Fixed DFA performance regression (by dfa-performance-fix patch)

Resolves: rhbz#1412800

grep-2.27-dfa-performance-fix.patch

@@ -0,0 +1,73 @@
+diff --git a/lib/dfa.c b/lib/dfa.c
+--- a/lib/dfa.c
++++ b/lib/dfa.c
+@@ -2807,39 +2807,33 @@ realloc_trans_if_necessary (struct dfa *d, state_num new_state)
+ static state_num
+ build_state (state_num s, struct dfa *d, unsigned char uc)
+ {
+-  state_num *trans;             /* The new transition table.  */
+-  state_num i, maxstate;
++  /* A pointer to the new transition table, and the table itself.  */
++  state_num **ptrans = (ACCEPTING (s, *d) ? d->fails : d->trans) + s;
++  state_num *trans = *ptrans;
+ 
+-  if (d->fails[s] != NULL)
+-    trans = d->fails[s];
+-  else
++  if (!trans)
+     {
+-      state_num **ptrans = (ACCEPTING (s, *d) ? d->fails : d->trans) + s;
+-      if (!*ptrans)
++      /* MAX_TRCOUNT is an arbitrary upper limit on the number of
++         transition tables that can exist at once, other than for
++         initial states.  Often-used transition tables are quickly
++         rebuilt, whereas rarely-used ones are cleared away.  */
++      if (MAX_TRCOUNT <= d->trcount)
+         {
+-          /* MAX_TRCOUNT is an arbitrary upper limit on the number of
+-             transition tables that can exist at once, other than for
+-             initial states.  Often-used transition tables are quickly
+-             rebuilt, whereas rarely-used ones are cleared away.  */
+-          if (MAX_TRCOUNT <= d->trcount)
++          for (state_num i = d->min_trcount; i < d->tralloc; i++)
+             {
+-              for (i = d->min_trcount; i < d->tralloc; i++)
+-                {
+-                  free (d->trans[i]);
+-                  free (d->fails[i]);
+-                  d->trans[i] = d->fails[i] = NULL;
+-                }
+-              d->trcount = 0;
++              free (d->trans[i]);
++              free (d->fails[i]);
++              d->trans[i] = d->fails[i] = NULL;
+             }
+-
+-          d->trcount++;
+-          *ptrans = xmalloc (NOTCHAR * sizeof *trans);
++          d->trcount = 0;
+         }
+-      trans = *ptrans;
++
++      d->trcount++;
++      *ptrans = trans = xmalloc (NOTCHAR * sizeof *trans);
+ 
+       /* Fill transition table with a default value which means that the
+          transited state has not been calculated yet.  */
+-      for (i = 0; i < NOTCHAR; i++)
++      for (int i = 0; i < NOTCHAR; i++)
+         trans[i] = -2;
+     }
+ 
+@@ -2857,8 +2851,8 @@ build_state (state_num s, struct dfa *d, unsigned char uc)
+   /* Now go through the new transition table, and make sure that the trans
+      and fail arrays are allocated large enough to hold a pointer for the
+      largest state mentioned in the table.  */
+-  maxstate = -1;
+-  for (i = 0; i < NOTCHAR; ++i)
++  state_num maxstate = -1;
++  for (int i = 0; i < NOTCHAR; i++)
+     if (maxstate < trans[i])
+       maxstate = trans[i];
+   realloc_trans_if_necessary (d, maxstate);
+

grep.spec

@@ -3,7 +3,7 @@
 Summary: Pattern matching utilities
 Name: grep
 Version: 2.27
-Release: 1%{?dist}
+Release: 2%{?dist}
 License: GPLv3+
 URL: http://www.gnu.org/software/grep/
 Group: Applications/Text
@@ -17,6 +17,8 @@ Source4: grepconf.sh
 Patch0: grep-2.27-man-fix-gs.patch
 # upstream ticket 39445
 Patch1: grep-2.27-help-align.patch
+# backported from gnulib (rhbz#1412800)
+Patch2: grep-2.27-dfa-performance-fix.patch
 Requires(post): /sbin/install-info
 Requires(preun): /sbin/install-info
 
@@ -36,6 +38,7 @@ GNU grep is needed by many scripts, so it shall be installed on every system.
 %setup -q
 %patch0 -p1 -b .man-fix-gs
 %patch1 -p1 -b .help-align
+%patch2 -p1 -b .dfa-performance-fix
 
 %build
 %global BUILD_FLAGS $RPM_OPT_FLAGS
@@ -86,6 +89,10 @@ fi
 %{_libexecdir}/grepconf.sh
 
 %changelog
+* Mon Feb 20 2017 Jaroslav Škarvada <jskarvad@redhat.com> - 2.27-2
+- Fixed DFA performance regression (by dfa-performance-fix patch)
+  Resolves: rhbz#1412800
+
 * Wed Dec  7 2016 Jaroslav Škarvada <jskarvad@redhat.com> - 2.27-1
 - New version
   Resolves: rhbz#1402379