diff options
-rw-r--r-- | lib/Transforms/Utils/Local.cpp | 11 | ||||
-rw-r--r-- | test/Transforms/InstCombine/deadcode.ll | 10 |
2 files changed, 20 insertions, 1 deletions
diff --git a/lib/Transforms/Utils/Local.cpp b/lib/Transforms/Utils/Local.cpp index 187ebdc797..4b648b3b8b 100644 --- a/lib/Transforms/Utils/Local.cpp +++ b/lib/Transforms/Utils/Local.cpp @@ -17,6 +17,7 @@ #include "llvm/DerivedTypes.h" #include "llvm/Instructions.h" #include "llvm/Intrinsics.h" +#include "llvm/IntrinsicInst.h" #include "llvm/Analysis/ConstantFolding.h" #include "llvm/Target/TargetData.h" #include "llvm/Support/GetElementPtrTypeIterator.h" @@ -173,8 +174,16 @@ bool llvm::ConstantFoldTerminator(BasicBlock *BB) { bool llvm::isInstructionTriviallyDead(Instruction *I) { if (!I->use_empty() || isa<TerminatorInst>(I)) return false; - if (!I->mayWriteToMemory()) return true; + if (!I->mayWriteToMemory()) + return true; + // Special case intrinsics that "may write to memory" but can be deleted when + // dead. + if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) + // Safe to delete llvm.stacksave if dead. + if (II->getIntrinsicID() == Intrinsic::stacksave) + return true; + return false; } diff --git a/test/Transforms/InstCombine/deadcode.ll b/test/Transforms/InstCombine/deadcode.ll index 6ff5ae8e34..43c1793155 100644 --- a/test/Transforms/InstCombine/deadcode.ll +++ b/test/Transforms/InstCombine/deadcode.ll @@ -1,4 +1,5 @@ ; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep {ret i32 %A} +; RUN: llvm-as < %s | opt -die | llvm-dis | not grep call.*llvm.stacksave define i32 @test(i32 %A) { %X = or i1 false, false @@ -12,3 +13,12 @@ C: ; preds = %T, %0 %C.upgrd.1 = phi i32 [ %B, %T ], [ %A, %0 ] ret i32 %C.upgrd.1 } + +define i32* @test2(i32 %width) { + %tmp = call i8* @llvm.stacksave( ) + %tmp14 = alloca i32, i32 %width + ret i32* %tmp14 +} + +declare i8* @llvm.stacksave() + |