Bug 1542736 - Part 2: Replace JS7_ISHEX with mozilla::IsAsciiHexDigit. r=jwalden

Clang and GCC generate slightly better assembly when IsAsciiHexDigit is called,
because the `cmp` instruction for the `< 127` check in JS7_ISHEX is no longer
emitted.

Differential Revision: https://phabricator.services.mozilla.com/D26505

--HG--
extra : moz-landing-system : lando

js/src/builtin/String.cpp

@@ -69,6 +69,7 @@ using JS::SymbolCode;
 
 using mozilla::AsciiAlphanumericToNumber;
 using mozilla::CheckedInt;
+using mozilla::IsAsciiHexDigit;
 using mozilla::IsNaN;
 using mozilla::IsSame;
 using mozilla::PodCopy;
@@ -230,7 +231,8 @@ static inline bool Unhex4(const RangedPtr<const CharT> chars,
                           char16_t* result) {
   CharT a = chars[0], b = chars[1], c = chars[2], d = chars[3];
 
-  if (!(JS7_ISHEX(a) && JS7_ISHEX(b) && JS7_ISHEX(c) && JS7_ISHEX(d))) {
+  if (!(IsAsciiHexDigit(a) && IsAsciiHexDigit(b) && IsAsciiHexDigit(c) &&
+        IsAsciiHexDigit(d))) {
     return false;
   }
 
@@ -247,7 +249,7 @@ static inline bool Unhex2(const RangedPtr<const CharT> chars,
                           char16_t* result) {
   CharT a = chars[0], b = chars[1];
 
-  if (!(JS7_ISHEX(a) && JS7_ISHEX(b))) {
+  if (!(IsAsciiHexDigit(a) && IsAsciiHexDigit(b))) {
     return false;
   }
 
@@ -3980,7 +3982,7 @@ static DecodeResult Decode(StringBuffer& sb, const CharT* chars, size_t length,
         return Decode_BadUri;
       }
 
-      if (!JS7_ISHEX(chars[k + 1]) || !JS7_ISHEX(chars[k + 2])) {
+      if (!IsAsciiHexDigit(chars[k + 1]) || !IsAsciiHexDigit(chars[k + 2])) {
         return Decode_BadUri;
       }
 
@@ -4021,7 +4023,8 @@ static DecodeResult Decode(StringBuffer& sb, const CharT* chars, size_t length,
             return Decode_BadUri;
           }
 
-          if (!JS7_ISHEX(chars[k + 1]) || !JS7_ISHEX(chars[k + 2])) {
+          if (!IsAsciiHexDigit(chars[k + 1]) ||
+              !IsAsciiHexDigit(chars[k + 2])) {
             return Decode_BadUri;
           }
 

js/src/frontend/TokenStream.cpp

@@ -50,6 +50,7 @@ using mozilla::DecodeOneUtf8CodePoint;
 using mozilla::IsAscii;
 using mozilla::IsAsciiAlpha;
 using mozilla::IsAsciiDigit;
+using mozilla::IsAsciiHexDigit;
 using mozilla::IsTrailingUnit;
 using mozilla::MakeScopeExit;
 using mozilla::MakeSpan;
@@ -1550,7 +1551,7 @@ uint32_t GeneralTokenStreamChars<Unit, AnyCharsAccess>::matchUnicodeEscape(
 
   char16_t v;
   unit = getCodeUnit();
-  if (JS7_ISHEX(unit) && this->sourceUnits.matchHexDigits(3, &v)) {
+  if (IsAsciiHexDigit(unit) && this->sourceUnits.matchHexDigits(3, &v)) {
     *codePoint = (AsciiAlphanumericToNumber(unit) << 12) | v;
     return 5;
   }
@@ -1583,7 +1584,7 @@ GeneralTokenStreamChars<Unit, AnyCharsAccess>::matchExtendedUnicodeEscape(
 
   size_t i = 0;
   uint32_t code = 0;
-  while (JS7_ISHEX(unit) && i < 6) {
+  while (IsAsciiHexDigit(unit) && i < 6) {
     code = (code << 4) | AsciiAlphanumericToNumber(unit);
     unit = getCodeUnit();
     i++;
@@ -2591,7 +2592,7 @@ MOZ_MUST_USE bool TokenStreamSpecific<Unit, AnyCharsAccess>::getTokenInternal(
       if (unit == 'x' || unit == 'X') {
         radix = 16;
         unit = getCodeUnit();
-        if (!JS7_ISHEX(unit)) {
+        if (!IsAsciiHexDigit(unit)) {
           // NOTE: |unit| may be EOF here.
           ungetCodeUnit(unit);
           error(JSMSG_MISSING_HEXDIGITS);
@@ -2601,7 +2602,7 @@ MOZ_MUST_USE bool TokenStreamSpecific<Unit, AnyCharsAccess>::getTokenInternal(
         // one past the '0x'
         numStart = this->sourceUnits.addressOfNextCodeUnit() - 1;
 
-        while (JS7_ISHEX(unit)) {
+        while (IsAsciiHexDigit(unit)) {
           unit = getCodeUnit();
         }
       } else if (unit == 'b' || unit == 'B') {
@@ -3173,7 +3174,7 @@ bool TokenStreamSpecific<Unit, AnyCharsAccess>::getStringOrTemplateToken(
 
               // Beware: |u3| may be a non-ASCII code point here; if
               // so it'll pass into this |if|-block.
-              if (!JS7_ISHEX(u3)) {
+              if (!IsAsciiHexDigit(u3)) {
                 if (parsingTemplate) {
                   // We put the code unit back so that we read it
                   // on the next pass, which matters if it was
@@ -3224,7 +3225,7 @@ bool TokenStreamSpecific<Unit, AnyCharsAccess>::getStringOrTemplateToken(
           // template literal, we must defer error reporting because
           // malformed escapes are okay in *tagged* template literals.
           char16_t v;
-          if (JS7_ISHEX(c2) && this->sourceUnits.matchHexDigits(3, &v)) {
+          if (IsAsciiHexDigit(c2) && this->sourceUnits.matchHexDigits(3, &v)) {
             unit = (AsciiAlphanumericToNumber(c2) << 12) | v;
           } else {
             // Beware: |c2| may not be an ASCII code point here!

js/src/frontend/TokenStream.h

@@ -1220,7 +1220,7 @@ class SourceUnits {
     char16_t v = 0;
     for (uint8_t i = 0; i < n; i++) {
       auto unit = CodeUnitValue(ptr[i]);
-      if (!JS7_ISHEX(unit)) {
+      if (!mozilla::IsAsciiHexDigit(unit)) {
         return false;
       }
 

js/src/util/Text.h

@@ -32,12 +32,9 @@ class JSLinearString;
  * Manually inline isdigit and isxdigit for performance; MSVC doesn't do this
  * for us.
  */
-#define JS7_ISA2F(c) \
-  ((((((unsigned)(c)) - 'a') <= 5) || (((unsigned)(c)) - 'A') <= 5))
 #define JS7_UNDEC(c) ((c) - '0')
 #define JS7_ISOCT(c) ((((unsigned)(c)) - '0') <= 7)
 #define JS7_UNOCT(c) (JS7_UNDEC(c))
-#define JS7_ISHEX(c) ((c) < 128 && (mozilla::IsAsciiDigit(c) || JS7_ISA2F(c)))
 
 static MOZ_ALWAYS_INLINE size_t js_strlen(const char16_t* s) {
   return std::char_traits<char16_t>::length(s);

js/src/vm/JSONParser.cpp

@@ -25,6 +25,7 @@ using namespace js;
 
 using mozilla::AsciiAlphanumericToNumber;
 using mozilla::IsAsciiDigit;
+using mozilla::IsAsciiHexDigit;
 using mozilla::RangedPtr;
 
 JSONParserBase::~JSONParserBase() {
@@ -204,17 +205,17 @@ JSONParserBase::Token JSONParser<CharT>::readString() {
 
       case 'u':
         if (end - current < 4 ||
-            !(JS7_ISHEX(current[0]) && JS7_ISHEX(current[1]) &&
-              JS7_ISHEX(current[2]) && JS7_ISHEX(current[3]))) {
+            !(IsAsciiHexDigit(current[0]) && IsAsciiHexDigit(current[1]) &&
+              IsAsciiHexDigit(current[2]) && IsAsciiHexDigit(current[3]))) {
           // Point to the first non-hexadecimal character (which may be
           // missing).
-          if (current == end || !JS7_ISHEX(current[0])) {
+          if (current == end || !IsAsciiHexDigit(current[0])) {
             ;  // already at correct location
-          } else if (current + 1 == end || !JS7_ISHEX(current[1])) {
+          } else if (current + 1 == end || !IsAsciiHexDigit(current[1])) {
             current += 1;
-          } else if (current + 2 == end || !JS7_ISHEX(current[2])) {
+          } else if (current + 2 == end || !IsAsciiHexDigit(current[2])) {
             current += 2;
-          } else if (current + 3 == end || !JS7_ISHEX(current[3])) {
+          } else if (current + 3 == end || !IsAsciiHexDigit(current[3])) {
             current += 3;
           } else {
             MOZ_CRASH("logic error determining first erroneous character");