#include "InstCombine.h"
#include "llvm/Support/PatternMatch.h"
+#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Analysis/InstructionSimplify.h"
using namespace llvm;
using namespace PatternMatch;
if (TI->isCast()) {
if (TI->getOperand(0)->getType() != FI->getOperand(0)->getType())
return 0;
+ // The select condition may be a vector. We may only change the operand
+ // type if the vector width remains the same (and matches the condition).
+ Type *CondTy = SI.getCondition()->getType();
+ if (CondTy->isVectorTy() && CondTy->getVectorNumElements() !=
+ FI->getOperand(0)->getType()->getVectorNumElements())
+ return 0;
} else {
return 0; // unknown unary op.
}
// Fold this by inserting a select from the input values.
- SelectInst *NewSI = SelectInst::Create(SI.getCondition(), TI->getOperand(0),
- FI->getOperand(0), SI.getName()+".v");
- InsertNewInstBefore(NewSI, SI);
+ Value *NewSI = Builder->CreateSelect(SI.getCondition(), TI->getOperand(0),
+ FI->getOperand(0), SI.getName()+".v");
return CastInst::Create(Instruction::CastOps(TI->getOpcode()), NewSI,
TI->getType());
}
}
// If we reach here, they do have operations in common.
- SelectInst *NewSI = SelectInst::Create(SI.getCondition(), OtherOpT,
- OtherOpF, SI.getName()+".v");
- InsertNewInstBefore(NewSI, SI);
+ Value *NewSI = Builder->CreateSelect(SI.getCondition(), OtherOpT,
+ OtherOpF, SI.getName()+".v");
if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TI)) {
if (MatchIsOpZero)
return BinaryOperator::Create(BO->getOpcode(), NewSI, MatchOp);
}
llvm_unreachable("Shouldn't get here");
- return 0;
}
static bool isSelect01(Constant *C1, Constant *C2) {
unsigned OpToFold = 0;
if ((SFO & 1) && FalseVal == TVI->getOperand(0)) {
OpToFold = 1;
- } else if ((SFO & 2) && FalseVal == TVI->getOperand(1)) {
+ } else if ((SFO & 2) && FalseVal == TVI->getOperand(1)) {
OpToFold = 2;
}
// Avoid creating select between 2 constants unless it's selecting
// between 0, 1 and -1.
if (!isa<Constant>(OOp) || isSelect01(C, cast<Constant>(OOp))) {
- Instruction *NewSel = SelectInst::Create(SI.getCondition(), OOp, C);
- InsertNewInstBefore(NewSel, SI);
+ Value *NewSel = Builder->CreateSelect(SI.getCondition(), OOp, C);
NewSel->takeName(TVI);
- if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TVI))
- return BinaryOperator::Create(BO->getOpcode(), FalseVal, NewSel);
- llvm_unreachable("Unknown instruction!!");
+ BinaryOperator *TVI_BO = cast<BinaryOperator>(TVI);
+ BinaryOperator *BO = BinaryOperator::Create(TVI_BO->getOpcode(),
+ FalseVal, NewSel);
+ if (isa<PossiblyExactOperator>(BO))
+ BO->setIsExact(TVI_BO->isExact());
+ if (isa<OverflowingBinaryOperator>(BO)) {
+ BO->setHasNoUnsignedWrap(TVI_BO->hasNoUnsignedWrap());
+ BO->setHasNoSignedWrap(TVI_BO->hasNoSignedWrap());
+ }
+ return BO;
}
}
}
unsigned OpToFold = 0;
if ((SFO & 1) && TrueVal == FVI->getOperand(0)) {
OpToFold = 1;
- } else if ((SFO & 2) && TrueVal == FVI->getOperand(1)) {
+ } else if ((SFO & 2) && TrueVal == FVI->getOperand(1)) {
OpToFold = 2;
}
// Avoid creating select between 2 constants unless it's selecting
// between 0, 1 and -1.
if (!isa<Constant>(OOp) || isSelect01(C, cast<Constant>(OOp))) {
- Instruction *NewSel = SelectInst::Create(SI.getCondition(), C, OOp);
- InsertNewInstBefore(NewSel, SI);
+ Value *NewSel = Builder->CreateSelect(SI.getCondition(), C, OOp);
NewSel->takeName(FVI);
- if (BinaryOperator *BO = dyn_cast<BinaryOperator>(FVI))
- return BinaryOperator::Create(BO->getOpcode(), TrueVal, NewSel);
- llvm_unreachable("Unknown instruction!!");
+ BinaryOperator *FVI_BO = cast<BinaryOperator>(FVI);
+ BinaryOperator *BO = BinaryOperator::Create(FVI_BO->getOpcode(),
+ TrueVal, NewSel);
+ if (isa<PossiblyExactOperator>(BO))
+ BO->setIsExact(FVI_BO->isExact());
+ if (isa<OverflowingBinaryOperator>(BO)) {
+ BO->setHasNoUnsignedWrap(FVI_BO->hasNoUnsignedWrap());
+ BO->setHasNoSignedWrap(FVI_BO->hasNoSignedWrap());
+ }
+ return BO;
}
}
}
return 0;
}
+/// SimplifyWithOpReplaced - See if V simplifies when its operand Op is
+/// replaced with RepOp.
+static Value *SimplifyWithOpReplaced(Value *V, Value *Op, Value *RepOp,
+ const DataLayout *TD,
+ const TargetLibraryInfo *TLI) {
+ // Trivial replacement.
+ if (V == Op)
+ return RepOp;
+
+ Instruction *I = dyn_cast<Instruction>(V);
+ if (!I)
+ return 0;
+
+ // If this is a binary operator, try to simplify it with the replaced op.
+ if (BinaryOperator *B = dyn_cast<BinaryOperator>(I)) {
+ if (B->getOperand(0) == Op)
+ return SimplifyBinOp(B->getOpcode(), RepOp, B->getOperand(1), TD, TLI);
+ if (B->getOperand(1) == Op)
+ return SimplifyBinOp(B->getOpcode(), B->getOperand(0), RepOp, TD, TLI);
+ }
+
+ // Same for CmpInsts.
+ if (CmpInst *C = dyn_cast<CmpInst>(I)) {
+ if (C->getOperand(0) == Op)
+ return SimplifyCmpInst(C->getPredicate(), RepOp, C->getOperand(1), TD,
+ TLI);
+ if (C->getOperand(1) == Op)
+ return SimplifyCmpInst(C->getPredicate(), C->getOperand(0), RepOp, TD,
+ TLI);
+ }
+
+ // TODO: We could hand off more cases to instsimplify here.
+
+ // If all operands are constant after substituting Op for RepOp then we can
+ // constant fold the instruction.
+ if (Constant *CRepOp = dyn_cast<Constant>(RepOp)) {
+ // Build a list of all constant operands.
+ SmallVector<Constant*, 8> ConstOps;
+ for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) {
+ if (I->getOperand(i) == Op)
+ ConstOps.push_back(CRepOp);
+ else if (Constant *COp = dyn_cast<Constant>(I->getOperand(i)))
+ ConstOps.push_back(COp);
+ else
+ break;
+ }
+
+ // All operands were constants, fold it.
+ if (ConstOps.size() == I->getNumOperands()) {
+ if (LoadInst *LI = dyn_cast<LoadInst>(I))
+ if (!LI->isVolatile())
+ return ConstantFoldLoadFromConstPtr(ConstOps[0], TD);
+
+ return ConstantFoldInstOperands(I->getOpcode(), I->getType(),
+ ConstOps, TD, TLI);
+ }
+ }
+
+ return 0;
+}
+
/// visitSelectInstWithICmp - Visit a SelectInst that has an
/// ICmpInst as its first operand.
///
Value *FalseVal = SI.getFalseValue();
// Check cases where the comparison is with a constant that
- // can be adjusted to fit the min/max idiom. We may edit ICI in
- // place here, so make sure the select is the only user.
+ // can be adjusted to fit the min/max idiom. We may move or edit ICI
+ // here, so make sure the select is the only user.
if (ICI->hasOneUse())
if (ConstantInt *CI = dyn_cast<ConstantInt>(CmpRHS)) {
// X < MIN ? T : F --> F
case ICmpInst::ICMP_UGT:
case ICmpInst::ICMP_SGT: {
// These transformations only work for selects over integers.
- const IntegerType *SelectTy = dyn_cast<IntegerType>(SI.getType());
+ IntegerType *SelectTy = dyn_cast<IntegerType>(SI.getType());
if (!SelectTy)
break;
ICI->setOperand(1, CmpRHS);
SI.setOperand(1, TrueVal);
SI.setOperand(2, FalseVal);
+
+ // Move ICI instruction right before the select instruction. Otherwise
+ // the sext/zext value may be defined after the ICI instruction uses it.
+ ICI->moveBefore(&SI);
+
Changed = true;
break;
}
// FIXME: Type and constness constraints could be lifted, but we have to
// watch code size carefully. We should consider xor instead of
// sub/add when we decide to do that.
- if (const IntegerType *Ty = dyn_cast<IntegerType>(CmpLHS->getType())) {
+ if (IntegerType *Ty = dyn_cast<IntegerType>(CmpLHS->getType())) {
if (TrueVal->getType() == Ty) {
if (ConstantInt *Cmp = dyn_cast<ConstantInt>(CmpRHS)) {
ConstantInt *C1 = NULL, *C2 = NULL;
}
}
- if (CmpLHS == TrueVal && CmpRHS == FalseVal) {
- // Transform (X == Y) ? X : Y -> Y
- if (Pred == ICmpInst::ICMP_EQ)
+ // If we have an equality comparison then we know the value in one of the
+ // arms of the select. See if substituting this value into the arm and
+ // simplifying the result yields the same value as the other arm.
+ if (Pred == ICmpInst::ICMP_EQ) {
+ if (SimplifyWithOpReplaced(FalseVal, CmpLHS, CmpRHS, TD, TLI) == TrueVal ||
+ SimplifyWithOpReplaced(FalseVal, CmpRHS, CmpLHS, TD, TLI) == TrueVal)
return ReplaceInstUsesWith(SI, FalseVal);
- // Transform (X != Y) ? X : Y -> X
- if (Pred == ICmpInst::ICMP_NE)
- return ReplaceInstUsesWith(SI, TrueVal);
- /// NOTE: if we wanted to, this is where to detect integer MIN/MAX
-
- } else if (CmpLHS == FalseVal && CmpRHS == TrueVal) {
- // Transform (X == Y) ? Y : X -> X
- if (Pred == ICmpInst::ICMP_EQ)
+ if (SimplifyWithOpReplaced(TrueVal, CmpLHS, CmpRHS, TD, TLI) == FalseVal ||
+ SimplifyWithOpReplaced(TrueVal, CmpRHS, CmpLHS, TD, TLI) == FalseVal)
return ReplaceInstUsesWith(SI, FalseVal);
- // Transform (X != Y) ? Y : X -> Y
- if (Pred == ICmpInst::ICMP_NE)
+ } else if (Pred == ICmpInst::ICMP_NE) {
+ if (SimplifyWithOpReplaced(TrueVal, CmpLHS, CmpRHS, TD, TLI) == FalseVal ||
+ SimplifyWithOpReplaced(TrueVal, CmpRHS, CmpLHS, TD, TLI) == FalseVal)
+ return ReplaceInstUsesWith(SI, TrueVal);
+ if (SimplifyWithOpReplaced(FalseVal, CmpLHS, CmpRHS, TD, TLI) == TrueVal ||
+ SimplifyWithOpReplaced(FalseVal, CmpRHS, CmpLHS, TD, TLI) == TrueVal)
return ReplaceInstUsesWith(SI, TrueVal);
- /// NOTE: if we wanted to, this is where to detect integer MIN/MAX
}
+
+ // NOTE: if we wanted to, this is where to detect integer MIN/MAX
+
+ if (CmpRHS != CmpLHS && isa<Constant>(CmpRHS)) {
+ if (CmpLHS == TrueVal && Pred == ICmpInst::ICMP_EQ) {
+ // Transform (X == C) ? X : Y -> (X == C) ? C : Y
+ SI.setOperand(1, CmpRHS);
+ Changed = true;
+ } else if (CmpLHS == FalseVal && Pred == ICmpInst::ICMP_NE) {
+ // Transform (X != C) ? Y : X -> (X != C) ? Y : C
+ SI.setOperand(2, CmpRHS);
+ Changed = true;
+ }
+ }
+
return Changed ? &SI : 0;
}
if (!IC || !IC->isEquality())
return 0;
- if (ConstantInt *C = dyn_cast<ConstantInt>(IC->getOperand(1)))
- if (!C->isZero())
- return 0;
+ if (!match(IC->getOperand(1), m_Zero()))
+ return 0;
ConstantInt *AndRHS;
Value *LHS = IC->getOperand(0);
return BinaryOperator::CreateOr(CondVal, FalseVal);
}
// Change: A = select B, false, C --> A = and !B, C
- Value *NotCond =
- InsertNewInstBefore(BinaryOperator::CreateNot(CondVal,
- "not."+CondVal->getName()), SI);
+ Value *NotCond = Builder->CreateNot(CondVal, "not."+CondVal->getName());
return BinaryOperator::CreateAnd(NotCond, FalseVal);
} else if (ConstantInt *C = dyn_cast<ConstantInt>(FalseVal)) {
if (C->getZExtValue() == false) {
return BinaryOperator::CreateAnd(CondVal, TrueVal);
}
// Change: A = select B, C, true --> A = or !B, C
- Value *NotCond =
- InsertNewInstBefore(BinaryOperator::CreateNot(CondVal,
- "not."+CondVal->getName()), SI);
+ Value *NotCond = Builder->CreateNot(CondVal, "not."+CondVal->getName());
return BinaryOperator::CreateOr(NotCond, TrueVal);
}
return BinaryOperator::CreateOr(CondVal, FalseVal);
else if (CondVal == FalseVal)
return BinaryOperator::CreateAnd(CondVal, TrueVal);
+
+ // select a, ~a, b -> (~a)&b
+ // select a, b, ~a -> (~a)|b
+ if (match(TrueVal, m_Not(m_Specific(CondVal))))
+ return BinaryOperator::CreateAnd(TrueVal, FalseVal);
+ else if (match(FalseVal, m_Not(m_Specific(CondVal))))
+ return BinaryOperator::CreateOr(TrueVal, FalseVal);
}
// Selecting between two integer constants?
// So at this point we know we have (Y -> OtherAddOp):
// select C, (add X, Y), (sub X, Z)
Value *NegVal; // Compute -Z
- if (Constant *C = dyn_cast<Constant>(SubOp->getOperand(1))) {
- NegVal = ConstantExpr::getNeg(C);
- } else if (SI.getType()->isFloatingPointTy()) {
- NegVal = InsertNewInstBefore(
- BinaryOperator::CreateFNeg(SubOp->getOperand(1),
- "tmp"), SI);
+ if (SI.getType()->isFPOrFPVectorTy()) {
+ NegVal = Builder->CreateFNeg(SubOp->getOperand(1));
} else {
- NegVal = InsertNewInstBefore(
- BinaryOperator::CreateNeg(SubOp->getOperand(1),
- "tmp"), SI);
+ NegVal = Builder->CreateNeg(SubOp->getOperand(1));
}
Value *NewTrueOp = OtherAddOp;
Value *NewFalseOp = NegVal;
if (AddOp != TI)
std::swap(NewTrueOp, NewFalseOp);
- Instruction *NewSel =
- SelectInst::Create(CondVal, NewTrueOp,
- NewFalseOp, SI.getName() + ".p");
+ Value *NewSel =
+ Builder->CreateSelect(CondVal, NewTrueOp,
+ NewFalseOp, SI.getName() + ".p");
- NewSel = InsertNewInstBefore(NewSel, SI);
- if (SI.getType()->isFloatingPointTy())
+ if (SI.getType()->isFPOrFPVectorTy())
return BinaryOperator::CreateFAdd(SubOp->getOperand(0), NewSel);
else
return BinaryOperator::CreateAdd(SubOp->getOperand(0), NewSel);
if (Instruction *NV = FoldOpIntoPhi(SI))
return NV;
+ if (SelectInst *TrueSI = dyn_cast<SelectInst>(TrueVal)) {
+ if (TrueSI->getCondition() == CondVal) {
+ if (SI.getTrueValue() == TrueSI->getTrueValue())
+ return 0;
+ SI.setOperand(1, TrueSI->getTrueValue());
+ return &SI;
+ }
+ }
+ if (SelectInst *FalseSI = dyn_cast<SelectInst>(FalseVal)) {
+ if (FalseSI->getCondition() == CondVal) {
+ if (SI.getFalseValue() == FalseSI->getFalseValue())
+ return 0;
+ SI.setOperand(2, FalseSI->getFalseValue());
+ return &SI;
+ }
+ }
+
if (BinaryOperator::isNot(CondVal)) {
SI.setOperand(0, BinaryOperator::getNotArgument(CondVal));
SI.setOperand(1, FalseVal);
return &SI;
}
+ if (VectorType *VecTy = dyn_cast<VectorType>(SI.getType())) {
+ unsigned VWidth = VecTy->getNumElements();
+ APInt UndefElts(VWidth, 0);
+ APInt AllOnesEltMask(APInt::getAllOnesValue(VWidth));
+ if (Value *V = SimplifyDemandedVectorElts(&SI, AllOnesEltMask, UndefElts)) {
+ if (V != &SI)
+ return ReplaceInstUsesWith(SI, V);
+ return &SI;
+ }
+
+ if (ConstantVector *CV = dyn_cast<ConstantVector>(CondVal)) {
+ // Form a shufflevector instruction.
+ SmallVector<Constant *, 8> Mask(VWidth);
+ Type *Int32Ty = Type::getInt32Ty(CV->getContext());
+ for (unsigned i = 0; i != VWidth; ++i) {
+ Constant *Elem = cast<Constant>(CV->getOperand(i));
+ if (ConstantInt *E = dyn_cast<ConstantInt>(Elem))
+ Mask[i] = ConstantInt::get(Int32Ty, i + (E->isZero() ? VWidth : 0));
+ else if (isa<UndefValue>(Elem))
+ Mask[i] = UndefValue::get(Int32Ty);
+ else
+ return 0;
+ }
+ Constant *MaskVal = ConstantVector::get(Mask);
+ Value *V = Builder->CreateShuffleVector(TrueVal, FalseVal, MaskVal);
+ return ReplaceInstUsesWith(SI, V);
+ }
+
+ if (isa<ConstantAggregateZero>(CondVal)) {
+ return ReplaceInstUsesWith(SI, FalseVal);
+ }
+ }
+
return 0;
}
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