RFA: patch to solve IRA PR37296

[Vladimir Makarov <vmakarov at redhat dot com>]

The following patch solves IRA PR37296.
The analysis of the problem could be found in

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37296

2008-09-03  Vladimir Makarov  <vmakarov@redhat.com>

   PR rtl-opt/37296

   * ira-int.h (ira_sort_insn_chain): Remove.

   * ira.c (basic_block_order_nums, chain_insn_order,
   chain_freq_compare, chain_bb_compare, ira_sort_insn_chain): Remove.
   (ira): Don't call ira_sort_insn_chain.

   * reload1.c (reload): Don't call ira_sort_insn_chain.

Index: ira.c
===================================================================
--- ira.c	(revision 139939)
+++ ira.c	(working copy)
@@ -1681,101 +1681,6 @@ expand_reg_info (int old_size)
 
 
 
-/* This page contains code for sorting the insn chain used by reload.
-   In the old register allocator, the insn chain order corresponds to
-   the order of insns in RTL.  By putting insns with higher execution
-   frequency BBs first, reload has a better chance to generate less
-   expensive operand reloads for such insns.  */
-
-/* Map bb index -> order number in the BB chain in RTL code.  */
-static int *basic_block_order_nums;
-
-/* Map chain insn uid -> order number in the insn chain before sorting
-   the insn chain.  */
-static int *chain_insn_order;
-
-/* The function is used to sort insn chain according insn execution
-   frequencies.  */
-static int
-chain_freq_compare (const void *v1p, const void *v2p)
-{
-  const struct insn_chain *c1 = *(struct insn_chain * const *)v1p;
-  const struct insn_chain *c2 = *(struct insn_chain * const *)v2p;
-  int diff;
-
-  diff = (BASIC_BLOCK (c2->block)->frequency
-	  - BASIC_BLOCK (c1->block)->frequency);
-  if (diff)
-    return diff;
-  /* Keep the same order in BB scope.  */
-  return (chain_insn_order[INSN_UID(c1->insn)]
-	  - chain_insn_order[INSN_UID(c2->insn)]);
-}
-
-/* Sort the insn chain according insn original order.  */
-static int
-chain_bb_compare (const void *v1p, const void *v2p)
-{
-  const struct insn_chain *c1 = *(struct insn_chain * const *)v1p;
-  const struct insn_chain *c2 = *(struct insn_chain * const *)v2p;
-  int diff;
-
-  diff = (basic_block_order_nums[c1->block]
-	  - basic_block_order_nums[c2->block]);
-  if (diff)
-    return diff;
-  /* Keep the same order in BB scope.  */
-  return (chain_insn_order[INSN_UID(c1->insn)]
-	  - chain_insn_order[INSN_UID(c2->insn)]);
-}
-
-/* Sort the insn chain according to insn frequencies if
-   FREQ_P or according to insn original order otherwise.  */
-void
-ira_sort_insn_chain (bool freq_p)
-{
-  struct insn_chain *chain, **chain_arr;
-  basic_block bb;
-  int i, n;
-  
-  chain_insn_order = (int *) ira_allocate (get_max_uid () * sizeof (int));
-  for (n = 0, chain = reload_insn_chain; chain != 0; chain = chain->next)
-    {
-      chain_insn_order[INSN_UID (chain->insn)] = n;
-      n++;
-    }
-  if (n <= 1)
-    return;
-  chain_arr
-    = (struct insn_chain **) ira_allocate (n * sizeof (struct insn_chain *));
-  basic_block_order_nums
-    = (int *) ira_allocate (sizeof (int) * last_basic_block);
-  n = 0;
-  FOR_EACH_BB (bb)
-    {
-      basic_block_order_nums[bb->index] = n++;
-    }
-  for (n = 0, chain = reload_insn_chain; chain != 0; chain = chain->next)
-    chain_arr[n++] = chain;
-  qsort (chain_arr, n, sizeof (struct insn_chain *),
-	 freq_p ? chain_freq_compare : chain_bb_compare);
-  ira_free (chain_insn_order);
-  for (i = 1; i < n - 1; i++)
-    {
-      chain_arr[i]->next = chain_arr[i + 1];
-      chain_arr[i]->prev = chain_arr[i - 1];
-    }
-  chain_arr[i]->next = NULL;
-  chain_arr[i]->prev = chain_arr[i - 1];
-  reload_insn_chain = chain_arr[0];
-  reload_insn_chain->prev = NULL;
-  reload_insn_chain->next = chain_arr[1];
-  ira_free (basic_block_order_nums);
-  ira_free (chain_arr);
-}
-
-
-
 /* All natural loops.  */
 struct loops ira_loops;
 
@@ -1966,9 +1871,6 @@ ira (FILE *f)
   df_set_flags (DF_NO_INSN_RESCAN);
   build_insn_chain ();
 
-  if (optimize)
-    ira_sort_insn_chain (true);
-
   reload_completed = !reload (get_insns (), optimize > 0);
 
   timevar_pop (TV_RELOAD);
Index: ira.h
===================================================================
--- ira.h	(revision 139939)
+++ ira.h	(working copy)
@@ -24,7 +24,6 @@ extern void ira_init_once (void);
 extern void ira_init (void);
 extern void ira_finish_once (void);
 extern rtx ira_eliminate_regs (rtx, enum machine_mode);
-extern void ira_sort_insn_chain (bool);
 
 extern void ira_sort_regnos_for_alter_reg (int *, int, unsigned int *);
 extern void ira_mark_allocation_change (int);
Index: reload1.c
===================================================================
--- reload1.c	(revision 139939)
+++ reload1.c	(working copy)
@@ -1118,11 +1118,6 @@ reload (rtx first, int global)
       obstack_free (&reload_obstack, reload_firstobj);
     }
 
-  if (flag_ira && optimize)
-    /* Restore the original insn chain order for correct reload work
-       (e.g. for correct inheritance).  */
-    ira_sort_insn_chain (false);
-
   /* If global-alloc was run, notify it of any register eliminations we have
      done.  */
   if (global)