From 67a71b3184ce20a901e874d0ee25e01397dd87ef Mon Sep 17 00:00:00 2001 From: Roman Divacky Date: Wed, 3 Mar 2010 17:27:15 +0000 Subject: Update LLVM to 97654. --- lib/Transforms/InstCombine/InstCombineSelect.cpp | 28 +++++++++++++++++++----- 1 file changed, 23 insertions(+), 5 deletions(-) (limited to 'lib/Transforms/InstCombine/InstCombineSelect.cpp') diff --git a/lib/Transforms/InstCombine/InstCombineSelect.cpp b/lib/Transforms/InstCombine/InstCombineSelect.cpp index 7807d9a63341..2fc932594f7b 100644 --- a/lib/Transforms/InstCombine/InstCombineSelect.cpp +++ b/lib/Transforms/InstCombine/InstCombineSelect.cpp @@ -539,9 +539,18 @@ Instruction *InstCombiner::visitSelectInst(SelectInst &SI) { !CFPf->getValueAPF().isZero())) return ReplaceInstUsesWith(SI, FalseVal); } - // Transform (X != Y) ? X : Y -> X - if (FCI->getPredicate() == FCmpInst::FCMP_ONE) + // Transform (X une Y) ? X : Y -> X + if (FCI->getPredicate() == FCmpInst::FCMP_UNE) { + // 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(TrueVal)) && + !CFPt->getValueAPF().isZero()) || + ((CFPf = dyn_cast(FalseVal)) && + !CFPf->getValueAPF().isZero())) 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){ @@ -557,9 +566,18 @@ Instruction *InstCombiner::visitSelectInst(SelectInst &SI) { !CFPf->getValueAPF().isZero())) return ReplaceInstUsesWith(SI, FalseVal); } - // Transform (X != Y) ? Y : X -> Y - if (FCI->getPredicate() == FCmpInst::FCMP_ONE) - return ReplaceInstUsesWith(SI, TrueVal); + // Transform (X une Y) ? Y : X -> Y + if (FCI->getPredicate() == FCmpInst::FCMP_UNE) { + // 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(TrueVal)) && + !CFPt->getValueAPF().isZero()) || + ((CFPf = dyn_cast(FalseVal)) && + !CFPf->getValueAPF().isZero())) + 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 -- cgit v1.3