From f20656e9446b9acde55b9dd41a2b47d7d5b7a56a Mon Sep 17 00:00:00 2001 From: Kenneth Graunke Date: Tue, 1 Mar 2011 12:24:58 -0800 Subject: [PATCH] glcpp: Rework lexer to use a SKIP state rather than REJECT. Previously, the rule deleted by this commit was matched every single time (being the longest match). If not skipping, it used REJECT to continue on to the actual correct rule. The flex manual advises against using REJECT where possible, as it is one of the most expensive lexer features. So using it on every match seems undesirable. Perhaps more importantly, it made it necessary for the #if directive rules to contain a look-ahead pattern to make them as long as the (now deleted) "skip the whole line" rule. This patch introduces an exclusive start state, SKIP, to avoid REJECTs. Each time the lexer is called, the code at the top of the rules section will run, implicitly switching the state to the correct one. Fixes piglit tests 16384-consecutive-chars.frag and 16385-consecutive-chars.frag. --- src/glsl/glcpp/glcpp-lex.l | 37 ++++++++++++++++--------------------- 1 file changed, 16 insertions(+), 21 deletions(-) diff --git a/src/glsl/glcpp/glcpp-lex.l b/src/glsl/glcpp/glcpp-lex.l index 11b73aea88b..2c9eda68d6e 100644 --- a/src/glsl/glcpp/glcpp-lex.l +++ b/src/glsl/glcpp/glcpp-lex.l @@ -57,7 +57,7 @@ void glcpp_set_column (int column_no , yyscan_t yyscanner); %option stack %option never-interactive -%x DONE COMMENT UNREACHABLE +%x DONE COMMENT UNREACHABLE SKIP SPACE [[:space:]] NONSPACE [^[:space:]] @@ -74,6 +74,17 @@ OCTAL_INTEGER 0[0-7]*[uU]? HEXADECIMAL_INTEGER 0[xX][0-9a-fA-F]+[uU]? %% + /* Implicitly switch between SKIP and INITIAL (non-skipping); + * don't switch if some other state was explicitly set. + */ + glcpp_parser_t *parser = yyextra; + if (YY_START == 0 || YY_START == SKIP) { + if (parser->lexing_if || parser->skip_stack == NULL || parser->skip_stack->type == SKIP_NO_SKIP) { + BEGIN 0; + } else { + BEGIN SKIP; + } + } /* Single-line comments */ "//"[^\n]* { @@ -137,6 +148,7 @@ HEXADECIMAL_INTEGER 0[xX][0-9a-fA-F]+[uU]? yylineno = strtol(ptr, &ptr, 0) - 1; } +{ {HASH}ifdef/.*\n { yyextra->lexing_if = 1; yyextra->space_tokens = 0; @@ -170,27 +182,10 @@ HEXADECIMAL_INTEGER 0[xX][0-9a-fA-F]+[uU]? yyextra->space_tokens = 0; return HASH_ENDIF; } - - /* When skipping (due to an #if 0 or similar) consume anything - * up to a newline. We do this with less priority than any - * #if-related directive (#if, #elif, #else, #endif), but with - * more priority than any other directive or token to avoid - * any side-effects from skipped content. - * - * We use the lexing_if flag to avoid skipping any part of an - * if conditional expression. */ -[^\n]+/\n { - /* Since this rule always matches, YY_USER_ACTION gets called for it, - * wrongly incrementing yycolumn. We undo that effect here. */ - yycolumn -= yyleng; - if (yyextra->lexing_if || - yyextra->skip_stack == NULL || - yyextra->skip_stack->type == SKIP_NO_SKIP) - { - REJECT; - } } +[^\n] ; + {HASH}error.* { char *p; for (p = yytext; !isalpha(p[0]); p++); /* skip " # " */ @@ -293,7 +288,7 @@ HEXADECIMAL_INTEGER 0[xX][0-9a-fA-F]+[uU]? } } -\n { +\n { yyextra->lexing_if = 0; yylineno++; yycolumn = 0; -- 2.30.2