Merge from gcc-2.8

[pf3gnuchains/gcc-fork.git] / gcc / loop.c

diff --git a/gcc/loop.c b/gcc/loop.c
index 6c0d00d..a26c04a 100644 (file)
--- a/gcc/loop.c
+++ b/gcc/loop.c
@@ -3633,11 +3633,20 @@ strength_reduce (scan_start, end, loop_top, insn_count,
   for (bl = loop_iv_list; bl; bl = bl->next)
     {
       rtx src;
+      rtx note;
 
       if (! bl->init_insn)
        continue;
 
-      src = SET_SRC (bl->init_set);
+      /* IF INIT_INSN has a REG_EQUAL or REG_EQUIV note and the value
+        is a constant, use the value of that.  */
+      if (((note = find_reg_note (bl->init_insn, REG_EQUAL, 0)) != NULL
+          && CONSTANT_P (XEXP (note, 0)))
+         || ((note = find_reg_note (bl->init_insn, REG_EQUIV, 0)) != NULL
+             && CONSTANT_P (XEXP (note, 0))))
+       src = XEXP (note, 0);
+      else
+       src = SET_SRC (bl->init_set);
 
       if (loop_dump_stream)
        fprintf (loop_dump_stream,
@@ -6185,8 +6194,8 @@ check_dbra_loop (loop_end, insn_count, loop_start)
 
          /* Now check other conditions:
 
-            The increment must be a constant and the comparison code
-            must be LT. 
+            The increment must be a constant, as must the initial value,
+            and the comparison code must be LT. 
 
             This test can probably be improved since +/- 1 in the constant
             can be obtained by changing LT to LE and vice versa; this is
@@ -6195,7 +6204,8 @@ check_dbra_loop (loop_end, insn_count, loop_start)
          if (comparison
              && GET_CODE (XEXP (comparison, 1)) == CONST_INT
              /* LE gets turned into LT */
-             && GET_CODE (comparison) == LT)
+             && GET_CODE (comparison) == LT
+             && GET_CODE (bl->initial_value) == CONST_INT)
            {
              HOST_WIDE_INT add_val, comparison_val;
              rtx initial_value;