diff options
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstCombineAtomicRMW.cpp | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAtomicRMW.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAtomicRMW.cpp index 58da7eb6759..b857741e840 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineAtomicRMW.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineAtomicRMW.cpp @@ -26,8 +26,7 @@ bool isIdempotentRMW(AtomicRMWInst& RMWI) { // TODO: Handle fadd, fsub? return false; - AtomicRMWInst::BinOp Op = RMWI.getOperation(); - switch(Op) { + switch(RMWI.getOperation()) { case AtomicRMWInst::Add: case AtomicRMWInst::Sub: case AtomicRMWInst::Or: @@ -55,12 +54,12 @@ bool isSaturating(AtomicRMWInst& RMWI) { if(!C) return false; - AtomicRMWInst::BinOp Op = RMWI.getOperation(); - switch(Op) { + switch(RMWI.getOperation()) { default: // TODO: fadd, fsub w/Nan - // Note: We avoid listing xchg to prevent transform cycles. return false; + case AtomicRMWInst::Xchg: + return true; case AtomicRMWInst::Or: return C->isAllOnesValue(); case AtomicRMWInst::And: @@ -87,7 +86,8 @@ Instruction *InstCombiner::visitAtomicRMWInst(AtomicRMWInst &RMWI) { // Any atomicrmw op which produces a known result in memory can be // replaced w/an atomicrmw xchg. - if (isSaturating(RMWI)) { + if (isSaturating(RMWI) && + RMWI.getOperation() != AtomicRMWInst::Xchg) { RMWI.setOperation(AtomicRMWInst::Xchg); return &RMWI; } |
