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Re: [PATCH v2 4/7] grep: add support for the PCRE v1 JIT API




On Sun, May 14, 2017 at 5:10 PM, Ævar Arnfjörð Bjarmason
<avarab@xxxxxxxxx> wrote:
> On Sun, May 14, 2017 at 4:43 PM, Simon Ruderich <simon@xxxxxxxxxxxx> wrote:
>> On Sat, May 13, 2017 at 11:45:32PM +0000, Ęvar Arnfjörš Bjarmason wrote:
>>> [snip]
>>>
>>> +#ifdef PCRE_CONFIG_JIT
>>> +     if (p->pcre1_jit_on)
>>> +             ret = pcre_jit_exec(p->pcre1_regexp, p->pcre1_extra_info, line,
>>> +                                 eol - line, 0, flags, ovector,
>>> +                                 ARRAY_SIZE(ovector), p->pcre1_jit_stack);
>>> +     else
>>> +             ret = pcre_exec(p->pcre1_regexp, p->pcre1_extra_info, line,
>>> +                             eol - line, 0, flags, ovector,
>>> +                             ARRAY_SIZE(ovector));
>>> +#else
>>>       ret = pcre_exec(p->pcre1_regexp, p->pcre1_extra_info, line, eol - line,
>>>                       0, flags, ovector, ARRAY_SIZE(ovector));
>>> +#endif
>>
>> Wouldn't it be simpler to remove the duplication and
>> unconditionally use the old pcre_exec() call? Something like
>> this:
>>
>>     +#ifdef PCRE_CONFIG_JIT
>>     +   if (p->pcre1_jit_on)
>>     +           ret = pcre_jit_exec(p->pcre1_regexp, p->pcre1_extra_info, line,
>>     +                               eol - line, 0, flags, ovector,
>>     +                               ARRAY_SIZE(ovector), p->pcre1_jit_stack);
>>     +   else
>>     +#endif
>>         ret = pcre_exec(p->pcre1_regexp, p->pcre1_extra_info, line, eol - line,
>>                         0, flags, ovector, ARRAY_SIZE(ovector));
>>
>>>       if (ret < 0 && ret != PCRE_ERROR_NOMATCH)
>>>               die("pcre_exec failed with error code %d", ret);
>>>       if (ret > 0) {
>>> @@ -394,7 +420,16 @@ static int pcre1match(struct grep_pat *p, const char *line, const char *eol,
>>>  static void free_pcre1_regexp(struct grep_pat *p)
>>>  {
>>>       pcre_free(p->pcre1_regexp);
>>> +#ifdef PCRE_CONFIG_JIT
>>> +     if (p->pcre1_jit_on) {
>>> +             pcre_free_study(p->pcre1_extra_info);
>>> +             pcre_jit_stack_free(p->pcre1_jit_stack);
>>> +     } else {
>>> +             pcre_free(p->pcre1_extra_info);
>>> +     }
>>> +#else
>>>       pcre_free(p->pcre1_extra_info);
>>> +#endif
>>
>> Same here. The pcre_free() is the same with and without the
>> ifdef.
>
> Yes I could do that, no reason not to, and as you point out it would
> reduce duplication.
>
> I wrote it like this trying to preserve the indentation with/without
> the macro being true, thinking someone would have an issue with it
> otherwise.
>
> I also thought just now that perhaps if it were changed the code like
> that it would warn under -Wmisleading-indentation, but at least on gcc
> that's not the case, it knows not to warn in the presence of macros.
>
> Unless someone feel strongly otherwise / can think of a good reason
> for why not, I'll change it as you suggest in the next version.
>
> Thanks for the review!

...and if I do change it do others think this is something that
warrants a comment & some whitespace padding? I.e.:

@@ -378,8 +392,17 @@ static int pcre1match(struct grep_pat *p, const
char *line, const char *eol,
        if (eflags & REG_NOTBOL)
                flags |= PCRE_NOTBOL;

+#ifdef PCRE_CONFIG_JIT
+       if (p->pcre1_jit_on)
+               ret = pcre_jit_exec(p->pcre1_regexp, p->pcre1_extra_info, line,
+                                   eol - line, 0, flags, ovector,
+                                   ARRAY_SIZE(ovector), p->pcre1_jit_stack);
+       else
+#endif
+       /* PCRE_CONFIG_JIT !p->pcre1_jit_on else branch */
        ret = pcre_exec(p->pcre1_regexp, p->pcre1_extra_info, line, eol - line,
                        0, flags, ovector, ARRAY_SIZE(ovector));
+
        if (ret < 0 && ret != PCRE_ERROR_NOMATCH)
                die("pcre_exec failed with error code %d", ret);
        if (ret > 0) {

and:

@@ -394,7 +417,16 @@ static int pcre1match(struct grep_pat *p, const
char *line, const char *eol,
 static void free_pcre1_regexp(struct grep_pat *p)
 {
        pcre_free(p->pcre1_regexp);
+
+#ifdef PCRE_CONFIG_JIT
+       if (p->pcre1_jit_on) {
+               pcre_free_study(p->pcre1_extra_info);
+               pcre_jit_stack_free(p->pcre1_jit_stack);
+       } else
+#endif
+       /* PCRE_CONFIG_JIT !p->pcre1_jit_on else branch */
        pcre_free(p->pcre1_extra_info);
+
        pcre_free((void *)p->pcre1_tables);
 }
 #else /* !USE_LIBPCRE1 */