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Fixed the lost FastMathFlags in Reassociate optimization.

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Reviewer: Hal Finkel.
Differential Revision: https://reviews.llvm.org/D26957



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@287695 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Vyacheslav Klochkov 2016-11-22 20:23:04 +00:00
parent abb5e38a8f
commit f060e3f4bc
2 changed files with 20 additions and 0 deletions
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6
lib/Transforms/Scalar/Reassociate.cpp
View File

@ -1778,6 +1778,12 @@ Value *ReassociatePass::OptimizeMul(BinaryOperator *I,
return nullptr; // All distinct factors, so nothing left for us to do.
IRBuilder<> Builder(I);
// The reassociate transformation for FP operations is performed only
// if unsafe algebra is permitted by FastMathFlags. Propagate those flags
// to the newly generated operations.
if (auto FPI = dyn_cast<FPMathOperator>(I))
Builder.setFastMathFlags(FPI->getFastMathFlags());
Value *V = buildMinimalMultiplyDAG(Builder, Factors);
if (Ops.empty())
return V;

14
test/Transforms/Reassociate/propagate-flags.ll Normal file
View File

@ -0,0 +1,14 @@
; RUN: opt < %s -reassociate -S | FileCheck %s
; CHECK-LABEL: func
; CHECK: fmul fast double
; CHECK-NEXT: fmul fast double
; CHECK-NEXT: ret
define double @func(double %a, double %b) {
entry:
%mul1 = fmul fast double %a, %a
%mul2 = fmul fast double %b, %b
%mul3 = fmul fast double %mul1, %mul2
ret double %mul3
}