perf: stricmp optimizations

* backported FastASCIIToLower from CSGO and applied it appropriately to strtools
* backported _V_stricmp conditional structure from CSGO
  but adjusted it to use a fast ASCII lookup table and also
  use tolower on non-ASCII characters for general safety
* select a few choice cases to migrate from stricmp to V_stricmp
  CSGO applies it to everything but these are few hotspots

Author: mastercoms

src/tier1/strtools.cpp

@@ -80,20 +80,20 @@
 #endif
 #include "tier0/memdbgon.h"
 
-static int FastToLower( char c )
-{
-	int i = (unsigned char) c;
-	if ( i < 0x80 )
-	{
-		// Brutally fast branchless ASCII tolower():
-		i += (((('A'-1) - i) & (i - ('Z'+1))) >> 26) & 0x20;
-	}
-	else
-	{
-		i += isupper( i ) ? 0x20 : 0;
-	}
-	return i;
-}
+#define USE_FAST_CASE_CONVERSION 1
+#if USE_FAST_CASE_CONVERSION
+/// Faster conversion of an ascii char to upper case. This function does not obey locale or any language
+/// setting. It should not be used to convert characters for printing, but it is a better choice
+/// for internal strings such as used for hash table keys, etc. It's meant to be inlined and used
+/// in places like the various dictionary classes. Not obeying locale also protects you from things
+/// like your hash values being different depending on the locale setting.
+#define FastASCIIToUpper( c ) ( ( ( (c) >= 'a' ) && ( (c) <= 'z' ) ) ? ( (c) - 32 ) : (c) )
+/// similar to FastASCIIToLower
+#define FastASCIIToLower( c ) ( ( ( (c) >= 'A' ) && ( (c) <= 'Z' ) ) ? ( (c) + 32 ) : (c) )
+#else
+#define FastASCIIToLower tolower
+#define FastASCIIToUpper toupper
+#endif
 
 void _V_memset (const char* file, int line, void *dest, int fill, int count)
 {
@@ -260,6 +260,17 @@ char *V_strnlwr(char *s, size_t count)
 	return pRet;
 }
 
+static constexpr uint8 lowerAsciiLookup[128] = {
+	0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F,
+	0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1A, 0x1B, 0x1C, 0x1D, 0x1E, 0x1F,
+	0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x2B, 0x2C, 0x2D, 0x2E, 0x2F,
+	0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3A, 0x3B, 0x3C, 0x3D, 0x3E, 0x3F,
+	0x40, 'a',  'b',  'c',  'd',  'e',  'f',  'g',  'h',  'i',  'j',  'k',  'l',  'm',  'n',  'o',
+	'p',  'q',  'r',  's',  't',  'u',  'v',  'w',  'x',  'y',  'z',  0x5B, 0x5C, 0x5D, 0x5E, 0x5F,
+	0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x6A, 0x6B, 0x6C, 0x6D, 0x6E, 0x6F,
+	0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7A, 0x7B, 0x7C, 0x7D, 0x7E, 0x7F
+};
+
 int V_stricmp( const char *str1, const char *str2 )
 {
 	// It is not uncommon to compare a string to itself. See
@@ -272,6 +283,7 @@ int V_stricmp( const char *str1, const char *str2 )
 	}
 	const unsigned char *s1 = (const unsigned char*)str1;
 	const unsigned char *s2 = (const unsigned char*)str2;
+#if 0
 	for ( ; *s1; ++s1, ++s2 )
 	{
 		if ( *s1 != *s2 )
@@ -291,6 +303,31 @@ int V_stricmp( const char *str1, const char *str2 )
 		}
 	}
 	return *s2 ? -1 : 0;
+#else
+	while (true)
+	{
+		unsigned char c1 = *s1++;
+		unsigned char c2 = *s2++;
+		if (c1 == c2)
+		{
+				if ( !c1 ) return 0;
+		}
+		else if ((((uint32)c1 | (uint32)c2) & 0xffffff80) == 0)
+		{
+				if (int32 res = lowerAsciiLookup[c1] - lowerAsciiLookup[c2])
+				{
+				return res;
+				}
+		}
+		else
+		{
+			if (int32 res = tolower(c1) - tolower(c2))
+			{
+				return res;
+			}
+		}
+	}
+#endif
 }
 
 int V_strnicmp( const char *str1, const char *str2, int n )
@@ -348,7 +385,7 @@ const char *StringAfterPrefix( const char *str, const char *prefix )
 		if ( !*prefix )
 			return str;
 	}
-	while ( FastToLower( *str++ ) == FastToLower( *prefix++ ) );
+	while ( tolower( *str++ ) == tolower( *prefix++ ) );
 	return NULL;
 }
 
@@ -638,7 +675,7 @@ char const* V_stristr( char const* pStr, char const* pSearch )
 	while (*pLetter != 0)
 	{
 		// Skip over non-matches
-		if (FastToLower((unsigned char)*pLetter) == FastToLower((unsigned char)*pSearch))
+		if (FastASCIIToLower((unsigned char)*pLetter) == FastASCIIToLower((unsigned char)*pSearch))
 		{
 			// Check for match
 			char const* pMatch = pLetter + 1;
@@ -649,7 +686,7 @@ char const* V_stristr( char const* pStr, char const* pSearch )
 				if (*pMatch == 0)
 					return 0;
 
-				if (FastToLower((unsigned char)*pMatch) != FastToLower((unsigned char)*pTest))
+				if (FastASCIIToLower((unsigned char)*pMatch) != FastASCIIToLower((unsigned char)*pTest))
 					break;
 
 				++pMatch;
@@ -696,7 +733,7 @@ char const* V_strnistr( char const* pStr, char const* pSearch, int n )
 			return 0;
 
 		// Skip over non-matches
-		if (FastToLower(*pLetter) == FastToLower(*pSearch))
+		if (FastASCIIToLower(*pLetter) == FastASCIIToLower(*pSearch))
 		{
 			int n1 = n - 1;
 
@@ -712,7 +749,7 @@ char const* V_strnistr( char const* pStr, char const* pSearch, int n )
 				if (*pMatch == 0)
 					return 0;
 
-				if (FastToLower(*pMatch) != FastToLower(*pTest))
+				if (FastASCIIToLower(*pMatch) != FastASCIIToLower(*pTest))
 					break;
 
 				++pMatch;
@@ -1421,7 +1458,7 @@ int _V_UCS2ToUnicode( const ucs2 *pUCS2, wchar_t *pUnicode, int cubDestSizeInByt
 	size_t nMaxUTF8 = cubDestSizeInBytes;
 	char *pIn = (char *)pUCS2;
 	char *pOut = (char *)pUnicode;
-	if ( conv_t > 0 )
+	if ( conv_t != nullptr  )
 	{
 		cchResult = iconv( conv_t, &pIn, &nLenUnicde, &pOut, &nMaxUTF8 );
 		iconv_close( conv_t );
@@ -1461,7 +1498,7 @@ int _V_UnicodeToUCS2( const wchar_t *pUnicode, int cubSrcInBytes, char *pUCS2, i
 	size_t nMaxUCS2 = cubDestSizeInBytes;
 	char *pIn = (char*)pUnicode;
 	char *pOut = pUCS2;
-	if ( conv_t > 0 )
+	if ( conv_t != nullptr  )
 	{
 		cchResult = iconv( conv_t, &pIn, &nLenUnicde, &pOut, &nMaxUCS2 );
 		iconv_close( conv_t );
@@ -1509,7 +1546,7 @@ int _V_UCS2ToUTF8( const ucs2 *pUCS2, char *pUTF8, int cubDestSizeInBytes )
 	size_t nMaxUTF8 = cubDestSizeInBytes - 1;
 	char *pIn = (char *)pUCS2;
 	char *pOut = (char *)pUTF8;
-	if ( conv_t > 0 )
+	if ( conv_t != nullptr  )
 	{
 		const size_t nBytesToWrite = nMaxUTF8;
 		cchResult = iconv( conv_t, &pIn, &nLenUnicde, &pOut, &nMaxUTF8 );
@@ -1554,7 +1591,7 @@ int _V_UTF8ToUCS2( const char *pUTF8, int cubSrcInBytes, ucs2 *pUCS2, int cubDes
 	size_t nMaxUTF8 = cubDestSizeInBytes;
 	char *pIn = (char *)pUTF8;
 	char *pOut = (char *)pUCS2;
-	if ( conv_t > 0 )
+	if ( conv_t != nullptr  )
 	{
 		cchResult = iconv( conv_t, &pIn, &nLenUnicde, &pOut, &nMaxUTF8 );
 		iconv_close( conv_t );
@@ -2275,7 +2312,7 @@ bool V_MakeRelativePath( const char *pFullPath, const char *pDirectory, char *pR
 	// Strip out common parts of the path
 	const char *pLastCommonPath = NULL;
 	const char *pLastCommonDir = NULL;
-	while ( *pPath && ( FastToLower( *pPath ) == FastToLower( *pDir ) || 
+	while ( *pPath && ( tolower( *pPath ) == tolower( *pDir ) || 
 						( PATHSEPARATOR( *pPath ) && ( PATHSEPARATOR( *pDir ) || (*pDir == 0) ) ) ) )
 	{
 		if ( PATHSEPARATOR( *pPath ) )

src/vgui2/src/LocalizedStringTable.cpp

@@ -731,7 +731,7 @@ bool CLocalizedStringTable::SymLess(localizedstring_t const &i1, localizedstring
 	const char *str2 = (i2.nameIndex == INVALID_LOCALIZE_STRING_INDEX) ? i2.pszValueString :
 											&g_StringTable.m_Names[i2.nameIndex];
 
-	return stricmp(str1, str2) < 0;
+	return V_stricmp(str1, str2) < 0;
 }
 
 

src/vgui2/vgui_controls/Panel.cpp

@@ -6343,7 +6343,7 @@ PanelAnimationMapEntry *Panel::FindPanelAnimationEntry( char const *scriptname,
 	{
 		PanelAnimationMapEntry *e = &map->entries[ i ];
 
-		if ( !stricmp( e->name(), scriptname ) )
+		if ( !V_stricmp( e->name(), scriptname ) )
 		{
 			return e;
 		}

src/vguimatsurface/TextureDictionary.cpp

@@ -983,7 +983,7 @@ int	CTextureDictionary::FindTextureIdForTextureFile( char const *pFileName )
 		if ( !mat )
 			continue;
 
-		if ( !stricmp( mat->GetName(), pFileName ) )
+		if ( ! V_stricmp( mat->GetName(), pFileName ) )
 			return i;
 	}
 

src/vstdlib/KeyValuesSystem.cpp

@@ -235,7 +235,7 @@ HKeySymbol CKeyValuesSystem::GetSymbolForString( const char *name, bool bCreate
 	hash_item_t *item = &m_HashTable[hash];
 	while (1)
 	{
-		if (!stricmp(name, (char *)m_Strings.GetBase() + item->stringIndex ))
+		if (!V_stricmp(name, (char *)m_Strings.GetBase() + item->stringIndex ))
 		{
 			return (HKeySymbol)item->stringIndex;
 		}