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-rw-r--r--lib/Transforms/InstCombine/InstructionCombining.cpp695
1 files changed, 3 insertions, 692 deletions
diff --git a/lib/Transforms/InstCombine/InstructionCombining.cpp b/lib/Transforms/InstCombine/InstructionCombining.cpp
index 852d442ace..e99000125c 100644
--- a/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -219,57 +219,6 @@ static inline Value *dyn_castFNegVal(Value *V) {
return 0;
}
-/// MatchSelectPattern - Pattern match integer [SU]MIN, [SU]MAX, and ABS idioms,
-/// returning the kind and providing the out parameter results if we
-/// successfully match.
-static SelectPatternFlavor
-MatchSelectPattern(Value *V, Value *&LHS, Value *&RHS) {
- SelectInst *SI = dyn_cast<SelectInst>(V);
- if (SI == 0) return SPF_UNKNOWN;
-
- ICmpInst *ICI = dyn_cast<ICmpInst>(SI->getCondition());
- if (ICI == 0) return SPF_UNKNOWN;
-
- LHS = ICI->getOperand(0);
- RHS = ICI->getOperand(1);
-
- // (icmp X, Y) ? X : Y
- if (SI->getTrueValue() == ICI->getOperand(0) &&
- SI->getFalseValue() == ICI->getOperand(1)) {
- switch (ICI->getPredicate()) {
- default: return SPF_UNKNOWN; // Equality.
- case ICmpInst::ICMP_UGT:
- case ICmpInst::ICMP_UGE: return SPF_UMAX;
- case ICmpInst::ICMP_SGT:
- case ICmpInst::ICMP_SGE: return SPF_SMAX;
- case ICmpInst::ICMP_ULT:
- case ICmpInst::ICMP_ULE: return SPF_UMIN;
- case ICmpInst::ICMP_SLT:
- case ICmpInst::ICMP_SLE: return SPF_SMIN;
- }
- }
-
- // (icmp X, Y) ? Y : X
- if (SI->getTrueValue() == ICI->getOperand(1) &&
- SI->getFalseValue() == ICI->getOperand(0)) {
- switch (ICI->getPredicate()) {
- default: return SPF_UNKNOWN; // Equality.
- case ICmpInst::ICMP_UGT:
- case ICmpInst::ICMP_UGE: return SPF_UMIN;
- case ICmpInst::ICMP_SGT:
- case ICmpInst::ICMP_SGE: return SPF_SMIN;
- case ICmpInst::ICMP_ULT:
- case ICmpInst::ICMP_ULE: return SPF_UMAX;
- case ICmpInst::ICMP_SLT:
- case ICmpInst::ICMP_SLE: return SPF_SMAX;
- }
- }
-
- // TODO: (X > 4) ? X : 5 --> (X >= 5) ? X : 5 --> MAX(X, 5)
-
- return SPF_UNKNOWN;
-}
-
/// isFreeToInvert - Return true if the specified value is free to invert (apply
/// ~ to). This happens in cases where the ~ can be eliminated.
static inline bool isFreeToInvert(Value *V) {
@@ -1994,12 +1943,6 @@ Instruction *InstCombiner::visitFRem(BinaryOperator &I) {
return commonRemTransforms(I);
}
-// isOneBitSet - Return true if there is exactly one bit set in the specified
-// constant.
-static bool isOneBitSet(const ConstantInt *CI) {
- return CI->getValue().isPowerOf2();
-}
-
/// getICmpCode - Encode a icmp predicate into a three bit mask. These bits
/// are carefully arranged to allow folding of expressions such as:
///
@@ -2240,10 +2183,10 @@ Instruction *InstCombiner::OptAndOp(Instruction *Op,
// Adding a one to a single bit bit-field should be turned into an XOR
// of the bit. First thing to check is to see if this AND is with a
// single bit constant.
- const APInt& AndRHSV = cast<ConstantInt>(AndRHS)->getValue();
+ const APInt &AndRHSV = cast<ConstantInt>(AndRHS)->getValue();
- // If there is only one bit set...
- if (isOneBitSet(cast<ConstantInt>(AndRHS))) {
+ // If there is only one bit set.
+ if (AndRHSV.isPowerOf2()) {
// Ok, at this point, we know that we are masking the result of the
// ADD down to exactly one bit. If the constant we are adding has
// no bits set below this bit, then we can eliminate the ADD.
@@ -4421,638 +4364,6 @@ const Type *InstCombiner::FindElementAtOffset(const Type *Ty, int64_t Offset,
}
-/// GetSelectFoldableOperands - We want to turn code that looks like this:
-/// %C = or %A, %B
-/// %D = select %cond, %C, %A
-/// into:
-/// %C = select %cond, %B, 0
-/// %D = or %A, %C
-///
-/// Assuming that the specified instruction is an operand to the select, return
-/// a bitmask indicating which operands of this instruction are foldable if they
-/// equal the other incoming value of the select.
-///
-static unsigned GetSelectFoldableOperands(Instruction *I) {
- switch (I->getOpcode()) {
- case Instruction::Add:
- case Instruction::Mul:
- case Instruction::And:
- case Instruction::Or:
- case Instruction::Xor:
- return 3; // Can fold through either operand.
- case Instruction::Sub: // Can only fold on the amount subtracted.
- case Instruction::Shl: // Can only fold on the shift amount.
- case Instruction::LShr:
- case Instruction::AShr:
- return 1;
- default:
- return 0; // Cannot fold
- }
-}
-
-/// GetSelectFoldableConstant - For the same transformation as the previous
-/// function, return the identity constant that goes into the select.
-static Constant *GetSelectFoldableConstant(Instruction *I) {
- switch (I->getOpcode()) {
- default: llvm_unreachable("This cannot happen!");
- case Instruction::Add:
- case Instruction::Sub:
- case Instruction::Or:
- case Instruction::Xor:
- case Instruction::Shl:
- case Instruction::LShr:
- case Instruction::AShr:
- return Constant::getNullValue(I->getType());
- case Instruction::And:
- return Constant::getAllOnesValue(I->getType());
- case Instruction::Mul:
- return ConstantInt::get(I->getType(), 1);
- }
-}
-
-/// FoldSelectOpOp - Here we have (select c, TI, FI), and we know that TI and FI
-/// have the same opcode and only one use each. Try to simplify this.
-Instruction *InstCombiner::FoldSelectOpOp(SelectInst &SI, Instruction *TI,
- Instruction *FI) {
- if (TI->getNumOperands() == 1) {
- // If this is a non-volatile load or a cast from the same type,
- // merge.
- if (TI->isCast()) {
- if (TI->getOperand(0)->getType() != FI->getOperand(0)->getType())
- 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);
- return CastInst::Create(Instruction::CastOps(TI->getOpcode()), NewSI,
- TI->getType());
- }
-
- // Only handle binary operators here.
- if (!isa<BinaryOperator>(TI))
- return 0;
-
- // Figure out if the operations have any operands in common.
- Value *MatchOp, *OtherOpT, *OtherOpF;
- bool MatchIsOpZero;
- if (TI->getOperand(0) == FI->getOperand(0)) {
- MatchOp = TI->getOperand(0);
- OtherOpT = TI->getOperand(1);
- OtherOpF = FI->getOperand(1);
- MatchIsOpZero = true;
- } else if (TI->getOperand(1) == FI->getOperand(1)) {
- MatchOp = TI->getOperand(1);
- OtherOpT = TI->getOperand(0);
- OtherOpF = FI->getOperand(0);
- MatchIsOpZero = false;
- } else if (!TI->isCommutative()) {
- return 0;
- } else if (TI->getOperand(0) == FI->getOperand(1)) {
- MatchOp = TI->getOperand(0);
- OtherOpT = TI->getOperand(1);
- OtherOpF = FI->getOperand(0);
- MatchIsOpZero = true;
- } else if (TI->getOperand(1) == FI->getOperand(0)) {
- MatchOp = TI->getOperand(1);
- OtherOpT = TI->getOperand(0);
- OtherOpF = FI->getOperand(1);
- MatchIsOpZero = true;
- } else {
- return 0;
- }
-
- // If we reach here, they do have operations in common.
- SelectInst *NewSI = SelectInst::Create(SI.getCondition(), OtherOpT,
- OtherOpF, SI.getName()+".v");
- InsertNewInstBefore(NewSI, SI);
-
- if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TI)) {
- if (MatchIsOpZero)
- return BinaryOperator::Create(BO->getOpcode(), MatchOp, NewSI);
- else
- return BinaryOperator::Create(BO->getOpcode(), NewSI, MatchOp);
- }
- llvm_unreachable("Shouldn't get here");
- return 0;
-}
-
-static bool isSelect01(Constant *C1, Constant *C2) {
- ConstantInt *C1I = dyn_cast<ConstantInt>(C1);
- if (!C1I)
- return false;
- ConstantInt *C2I = dyn_cast<ConstantInt>(C2);
- if (!C2I)
- return false;
- return (C1I->isZero() || C1I->isOne()) && (C2I->isZero() || C2I->isOne());
-}
-
-/// FoldSelectIntoOp - Try fold the select into one of the operands to
-/// facilitate further optimization.
-Instruction *InstCombiner::FoldSelectIntoOp(SelectInst &SI, Value *TrueVal,
- Value *FalseVal) {
- // See the comment above GetSelectFoldableOperands for a description of the
- // transformation we are doing here.
- if (Instruction *TVI = dyn_cast<Instruction>(TrueVal)) {
- if (TVI->hasOneUse() && TVI->getNumOperands() == 2 &&
- !isa<Constant>(FalseVal)) {
- if (unsigned SFO = GetSelectFoldableOperands(TVI)) {
- unsigned OpToFold = 0;
- if ((SFO & 1) && FalseVal == TVI->getOperand(0)) {
- OpToFold = 1;
- } else if ((SFO & 2) && FalseVal == TVI->getOperand(1)) {
- OpToFold = 2;
- }
-
- if (OpToFold) {
- Constant *C = GetSelectFoldableConstant(TVI);
- Value *OOp = TVI->getOperand(2-OpToFold);
- // Avoid creating select between 2 constants unless it's selecting
- // between 0 and 1.
- if (!isa<Constant>(OOp) || isSelect01(C, cast<Constant>(OOp))) {
- Instruction *NewSel = SelectInst::Create(SI.getCondition(), OOp, C);
- InsertNewInstBefore(NewSel, SI);
- NewSel->takeName(TVI);
- if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TVI))
- return BinaryOperator::Create(BO->getOpcode(), FalseVal, NewSel);
- llvm_unreachable("Unknown instruction!!");
- }
- }
- }
- }
- }
-
- if (Instruction *FVI = dyn_cast<Instruction>(FalseVal)) {
- if (FVI->hasOneUse() && FVI->getNumOperands() == 2 &&
- !isa<Constant>(TrueVal)) {
- if (unsigned SFO = GetSelectFoldableOperands(FVI)) {
- unsigned OpToFold = 0;
- if ((SFO & 1) && TrueVal == FVI->getOperand(0)) {
- OpToFold = 1;
- } else if ((SFO & 2) && TrueVal == FVI->getOperand(1)) {
- OpToFold = 2;
- }
-
- if (OpToFold) {
- Constant *C = GetSelectFoldableConstant(FVI);
- Value *OOp = FVI->getOperand(2-OpToFold);
- // Avoid creating select between 2 constants unless it's selecting
- // between 0 and 1.
- if (!isa<Constant>(OOp) || isSelect01(C, cast<Constant>(OOp))) {
- Instruction *NewSel = SelectInst::Create(SI.getCondition(), C, OOp);
- InsertNewInstBefore(NewSel, SI);
- NewSel->takeName(FVI);
- if (BinaryOperator *BO = dyn_cast<BinaryOperator>(FVI))
- return BinaryOperator::Create(BO->getOpcode(), TrueVal, NewSel);
- llvm_unreachable("Unknown instruction!!");
- }
- }
- }
- }
- }
-
- return 0;
-}
-
-/// visitSelectInstWithICmp - Visit a SelectInst that has an
-/// ICmpInst as its first operand.
-///
-Instruction *InstCombiner::visitSelectInstWithICmp(SelectInst &SI,
- ICmpInst *ICI) {
- bool Changed = false;
- ICmpInst::Predicate Pred = ICI->getPredicate();
- Value *CmpLHS = ICI->getOperand(0);
- Value *CmpRHS = ICI->getOperand(1);
- Value *TrueVal = SI.getTrueValue();
- 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.
- if (ICI->hasOneUse())
- if (ConstantInt *CI = dyn_cast<ConstantInt>(CmpRHS)) {
- switch (Pred) {
- default: break;
- case ICmpInst::ICMP_ULT:
- case ICmpInst::ICMP_SLT: {
- // X < MIN ? T : F --> F
- if (CI->isMinValue(Pred == ICmpInst::ICMP_SLT))
- return ReplaceInstUsesWith(SI, FalseVal);
- // X < C ? X : C-1 --> X > C-1 ? C-1 : X
- Constant *AdjustedRHS = SubOne(CI);
- if ((CmpLHS == TrueVal && AdjustedRHS == FalseVal) ||
- (CmpLHS == FalseVal && AdjustedRHS == TrueVal)) {
- Pred = ICmpInst::getSwappedPredicate(Pred);
- CmpRHS = AdjustedRHS;
- std::swap(FalseVal, TrueVal);
- ICI->setPredicate(Pred);
- ICI->setOperand(1, CmpRHS);
- SI.setOperand(1, TrueVal);
- SI.setOperand(2, FalseVal);
- Changed = true;
- }
- break;
- }
- case ICmpInst::ICMP_UGT:
- case ICmpInst::ICMP_SGT: {
- // X > MAX ? T : F --> F
- if (CI->isMaxValue(Pred == ICmpInst::ICMP_SGT))
- return ReplaceInstUsesWith(SI, FalseVal);
- // X > C ? X : C+1 --> X < C+1 ? C+1 : X
- Constant *AdjustedRHS = AddOne(CI);
- if ((CmpLHS == TrueVal && AdjustedRHS == FalseVal) ||
- (CmpLHS == FalseVal && AdjustedRHS == TrueVal)) {
- Pred = ICmpInst::getSwappedPredicate(Pred);
- CmpRHS = AdjustedRHS;
- std::swap(FalseVal, TrueVal);
- ICI->setPredicate(Pred);
- ICI->setOperand(1, CmpRHS);
- SI.setOperand(1, TrueVal);
- SI.setOperand(2, FalseVal);
- Changed = true;
- }
- break;
- }
- }
-
- // (x <s 0) ? -1 : 0 -> ashr x, 31 -> all ones if signed
- // (x >s -1) ? -1 : 0 -> ashr x, 31 -> all ones if not signed
- CmpInst::Predicate Pred = CmpInst::BAD_ICMP_PREDICATE;
- if (match(TrueVal, m_ConstantInt<-1>()) &&
- match(FalseVal, m_ConstantInt<0>()))
- Pred = ICI->getPredicate();
- else if (match(TrueVal, m_ConstantInt<0>()) &&
- match(FalseVal, m_ConstantInt<-1>()))
- Pred = CmpInst::getInversePredicate(ICI->getPredicate());
-
- if (Pred != CmpInst::BAD_ICMP_PREDICATE) {
- // If we are just checking for a icmp eq of a single bit and zext'ing it
- // to an integer, then shift the bit to the appropriate place and then
- // cast to integer to avoid the comparison.
- const APInt &Op1CV = CI->getValue();
-
- // sext (x <s 0) to i32 --> x>>s31 true if signbit set.
- // sext (x >s -1) to i32 --> (x>>s31)^-1 true if signbit clear.
- if ((Pred == ICmpInst::ICMP_SLT && Op1CV == 0) ||
- (Pred == ICmpInst::ICMP_SGT && Op1CV.isAllOnesValue())) {
- Value *In = ICI->getOperand(0);
- Value *Sh = ConstantInt::get(In->getType(),
- In->getType()->getScalarSizeInBits()-1);
- In = InsertNewInstBefore(BinaryOperator::CreateAShr(In, Sh,
- In->getName()+".lobit"),
- *ICI);
- if (In->getType() != SI.getType())
- In = CastInst::CreateIntegerCast(In, SI.getType(),
- true/*SExt*/, "tmp", ICI);
-
- if (Pred == ICmpInst::ICMP_SGT)
- In = InsertNewInstBefore(BinaryOperator::CreateNot(In,
- In->getName()+".not"), *ICI);
-
- return ReplaceInstUsesWith(SI, In);
- }
- }
- }
-
- if (CmpLHS == TrueVal && CmpRHS == FalseVal) {
- // Transform (X == Y) ? X : Y -> Y
- if (Pred == ICmpInst::ICMP_EQ)
- 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)
- return ReplaceInstUsesWith(SI, FalseVal);
- // Transform (X != Y) ? Y : X -> Y
- if (Pred == ICmpInst::ICMP_NE)
- return ReplaceInstUsesWith(SI, TrueVal);
- /// NOTE: if we wanted to, this is where to detect integer MIN/MAX
- }
- return Changed ? &SI : 0;
-}
-
-
-/// CanSelectOperandBeMappingIntoPredBlock - SI is a select whose condition is a
-/// PHI node (but the two may be in different blocks). See if the true/false
-/// values (V) are live in all of the predecessor blocks of the PHI. For
-/// example, cases like this cannot be mapped:
-///
-/// X = phi [ C1, BB1], [C2, BB2]
-/// Y = add
-/// Z = select X, Y, 0
-///
-/// because Y is not live in BB1/BB2.
-///
-static bool CanSelectOperandBeMappingIntoPredBlock(const Value *V,
- const SelectInst &SI) {
- // If the value is a non-instruction value like a constant or argument, it
- // can always be mapped.
- const Instruction *I = dyn_cast<Instruction>(V);
- if (I == 0) return true;
-
- // If V is a PHI node defined in the same block as the condition PHI, we can
- // map the arguments.
- const PHINode *CondPHI = cast<PHINode>(SI.getCondition());
-
- if (const PHINode *VP = dyn_cast<PHINode>(I))
- if (VP->getParent() == CondPHI->getParent())
- return true;
-
- // Otherwise, if the PHI and select are defined in the same block and if V is
- // defined in a different block, then we can transform it.
- if (SI.getParent() == CondPHI->getParent() &&
- I->getParent() != CondPHI->getParent())
- return true;
-
- // Otherwise we have a 'hard' case and we can't tell without doing more
- // detailed dominator based analysis, punt.
- return false;
-}
-
-/// FoldSPFofSPF - We have an SPF (e.g. a min or max) of an SPF of the form:
-/// SPF2(SPF1(A, B), C)
-Instruction *InstCombiner::FoldSPFofSPF(Instruction *Inner,
- SelectPatternFlavor SPF1,
- Value *A, Value *B,
- Instruction &Outer,
- SelectPatternFlavor SPF2, Value *C) {
- if (C == A || C == B) {
- // MAX(MAX(A, B), B) -> MAX(A, B)
- // MIN(MIN(a, b), a) -> MIN(a, b)
- if (SPF1 == SPF2)
- return ReplaceInstUsesWith(Outer, Inner);
-
- // MAX(MIN(a, b), a) -> a
- // MIN(MAX(a, b), a) -> a
- if ((SPF1 == SPF_SMIN && SPF2 == SPF_SMAX) ||
- (SPF1 == SPF_SMAX && SPF2 == SPF_SMIN) ||
- (SPF1 == SPF_UMIN && SPF2 == SPF_UMAX) ||
- (SPF1 == SPF_UMAX && SPF2 == SPF_UMIN))
- return ReplaceInstUsesWith(Outer, C);
- }
-
- // TODO: MIN(MIN(A, 23), 97)
- return 0;
-}
-
-
-
-
-Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
- Value *CondVal = SI.getCondition();
- Value *TrueVal = SI.getTrueValue();
- Value *FalseVal = SI.getFalseValue();
-
- // select true, X, Y -> X
- // select false, X, Y -> Y
- if (ConstantInt *C = dyn_cast<ConstantInt>(CondVal))
- return ReplaceInstUsesWith(SI, C->getZExtValue() ? TrueVal : FalseVal);
-
- // select C, X, X -> X
- if (TrueVal == FalseVal)
- return ReplaceInstUsesWith(SI, TrueVal);
-
- if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X
- return ReplaceInstUsesWith(SI, FalseVal);
- if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X
- return ReplaceInstUsesWith(SI, TrueVal);
- if (isa<UndefValue>(CondVal)) { // select undef, X, Y -> X or Y
- if (isa<Constant>(TrueVal))
- return ReplaceInstUsesWith(SI, TrueVal);
- else
- return ReplaceInstUsesWith(SI, FalseVal);
- }
-
- if (SI.getType() == Type::getInt1Ty(SI.getContext())) {
- if (ConstantInt *C = dyn_cast<ConstantInt>(TrueVal)) {
- if (C->getZExtValue()) {
- // Change: A = select B, true, C --> A = or B, C
- return BinaryOperator::CreateOr(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::CreateAnd(NotCond, FalseVal);
- }
- } else if (ConstantInt *C = dyn_cast<ConstantInt>(FalseVal)) {
- if (C->getZExtValue() == false) {
- // Change: A = select B, C, false --> A = and B, C
- return BinaryOperator::CreateAnd(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::CreateOr(NotCond, TrueVal);
- }
- }
-
- // select a, b, a -> a&b
- // select a, a, b -> a|b
- if (CondVal == TrueVal)
- return BinaryOperator::CreateOr(CondVal, FalseVal);
- else if (CondVal == FalseVal)
- return BinaryOperator::CreateAnd(CondVal, TrueVal);
- }
-
- // Selecting between two integer constants?
- if (ConstantInt *TrueValC = dyn_cast<ConstantInt>(TrueVal))
- if (ConstantInt *FalseValC = dyn_cast<ConstantInt>(FalseVal)) {
- // select C, 1, 0 -> zext C to int
- if (FalseValC->isZero() && TrueValC->getValue() == 1) {
- return CastInst::Create(Instruction::ZExt, CondVal, SI.getType());
- } else if (TrueValC->isZero() && FalseValC->getValue() == 1) {
- // select C, 0, 1 -> zext !C to int
- Value *NotCond =
- InsertNewInstBefore(BinaryOperator::CreateNot(CondVal,
- "not."+CondVal->getName()), SI);
- return CastInst::Create(Instruction::ZExt, NotCond, SI.getType());
- }
-
- if (ICmpInst *IC = dyn_cast<ICmpInst>(SI.getCondition())) {
- // If one of the constants is zero (we know they can't both be) and we
- // have an icmp instruction with zero, and we have an 'and' with the
- // non-constant value, eliminate this whole mess. This corresponds to
- // cases like this: ((X & 27) ? 27 : 0)
- if (TrueValC->isZero() || FalseValC->isZero())
- if (IC->isEquality() && isa<ConstantInt>(IC->getOperand(1)) &&
- cast<Constant>(IC->getOperand(1))->isNullValue())
- if (Instruction *ICA = dyn_cast<Instruction>(IC->getOperand(0)))
- if (ICA->getOpcode() == Instruction::And &&
- isa<ConstantInt>(ICA->getOperand(1)) &&
- (ICA->getOperand(1) == TrueValC ||
- ICA->getOperand(1) == FalseValC) &&
- isOneBitSet(cast<ConstantInt>(ICA->getOperand(1)))) {
- // Okay, now we know that everything is set up, we just don't
- // know whether we have a icmp_ne or icmp_eq and whether the
- // true or false val is the zero.
- bool ShouldNotVal = !TrueValC->isZero();
- ShouldNotVal ^= IC->getPredicate() == ICmpInst::ICMP_NE;
- Value *V = ICA;
- if (ShouldNotVal)
- V = InsertNewInstBefore(BinaryOperator::Create(
- Instruction::Xor, V, ICA->getOperand(1)), SI);
- return ReplaceInstUsesWith(SI, V);
- }
- }
- }
-
- // See if we are selecting two values based on a comparison of the two values.
- if (FCmpInst *FCI = dyn_cast<FCmpInst>(CondVal)) {
- if (FCI->getOperand(0) == TrueVal && FCI->getOperand(1) == FalseVal) {
- // Transform (X == Y) ? X : Y -> Y
- if (FCI->getPredicate() == FCmpInst::FCMP_OEQ) {
- // This is not safe in general for floating point:
- // consider X== -0, Y== +0.
- // It becomes safe if either operand is a nonzero constant.
- ConstantFP *CFPt, *CFPf;
- if (((CFPt = dyn_cast<ConstantFP>(TrueVal)) &&
- !CFPt->getValueAPF().isZero()) ||
- ((CFPf = dyn_cast<ConstantFP>(FalseVal)) &&
- !CFPf->getValueAPF().isZero()))
- return ReplaceInstUsesWith(SI, FalseVal);
- }
- // Transform (X != Y) ? X : Y -> X
- if (FCI->getPredicate() == FCmpInst::FCMP_ONE)
- return ReplaceInstUsesWith(SI, TrueVal);
- // NOTE: if we wanted to, this is where to detect MIN/MAX
-
- } else if (FCI->getOperand(0) == FalseVal && FCI->getOperand(1) == TrueVal){
- // Transform (X == Y) ? Y : X -> X
- if (FCI->getPredicate() == FCmpInst::FCMP_OEQ) {
- // This is not safe in general for floating point:
- // consider X== -0, Y== +0.
- // It becomes safe if either operand is a nonzero constant.
- ConstantFP *CFPt, *CFPf;
- if (((CFPt = dyn_cast<ConstantFP>(TrueVal)) &&
- !CFPt->getValueAPF().isZero()) ||
- ((CFPf = dyn_cast<ConstantFP>(FalseVal)) &&
- !CFPf->getValueAPF().isZero()))
- return ReplaceInstUsesWith(SI, FalseVal);
- }
- // Transform (X != Y) ? Y : X -> Y
- if (FCI->getPredicate() == FCmpInst::FCMP_ONE)
- return ReplaceInstUsesWith(SI, TrueVal);
- // NOTE: if we wanted to, this is where to detect MIN/MAX
- }
- // NOTE: if we wanted to, this is where to detect ABS
- }
-
- // See if we are selecting two values based on a comparison of the two values.
- if (ICmpInst *ICI = dyn_cast<ICmpInst>(CondVal))
- if (Instruction *Result = visitSelectInstWithICmp(SI, ICI))
- return Result;
-
- if (Instruction *TI = dyn_cast<Instruction>(TrueVal))
- if (Instruction *FI = dyn_cast<Instruction>(FalseVal))
- if (TI->hasOneUse() && FI->hasOneUse()) {
- Instruction *AddOp = 0, *SubOp = 0;
-
- // Turn (select C, (op X, Y), (op X, Z)) -> (op X, (select C, Y, Z))
- if (TI->getOpcode() == FI->getOpcode())
- if (Instruction *IV = FoldSelectOpOp(SI, TI, FI))
- return IV;
-
- // Turn select C, (X+Y), (X-Y) --> (X+(select C, Y, (-Y))). This is
- // even legal for FP.
- if ((TI->getOpcode() == Instruction::Sub &&
- FI->getOpcode() == Instruction::Add) ||
- (TI->getOpcode() == Instruction::FSub &&
- FI->getOpcode() == Instruction::FAdd)) {
- AddOp = FI; SubOp = TI;
- } else if ((FI->getOpcode() == Instruction::Sub &&
- TI->getOpcode() == Instruction::Add) ||
- (FI->getOpcode() == Instruction::FSub &&
- TI->getOpcode() == Instruction::FAdd)) {
- AddOp = TI; SubOp = FI;
- }
-
- if (AddOp) {
- Value *OtherAddOp = 0;
- if (SubOp->getOperand(0) == AddOp->getOperand(0)) {
- OtherAddOp = AddOp->getOperand(1);
- } else if (SubOp->getOperand(0) == AddOp->getOperand(1)) {
- OtherAddOp = AddOp->getOperand(0);
- }
-
- if (OtherAddOp) {
- // 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 {
- NegVal = InsertNewInstBefore(
- BinaryOperator::CreateNeg(SubOp->getOperand(1),
- "tmp"), SI);
- }
-
- Value *NewTrueOp = OtherAddOp;
- Value *NewFalseOp = NegVal;
- if (AddOp != TI)
- std::swap(NewTrueOp, NewFalseOp);
- Instruction *NewSel =
- SelectInst::Create(CondVal, NewTrueOp,
- NewFalseOp, SI.getName() + ".p");
-
- NewSel = InsertNewInstBefore(NewSel, SI);
- return BinaryOperator::CreateAdd(SubOp->getOperand(0), NewSel);
- }
- }
- }
-
- // See if we can fold the select into one of our operands.
- if (SI.getType()->isInteger()) {
- if (Instruction *FoldI = FoldSelectIntoOp(SI, TrueVal, FalseVal))
- return FoldI;
-
- // MAX(MAX(a, b), a) -> MAX(a, b)
- // MIN(MIN(a, b), a) -> MIN(a, b)
- // MAX(MIN(a, b), a) -> a
- // MIN(MAX(a, b), a) -> a
- Value *LHS, *RHS, *LHS2, *RHS2;
- if (SelectPatternFlavor SPF = MatchSelectPattern(&SI, LHS, RHS)) {
- if (SelectPatternFlavor SPF2 = MatchSelectPattern(LHS, LHS2, RHS2))
- if (Instruction *R = FoldSPFofSPF(cast<Instruction>(LHS),SPF2,LHS2,RHS2,
- SI, SPF, RHS))
- return R;
- if (SelectPatternFlavor SPF2 = MatchSelectPattern(RHS, LHS2, RHS2))
- if (Instruction *R = FoldSPFofSPF(cast<Instruction>(RHS),SPF2,LHS2,RHS2,
- SI, SPF, LHS))
- return R;
- }
-
- // TODO.
- // ABS(-X) -> ABS(X)
- // ABS(ABS(X)) -> ABS(X)
- }
-
- // See if we can fold the select into a phi node if the condition is a select.
- if (isa<PHINode>(SI.getCondition()))
- // The true/false values have to be live in the PHI predecessor's blocks.
- if (CanSelectOperandBeMappingIntoPredBlock(TrueVal, SI) &&
- CanSelectOperandBeMappingIntoPredBlock(FalseVal, SI))
- if (Instruction *NV = FoldOpIntoPhi(SI))
- return NV;
-
- if (BinaryOperator::isNot(CondVal)) {
- SI.setOperand(0, BinaryOperator::getNotArgument(CondVal));
- SI.setOperand(1, FalseVal);
- SI.setOperand(2, TrueVal);
- return &SI;
- }
-
- return 0;
-}
-
/// EnforceKnownAlignment - If the specified pointer points to an object that
/// we control, modify the object's alignment to PrefAlign. This isn't
/// often possible though. If alignment is important, a more reliable approach
generated by cgit v1.2.3-18-g5258 (git 2.32.0) at 2025-04-29 12:57:09 +0000