[MS] Mangle a unique ID into all MS inline asm labels

This solves PR23715 in a way that is compatible with LTO.

MSVC supports jumping to source-level labels and between inline asm
blocks, but we don't.

Also revert the old solution, r255201, which was to mark these calls as
noduplicate.

llvm-svn: 288059

1 files changed, 5 insertions, 7 deletions

diff --git a/clang/lib/Sema/SemaStmtAsm.cpp b/clang/lib/Sema/SemaStmtAsm.cpp
index b36abb46c4a..f11e7aaa34f 100644
--- a/clang/lib/Sema/SemaStmtAsm.cpp
+++ b/clang/lib/Sema/SemaStmtAsm.cpp
@@ -753,14 +753,12 @@ LabelDecl *Sema::GetOrCreateMSAsmLabel(StringRef ExternalLabelName,
     // Create an internal name for the label.  The name should not be a valid mangled
     // name, and should be unique.  We use a dot to make the name an invalid mangled
     // name.
-    OS << "__MSASMLABEL_." << MSAsmLabelNameCounter++ << "__";
-    for (auto it = ExternalLabelName.begin(); it != ExternalLabelName.end();
-         ++it) {
-      OS << *it;
-      if (*it == '$') {
-        // We escape '$' in asm strings by replacing it with "$$"
+    OS << "__MSASMLABEL_.{:uid}__";
+    for (char C : ExternalLabelName) {
+      OS << C;
+      // We escape '$' in asm strings by replacing it with "$$"
+      if (C == '$')
         OS << '$';
-      }
     }
     Label->setMSAsmLabel(OS.str());
   }