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

1 files changed, 1 insertions, 1 deletions

diff --git a/llvm/lib/Analysis/ModuleSummaryAnalysis.cpp b/llvm/lib/Analysis/ModuleSummaryAnalysis.cpp
index 29d95d0e989..8232bf07caf 100644
--- a/llvm/lib/Analysis/ModuleSummaryAnalysis.cpp
+++ b/llvm/lib/Analysis/ModuleSummaryAnalysis.cpp
@@ -319,7 +319,7 @@ static void computeFunctionSummary(ModuleSummaryIndex &Index, const Module &M,
       auto *CalledValue = CS.getCalledValue();
       auto *CalledFunction = CS.getCalledFunction();
       if (CalledValue && !CalledFunction) {
-        CalledValue = CalledValue->stripPointerCastsNoFollowAliases();
+        CalledValue = CalledValue->stripPointerCasts();
         // Stripping pointer casts can reveal a called function.
         CalledFunction = dyn_cast<Function>(CalledValue);
       }