Remove dead loop iterations in regex.c

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.

1 files changed, 12 insertions, 16 deletions

diff --git a/src/regex.c b/src/regex.c
index 5f51b43e6c8..41c1d3f6106 100644
--- a/src/regex.c
+++ b/src/regex.c
@@ -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 */