optimized Token::Match() a bit by always inlining Token::multiCompare() (#5332)

Scanning `mame_regtest` with `DISABLE_VALUEFLOW=1` and `--enable=all
--inconclusive`:

Clang 15 `1,170,770,173` -> `1,167,227,434`
GGC 12 `1,370,070,422` -> `1,366,775,852`

Author: firewave

lib/token.cpp

@@ -424,7 +424,13 @@ const std::string &Token::strAt(int index) const
     return tok ? tok->mStr : emptyString;
 }
 
-static int multiComparePercent(const Token *tok, const char*& haystack, nonneg int varid)
+static
+#if defined(__GNUC__)
+// GCC does not inline this by itself
+// need to use the old syntax since the C++11 [[xxx:always_inline]] cannot be used here
+inline __attribute__((always_inline))
+#endif
+int multiComparePercent(const Token *tok, const char*& haystack, nonneg int varid)
 {
     ++haystack;
     // Compare only the first character of the string for optimization reasons
@@ -556,7 +562,12 @@ static int multiComparePercent(const Token *tok, const char*& haystack, nonneg i
     return 0xFFFF;
 }
 
-int Token::multiCompare(const Token *tok, const char *haystack, nonneg int varid)
+static
+#if defined(__GNUC__)
+// need to use the old syntax since the C++11 [[xxx:always_inline]] cannot be used here
+inline __attribute__((always_inline))
+#endif
+int multiCompareImpl(const Token *tok, const char *haystack, nonneg int varid)
 {
     const char *needle = tok->str().c_str();
     const char *needlePointer = needle;
@@ -609,6 +620,12 @@ int Token::multiCompare(const Token *tok, const char *haystack, nonneg int varid
     return -1;
 }
 
+// cppcheck-suppress unusedFunction - used in tests only
+int Token::multiCompare(const Token *tok, const char *haystack, nonneg int varid)
+{
+    return multiCompareImpl(tok, haystack, varid);
+}
+
 bool Token::simpleMatch(const Token *tok, const char pattern[], size_t pattern_len)
 {
     if (!tok)
@@ -730,7 +747,7 @@ bool Token::Match(const Token *tok, const char pattern[], nonneg int varid)
 
         // Parse multi options, such as void|int|char (accept token which is one of these 3)
         else {
-            const int res = multiCompare(tok, p, varid);
+            const int res = multiCompareImpl(tok, p, varid);
             if (res == 0) {
                 // Empty alternative matches, use the same token on next round
                 while (*p && *p != ' ')

lib/token.h

@@ -154,6 +154,8 @@ struct TokenImpl {
  * The Token class also has other functions for management of token list, matching tokens, etc.
  */
 class CPPCHECKLIB Token {
+    friend class TestToken;
+
 private:
     TokensFrontBack* mTokensFrontBack{};
 
@@ -788,6 +790,7 @@ class CPPCHECKLIB Token {
         return const_cast<Token *>(findmatch(const_cast<const Token *>(startTok), pattern, end, varId));
     }
 
+private:
     /**
      * Needle is build from multiple alternatives. If one of
      * them is equal to haystack, return value is 1. If there
@@ -804,6 +807,7 @@ class CPPCHECKLIB Token {
      */
     static int multiCompare(const Token *tok, const char *haystack, nonneg int varid);
 
+public:
     nonneg int fileIndex() const {
         return mImpl->mFileIndex;
     }