[x86] RFA: Use new rtl iterators in ix86_loop_unroll_adjust

[Richard Sandiford]

This is part of a series to remove uses of for_each_rtx from the ports.

It looks like this code should be iterating over the pattern rather than
the full insn, or do MEMs in notes really count?  If we iterate over the
pattern then there should be no need for the test for null.

Tested by making sure there were no code changes for gcc.dg, gcc.c-torture
and g++.dg for x86_64-linux-gnu, and also by a boostrap.  OK to install?

Thanks,
Richard


gcc/
        * config/i386/i386.c (ix86_loop_memcount): Delete.
        (ix86_loop_unroll_adjust): Use FOR_EACH_SUBRTX.

Index: gcc/config/i386/i386.c
===================================================================
--- gcc/config/i386/i386.c      2014-10-25 09:51:15.992799283 +0100
+++ gcc/config/i386/i386.c      2014-10-25 09:51:16.373802679 +0100
@@ -47405,29 +47405,6 @@ ix86_simd_clone_usable (struct cgraph_no
     }
 }
 
-/* This function gives out the number of memory references.
-   This value determines the unrolling factor for
-   bdver3 and bdver4 architectures. */
-
-static int
-ix86_loop_memcount (rtx *x, unsigned *mem_count)
-{
-  if (*x != NULL_RTX && MEM_P (*x))
-   {
-     enum machine_mode mode;
-     unsigned int n_words;
-
-     mode = GET_MODE (*x);
-     n_words = GET_MODE_SIZE (mode) / UNITS_PER_WORD;
-
-    if (n_words > 4)
-       (*mem_count)+=2;
-    else
-       (*mem_count)+=1;
-   }
-  return 0;
-}
-
 /* This function adjusts the unroll factor based on
    the hardware capabilities. For ex, bdver3 has
    a loop buffer which makes unrolling of smaller
@@ -47447,14 +47424,22 @@ ix86_loop_unroll_adjust (unsigned nunrol
      return nunroll;
 
   /* Count the number of memory references within the loop body.  */
+  subrtx_iterator::array_type array;
   bbs = get_loop_body (loop);
   for (i = 0; i < loop->num_nodes; i++)
-    {
-      for (insn = BB_HEAD (bbs[i]); insn != BB_END (bbs[i]); insn = NEXT_INSN 
(insn))
-        if (NONDEBUG_INSN_P (insn))
-            for_each_rtx_in_insn (&insn, (rtx_function) ix86_loop_memcount,
-                                 &mem_count);
-    }
+    FOR_BB_INSNS (bbs[i], insn)
+      if (NONDEBUG_INSN_P (insn))
+       FOR_EACH_SUBRTX (iter, array, insn, NONCONST)
+         if (const_rtx x = *iter)
+           if (MEM_P (x))
+             {
+               enum machine_mode mode = GET_MODE (x);
+               unsigned int n_words = GET_MODE_SIZE (mode) / UNITS_PER_WORD;
+               if (n_words > 4)
+                 mem_count += 2;
+               else
+                 mem_count += 1;
+             }
   free (bbs);
 
   if (mem_count && mem_count <=32)