LTO: Don't bother trying to mangle unnamed globals, as they can't be preserved with MustPreserveSymbols.

Summary: Should fix sanitizer-windows bot.

Reviewers: joker.eph

Subscribers: llvm-commits, joker.eph

Differential Revision: http://reviews.llvm.org/D19635

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@267820 91177308-0d34-0410-b5e6-96231b3b80d8

lib/LTO/LTOCodeGenerator.cpp

@@ -381,6 +381,10 @@ void LTOCodeGenerator::applyScopeRestrictions() {
   // candidate GlobalValue if it can be internalized or not.
   SmallString<64> MangledName;
   auto mustPreserveGV = [&](const GlobalValue &GV) -> bool {
+    // Unnamed globals can't be mangled, but they can't be preserved either.
+    if (!GV.hasName())
+      return false;
+
     // Need to mangle the GV as the "MustPreserveSymbols" StringSet is filled
     // with the linker supplied name, which on Darwin includes a leading
     // underscore.

test/LTO/X86/unnamed.ll

@@ -0,0 +1,10 @@
+; RUN: llvm-as -o %t.bc %s
+; RUN: llvm-lto -save-merged-module -o %t2 %t.bc
+; RUN: llvm-dis -o - %t2.merged.bc | FileCheck %s
+
+; CHECK-NOT: global i32
+
+target triple = "x86_64-unknown-linux-gnu"
+
+@0 = private global i32 42
+@foo = constant i32* @0