Do not mangle in MS-way the globals with magic \001 in the name.
Based on the patch by David Nadlinger!


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179889 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/Mangler.cpp b/lib/Target/Mangler.cpp
index edfd421..d31efa8 100644
--- a/lib/Target/Mangler.cpp
+++ b/lib/Target/Mangler.cpp
@@ -188,7 +188,12 @@
   
   // If this global has a name, handle it simply.
   if (GV->hasName()) {
-    getNameWithPrefix(OutName, GV->getName(), PrefixTy);
+    StringRef Name = GV->getName();
+    getNameWithPrefix(OutName, Name, PrefixTy);
+    // No need to do anything else if the global has the special "do not mangle"
+    // flag in the name.
+    if (Name[0] == 1)
+      return;
   } else {
     // Get the ID for the global, assigning a new one if we haven't got one
     // already.
diff --git a/test/CodeGen/X86/fastcall-correct-mangling.ll b/test/CodeGen/X86/fastcall-correct-mangling.ll
index 33b18bb..3569d36 100644
--- a/test/CodeGen/X86/fastcall-correct-mangling.ll
+++ b/test/CodeGen/X86/fastcall-correct-mangling.ll
@@ -7,3 +7,8 @@
         ret void
 }
 
+define x86_fastcallcc i32 @"\01DoNotMangle"(i32 %a) {
+; CHECK: DoNotMangle:
+entry:
+  ret i32 %a
+}
diff --git a/test/CodeGen/X86/stdcall.ll b/test/CodeGen/X86/stdcall.ll
index a7c2517..73826ed 100644
--- a/test/CodeGen/X86/stdcall.ll
+++ b/test/CodeGen/X86/stdcall.ll
@@ -1,16 +1,24 @@
-; RUN: llc < %s | FileCheck %s
+; RUN: llc -mtriple="i386-pc-mingw32" < %s | FileCheck %s
 ; PR5851
 
-target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-f80:128:128-v64:64:64-v128:128:128-a0:0:64-f80:32:32-n8:16:32"
-target triple = "i386-pc-mingw32"
-
 %0 = type { void (...)* }
 
+define internal x86_stdcallcc void @MyFunc() nounwind {
+entry:
+; CHECK: MyFunc@0:
+; CHECK: ret
+  ret void
+}
+
+; PR14410
+define x86_stdcallcc i32 @"\01DoNotMangle"(i32 %a) {
+; CHECK: DoNotMangle:
+; CHECK: ret $4
+entry:
+  ret i32 %a
+}
+
 @B = global %0 { void (...)* bitcast (void ()* @MyFunc to void (...)*) }, align 4
 ; CHECK: _B:
 ; CHECK: .long _MyFunc@0
 
-define internal x86_stdcallcc void @MyFunc() nounwind {
-entry:
-  ret void
-}