tracer.c (mark_bb_seen): Use SBITMAP_SIZE.

	* tracer.c (mark_bb_seen): Use SBITMAP_SIZE.

	* alias.c (MAX_ALIAS_LOOP_PASSES): Update comment with rationale,
	or rather a lack thereof.
	(init_alias_analysis): Propagate the latest information across
	the CFG in topological order to propagate as far as possible in
	each iteration.  Ignore debug insns.

From-SVN: r190602

gcc/ChangeLog

+2012-08-22  Steven Bosscher  <steven@gcc.gnu.org>
+
+	* tracer.c (mark_bb_seen): Use SBITMAP_SIZE.
+
+	* alias.c (MAX_ALIAS_LOOP_PASSES): Update comment with rationale,
+	or rather a lack thereof.
+	(init_alias_analysis): Propagate the latest information across
+	the CFG in topological order to propagate as far as possible in
+	each iteration.  Ignore debug insns.
+
 2012-08-22  H.J. Lu  <hongjiu.lu@intel.com>
 
 	* doc/invoke.texi: Document -mlong-double-64/-mlong-double-80.

gcc/alias.c

@@ -168,7 +168,10 @@ static void memory_modified_1 (rtx, const_rtx, void *);
 #define SIZE_FOR_MODE(X) (GET_MODE_SIZE (GET_MODE (X)))
 
 /* Cap the number of passes we make over the insns propagating alias
-   information through set chains.   10 is a completely arbitrary choice.  */
+   information through set chains.
+   ??? 10 is a completely arbitrary choice.  This should be based on the
+   maximum loop depth in the CFG, but we do not have this information
+   available (even if current_loops _is_ available).  */
 #define MAX_ALIAS_LOOP_PASSES 10
 
 /* reg_base_value[N] gives an address to which register N is related.
@@ -2764,6 +2767,8 @@ init_alias_analysis (void)
   int i;
   unsigned int ui;
   rtx insn, val;
+  int rpo_cnt;
+  int *rpo;
 
   timevar_push (TV_ALIAS_ANALYSIS);
 
@@ -2786,6 +2791,9 @@ init_alias_analysis (void)
      "constant" information from the previous pass to propagate alias
      information through another level of assignments.
 
+     The propagation is done on the CFG in reverse post-order, to propagate
+     things forward as far as possible in each iteration.
+
      This could get expensive if the assignment chains are long.  Maybe
      we should throttle the number of iterations, possibly based on
      the optimization level or flag_expensive_optimizations.
@@ -2801,6 +2809,9 @@ init_alias_analysis (void)
      The state of the arrays for the set chain in question does not matter
      since the program has undefined behavior.  */
 
+  rpo = XNEWVEC (int, n_basic_blocks);
+  rpo_cnt = pre_and_rev_post_order_compute (NULL, rpo, false);
+
   pass = 0;
   do
     {
@@ -2833,9 +2844,12 @@ init_alias_analysis (void)
 	      FIRST_PSEUDO_REGISTER * sizeof (rtx));
 
       /* Walk the insns adding values to the new_reg_base_value array.  */
-      for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
+      for (i = 0; i < rpo_cnt; i++)
 	{
-	  if (INSN_P (insn))
+	  basic_block bb = BASIC_BLOCK (rpo[i]);
+	  FOR_BB_INSNS (bb, insn)
+	    {
+	      if (NONDEBUG_INSN_P (insn))
 		{
 		  rtx note, set;
 
@@ -2908,6 +2922,7 @@ init_alias_analysis (void)
 		       && NOTE_KIND (insn) == NOTE_INSN_FUNCTION_BEG)
 		copying_arguments = false;
 	    }
+	}
 
       /* Now propagate values from new_reg_base_value to reg_base_value.  */
       gcc_assert (maxreg == (unsigned int) max_reg_num ());
@@ -2925,6 +2940,7 @@ init_alias_analysis (void)
 	}
     }
   while (changed && ++pass < MAX_ALIAS_LOOP_PASSES);
+  XDELETEVEC (rpo);
 
   /* Fill in the remaining entries.  */
   FOR_EACH_VEC_ELT (rtx, reg_known_value, i, val)

gcc/tracer.c

@@ -69,7 +69,7 @@ sbitmap bb_seen;
 static inline void
 mark_bb_seen (basic_block bb)
 {
-  unsigned int size = SBITMAP_SIZE_BYTES (bb_seen) * 8;
+  unsigned int size = SBITMAP_SIZE (bb_seen);
 
   if ((unsigned int)bb->index >= size)
     bb_seen = sbitmap_resize (bb_seen, size * 2, 0);