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Minor fixes to improve regex debugging code. 

When REG_DEBUG is defined, ensure that an un-filled "struct cnfa"
is all-zeroes, not just that it has nstates == 0.  This is mainly
so that looking at "struct subre" structs in gdb doesn't distract
one with a lot of garbage fields during regex compilation.

Adjust some places that print debug output to have suitable fflush
calls afterwards.

In passing, correct an erroneous ancient comment: the concatenation
subre-s created by parsebranch() have op == '.' not ','.

Noted while fooling around with some regex performance improvements.
This commit is contained in:
Tom Lane 2021-02-14 19:53:28 -05:00
parent c7ecd6af01
commit 2dd6733108
3 changed files with 15 additions and 4 deletions
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6
src/backend/regex/regc_nfa.c
View File

@ -2951,11 +2951,11 @@ carc_cmp(const void *a, const void *b)
static void
freecnfa(struct cnfa *cnfa)
{
assert(cnfa->nstates != 0); /* not empty already */
cnfa->nstates = 0;
assert(!NULLCNFA(*cnfa)); /* not empty already */
FREE(cnfa->stflags);
FREE(cnfa->states);
FREE(cnfa->arcs);
ZAPCNFA(*cnfa);
}
/*
@ -3012,13 +3012,13 @@ dumpstate(struct state *s,
fprintf(f, "\tno out arcs\n");
else
dumparcs(s, f);
fflush(f);
for (a = s->ins; a != NULL; a = a->inchain)
{
if (a->to != s)
fprintf(f, "\tlink from %d to %d on %d's in-chain\n",
a->from->no, a->to->no, s->no);
}
fflush(f);
}
/*

5
src/backend/regex/regcomp.c
View File

@ -479,7 +479,10 @@ pg_regcomp(regex_t *re,
#ifdef REG_DEBUG
if (flags & REG_DUMP)
{
dump(re, stdout);
fflush(stdout);
}
#endif
assert(v->err == 0);
@ -721,7 +724,7 @@ parse(struct vars *v,
*
* This mostly manages concatenation, working closely with parseqatom().
* Concatenated things are bundled up as much as possible, with separate
* ',' nodes introduced only when necessary due to substructure.
* '.' nodes introduced only when necessary due to substructure.
*/
static struct subre *
parsebranch(struct vars *v,

8
src/include/regex/regguts.h
View File

@ -368,7 +368,15 @@ struct cnfa
struct carc *arcs; /* the area for the lists */
};
/*
* When debugging, it's helpful if an un-filled CNFA is all-zeroes.
* In production, though, we only require nstates to be zero.
*/
#ifdef REG_DEBUG
#define ZAPCNFA(cnfa) memset(&(cnfa), 0, sizeof(cnfa))
#else
#define ZAPCNFA(cnfa) ((cnfa).nstates = 0)
#endif
#define NULLCNFA(cnfa) ((cnfa).nstates == 0)
/*