IR. Change strip* family of functions to not look through aliases.
I noticed another instance of the issue where references to aliases were
being replaced with aliasees, this time in InstCombine. In the instance that
I saw it turned out to be only a QoI issue (a symbol ended up being missing
from the symbol table due to the last reference to the alias being removed,
preventing HWASAN from symbolizing a global reference), but it could easily
have manifested as incorrect behaviour.
Since this is the third such issue encountered (previously: D65118, D65314)
it seems to be time to address this common error/QoI issue once and for all
and make the strip* family of functions not look through aliases.
Includes a test for the specific issue that I saw, but no doubt there are
other similar bugs fixed here.
As with D65118 this has been tested to make sure that the optimization isn't
load bearing. I built Clang, Chromium for Linux, Android and Windows as well
as the test-suite and there were no size regressions.
Differential Revision: https://reviews.llvm.org/D66606
llvm-svn: 369697
diff --git a/llvm/lib/Analysis/ConstantFolding.cpp b/llvm/lib/Analysis/ConstantFolding.cpp
index 2d7b479..f7cc53b 100644
--- a/llvm/lib/Analysis/ConstantFolding.cpp
+++ b/llvm/lib/Analysis/ConstantFolding.cpp
@@ -781,10 +781,10 @@
}
/// Strip the pointer casts, but preserve the address space information.
-Constant* StripPtrCastKeepAS(Constant* Ptr, Type *&ElemTy) {
+Constant *StripPtrCastKeepAS(Constant *Ptr, Type *&ElemTy) {
assert(Ptr->getType()->isPointerTy() && "Not a pointer type");
auto *OldPtrTy = cast<PointerType>(Ptr->getType());
- Ptr = cast<Constant>(Ptr->stripPointerCastsNoFollowAliases());
+ Ptr = cast<Constant>(Ptr->stripPointerCasts());
auto *NewPtrTy = cast<PointerType>(Ptr->getType());
ElemTy = NewPtrTy->getPointerElementType();