[clang] [Clang] [Lexer] Detect SSE4.2 availability at runtime in fastParseASCIIIdentifier (PR #171914)

[Mikael Holmen via cfe-commits]

================
@@ -1943,12 +1955,20 @@ fastParseASCIIIdentifier(const char *CurPtr,
       continue;
     return CurPtr;
   }
-#endif
 
-  unsigned char C = *CurPtr;
-  while (isAsciiIdentifierContinue(C))
-    C = *++CurPtr;
-  return CurPtr;
+  return fastParseASCIIIdentifierScalar(CurPtr);
+}
+
+__attribute__((target("sse4.2"))) static const char *
+fastParseASCIIIdentifier(const char *CurPtr, const char *BufferEnd) {
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mikaelholmen wrote:

> I am still unable to reproduce. Are you able to reproduce on godbolt? Sorry for the inconvenience.

I'm sorry, but my godbolt skills reach just far enough to use it to run clang/opt/llc on some small code example, but not to compile the entire compiler.

https://github.com/llvm/llvm-project/pull/171914