[Mangle] Add flag to asm labels to disable '\01' prefixing

LLDB synthesizes decls using asm labels. These decls cannot have a mangle
different than the one specified in the label name. I.e., the '\01' prefix
should not be added.

Fixes an expression evaluation failure in lldb's TestVirtual.py on iOS.

rdar://45827323

Differential Revision: https://reviews.llvm.org/D67774

llvm-svn: 372903

1 files changed, 9 insertions, 3 deletions

diff --git a/clang/lib/AST/Mangle.cpp b/clang/lib/AST/Mangle.cpp
index 28de87fde9e..b158fe85a47 100644
--- a/clang/lib/AST/Mangle.cpp
+++ b/clang/lib/AST/Mangle.cpp
@@ -122,15 +122,21 @@ void MangleContext::mangleName(const NamedDecl *D, raw_ostream &Out) {
   if (const AsmLabelAttr *ALA = D->getAttr<AsmLabelAttr>()) {
     // If we have an asm name, then we use it as the mangling.
 
+    // If the label isn't literal, or if this is an alias for an LLVM intrinsic,
+    // do not add a "\01" prefix.
+    if (!ALA->getIsLiteralLabel() || ALA->getLabel().startswith("llvm.")) {
+      Out << ALA->getLabel();
+      return;
+    }
+
     // Adding the prefix can cause problems when one file has a "foo" and
     // another has a "\01foo". That is known to happen on ELF with the
     // tricks normally used for producing aliases (PR9177). Fortunately the
     // llvm mangler on ELF is a nop, so we can just avoid adding the \01
-    // marker.  We also avoid adding the marker if this is an alias for an
-    // LLVM intrinsic.
+    // marker.
     char GlobalPrefix =
         getASTContext().getTargetInfo().getDataLayout().getGlobalPrefix();
-    if (GlobalPrefix && !ALA->getLabel().startswith("llvm."))
+    if (GlobalPrefix)
       Out << '\01'; // LLVM IR Marker for __asm("foo")
 
     Out << ALA->getLabel();