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| author | Nick Lewycky <nicholas@mxc.ca> | 2011-08-02 21:19:27 +0000 |
|---|---|---|
| committer | Nick Lewycky <nicholas@mxc.ca> | 2011-08-02 21:19:27 +0000 |
| commit | 3e69c13c301acee99c8bde7e692777bf856a6362 (patch) | |
| tree | 73217bfa6048a7be0f53b89f36111650c3d25207 | |
| parent | 11066fb9374d80a1564d9bbcc93ccc2402fb1f97 (diff) | |
| download | external_llvm-3e69c13c301acee99c8bde7e692777bf856a6362.zip external_llvm-3e69c13c301acee99c8bde7e692777bf856a6362.tar.gz external_llvm-3e69c13c301acee99c8bde7e692777bf856a6362.tar.bz2 | |
Lifetime intrinsics on undef are dead.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@136722 91177308-0d34-0410-b5e6-96231b3b80d8
| -rw-r--r-- | lib/Transforms/Utils/Local.cpp | 12 | ||||
| -rw-r--r-- | test/Transforms/InstCombine/deadcode.ll | 11 |
2 files changed, 19 insertions, 4 deletions
diff --git a/lib/Transforms/Utils/Local.cpp b/lib/Transforms/Utils/Local.cpp index 2d43e37..60dc15d 100644 --- a/lib/Transforms/Utils/Local.cpp +++ b/lib/Transforms/Utils/Local.cpp @@ -229,10 +229,10 @@ bool llvm::isInstructionTriviallyDead(Instruction *I) { // We don't want debug info removed by anything this general, unless // debug info is empty. if (DbgDeclareInst *DDI = dyn_cast<DbgDeclareInst>(I)) { - if (DDI->getAddress()) + if (DDI->getAddress()) return false; return true; - } + } if (DbgValueInst *DVI = dyn_cast<DbgValueInst>(I)) { if (DVI->getValue()) return false; @@ -243,10 +243,16 @@ bool llvm::isInstructionTriviallyDead(Instruction *I) { // Special case intrinsics that "may have side effects" but can be deleted // when dead. - if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) + if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) { // Safe to delete llvm.stacksave if dead. if (II->getIntrinsicID() == Intrinsic::stacksave) return true; + + // Lifetime intrinsics are dead when their right-hand is undef. + if (II->getIntrinsicID() == Intrinsic::lifetime_start || + II->getIntrinsicID() == Intrinsic::lifetime_end) + return isa<UndefValue>(II->getArgOperand(1)); + } return false; } diff --git a/test/Transforms/InstCombine/deadcode.ll b/test/Transforms/InstCombine/deadcode.ll index 52af0ef..7c7f1ab 100644 --- a/test/Transforms/InstCombine/deadcode.ll +++ b/test/Transforms/InstCombine/deadcode.ll @@ -1,5 +1,5 @@ ; RUN: opt < %s -instcombine -S | grep {ret i32 %A} -; RUN: opt < %s -die -S | not grep call.*llvm.stacksave +; RUN: opt < %s -die -S | not grep call.*llvm define i32 @test(i32 %A) { %X = or i1 false, false @@ -22,3 +22,12 @@ define i32* @test2(i32 %width) { declare i8* @llvm.stacksave() +declare void @llvm.lifetime.start(i64, i8*) +declare void @llvm.lifetime.end(i64, i8*) + +define void @test3() { + call void @llvm.lifetime.start(i64 -1, i8* undef) + call void @llvm.lifetime.end(i64 -1, i8* undef) + ret void +} + |