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Remove dead loop iterations in regex.c

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RE_CHAR_TO_MULTIBYTE(c) yields c for ASCII characters and a byte8
character for c ≥ 0x80.  Furthermore, CHAR_BYTE8_P(c) is true only
for byte8 characters.  This means that

	c = RE_CHAR_TO_MULTIBYTE (ch);
	if (! CHAR_BYTE8_P (c) && re_iswctype (c, cc))

is equivalent to:

	c = c;
	if (! false && re_iswctype (c, cc))

for 0 ⪬ c < 0x80, and

	c = BYTE8_TO_CHAR (c);
	if (! true && re_iswctype (c, cc))

for 0x80 ⪬ c < 0x100.  In other words, the loop never executes for
c ≥ 0x80 and RE_CHAR_TO_MULTIBYTE call is unnecessary for c < 0x80.

* src/regex.c (regex_compile): Simplyfy a for loop by eliminating
dead iterations and unnecessary macro calls.
This commit is contained in:
Michal Nazarewicz 2016-08-03 03:52:49 +02:00
parent c579b28f62
commit 0e7eb64076
1 changed files with 12 additions and 16 deletions
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28
src/regex.c
View file

@ -2888,22 +2888,18 @@ regex_compile (const_re_char *pattern, size_t size,
done until now. */
SETUP_BUFFER_SYNTAX_TABLE ();
for (ch = 0; ch < 256; ++ch)
{
c = RE_CHAR_TO_MULTIBYTE (ch);
if (! CHAR_BYTE8_P (c)
&& re_iswctype (c, cc))
{
SET_LIST_BIT (ch);
c1 = TRANSLATE (c);
if (c1 == c)
continue;
if (ASCII_CHAR_P (c1))
SET_LIST_BIT (c1);
else if ((c1 = RE_CHAR_TO_UNIBYTE (c1)) >= 0)
SET_LIST_BIT (c1);
}
}
for (c = 0; c < 0x80; ++c)
if (re_iswctype (c, cc))
{
SET_LIST_BIT (c);
c1 = TRANSLATE (c);
if (c1 == c)
continue;
if (ASCII_CHAR_P (c1))
SET_LIST_BIT (c1);
else if ((c1 = RE_CHAR_TO_UNIBYTE (c1)) >= 0)
SET_LIST_BIT (c1);
}
SET_RANGE_TABLE_WORK_AREA_BIT
(range_table_work, re_wctype_to_bit (cc));
#endif /* emacs */