>(BCI->getOperand(0)) && GEP.hasAllConstantIndices() &&
+ StrippedPtrTy->getAddressSpace() == GEP.getPointerAddressSpace()) {
+
// Determine how much the GEP moves the pointer. We are guaranteed to get
// a constant back from EmitGEPOffset.
ConstantInt *OffsetV = cast<ConstantInt>(EmitGEPOffset(&GEP));
int64_t Offset = OffsetV->getSExtValue();
-
+
// If this GEP instruction doesn't move the pointer, just replace the GEP
// with a bitcast of the real input to the dest type.
if (Offset == 0) {
// free undef -> unreachable.
if (isa<UndefValue>(Op)) {
// Insert a new store to null because we cannot modify the CFG here.
- new StoreInst(ConstantInt::getTrue(FI.getContext()),
- UndefValue::get(Type::getInt1PtrTy(FI.getContext())), &FI);
+ Builder->CreateStore(ConstantInt::getTrue(FI.getContext()),
+ UndefValue::get(Type::getInt1PtrTy(FI.getContext())));
return EraseInstFromFunction(FI);
}
case Intrinsic::sadd_with_overflow:
if (*EV.idx_begin() == 0) { // Normal result.
Value *LHS = II->getArgOperand(0), *RHS = II->getArgOperand(1);
- II->replaceAllUsesWith(UndefValue::get(II->getType()));
+ ReplaceInstUsesWith(*II, UndefValue::get(II->getType()));
EraseInstFromFunction(*II);
return BinaryOperator::CreateAdd(LHS, RHS);
}
case Intrinsic::ssub_with_overflow:
if (*EV.idx_begin() == 0) { // Normal result.
Value *LHS = II->getArgOperand(0), *RHS = II->getArgOperand(1);
- II->replaceAllUsesWith(UndefValue::get(II->getType()));
+ ReplaceInstUsesWith(*II, UndefValue::get(II->getType()));
EraseInstFromFunction(*II);
return BinaryOperator::CreateSub(LHS, RHS);
}
case Intrinsic::smul_with_overflow:
if (*EV.idx_begin() == 0) { // Normal result.
Value *LHS = II->getArgOperand(0), *RHS = II->getArgOperand(1);
- II->replaceAllUsesWith(UndefValue::get(II->getType()));
+ ReplaceInstUsesWith(*II, UndefValue::get(II->getType()));
EraseInstFromFunction(*II);
return BinaryOperator::CreateMul(LHS, RHS);
}
Worklist.push_back(BB);
SmallVector<Instruction*, 128> InstrsForInstCombineWorklist;
- SmallPtrSet<ConstantExpr*, 64> FoldedConstants;
-
+ DenseMap<ConstantExpr*, Constant*> FoldedConstants;
+
do {
BB = Worklist.pop_back_val();
i != e; ++i) {
ConstantExpr *CE = dyn_cast<ConstantExpr>(i);
if (CE == 0) continue;
-
- // If we already folded this constant, don't try again.
- if (!FoldedConstants.insert(CE))
- continue;
-
- Constant *NewC = ConstantFoldConstantExpression(CE, TD);
- if (NewC && NewC != CE) {
- *i = NewC;
+
+ Constant*& FoldRes = FoldedConstants[CE];
+ if (!FoldRes)
+ FoldRes = ConstantFoldConstantExpression(CE, TD);
+ if (!FoldRes)
+ FoldRes = CE;
+
+ if (FoldRes != CE) {
+ *i = FoldRes;
MadeIRChange = true;
}
}
// Now that we have an instruction, try combining it to simplify it.
Builder->SetInsertPoint(I->getParent(), I);
+ Builder->SetCurrentDebugLocation(I->getDebugLoc());
#ifndef NDEBUG
std::string OrigI;
DEBUG(errs() << "IC: Old = " << *I << '\n'
<< " New = " << *Result << '\n');
+ if (!I->getDebugLoc().isUnknown())
+ Result->setDebugLoc(I->getDebugLoc());
// Everything uses the new instruction now.
I->replaceAllUsesWith(Result);
bool InstCombiner::runOnFunction(Function &F) {
- MustPreserveLCSSA = mustPreserveAnalysisID(LCSSAID);
TD = getAnalysisIfAvailable<TargetData>();
bool EverMadeChange = false;
+ // Lower dbg.declare intrinsics otherwise their value may be clobbered
+ // by instcombiner.
+ EverMadeChange = LowerDbgDeclare(F);
+
// Iterate while there is work to do.
unsigned Iteration = 0;
while (DoOneIteration(F, Iteration++))
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