[llvm] r263550 - [GlobalOpt] Don't look through aliases when sorting names of globals.

[Benjamin Kramer via llvm-commits]

Author: d0k
Date: Tue Mar 15 09:18:26 2016
New Revision: 263550

URL: http://llvm.org/viewvc/llvm-project?rev=263550&view=rev
Log:
[GlobalOpt] Don't look through aliases when sorting names of globals.

If both are different aliases to the same value the sorting becomes
non-deterministic as array_pod_sort is not stable.

Modified:
    llvm/trunk/lib/Transforms/IPO/GlobalOpt.cpp
    llvm/trunk/test/Transforms/GlobalOpt/alias-used.ll

Modified: llvm/trunk/lib/Transforms/IPO/GlobalOpt.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/IPO/GlobalOpt.cpp?rev=263550&r1=263549&r2=263550&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/IPO/GlobalOpt.cpp (original)
+++ llvm/trunk/lib/Transforms/IPO/GlobalOpt.cpp Tue Mar 15 09:18:26 2016
@@ -2199,8 +2199,9 @@ static bool EvaluateStaticConstructor(Fu
 }
 
 static int compareNames(Constant *const *A, Constant *const *B) {
-  return (*A)->stripPointerCasts()->getName().compare(
-      (*B)->stripPointerCasts()->getName());
+  Value *AStripped = (*A)->stripPointerCastsNoFollowAliases();
+  Value *BStripped = (*B)->stripPointerCastsNoFollowAliases();
+  return AStripped->getName().compare(BStripped->getName());
 }
 
 static void setUsedInitializer(GlobalVariable &V,

Modified: llvm/trunk/test/Transforms/GlobalOpt/alias-used.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/GlobalOpt/alias-used.ll?rev=263550&r1=263549&r2=263550&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/GlobalOpt/alias-used.ll (original)
+++ llvm/trunk/test/Transforms/GlobalOpt/alias-used.ll Tue Mar 15 09:18:26 2016
@@ -7,7 +7,7 @@
 @ia = internal alias i8, i8* @i
 
 @llvm.used = appending global [3 x i8*] [i8* bitcast (void ()* @fa to i8*), i8* bitcast (void ()* @f to i8*), i8* @ca], section "llvm.metadata"
-; CHECK-DAG: @llvm.used = appending global [3 x i8*] [i8* @ca, i8* bitcast (void ()* @fa to i8*), i8* bitcast (void ()* @f to i8*)], section "llvm.metadata"
+; CHECK-DAG: @llvm.used = appending global [3 x i8*] [i8* @ca, i8* bitcast (void ()* @f to i8*), i8* bitcast (void ()* @fa to i8*)], section "llvm.metadata"
 
 @llvm.compiler.used = appending global [4 x i8*] [i8* bitcast (void ()* @fa3 to i8*), i8* bitcast (void ()* @fa to i8*), i8* @ia, i8* @i], section "llvm.metadata"
 ; CHECK-DAG: @llvm.compiler.used = appending global [2 x i8*] [i8* bitcast (void ()* @fa3 to i8*), i8* @ia], section "llvm.metadata"