optimization/7120: Run once loop should *always* be unrolled

[Alan Modra]

On Tue, Jun 25, 2002 at 04:21:32PM -0000, davem@gcc.gnu.org wrote:
> Synopsis: Run once loop should *always* be unrolled

This patch cures the problem.  bootstrap i686-linux in progress.

	* unroll.c (loop_iterations): Handle EQ loops.

Index: gcc/unroll.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/unroll.c,v
retrieving revision 1.168
diff -u -p -r1.168 unroll.c
--- gcc/unroll.c	15 Jun 2002 01:10:49 -0000	1.168
+++ gcc/unroll.c	26 Jun 2002 03:19:38 -0000
@@ -3941,12 +3941,6 @@ loop_iterations (loop)
 	}
       return 0;
     }
-  else if (comparison_code == EQ)
-    {
-      if (loop_dump_stream)
-	fprintf (loop_dump_stream, "Loop iterations: EQ comparison loop.\n");
-      return 0;
-    }
   else if (GET_CODE (final_value) != CONST_INT)
     {
       if (loop_dump_stream)
@@ -3957,6 +3951,15 @@ loop_iterations (loop)
 	  fprintf (loop_dump_stream, ".\n");
 	}
       return 0;
+    }
+  else if (comparison_code == EQ)
+    {
+      if (loop_dump_stream)
+	fprintf (loop_dump_stream, "Loop iterations: EQ comparison loop.\n");
+      if (INTVAL (increment) == 0)
+	return 0;
+      loop_info->n_iterations = 1;
+      return loop_info->n_iterations;
     }
 
   /* Final_larger is 1 if final larger, 0 if they are equal, otherwise -1.  */

-- 
Alan Modra
IBM OzLabs - Linux Technology Centre