[llvm] [clang-tools-extra] [clang] [compiler-rt] [PGO][GlobalValue][LTO]In GlobalValues::getGlobalIdentifier, use semicolon as delimiter for local-linkage varibles. (PR #74008)

[Fangrui Song via cfe-commits]

================
@@ -144,25 +145,27 @@ void GlobalObject::copyAttributesFrom(const GlobalObject *Src) {
 std::string GlobalValue::getGlobalIdentifier(StringRef Name,
                                              GlobalValue::LinkageTypes Linkage,
                                              StringRef FileName) {
-
   // Value names may be prefixed with a binary '1' to indicate
   // that the backend should not modify the symbols due to any platform
   // naming convention. Do not include that '1' in the PGO profile name.
   if (Name[0] == '\1')
     Name = Name.substr(1);
 
-  std::string NewName = std::string(Name);
+  SmallString<64> GlobalName;
   if (llvm::GlobalValue::isLocalLinkage(Linkage)) {
     // For local symbols, prepend the main file name to distinguish them.
     // Do not include the full path in the file name since there's no guarantee
     // that it will stay the same, e.g., if the files are checked out from
     // version control in different locations.
     if (FileName.empty())
-      NewName = NewName.insert(0, "<unknown>:");
+      GlobalName.append("<unknown>");
     else
-      NewName = NewName.insert(0, FileName.str() + ":");
+      GlobalName.append(FileName.str());
+
+    GlobalName.append({kGlobalIdentifierDelimiter});
----------------
MaskRay wrote:

Nit; use `+=` or `push_back`

https://github.com/llvm/llvm-project/pull/74008