diff options
| -rw-r--r-- | parser.h | 4 | ||||
| -rw-r--r-- | perly.c | 50 | ||||
| -rw-r--r-- | sv.c | 2 | ||||
| -rw-r--r-- | toke.c | 2 |
4 files changed, 33 insertions, 25 deletions
@@ -44,7 +44,9 @@ typedef struct yy_parser { int yylen; /* length of active reduction */ yy_stack_frame *stack; /* base of stack */ - yy_stack_frame *stack_max1;/* (top-1)th element of alloacted stack */ + yy_stack_frame *stack_maxbase;/* (stack + alloced size - YY_MAXRULE) + * it's offset by -YY_MAXRULE to make + * overflow checks quicker */ yy_stack_frame *ps; /* current stack frame */ /* lexer state */ @@ -58,6 +58,15 @@ typedef signed char yysigned_char; # define YYSIZE_T size_t +/* the max number of RHS shifted elements that can make up a rule. + * This should really be auto-generated from the max value in yyr2[] + * but that involves extra work, so set it slightly higher than the + * current max, and assert each time yyr2[] is accessed. + * Used to determine if the parse stack needs extending. + */ + +#define YY_MAXRULE 15 + #define YYEOF 0 #define YYTERROR 1 @@ -275,7 +284,7 @@ Perl_yyparse (pTHX_ int gramtype) SAVEINT(parser->yyerrstatus); SAVEINT(parser->yylen); SAVEVPTR(parser->stack); - SAVEVPTR(parser->stack_max1); + SAVEVPTR(parser->stack_maxbase); SAVEVPTR(parser->ps); /* initialise state for this parse */ @@ -283,7 +292,7 @@ Perl_yyparse (pTHX_ int gramtype) parser->yyerrstatus = 0; parser->yylen = 0; Newx(parser->stack, YYINITDEPTH, yy_stack_frame); - parser->stack_max1 = parser->stack + YYINITDEPTH - 1; + parser->stack_maxbase = parser->stack + YYINITDEPTH - YY_MAXRULE; ps = parser->ps = parser->stack; ps->state = 0; SAVEDESTRUCTOR_X(S_clear_yystack, parser); @@ -291,35 +300,31 @@ Perl_yyparse (pTHX_ int gramtype) while (1) { /* main loop: shift some tokens, then reduce when possible */ + /* grow the stack to accommodate longest possible rule */ + if (ps >= parser->stack_maxbase) { + Size_t pos = ps - parser->stack; + Size_t newsize = 2 * (parser->stack_maxbase + YY_MAXRULE + - parser->stack); + /* this will croak on insufficient memory */ + Renew(parser->stack, newsize, yy_stack_frame); + ps = parser->ps = parser->stack + pos; + parser->stack_maxbase = parser->stack + newsize - YY_MAXRULE; + + YYDPRINTF((Perl_debug_log, + "parser stack size increased to %lu frames\n", + (unsigned long int)newsize)); + } + while (1) { /* shift a token, or quit when it's possible to reduce */ + assert(ps < parser->stack_maxbase + YY_MAXRULE); yystate = ps->state; YYDPRINTF ((Perl_debug_log, "Entering state %d\n", yystate)); parser->yylen = 0; - { - /* grow the stack? We always leave 1 spare slot, - * in case of a '' -> 'foo' reduction. - * Note that stack_max1 points to the (top-1)th allocated stack - * element to make this check fast */ - - if (ps >= parser->stack_max1) { - Size_t pos = ps - parser->stack; - Size_t newsize = 2 * (parser->stack_max1 + 2 - parser->stack); - /* this will croak on insufficient memory */ - Renew(parser->stack, newsize, yy_stack_frame); - ps = parser->ps = parser->stack + pos; - parser->stack_max1 = parser->stack + newsize - 1; - - YYDPRINTF((Perl_debug_log, - "parser stack size increased to %lu frames\n", - (unsigned long int)newsize)); - } - } - /* Do appropriate processing given the current state. */ /* Read a lookahead token if we need one and don't already have one. */ @@ -407,6 +412,7 @@ Perl_yyparse (pTHX_ int gramtype) /* yyn is the number of a rule to reduce with. */ parser->yylen = yyr2[yyn]; + assert(parser->yylen <= YY_MAXRULE); /* see defn of YY_MAXRULE above */ /* If YYLEN is nonzero, implement the default value of the action: "$$ = $1". @@ -13130,7 +13130,7 @@ Perl_parser_dup(pTHX_ const yy_parser *const proto, CLONE_PARAMS *const param) parser->old_parser = NULL; parser->stack = NULL; parser->ps = NULL; - parser->stack_max1 = 0; + parser->stack_maxbase = NULL; /* XXX parser->stack->state = 0; */ /* XXX eventually, just Copy() most of the parser struct ? */ @@ -705,7 +705,7 @@ Perl_lex_start(pTHX_ SV *line, PerlIO *rsfp, U32 flags) PL_parser = parser; parser->stack = NULL; - parser->stack_max1 = NULL; + parser->stack_maxbase = NULL; parser->ps = NULL; /* on scope exit, free this parser and restore any outer one */ |