[GlobalOpt] Sort members of llvm.used deterministically (#5209)

Patch by Jake VanAdrighem!

Summary:
Fix the way we sort the llvm.used and llvm.compiler.used members.

This bug seems to have been introduced in rL183756 through a set of improper casts to GlobalValue*. In subsequent patches this problem was missed and transformed into a getName call on a ConstantExpr.

Reviewers: silvas

Subscribers: silvas, llvm-commits

Differential Revision: http://reviews.llvm.org/D12851

llvm-svn: 248728

Co-authored-by: Sean Silva <[email protected]>

lib/Transforms/IPO/GlobalOpt.cpp

@@ -2721,7 +2721,8 @@ static bool EvaluateStaticConstructor(Function *F, const DataLayout &DL,
 
 // HLSL Change: changed calling convention to __cdecl
 static int __cdecl compareNames(Constant *const *A, Constant *const *B) {
-  return (*A)->getName().compare((*B)->getName());
+  return (*A)->stripPointerCasts()->getName().compare(
+      (*B)->stripPointerCasts()->getName());
 }
 
 static void setUsedInitializer(GlobalVariable &V,

test/Transforms/GlobalOpt/alias-used.ll

@@ -7,7 +7,7 @@
 @ia = internal alias 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* 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"
 
 @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"