diff options
| -rw-r--r-- | lib/Transforms/Utils/PromoteMemoryToRegister.cpp | 4 | ||||
| -rw-r--r-- | test/Transforms/Mem2Reg/atomic.ll | 12 |
2 files changed, 16 insertions, 0 deletions
diff --git a/lib/Transforms/Utils/PromoteMemoryToRegister.cpp b/lib/Transforms/Utils/PromoteMemoryToRegister.cpp index e5a00f4..db3e942 100644 --- a/lib/Transforms/Utils/PromoteMemoryToRegister.cpp +++ b/lib/Transforms/Utils/PromoteMemoryToRegister.cpp @@ -86,11 +86,15 @@ bool llvm::isAllocaPromotable(const AllocaInst *AI) { UI != UE; ++UI) { // Loop over all of the uses of the alloca const User *U = *UI; if (const LoadInst *LI = dyn_cast<LoadInst>(U)) { + // Note that atomic loads can be transformed; atomic semantics do + // not have any meaning for a local alloca. if (LI->isVolatile()) return false; } else if (const StoreInst *SI = dyn_cast<StoreInst>(U)) { if (SI->getOperand(0) == AI) return false; // Don't allow a store OF the AI, only INTO the AI. + // Note that atomic stores can be transformed; atomic semantics do + // not have any meaning for a local alloca. if (SI->isVolatile()) return false; } else if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(U)) { diff --git a/test/Transforms/Mem2Reg/atomic.ll b/test/Transforms/Mem2Reg/atomic.ll new file mode 100644 index 0000000..982c413 --- /dev/null +++ b/test/Transforms/Mem2Reg/atomic.ll @@ -0,0 +1,12 @@ +; RUN: opt -mem2reg < %s -S | FileCheck %s + +; mem2reg is allowed with arbitrary atomic operations (although we only support +; it for atomic load and store at the moment). +define i32 @test1(i32 %x) { +; CHECK: @test1 +; CHECK: ret i32 %x + %a = alloca i32 + store atomic i32 %x, i32* %a seq_cst, align 4 + %r = load atomic i32* %a seq_cst, align 4 + ret i32 %r +} |