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| author | Sanjay Patel <spatel@rotateright.com> | 2018-10-31 14:57:23 +0000 |
|---|---|---|
| committer | Sanjay Patel <spatel@rotateright.com> | 2018-10-31 14:57:23 +0000 |
| commit | 85cba3b6fb4b797d26a16fefb6611c796a71cd1c (patch) | |
| tree | fad9bfae0d72067f2eef9aba810b9364188dedab /llvm/lib | |
| parent | 7d6d9eb6889c3f78a4466488d03744e408f39f1c (diff) | |
| download | bcm5719-llvm-85cba3b6fb4b797d26a16fefb6611c796a71cd1c.tar.gz bcm5719-llvm-85cba3b6fb4b797d26a16fefb6611c796a71cd1c.zip | |
[InstSimplify] fold 'fcmp nnan oge X, 0.0' when X is not negative
This re-raises some of the open questions about how to apply and use fast-math-flags in IR from PR38086:
https://bugs.llvm.org/show_bug.cgi?id=38086
...but given the current implementation (no FMF on casts), this is likely the only way to predicate the
transform.
This is part of solving PR39475:
https://bugs.llvm.org/show_bug.cgi?id=39475
Differential Revision: https://reviews.llvm.org/D53874
llvm-svn: 345725
Diffstat (limited to 'llvm/lib')
| -rw-r--r-- | llvm/lib/Analysis/InstructionSimplify.cpp | 4 | ||||
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp | 5 |
2 files changed, 7 insertions, 2 deletions
diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp index b1381932e7f..efe88507aef 100644 --- a/llvm/lib/Analysis/InstructionSimplify.cpp +++ b/llvm/lib/Analysis/InstructionSimplify.cpp @@ -3612,6 +3612,10 @@ static Value *SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS, } if (C->isZero()) { switch (Pred) { + case FCmpInst::FCMP_OGE: + if (FMF.noNaNs() && CannotBeOrderedLessThanZero(LHS, Q.TLI)) + return getTrue(RetTy); + break; case FCmpInst::FCMP_UGE: if (CannotBeOrderedLessThanZero(LHS, Q.TLI)) return getTrue(RetTy); diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp index d7af4b88a81..d3702a4885c 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp @@ -5433,8 +5433,8 @@ Instruction *InstCombiner::visitFCmpInst(FCmpInst &I) { break; // fabs(x) < 0 --> false case FCmpInst::FCMP_OLT: - llvm_unreachable("handled by SimplifyFCmpInst"); - // fabs(x) > 0 --> x != 0 + llvm_unreachable("fcmp should have simplified"); + // fabs(x) > 0 --> x != 0 case FCmpInst::FCMP_OGT: return new FCmpInst(FCmpInst::FCMP_ONE, CI->getArgOperand(0), RHSC); // fabs(x) <= 0 --> x == 0 @@ -5442,6 +5442,7 @@ Instruction *InstCombiner::visitFCmpInst(FCmpInst &I) { return new FCmpInst(FCmpInst::FCMP_OEQ, CI->getArgOperand(0), RHSC); // fabs(x) >= 0 --> !isnan(x) case FCmpInst::FCMP_OGE: + assert(!I.hasNoNaNs() && "fcmp should have simplified"); return new FCmpInst(FCmpInst::FCMP_ORD, CI->getArgOperand(0), RHSC); // fabs(x) == 0 --> x == 0 // fabs(x) != 0 --> x != 0 |
