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Bug 898912 (part 2) - Merge oneCharTokens[] into firstCharKinds[] to avoid a lookup in the |OneChar| token case. r=till.

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--HG--
extra : rebase_source : b978dab8b0cc96b511ab339e597be6805cb3b584
This commit is contained in:
Nicholas Nethercote 2013-07-29 18:23:42 -07:00
parent d20d35c775
commit 4889d32ca6
2 changed files with 40 additions and 39 deletions
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78
js/src/frontend/TokenStream.cpp
View File

@ -297,31 +297,9 @@ TokenStream::TokenStream(ExclusiveContext *cx, const CompileOptions &options,
// this line then adjust the next character.
userbuf.setAddressOfNextRawChar(base);
/*
* This table holds all the token kinds that satisfy these properties:
* - A single char long.
* - Cannot be a prefix of any longer token (e.g. '+' is excluded because
* '+=' is a valid token).
*
* The few token kinds satisfying these properties cover roughly 35--45%
* of the tokens seen in practice.
*
* Nb: the following tables could be static, but initializing them this way
* is much easier. Don't worry, the time to initialize them for each
* TokenStream is trivial. See bug 639420.
*/
memset(oneCharTokens, 0, sizeof(oneCharTokens));
oneCharTokens[unsigned(';')] = TOK_SEMI;
oneCharTokens[unsigned(',')] = TOK_COMMA;
oneCharTokens[unsigned('?')] = TOK_HOOK;
oneCharTokens[unsigned(':')] = TOK_COLON;
oneCharTokens[unsigned('[')] = TOK_LB;
oneCharTokens[unsigned(']')] = TOK_RB;
oneCharTokens[unsigned('{')] = TOK_LC;
oneCharTokens[unsigned('}')] = TOK_RC;
oneCharTokens[unsigned('(')] = TOK_LP;
oneCharTokens[unsigned(')')] = TOK_RP;
oneCharTokens[unsigned('~')] = TOK_BITNOT;
// Nb: the following tables could be static, but initializing them here is
// much easier. Don't worry, the time to initialize them for each
// TokenStream is trivial. See bug 639420.
/* See getChar() for an explanation of maybeEOL[]. */
memset(maybeEOL, 0, sizeof(maybeEOL));
@ -994,8 +972,22 @@ TokenStream::checkForKeyword(const jschar *s, size_t length, TokenKind *ttp)
}
enum FirstCharKind {
Other,
OneChar,
// A jschar has the 'OneChar' kind if it, by itself, constitutes a valid
// token that cannot also be a prefix of a longer token. E.g. ';' has the
// OneChar kind, but '+' does not, because '++' and '+=' are valid longer tokens
// that begin with '+'.
//
// The few token kinds satisfying these properties cover roughly 35--45%
// of the tokens seen in practice.
//
// We represent the 'OneChar' kind with any positive value less than
// TOK_LIMIT. This representation lets us associate each one-char token
// jschar with a TokenKind and thus avoid a subsequent jschar-to-TokenKind
// conversion.
OneChar_Min = 0,
OneChar_Max = TOK_LIMIT - 1,
Other = TOK_LIMIT,
Ident,
Dot,
Equals,
@ -1006,10 +998,10 @@ enum FirstCharKind {
/* These two must be last, so that |c >= Space| matches both. */
Space,
EOL
};
EOL,
#define _______ Other
LastCharKind = EOL
};
/*
* OneChar: 40, 41, 44, 58, 59, 63, 91, 93, 123, 125, 126:
@ -1024,25 +1016,35 @@ enum FirstCharKind {
* Space: 9, 11, 12, 32: '\t', '\v', '\f', ' '
* EOL: 10, 13: '\n', '\r'
*/
#define T_COMMA TOK_COMMA
#define T_COLON TOK_COLON
#define T_BITNOT TOK_BITNOT
#define _______ Other
static const uint8_t firstCharKinds[] = {
/* 0 1 2 3 4 5 6 7 8 9 */
/* 0+ */ _______, _______, _______, _______, _______, _______, _______, _______, _______, Space,
/* 10+ */ EOL, Space, Space, EOL, _______, _______, _______, _______, _______, _______,
/* 20+ */ _______, _______, _______, _______, _______, _______, _______, _______, _______, _______,
/* 30+ */ _______, _______, Space, _______, String, _______, Ident, _______, _______, String,
/* 40+ */ OneChar, OneChar, _______, Plus, OneChar, _______, Dot, _______, BasePrefix, Dec,
/* 50+ */ Dec, Dec, Dec, Dec, Dec, Dec, Dec, Dec, OneChar, OneChar,
/* 60+ */ _______, Equals, _______, OneChar, _______, Ident, Ident, Ident, Ident, Ident,
/* 40+ */ TOK_LP, TOK_RP, _______, Plus, T_COMMA,_______, Dot, _______, BasePrefix, Dec,
/* 50+ */ Dec, Dec, Dec, Dec, Dec, Dec, Dec, Dec, T_COLON,TOK_SEMI,
/* 60+ */ _______, Equals, _______,TOK_HOOK, _______, Ident, Ident, Ident, Ident, Ident,
/* 70+ */ Ident, Ident, Ident, Ident, Ident, Ident, Ident, Ident, Ident, Ident,
/* 80+ */ Ident, Ident, Ident, Ident, Ident, Ident, Ident, Ident, Ident, Ident,
/* 90+ */ Ident, OneChar, _______, OneChar, _______, Ident, _______, Ident, Ident, Ident,
/* 90+ */ Ident, TOK_LB, _______, TOK_RB, _______, Ident, _______, Ident, Ident, Ident,
/* 100+ */ Ident, Ident, Ident, Ident, Ident, Ident, Ident, Ident, Ident, Ident,
/* 110+ */ Ident, Ident, Ident, Ident, Ident, Ident, Ident, Ident, Ident, Ident,
/* 120+ */ Ident, Ident, Ident, OneChar, _______, OneChar, OneChar, _______
/* 120+ */ Ident, Ident, Ident, TOK_LC, _______, TOK_RC,T_BITNOT, _______
};
#undef T_COMMA
#undef T_COLON
#undef T_BITNOT
#undef _______
static_assert(LastCharKind < (1 << (sizeof(firstCharKinds[0]) * 8)),
"Elements of firstCharKinds[] are too small");
TokenKind
TokenStream::getTokenInternal()
{
@ -1125,8 +1127,8 @@ TokenStream::getTokenInternal()
/*
* Look for an unambiguous single-char token.
*/
if (c1kind == OneChar) {
tt = (TokenKind)oneCharTokens[c];
if (c1kind < OneChar_Max) {
tt = (TokenKind)c1kind;
goto out;
}

1
js/src/frontend/TokenStream.h
View File

@ -917,7 +917,6 @@ class MOZ_STACK_CLASS TokenStream
const char *filename; /* input filename or null */
jschar *sourceMap; /* source map's filename or null */
CharBuffer tokenbuf; /* current token string buffer */
int8_t oneCharTokens[128]; /* table of one-char tokens, indexed by 7-bit char */
bool maybeEOL[256]; /* probabilistic EOL lookup table */
bool maybeStrSpecial[256];/* speeds up string scanning */
uint8_t isExprEnding[TOK_LIMIT]; /* which tokens definitely terminate exprs? */