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-rw-r--r--lib/Transforms/InstCombine/InstCombineCompares.cpp109
1 files changed, 65 insertions, 44 deletions
diff --git a/lib/Transforms/InstCombine/InstCombineCompares.cpp b/lib/Transforms/InstCombine/InstCombineCompares.cpp
index c7ed098cbf88..c78760b20692 100644
--- a/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -42,13 +42,12 @@ static ConstantInt *ExtractElement(Constant *V, Constant *Idx) {
static bool HasAddOverflow(ConstantInt *Result,
ConstantInt *In1, ConstantInt *In2,
bool IsSigned) {
- if (IsSigned)
- if (In2->getValue().isNegative())
- return Result->getValue().sgt(In1->getValue());
- else
- return Result->getValue().slt(In1->getValue());
- else
+ if (!IsSigned)
return Result->getValue().ult(In1->getValue());
+
+ if (In2->isNegative())
+ return Result->getValue().sgt(In1->getValue());
+ return Result->getValue().slt(In1->getValue());
}
/// AddWithOverflow - Compute Result = In1+In2, returning true if the result
@@ -77,13 +76,13 @@ static bool AddWithOverflow(Constant *&Result, Constant *In1,
static bool HasSubOverflow(ConstantInt *Result,
ConstantInt *In1, ConstantInt *In2,
bool IsSigned) {
- if (IsSigned)
- if (In2->getValue().isNegative())
- return Result->getValue().slt(In1->getValue());
- else
- return Result->getValue().sgt(In1->getValue());
- else
+ if (!IsSigned)
return Result->getValue().ugt(In1->getValue());
+
+ if (In2->isNegative())
+ return Result->getValue().slt(In1->getValue());
+
+ return Result->getValue().sgt(In1->getValue());
}
/// SubWithOverflow - Compute Result = In1-In2, returning true if the result
@@ -128,8 +127,7 @@ static bool isSignBitCheck(ICmpInst::Predicate pred, ConstantInt *RHS,
case ICmpInst::ICMP_UGT:
// True if LHS u> RHS and RHS == high-bit-mask - 1
TrueIfSigned = true;
- return RHS->getValue() ==
- APInt::getSignedMaxValue(RHS->getType()->getPrimitiveSizeInBits());
+ return RHS->isMaxValue(true);
case ICmpInst::ICMP_UGE:
// True if LHS u>= RHS and RHS == high-bit-mask (2^7, 2^15, 2^31, etc)
TrueIfSigned = true;
@@ -278,8 +276,7 @@ FoldCmpLoadFromIndexedGlobal(GetElementPtrInst *GEP, GlobalVariable *GV,
// If this is indexing an array of structures, get the structure element.
if (!LaterIndices.empty())
- Elt = ConstantExpr::getExtractValue(Elt, LaterIndices.data(),
- LaterIndices.size());
+ Elt = ConstantExpr::getExtractValue(Elt, LaterIndices);
// If the element is masked, handle it.
if (AndCst) Elt = ConstantExpr::getAnd(Elt, AndCst);
@@ -828,7 +825,7 @@ Instruction *InstCombiner::FoldICmpDivCst(ICmpInst &ICI, BinaryOperator *DivI,
LoOverflow = AddWithOverflow(LoBound, HiBound, DivNeg, true) ? -1 : 0;
}
}
- } else if (DivRHS->getValue().isNegative()) { // Divisor is < 0.
+ } else if (DivRHS->isNegative()) { // Divisor is < 0.
if (DivI->isExact())
RangeSize = cast<ConstantInt>(ConstantExpr::getNeg(RangeSize));
if (CmpRHSV == 0) { // (X / neg) op 0
@@ -1028,7 +1025,7 @@ Instruction *InstCombiner::visitICmpInstWithInstAndIntCst(ICmpInst &ICI,
// If the sign bit of the XorCST is not set, there is no change to
// the operation, just stop using the Xor.
- if (!XorCST->getValue().isNegative()) {
+ if (!XorCST->isNegative()) {
ICI.setOperand(0, CompareVal);
Worklist.Add(LHSI);
return &ICI;
@@ -1061,7 +1058,7 @@ Instruction *InstCombiner::visitICmpInstWithInstAndIntCst(ICmpInst &ICI,
}
// (icmp u/s (xor A ~SignBit), C) -> (icmp s/u (xor C ~SignBit), A)
- if (!ICI.isEquality() && XorCST->getValue().isMaxSignedValue()) {
+ if (!ICI.isEquality() && XorCST->isMaxValue(true)) {
const APInt &NotSignBit = XorCST->getValue();
ICmpInst::Predicate Pred = ICI.isSigned()
? ICI.getUnsignedPredicate()
@@ -1087,22 +1084,33 @@ Instruction *InstCombiner::visitICmpInstWithInstAndIntCst(ICmpInst &ICI,
// have its sign bit set or if it is an equality comparison.
// Extending a relational comparison when we're checking the sign
// bit would not work.
- if (Cast->hasOneUse() &&
- (ICI.isEquality() ||
- (AndCST->getValue().isNonNegative() && RHSV.isNonNegative()))) {
- uint32_t BitWidth =
- cast<IntegerType>(Cast->getOperand(0)->getType())->getBitWidth();
- APInt NewCST = AndCST->getValue().zext(BitWidth);
- APInt NewCI = RHSV.zext(BitWidth);
- Value *NewAnd =
+ if (ICI.isEquality() ||
+ (!AndCST->isNegative() && RHSV.isNonNegative())) {
+ Value *NewAnd =
Builder->CreateAnd(Cast->getOperand(0),
- ConstantInt::get(ICI.getContext(), NewCST),
- LHSI->getName());
+ ConstantExpr::getZExt(AndCST, Cast->getSrcTy()));
+ NewAnd->takeName(LHSI);
return new ICmpInst(ICI.getPredicate(), NewAnd,
- ConstantInt::get(ICI.getContext(), NewCI));
+ ConstantExpr::getZExt(RHS, Cast->getSrcTy()));
}
}
-
+
+ // If the LHS is an AND of a zext, and we have an equality compare, we can
+ // shrink the and/compare to the smaller type, eliminating the cast.
+ if (ZExtInst *Cast = dyn_cast<ZExtInst>(LHSI->getOperand(0))) {
+ const IntegerType *Ty = cast<IntegerType>(Cast->getSrcTy());
+ // Make sure we don't compare the upper bits, SimplifyDemandedBits
+ // should fold the icmp to true/false in that case.
+ if (ICI.isEquality() && RHSV.getActiveBits() <= Ty->getBitWidth()) {
+ Value *NewAnd =
+ Builder->CreateAnd(Cast->getOperand(0),
+ ConstantExpr::getTrunc(AndCST, Ty));
+ NewAnd->takeName(LHSI);
+ return new ICmpInst(ICI.getPredicate(), NewAnd,
+ ConstantExpr::getTrunc(RHS, Ty));
+ }
+ }
+
// If this is: (X >> C1) & C2 != C3 (where any shift and any compare
// could exist), turn it into (X & (C2 << C1)) != (C3 << C1). This
// happens a LOT in code produced by the C front-end, for bitfield
@@ -1396,18 +1404,27 @@ Instruction *InstCombiner::visitICmpInstWithInstAndIntCst(ICmpInst &ICI,
case Instruction::Xor:
// For the xor case, we can xor two constants together, eliminating
// the explicit xor.
- if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1)))
- return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
+ if (Constant *BOC = dyn_cast<Constant>(BO->getOperand(1))) {
+ return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
ConstantExpr::getXor(RHS, BOC));
-
- // FALLTHROUGH
+ } else if (RHSV == 0) {
+ // Replace ((xor A, B) != 0) with (A != B)
+ return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
+ BO->getOperand(1));
+ }
+ break;
case Instruction::Sub:
- // Replace (([sub|xor] A, B) != 0) with (A != B)
- if (RHSV == 0)
+ // Replace ((sub A, B) != C) with (B != A-C) if A & C are constants.
+ if (ConstantInt *BOp0C = dyn_cast<ConstantInt>(BO->getOperand(0))) {
+ if (BO->hasOneUse())
+ return new ICmpInst(ICI.getPredicate(), BO->getOperand(1),
+ ConstantExpr::getSub(BOp0C, RHS));
+ } else if (RHSV == 0) {
+ // Replace ((sub A, B) != 0) with (A != B)
return new ICmpInst(ICI.getPredicate(), BO->getOperand(0),
BO->getOperand(1));
+ }
break;
-
case Instruction::Or:
// If bits are being or'd in that are not present in the constant we
// are comparing against, then the comparison could never succeed!
@@ -1434,7 +1451,11 @@ Instruction *InstCombiner::visitICmpInstWithInstAndIntCst(ICmpInst &ICI,
return new ICmpInst(isICMP_NE ? ICmpInst::ICMP_EQ :
ICmpInst::ICMP_NE, LHSI,
Constant::getNullValue(RHS->getType()));
-
+
+ // Don't perform the following transforms if the AND has multiple uses
+ if (!BO->hasOneUse())
+ break;
+
// Replace (and X, (1 << size(X)-1) != 0) with x s< 0
if (BOC->getValue().isSignBit()) {
Value *X = BO->getOperand(0);
@@ -1659,9 +1680,9 @@ static Instruction *ProcessUGT_ADDCST_ADD(ICmpInst &I, Value *A, Value *B,
// result and the overflow bit.
Module *M = I.getParent()->getParent()->getParent();
- const Type *NewType = IntegerType::get(OrigAdd->getContext(), NewWidth);
+ Type *NewType = IntegerType::get(OrigAdd->getContext(), NewWidth);
Value *F = Intrinsic::getDeclaration(M, Intrinsic::sadd_with_overflow,
- &NewType, 1);
+ NewType);
InstCombiner::BuilderTy *Builder = IC.Builder;
@@ -1701,8 +1722,8 @@ static Instruction *ProcessUAddIdiom(Instruction &I, Value *OrigAddV,
Builder->SetInsertPoint(OrigAdd);
Module *M = I.getParent()->getParent()->getParent();
- const Type *Ty = LHS->getType();
- Value *F = Intrinsic::getDeclaration(M, Intrinsic::uadd_with_overflow, &Ty,1);
+ Type *Ty = LHS->getType();
+ Value *F = Intrinsic::getDeclaration(M, Intrinsic::uadd_with_overflow, Ty);
CallInst *Call = Builder->CreateCall2(F, LHS, RHS, "uadd");
Value *Add = Builder->CreateExtractValue(Call, 0);
@@ -2364,7 +2385,7 @@ Instruction *InstCombiner::visitICmpInst(ICmpInst &I) {
BO1->getOperand(0));
}
- if (CI->getValue().isMaxSignedValue()) {
+ if (CI->isMaxValue(true)) {
ICmpInst::Predicate Pred = I.isSigned()
? I.getUnsignedPredicate()
: I.getSignedPredicate();
generated by cgit v1.2.3 (git 2.25.1) at 2025-02-24 18:04:53 +0000