diff options
| -rw-r--r-- | lib/Transforms/InstCombine/InstCombineCasts.cpp | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/lib/Transforms/InstCombine/InstCombineCasts.cpp b/lib/Transforms/InstCombine/InstCombineCasts.cpp index 77ad828958..5dd6fe5e27 100644 --- a/lib/Transforms/InstCombine/InstCombineCasts.cpp +++ b/lib/Transforms/InstCombine/InstCombineCasts.cpp @@ -882,10 +882,6 @@ Instruction *InstCombiner::transformSExtICmp(ICmpInst *ICI, Instruction &CI) { Value *Op0 = ICI->getOperand(0), *Op1 = ICI->getOperand(1); ICmpInst::Predicate Pred = ICI->getPredicate(); - // Transforming icmps with more than one use is not profitable. - if (!ICI->hasOneUse()) - return 0; - if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Op1)) { // (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 @@ -906,7 +902,8 @@ Instruction *InstCombiner::transformSExtICmp(ICmpInst *ICI, Instruction &CI) { // If we know that only one bit of the LHS of the icmp can be set and we // have an equality comparison with zero or a power of 2, we can transform // the icmp and sext into bitwise/integer operations. - if (ICI->isEquality() && (Op1C->isZero() || Op1C->getValue().isPowerOf2())){ + if (ICI->hasOneUse() && + ICI->isEquality() && (Op1C->isZero() || Op1C->getValue().isPowerOf2())){ unsigned BitWidth = Op1C->getType()->getBitWidth(); APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0); APInt TypeMask(APInt::getAllOnesValue(BitWidth)); @@ -916,6 +913,9 @@ Instruction *InstCombiner::transformSExtICmp(ICmpInst *ICI, Instruction &CI) { if (KnownZeroMask.isPowerOf2()) { Value *In = ICI->getOperand(0); + assert((Op1C->isZero() || Op1C->getValue() == KnownZeroMask) && + "Constant icmp not folded?"); + if (!Op1C->isZero() == (Pred == ICmpInst::ICMP_NE)) { // sext ((x & 2^n) == 0) -> (x >> n) - 1 // sext ((x & 2^n) != 2^n) -> (x >> n) - 1 @@ -932,7 +932,7 @@ Instruction *InstCombiner::transformSExtICmp(ICmpInst *ICI, Instruction &CI) { "sext"); } else { // sext ((x & 2^n) != 0) -> (x << bitwidth-n) a>> bitwidth-1 - // sext ((x & 2^n) != 2^n) -> (x << bitwidth-n) a>> bitwidth-1 + // sext ((x & 2^n) == 2^n) -> (x << bitwidth-n) a>> bitwidth-1 unsigned ShiftAmt = KnownZeroMask.countLeadingZeros(); // Perform a left shift to place the desired bit in the MSB. if (ShiftAmt) |