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| author | Paul Eggert <eggert@cs.ucla.edu> | 2020-08-26 00:07:08 -0700 |
|---|---|---|
| committer | Paul Eggert <eggert@cs.ucla.edu> | 2020-08-26 00:20:31 -0700 |
| commit | 768bea30cbc0a5e7851fa60ad1ea7ec14cf2cdd8 (patch) | |
| tree | f21a0af8dddb6376f460593c85b31628afb320ba /src/regex-emacs.c | |
| parent | 438975bbaa25b7de74993e7928c45cf5779442b8 (diff) | |
| download | emacs-768bea30cbc0a5e7851fa60ad1ea7ec14cf2cdd8.tar.gz | |
regex-emacs omit allocation of 3 slots
* src/regex-emacs.c (re_match_2_internal): Avoid
unnecessary allocation of REGEND[0], BEST_REGSTART[0],
BEST_REGEND[0].
Diffstat (limited to 'src/regex-emacs.c')
| -rw-r--r-- | src/regex-emacs.c | 26 |
1 files changed, 13 insertions, 13 deletions
diff --git a/src/regex-emacs.c b/src/regex-emacs.c index 954a193371a..da73f58f503 100644 --- a/src/regex-emacs.c +++ b/src/regex-emacs.c @@ -3923,8 +3923,7 @@ re_match_2_internal (struct re_pattern_buffer *bufp, attempt) by a subexpression part of the pattern, that is, the regnum-th regstart pointer points to where in the pattern we began matching and the regnum-th regend points to right after where we - stopped matching the regnum-th subexpression. (The zeroth register - keeps track of what the whole pattern matches.) */ + stopped matching the regnum-th subexpression. */ re_char **regstart UNINIT, **regend UNINIT; /* The following record the register info as found in the above @@ -3973,20 +3972,21 @@ re_match_2_internal (struct re_pattern_buffer *bufp, /* Do not bother to initialize all the register variables if there are no groups in the pattern, as it takes a fair amount of time. If there are groups, we include space for register 0 (the whole - pattern), even though we never use it, since it simplifies the - array indexing. We should fix this. */ - if (bufp->re_nsub) + pattern) in REGSTART[0], even though we never use it, to avoid + the undefined behavior of subtracting 1 from REGSTART. */ + ptrdiff_t re_nsub = num_regs - 1; + if (0 < re_nsub) { - regstart = SAFE_ALLOCA (num_regs * 4 * sizeof *regstart); + regstart = SAFE_ALLOCA ((re_nsub * 4 + 1) * sizeof *regstart); regend = regstart + num_regs; - best_regstart = regend + num_regs; - best_regend = best_regstart + num_regs; - } + best_regstart = regend + re_nsub; + best_regend = best_regstart + re_nsub; - /* Initialize subexpression text positions to -1 to mark ones that no - start_memory/stop_memory has been seen for. */ - for (ptrdiff_t reg = 1; reg < num_regs; reg++) - regstart[reg] = regend[reg] = NULL; + /* Initialize subexpression text positions to unset, to mark ones + that no start_memory/stop_memory has been seen for. */ + for (re_char **apos = regstart + 1; apos < best_regstart + 1; apos++) + *apos = NULL; + } /* We move 'string1' into 'string2' if the latter's empty -- but not if 'string1' is null. */ |