[clang] [Clang][NFC] Optimize isAsciiIdentifierContinue (PR #78699)

[Timm Baeder via cfe-commits]

================
@@ -59,12 +59,29 @@ LLVM_READONLY inline bool isAsciiIdentifierStart(unsigned char c,
   return AllowDollar && c == '$';
 }
 
+
+LLVM_READONLY inline bool isAsciiIdentifierContinue(unsigned char c) {
+  // Precomputed CHAR_UPPER|CHAR_LOWER|CHAR_DIGIT|CHAR_UNDER
+  static constexpr unsigned char IDContinue[256] = {
+      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+      1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1,
+      1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 1,
+      0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
+      1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+      0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
+  return IDContinue[c];
+}
+
 /// Returns true if this is a body character of a C identifier,
 /// which is [a-zA-Z0-9_].
 LLVM_READONLY inline bool isAsciiIdentifierContinue(unsigned char c,
-                                                    bool AllowDollar = false) {
-  using namespace charinfo;
-  if (InfoTable[c] & (CHAR_UPPER|CHAR_LOWER|CHAR_DIGIT|CHAR_UNDER))
+                                                    bool AllowDollar) {
----------------
tbaederr wrote:

Why is the default value gone?

https://github.com/llvm/llvm-project/pull/78699