fix PR8267 - Instcombine shouldn't optimizer away volatile memcpy's.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@115296 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/InstCombine/InstCombineCalls.cpp b/lib/Transforms/InstCombine/InstCombineCalls.cpp
index 0ebe3b4..ed078ec 100644
--- a/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -280,7 +280,8 @@
// memmove/cpy/set of zero bytes is a noop.
if (Constant *NumBytes = dyn_cast<Constant>(MI->getLength())) {
- if (NumBytes->isNullValue()) return EraseInstFromFunction(CI);
+ if (NumBytes->isNullValue())
+ return EraseInstFromFunction(CI);
if (ConstantInt *CI = dyn_cast<ConstantInt>(NumBytes))
if (CI->getZExtValue() == 1) {
@@ -289,6 +290,10 @@
// alignment is sufficient.
}
}
+
+ // No other transformations apply to volatile transfers.
+ if (MI->isVolatile())
+ return 0;
// If we have a memmove and the source operation is a constant global,
// then the source and dest pointers can't alias, so we can change this