Revert fixes to allocation of regex matching

The fix was not complete, and completing it was proving too complicated.

- Revert "* src/regex.c (re_search_2): Make new code safe for
          -Wjump-misses-init."
  This reverts commit c2a17924a57483d14692c8913edbe8ad24b5ffbb.
- Revert "Port to GCC 6.2.1 + --enable-gcc-warnings"
  This reverts commit f6134bbda259c115c06d4a9a3ab5c39340a15949.
- Revert "Fix handling of allocation in regex matching"
  This reverts commit ad66b3fadb7ae22a4cbb82bb1507c39ceadf3897.
- Revert "Fix handling of buffer relocation in regex.c functions"
  This reverts commit ee04aedc723b035eedaf975422d4eb242894121b.

1 files changed, 12 insertions, 28 deletions

diff --git a/src/search.c b/src/search.c
index b50e7f032d5..fa5ac44de9d 100644
--- a/src/search.c
+++ b/src/search.c
@@ -287,10 +287,8 @@ looking_at_1 (Lisp_Object string, bool posix)
   immediate_quit = 1;
   QUIT;			/* Do a pending quit right away, to avoid paradoxical behavior */
 
-  /* Get pointers and sizes of the two strings that make up the
-     visible portion of the buffer.  Note that we can use pointers
-     here, unlike in search_buffer, because we only call re_match_2
-     once, after which we never use the pointers again.  */
+  /* Get pointers and sizes of the two strings
+     that make up the visible portion of the buffer. */
 
   p1 = BEGV_ADDR;
   s1 = GPT_BYTE - BEGV_BYTE;
@@ -409,7 +407,6 @@ string_match_1 (Lisp_Object regexp, Lisp_Object string, Lisp_Object start,
 		   (NILP (Vinhibit_changing_match_data)
 		    ? &search_regs : NULL));
   immediate_quit = 0;
-  re_match_object = Qnil;       /* Stop protecting string from GC.  */
 
   /* Set last_thing_searched only when match data is changed.  */
   if (NILP (Vinhibit_changing_match_data))
@@ -480,7 +477,6 @@ fast_string_match_internal (Lisp_Object regexp, Lisp_Object string,
 		   SBYTES (string), 0,
 		   SBYTES (string), 0);
   immediate_quit = 0;
-  re_match_object = Qnil;       /* Stop protecting string from GC.  */
   return val;
 }
 
@@ -568,7 +564,6 @@ fast_looking_at (Lisp_Object regexp, ptrdiff_t pos, ptrdiff_t pos_byte,
   len = re_match_2 (buf, (char *) p1, s1, (char *) p2, s2,
 		    pos_byte, NULL, limit_byte);
   immediate_quit = 0;
-  re_match_object = Qnil;       /* Stop protecting string from GC.  */
 
   return len;
 }
@@ -1183,8 +1178,8 @@ search_buffer (Lisp_Object string, ptrdiff_t pos, ptrdiff_t pos_byte,
 
   if (RE && !(trivial_regexp_p (string) && NILP (Vsearch_spaces_regexp)))
     {
-      unsigned char *base;
-      ptrdiff_t off1, off2, s1, s2;
+      unsigned char *p1, *p2;
+      ptrdiff_t s1, s2;
       struct re_pattern_buffer *bufp;
 
       bufp = compile_pattern (string,
@@ -1198,19 +1193,16 @@ search_buffer (Lisp_Object string, ptrdiff_t pos, ptrdiff_t pos_byte,
 				   can take too long. */
       QUIT;			/* Do a pending quit right away,
 				   to avoid paradoxical behavior */
-      /* Get offsets and sizes of the two strings that make up the
-         visible portion of the buffer.  We compute offsets instead of
-         pointers because re_search_2 may call malloc and therefore
-         change the buffer text address.  */
+      /* Get pointers and sizes of the two strings
+	 that make up the visible portion of the buffer. */
 
-      base = current_buffer->text->beg;
-      off1 = BEGV_ADDR - base;
+      p1 = BEGV_ADDR;
       s1 = GPT_BYTE - BEGV_BYTE;
-      off2 = GAP_END_ADDR - base;
+      p2 = GAP_END_ADDR;
       s2 = ZV_BYTE - GPT_BYTE;
       if (s1 < 0)
 	{
-          off2 = off1;
+	  p2 = p1;
 	  s2 = ZV_BYTE - BEGV_BYTE;
 	  s1 = 0;
 	}
@@ -1225,16 +1217,12 @@ search_buffer (Lisp_Object string, ptrdiff_t pos, ptrdiff_t pos_byte,
 	{
 	  ptrdiff_t val;
 
-          val = re_search_2 (bufp,
-                             (char*) (base + off1), s1,
-                             (char*) (base + off2), s2,
+	  val = re_search_2 (bufp, (char *) p1, s1, (char *) p2, s2,
 			     pos_byte - BEGV_BYTE, lim_byte - pos_byte,
 			     (NILP (Vinhibit_changing_match_data)
 			      ? &search_regs : &search_regs_1),
 			     /* Don't allow match past current point */
 			     pos_byte - BEGV_BYTE);
-	  /* Update 'base' due to possible relocation inside re_search_2.  */
-	  base = current_buffer->text->beg;
 	  if (val == -2)
 	    {
 	      matcher_overflow ();
@@ -1274,15 +1262,11 @@ search_buffer (Lisp_Object string, ptrdiff_t pos, ptrdiff_t pos_byte,
 	{
 	  ptrdiff_t val;
 
-          val = re_search_2 (bufp,
-                             (char*) (base + off1), s1,
-                             (char*) (base + off2), s2,
-                             pos_byte - BEGV_BYTE, lim_byte - pos_byte,
+	  val = re_search_2 (bufp, (char *) p1, s1, (char *) p2, s2,
+			     pos_byte - BEGV_BYTE, lim_byte - pos_byte,
 			     (NILP (Vinhibit_changing_match_data)
 			      ? &search_regs : &search_regs_1),
 			     lim_byte - BEGV_BYTE);
-	  /* Update 'base' due to possible relocation inside re_search_2.  */
-	  base = current_buffer->text->beg;
 	  if (val == -2)
 	    {
 	      matcher_overflow ();