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| author | Eli Friedman <eli.friedman@gmail.com> | 2011-03-09 01:28:35 +0000 |
|---|---|---|
| committer | Eli Friedman <eli.friedman@gmail.com> | 2011-03-09 01:28:35 +0000 |
| commit | a81a82dcaf89eb56874111908b420f47a64c6903 (patch) | |
| tree | 1a0aebafd8143fd7c668bd0e2864f173dfd06a97 /llvm | |
| parent | 20a6fcabd3c75758d3dd511a56f0bcb95e6df56b (diff) | |
| download | bcm5719-llvm-a81a82dcaf89eb56874111908b420f47a64c6903.tar.gz bcm5719-llvm-a81a82dcaf89eb56874111908b420f47a64c6903.zip | |
PR9346: Prevent SimplifyDemandedBits from incorrectly introducing
INT_MIN % -1.
llvm-svn: 127306
Diffstat (limited to 'llvm')
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp | 4 | ||||
| -rw-r--r-- | llvm/test/Transforms/InstCombine/2011-03-08-SRemMinusOneBadOpt.ll | 12 |
2 files changed, 16 insertions, 0 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp index b12d4c36874..6e727ce6e35 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp @@ -684,6 +684,10 @@ Value *InstCombiner::SimplifyDemandedUseBits(Value *V, APInt DemandedMask, break; case Instruction::SRem: if (ConstantInt *Rem = dyn_cast<ConstantInt>(I->getOperand(1))) { + // X % -1 demands all the bits because we don't want to introduce + // INT_MIN % -1 (== undef) by accident. + if (Rem->isAllOnesValue()) + break; APInt RA = Rem->getValue().abs(); if (RA.isPowerOf2()) { if (DemandedMask.ult(RA)) // srem won't affect demanded bits diff --git a/llvm/test/Transforms/InstCombine/2011-03-08-SRemMinusOneBadOpt.ll b/llvm/test/Transforms/InstCombine/2011-03-08-SRemMinusOneBadOpt.ll new file mode 100644 index 00000000000..6a3e3e40e6d --- /dev/null +++ b/llvm/test/Transforms/InstCombine/2011-03-08-SRemMinusOneBadOpt.ll @@ -0,0 +1,12 @@ +; RUN: opt < %s -instcombine -S | FileCheck %s +; PR9346 + +define i32 @test(i64 %x) nounwind { +; CHECK: ret i32 0 +entry: + %or = or i64 %x, 4294967294 + %conv = trunc i64 %or to i32 + %rem.i = srem i32 %conv, -1 + ret i32 %rem.i +} + |
