re PR rtl-optimization/4311 (unrolling loops creates non-ending loop)

        PR opt/4311
        * loop.h (LOOP_FIRST_PASS): New.
        * loop.c (strength_reduce): Mind it when deciding to unroll.
        * toplev.c (rest_of_compilation): Set it.

From-SVN: r51798

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index d452251..5a4f4f3 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+2002-04-02  Richard Henderson  <rth@redhat.com>
+
+       PR opt/4311
+       * loop.h (LOOP_FIRST_PASS): New.
+       * loop.c (strength_reduce): Mind it when deciding to unroll.
+       * toplev.c (rest_of_compilation): Set it.
+
 2002-04-02  David S. Miller  <davem@redhat.com>
 
        * config/sparc/sparc.md (ldd peephole2s): Fix final arg to

diff --git a/gcc/loop.c b/gcc/loop.c
index 99281d0..b51b2a8 100644 (file)
--- a/gcc/loop.c
+++ b/gcc/loop.c
@@ -5214,7 +5214,8 @@ strength_reduce (loop, flags)
      collected.  Always unroll loops that would be as small or smaller
      unrolled than when rolled.  */
   if ((flags & LOOP_UNROLL)
-      || (loop_info->n_iterations > 0
+      || (!(flags & LOOP_FIRST_PASS)
+         && loop_info->n_iterations > 0
          && unrolled_insn_copies <= insn_count))
     unroll_loop (loop, insn_count, 1);
 

diff --git a/gcc/loop.h b/gcc/loop.h
index 55f70ff..8e3a935 100644 (file)
--- a/gcc/loop.h
+++ b/gcc/loop.h
@@ -28,6 +28,7 @@ Software Foundation, 59 Temple Place - Suite 330, Boston, MA
 #define LOOP_UNROLL 1
 #define LOOP_BCT 2
 #define LOOP_PREFETCH 4
+#define LOOP_FIRST_PASS 8
 
 /* Get the loop info pointer of a loop.  */
 #define LOOP_INFO(LOOP) ((struct loop_info *) (LOOP)->aux)

diff --git a/gcc/toplev.c b/gcc/toplev.c
index 2400959..9fa22fc 100644 (file)
--- a/gcc/toplev.c
+++ b/gcc/toplev.c
@@ -2805,8 +2805,7 @@ rest_of_compilation (decl)
          cleanup_barriers ();
 
          /* We only want to perform unrolling once.  */
-
-         loop_optimize (insns, rtl_dump_file, 0);
+         loop_optimize (insns, rtl_dump_file, LOOP_FIRST_PASS);
 
          /* The first call to loop_optimize makes some instructions
             trivially dead.  We delete those instructions now in the