From 853b962416bcb5c85df455eb4d89c896f9147ee8 Mon Sep 17 00:00:00 2001
From: Teresa Johnson <tejohnson@google.com>
Date: Fri, 4 Jan 2019 19:04:54 +0000
Subject: [ThinLTO] Handle chains of aliases

At -O0, globalopt is not run during the compile step, and we can have a
chain of an alias having an immediate aliasee of another alias. The
summaries are constructed assuming aliases in a canonical form
(flattened chains), and as a result only the base object but no
intermediate aliases were preserved.

Fix by adding a pass that canonicalize aliases, which ensures each
alias is a direct alias of the base object.

Reviewers: pcc, davidxl

Subscribers: mehdi_amini, inglorion, eraman, steven_wu, dexonsmith, arphaman, llvm-commits

Differential Revision: https://reviews.llvm.org/D54507

llvm-svn: 350423
---
 llvm/lib/Transforms/Utils/Utils.cpp | 1 +
 1 file changed, 1 insertion(+)

(limited to 'llvm/lib/Transforms/Utils/Utils.cpp')

diff --git a/llvm/lib/Transforms/Utils/Utils.cpp b/llvm/lib/Transforms/Utils/Utils.cpp
index afd842f5991..95416de0743 100644
--- a/llvm/lib/Transforms/Utils/Utils.cpp
+++ b/llvm/lib/Transforms/Utils/Utils.cpp
@@ -26,6 +26,7 @@ using namespace llvm;
 void llvm::initializeTransformUtils(PassRegistry &Registry) {
   initializeAddDiscriminatorsLegacyPassPass(Registry);
   initializeBreakCriticalEdgesPass(Registry);
+  initializeCanonicalizeAliasesLegacyPassPass(Registry);
   initializeInstNamerPass(Registry);
   initializeLCSSAWrapperPassPass(Registry);
   initializeLibCallsShrinkWrapLegacyPassPass(Registry);
-- 
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