diff options
| -rw-r--r-- | lib/Transforms/InstCombine/InstCombineCompares.cpp | 51 | ||||
| -rw-r--r-- | test/Transforms/InstCombine/icmp.ll | 4 |
2 files changed, 21 insertions, 34 deletions
diff --git a/lib/Transforms/InstCombine/InstCombineCompares.cpp b/lib/Transforms/InstCombine/InstCombineCompares.cpp index 24af2bfaf5..a96e754f3d 100644 --- a/lib/Transforms/InstCombine/InstCombineCompares.cpp +++ b/lib/Transforms/InstCombine/InstCombineCompares.cpp @@ -139,38 +139,27 @@ static bool isSignBitCheck(ICmpInst::Predicate pred, ConstantInt *RHS, } } -/// Returns true if the exploded icmp can be expressed as a comparison to zero -/// and update the predicate accordingly. The signedness of the comparison is +/// Returns true if the exploded icmp can be expressed as a signed comparison +/// to zero and updates the predicate accordingly. +/// The signedness of the comparison is preserved. static bool isSignTest(ICmpInst::Predicate &pred, const ConstantInt *RHS) { if (!ICmpInst::isSigned(pred)) return false; if (RHS->isZero()) - return true; + return ICmpInst::isRelational(pred); - if (RHS->isOne()) - switch (pred) { - case ICmpInst::ICMP_SGE: - pred = ICmpInst::ICMP_SGT; - return true; - case ICmpInst::ICMP_SLT: + if (RHS->isOne()) { + if (pred == ICmpInst::ICMP_SLT) { pred = ICmpInst::ICMP_SLE; return true; - default: - return false; } - - if (RHS->isAllOnesValue()) - switch (pred) { - case ICmpInst::ICMP_SLE: - pred = ICmpInst::ICMP_SLT; - return true; - case ICmpInst::ICMP_SGT: + } else if (RHS->isAllOnesValue()) { + if (pred == ICmpInst::ICMP_SGT) { pred = ICmpInst::ICMP_SGE; return true; - default: - return false; } + } return false; } @@ -1322,17 +1311,15 @@ Instruction *InstCombiner::visitICmpInstWithInstAndIntCst(ICmpInst &ICI, ConstantInt *Val = dyn_cast<ConstantInt>(LHSI->getOperand(1)); if (!Val) break; - if (!ICI.isEquality()) { - // If this is a signed comparison to 0 and the mul is sign preserving, - // use the mul LHS operand instead. - ICmpInst::Predicate pred = ICI.getPredicate(); - if (isSignTest(pred, RHS) && !Val->isZero() && - cast<BinaryOperator>(LHSI)->hasNoSignedWrap()) - return new ICmpInst(Val->isNegative() ? - ICmpInst::getSwappedPredicate(pred) : pred, - LHSI->getOperand(0), - Constant::getNullValue(RHS->getType())); - } + // If this is a signed comparison to 0 and the mul is sign preserving, + // use the mul LHS operand instead. + ICmpInst::Predicate pred = ICI.getPredicate(); + if (isSignTest(pred, RHS) && !Val->isZero() && + cast<BinaryOperator>(LHSI)->hasNoSignedWrap()) + return new ICmpInst(Val->isNegative() ? + ICmpInst::getSwappedPredicate(pred) : pred, + LHSI->getOperand(0), + Constant::getNullValue(RHS->getType())); break; } @@ -1613,7 +1600,7 @@ Instruction *InstCombiner::visitICmpInstWithInstAndIntCst(ICmpInst &ICI, } break; case Instruction::Mul: - if (RHSV == 0) { + if (RHSV == 0 && BO->hasNoSignedWrap()) { if (ConstantInt *BOC = dyn_cast<ConstantInt>(BO->getOperand(1))) { // The trivial case (mul X, 0) is handled by InstSimplify // General case : (mul X, C) != 0 iff X != 0 diff --git a/test/Transforms/InstCombine/icmp.ll b/test/Transforms/InstCombine/icmp.ll index 2bfdb5c70b..446c0e01dc 100644 --- a/test/Transforms/InstCombine/icmp.ll +++ b/test/Transforms/InstCombine/icmp.ll @@ -858,7 +858,7 @@ define i1 @icmp_mul(i32 %x) { ; CHECK: @icmp_mul_neq0 ; CHECK-NEXT: icmp ne i32 %x, 0 define i1 @icmp_mul_neq0(i32 %x) { - %mul = mul i32 %x, -12 + %mul = mul nsw i32 %x, -12 %cmp = icmp ne i32 %mul, 0 ret i1 %cmp } @@ -866,7 +866,7 @@ define i1 @icmp_mul_neq0(i32 %x) { ; CHECK: @icmp_mul_eq0 ; CHECK-NEXT: icmp eq i32 %x, 0 define i1 @icmp_mul_eq0(i32 %x) { - %mul = mul i32 %x, 12 + %mul = mul nsw i32 %x, 12 %cmp = icmp eq i32 %mul, 0 ret i1 %cmp } |