diff options
Diffstat (limited to 'perly.c')
| -rw-r--r-- | perly.c | 111 |
1 files changed, 1 insertions, 110 deletions
@@ -199,95 +199,10 @@ S_clear_yystack(pTHX_ const yy_parser *parser) YYDPRINTF ((Perl_debug_log, "clearing the parse stack\n")); - /* Freeing ops on the stack, and the op_latefree / op_latefreed / - * op_attached flags: - * - * When we pop tokens off the stack during error recovery, or when - * we pop all the tokens off the stack after a die during a shift or - * reduce (i.e. Perl_croak somewhere in yylex() or in one of the - * newFOO() functions), then it's possible that some of these tokens are - * of type opval, pointing to an OP. All these ops are orphans; each is - * its own miniature subtree that has not yet been attached to a - * larger tree. In this case, we should clearly free the op (making - * sure, for each op we free that we have PL_comppad pointing to the - * right place for freeing any SVs attached to the op in threaded - * builds. - * - * However, there is a particular problem if we die in newFOO() called - * by a reducing action; e.g. - * - * foo : bar baz boz - * { $$ = newFOO($1,$2,$3) } - * - * where - * OP *newFOO { ....; if (...) croak; .... } - * - * In this case, when we come to clean bar baz and boz off the stack, - * we don't know whether newFOO() has already: - * * freed them - * * left them as is - * * attached them to part of a larger tree - * * attached them to PL_compcv - * * attached them to PL_compcv then freed it (as in BEGIN {die } ) - * - * To get round this problem, we set the flag op_latefree on every op - * that gets pushed onto the parser stack. If op_free() sees this - * flag, it clears the op and frees any children,, but *doesn't* free - * the op itself; instead it sets the op_latefreed flag. This means - * that we can safely call op_free() multiple times on each stack op. - * So, when clearing the stack, we first, for each op that was being - * reduced, call op_free with op_latefree=1. This ensures that all ops - * hanging off these op are freed, but the reducing ops themselves are - * just undefed. Then we set op_latefreed=0 on *all* ops on the stack - * and free them. A little thought should convince you that this - * two-part approach to the reducing ops should handle the first three - * cases above safely. - * - * In the case of attaching to PL_compcv (currently just newATTRSUB - * does this), then we set the op_attached flag on the op that has - * been so attached, then avoid doing the final op_free during - * cleanup, on the assumption that it will happen (or has already - * happened) when PL_compcv is freed. - * - * Note this is fairly fragile mechanism. A more robust approach - * would be to use two of these flag bits as 2-bit reference count - * field for each op, indicating whether it is pointed to from: - * * a parent op - * * the parser stack - * * a CV - * but this would involve reworking all code (core and external) that - * manipulate op trees. - * - * XXX DAPM 17/1/07 I've decided its too fragile for now, and so have - * disabled it */ - -#define DISABLE_STACK_FREE - - -#ifdef DISABLE_STACK_FREE for (i=0; i< parser->yylen; i++) { SvREFCNT_dec(ps[-i].compcv); } ps -= parser->yylen; -#else - /* clear any reducing ops (1st pass) */ - - for (i=0; i< parser->yylen; i++) { - LEAVE_SCOPE(ps[-i].savestack_ix); - if (yy_type_tab[yystos[ps[-i].state]] == toketype_opval - && ps[-i].val.opval) { - if ( ! (ps[-i].val.opval->op_attached - && !ps[-i].val.opval->op_latefreed)) - { - if (ps[-i].compcv != PL_compcv) { - PL_compcv = ps[-i].compcv; - PAD_SET_CUR_NOSAVE(CvPADLIST(PL_compcv), 1); - } - op_free(ps[-i].val.opval); - } - } - } -#endif /* now free whole the stack, including the just-reduced ops */ @@ -301,11 +216,7 @@ S_clear_yystack(pTHX_ const yy_parser *parser) PAD_SET_CUR_NOSAVE(CvPADLIST(PL_compcv), 1); } YYDPRINTF ((Perl_debug_log, "(freeing op)\n")); -#ifndef DISABLE_STACK_FREE - ps->val.opval->op_latefree = 0; - if (!(ps->val.opval->op_attached && !ps->val.opval->op_latefreed)) -#endif - op_free(ps->val.opval); + op_free(ps->val.opval); } SvREFCNT_dec(ps->compcv); ps--; @@ -383,13 +294,6 @@ Perl_yyparse (pTHX_ int gramtype) YYDPRINTF ((Perl_debug_log, "Entering state %d\n", yystate)); -#ifndef DISABLE_STACK_FREE - if (yy_type_tab[yystos[yystate]] == toketype_opval && ps->val.opval) { - ps->val.opval->op_latefree = 1; - ps->val.opval->op_latefreed = 0; - } -#endif - parser->yylen = 0; { @@ -546,20 +450,9 @@ Perl_yyparse (pTHX_ int gramtype) } - /* any just-reduced ops with the op_latefreed flag cleared need to be - * freed; the rest need the flag resetting */ { int i; for (i=0; i< parser->yylen; i++) { -#ifndef DISABLE_STACK_FREE - if (yy_type_tab[yystos[ps[-i].state]] == toketype_opval - && ps[-i].val.opval) - { - ps[-i].val.opval->op_latefree = 0; - if (ps[-i].val.opval->op_latefreed) - op_free(ps[-i].val.opval); - } -#endif SvREFCNT_dec(ps[-i].compcv); } } @@ -620,7 +513,6 @@ Perl_yyparse (pTHX_ int gramtype) PL_compcv = ps->compcv; PAD_SET_CUR_NOSAVE(CvPADLIST(PL_compcv), 1); } - ps->val.opval->op_latefree = 0; op_free(ps->val.opval); } SvREFCNT_dec(ps->compcv); @@ -670,7 +562,6 @@ Perl_yyparse (pTHX_ int gramtype) PL_compcv = ps->compcv; PAD_SET_CUR_NOSAVE(CvPADLIST(PL_compcv), 1); } - ps->val.opval->op_latefree = 0; op_free(ps->val.opval); } SvREFCNT_dec(ps->compcv); |