fix PR8267 - Instcombine shouldn't optimizer away volatile memcpy's.
llvm-svn: 115296
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
index 0ebe3b4..ed078ec 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/llvm/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
diff --git a/llvm/test/Transforms/InstCombine/memcpy.ll b/llvm/test/Transforms/InstCombine/memcpy.ll
index 421156d..8a2e3aa 100644
--- a/llvm/test/Transforms/InstCombine/memcpy.ll
+++ b/llvm/test/Transforms/InstCombine/memcpy.ll
@@ -2,9 +2,18 @@
declare void @llvm.memcpy.p0i8.p0i8.i32(i8* nocapture, i8* nocapture, i32, i32, i1) nounwind
-define void @test4(i8* %a) {
+define void @test1(i8* %a) {
tail call void @llvm.memcpy.p0i8.p0i8.i32(i8* %a, i8* %a, i32 100, i32 1, i1 false)
ret void
-}
-; CHECK: define void @test4
+; CHECK: define void @test1
; CHECK-NEXT: ret void
+}
+
+
+; PR8267
+define void @test2(i8* %a) {
+ tail call void @llvm.memcpy.p0i8.p0i8.i32(i8* %a, i8* %a, i32 100, i32 1, i1 true)
+ ret void
+; CHECK: define void @test2
+; CHECK-NEXT: call void @llvm.memcpy
+}