Don't narrow the load and store in a load+twiddle+store sequence unless
there are clearly no stores between the load and the store. This fixes
this miscompile reported as PR7833.
This breaks the test/CodeGen/X86/narrow_op-2.ll optimization, which is
safe, but awkward to prove safe. Move it to X86's README.txt.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112861 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 7ffbf8d..c9c4d91 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -5798,7 +5798,8 @@
return SDValue();
SDValue N0 = Value.getOperand(0);
- if (ISD::isNormalLoad(N0.getNode()) && N0.hasOneUse()) {
+ if (ISD::isNormalLoad(N0.getNode()) && N0.hasOneUse() &&
+ Chain == SDValue(N0.getNode(), 1)) {
LoadSDNode *LD = cast<LoadSDNode>(N0);
if (LD->getBasePtr() != Ptr)
return SDValue();