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Avoid unnecessary "if-before-free" tests.

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This change removes all obvious useless if-before-free tests.
E.g., it replaces code like this:

        if (some_expression)
                free (some_expression);

with the now-equivalent:

        free (some_expression);

It is equivalent not just because POSIX has required free(NULL)
to work for a long time, but simply because it has worked for
so long that no reasonable porting target fails the test.
Here's some evidence from nearly 1.5 years ago:

    http://www.winehq.org/pipermail/wine-patches/2006-October/031544.html

FYI, the change below was prepared by running the following:

  git ls-files -z | xargs -0 \
  perl -0x3b -pi -e \
    's/\bif\s*\(\s*(\S+?)(?:\s*!=\s*NULL)?\s*\)\s+(free\s*\(\s*\1\s*\))/$2/s'

Note however, that it doesn't handle brace-enclosed blocks like
"if (x) { free (x); }".  But that's ok, since there were none like
that in git sources.

Beware: if you do use the above snippet, note that it can
produce syntactically invalid C code.  That happens when the
affected "if"-statement has a matching "else".
E.g., it would transform this

  if (x)
    free (x);
  else
    foo ();

into this:

  free (x);
  else
    foo ();

There were none of those here, either.

If you're interested in automating detection of the useless
tests, you might like the useless-if-before-free script in gnulib:
[it *does* detect brace-enclosed free statements, and has a --name=S
 option to make it detect free-like functions with different names]

  http://git.sv.gnu.org/gitweb/?p=gnulib.git;a=blob;f=build-aux/useless-if-before-free

Addendum:
  Remove one more (in imap-send.c), spotted by Jean-Luc Herren <jlh@gmx.ch>.

Signed-off-by: Jim Meyering <meyering@redhat.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Jim Meyering
2008-01-31 18:26:32 +01:00
committed by Junio C Hamano
parent 22c430ad84
commit 8e0f70033b
17 changed files with 28 additions and 55 deletions
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9
diff.c
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@ -118,8 +118,7 @@ static int parse_funcname_pattern(const char *var, const char *ep, const char *v
pp->next = funcname_pattern_list;
funcname_pattern_list = pp;
}
if (pp->pattern)
free(pp->pattern);
free(pp->pattern);
pp->pattern = xstrdup(value);
return 0;
}
@ -492,10 +491,8 @@ static void free_diff_words_data(struct emit_callback *ecbdata)
ecbdata->diff_words->plus.text.size)
diff_words_show(ecbdata->diff_words);
if (ecbdata->diff_words->minus.text.ptr)
free (ecbdata->diff_words->minus.text.ptr);
if (ecbdata->diff_words->plus.text.ptr)
free (ecbdata->diff_words->plus.text.ptr);
free (ecbdata->diff_words->minus.text.ptr);
free (ecbdata->diff_words->plus.text.ptr);
free(ecbdata->diff_words);
ecbdata->diff_words = NULL;
}