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| author | Sanjay Patel <spatel@rotateright.com> | 2019-11-15 16:06:43 -0500 |
|---|---|---|
| committer | Sanjay Patel <spatel@rotateright.com> | 2019-11-15 16:14:35 -0500 |
| commit | ee0882bdf866ad8877dfda3820a822c851d0733a (patch) | |
| tree | 9e9535a3ba357ec66706cca576ce472152c7d946 /llvm | |
| parent | 782392db8122cafb5e0e4ad5fe0c24c46f11b2b7 (diff) | |
| download | bcm5719-llvm-ee0882bdf866ad8877dfda3820a822c851d0733a.tar.gz bcm5719-llvm-ee0882bdf866ad8877dfda3820a822c851d0733a.zip | |
[SimplifyCFG] propagate fast-math-flags (FMF) from phi to select
This is another step towards having FMF apply only to FP values
rather than those + fcmp. See PR38086 for one of the original
discussions/motivations:
https://bugs.llvm.org/show_bug.cgi?id=38086
And the test here is derived from PR39535:
https://bugs.llvm.org/show_bug.cgi?id=39535
Currently, we lose FMF when converting any phi to select in
SimplifyCFG. There are a small number of similar changes needed
to correct within SimplifyCFG, so it should be quick to patch
this pass up.
FMF was extended to select and phi with:
D61917
D67564
Differential Revision: https://reviews.llvm.org/D70208
Diffstat (limited to 'llvm')
| -rw-r--r-- | llvm/lib/Transforms/Utils/SimplifyCFG.cpp | 8 | ||||
| -rw-r--r-- | llvm/test/Transforms/SimplifyCFG/HoistCode.ll | 2 |
2 files changed, 8 insertions, 2 deletions
diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp index 9644ba31f4d..ab1a474db9a 100644 --- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp +++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp @@ -1404,10 +1404,16 @@ HoistTerminator: // These values do not agree. Insert a select instruction before NT // that determines the right value. SelectInst *&SI = InsertedSelects[std::make_pair(BB1V, BB2V)]; - if (!SI) + if (!SI) { + // Propagate fast-math-flags from phi node to its replacement select. + IRBuilder<>::FastMathFlagGuard FMFGuard(Builder); + if (isa<FPMathOperator>(PN)) + Builder.setFastMathFlags(PN.getFastMathFlags()); + SI = cast<SelectInst>( Builder.CreateSelect(BI->getCondition(), BB1V, BB2V, BB1V->getName() + "." + BB2V->getName(), BI)); + } // Make the PHI node use the select for all incoming values for BB1/BB2 for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) diff --git a/llvm/test/Transforms/SimplifyCFG/HoistCode.ll b/llvm/test/Transforms/SimplifyCFG/HoistCode.ll index 1fb9c46e882..575cb4f19eb 100644 --- a/llvm/test/Transforms/SimplifyCFG/HoistCode.ll +++ b/llvm/test/Transforms/SimplifyCFG/HoistCode.ll @@ -19,7 +19,7 @@ define float @PR39535min(float %x) { ; CHECK-LABEL: @PR39535min( ; CHECK-NEXT: entry: ; CHECK-NEXT: [[TOBOOL:%.*]] = fcmp une float [[X:%.*]], 0.000000e+00 -; CHECK-NEXT: [[DOTX:%.*]] = select i1 [[TOBOOL]], float 0.000000e+00, float [[X]] +; CHECK-NEXT: [[DOTX:%.*]] = select fast i1 [[TOBOOL]], float 0.000000e+00, float [[X]] ; CHECK-NEXT: ret float [[DOTX]] ; entry: |
