(loop_comparison_code): New static variable.

(unroll_loop): Add check for loop_comparison_code
(loop_iterations): Set loop_comparison_code.

From-SVN: r12991

diff --git a/gcc/unroll.c b/gcc/unroll.c
index a282be3d99146eac5c52864031c9b893282939b3..b720074b6046fa81d0a6d11053d4b24b28c5bc47 100644 (file)
--- a/gcc/unroll.c
+++ b/gcc/unroll.c
@@ -191,6 +191,7 @@ static rtx loop_iteration_var;
 static rtx loop_initial_value;
 static rtx loop_increment;
 static rtx loop_final_value;
+static enum rtx_code loop_comparison_code;
 
 /* Forward declarations.  */
 
@@ -878,18 +879,23 @@ unroll_loop (loop_end, insn_count, loop_start, end_insert_before,
          for (i = 0; i < unroll_number; i++)
            labels[i] = gen_label_rtx ();
 
-         /* Check for the case where the initial value is greater than or equal
-            to the final value.  In that case, we want to execute exactly
-            one loop iteration.  The code below will fail for this case.  */
+         /* Check for the case where the initial value is greater than or
+            equal to the final value.  In that case, we want to execute
+            exactly one loop iteration.  The code below will fail for this
+            case.  This check does not apply if the loop has a NE
+            comparison at the end.  */
 
-         emit_cmp_insn (initial_value, final_value, neg_inc ? LE : GE,
-                        NULL_RTX, mode, 0, 0);
-         if (neg_inc)
-           emit_jump_insn (gen_ble (labels[1]));
-         else
-           emit_jump_insn (gen_bge (labels[1]));
-         JUMP_LABEL (get_last_insn ()) = labels[1];
-         LABEL_NUSES (labels[1])++;
+         if (loop_comparison_code != NE)
+           {
+             emit_cmp_insn (initial_value, final_value, neg_inc ? LE : GE,
+                            NULL_RTX, mode, 0, 0);
+             if (neg_inc)
+               emit_jump_insn (gen_ble (labels[1]));
+             else
+               emit_jump_insn (gen_bge (labels[1]));
+             JUMP_LABEL (get_last_insn ()) = labels[1];
+             LABEL_NUSES (labels[1])++;
+           }
 
          /* Assuming the unroll_number is 4, and the increment is 2, then
             for a negative increment:  for a positive increment:
@@ -3355,6 +3361,7 @@ loop_iterations (loop_start, loop_end)
   loop_initial_value = initial_value;
   loop_increment = increment;
   loop_final_value = final_value;
+  loop_comparison_code = comparison_code;
 
   if (increment == 0)
     {