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
     {
@@ -2833,80 +2844,84 @@ 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)
 	    {
-	      rtx note, set;
+	      if (NONDEBUG_INSN_P (insn))
+		{
+		  rtx note, set;
 
 #if defined (HAVE_prologue) || defined (HAVE_epilogue)
-	      /* The prologue/epilogue insns are not threaded onto the
-		 insn chain until after reload has completed.  Thus,
-		 there is no sense wasting time checking if INSN is in
-		 the prologue/epilogue until after reload has completed.  */
-	      if (reload_completed
-		  && prologue_epilogue_contains (insn))
-		continue;
+		  /* The prologue/epilogue insns are not threaded onto the
+		     insn chain until after reload has completed.  Thus,
+		     there is no sense wasting time checking if INSN is in
+		     the prologue/epilogue until after reload has completed.  */
+		  if (reload_completed
+		      && prologue_epilogue_contains (insn))
+		    continue;
 #endif
 
-	      /* If this insn has a noalias note, process it,  Otherwise,
-		 scan for sets.  A simple set will have no side effects
-		 which could change the base value of any other register.  */
+		  /* If this insn has a noalias note, process it,  Otherwise,
+		     scan for sets.  A simple set will have no side effects
+		     which could change the base value of any other register.  */
 
-	      if (GET_CODE (PATTERN (insn)) == SET
-		  && REG_NOTES (insn) != 0
-		  && find_reg_note (insn, REG_NOALIAS, NULL_RTX))
-		record_set (SET_DEST (PATTERN (insn)), NULL_RTX, NULL);
-	      else
-		note_stores (PATTERN (insn), record_set, NULL);
+		  if (GET_CODE (PATTERN (insn)) == SET
+		      && REG_NOTES (insn) != 0
+		      && find_reg_note (insn, REG_NOALIAS, NULL_RTX))
+		    record_set (SET_DEST (PATTERN (insn)), NULL_RTX, NULL);
+		  else
+		    note_stores (PATTERN (insn), record_set, NULL);
 
-	      set = single_set (insn);
+		  set = single_set (insn);
 
-	      if (set != 0
-		  && REG_P (SET_DEST (set))
-		  && REGNO (SET_DEST (set)) >= FIRST_PSEUDO_REGISTER)
-		{
-		  unsigned int regno = REGNO (SET_DEST (set));
-		  rtx src = SET_SRC (set);
-		  rtx t;
-
-		  note = find_reg_equal_equiv_note (insn);
-		  if (note && REG_NOTE_KIND (note) == REG_EQUAL
-		      && DF_REG_DEF_COUNT (regno) != 1)
-		    note = NULL_RTX;
-
-		  if (note != NULL_RTX
-		      && GET_CODE (XEXP (note, 0)) != EXPR_LIST
-		      && ! rtx_varies_p (XEXP (note, 0), 1)
-		      && ! reg_overlap_mentioned_p (SET_DEST (set),
-						    XEXP (note, 0)))
-		    {
-		      set_reg_known_value (regno, XEXP (note, 0));
-		      set_reg_known_equiv_p (regno,
-			REG_NOTE_KIND (note) == REG_EQUIV);
-		    }
-		  else if (DF_REG_DEF_COUNT (regno) == 1
-			   && GET_CODE (src) == PLUS
-			   && REG_P (XEXP (src, 0))
-			   && (t = get_reg_known_value (REGNO (XEXP (src, 0))))
-			   && CONST_INT_P (XEXP (src, 1)))
-		    {
-		      t = plus_constant (GET_MODE (src), t,
-					 INTVAL (XEXP (src, 1)));
-		      set_reg_known_value (regno, t);
-		      set_reg_known_equiv_p (regno, false);
-		    }
-		  else if (DF_REG_DEF_COUNT (regno) == 1
-			   && ! rtx_varies_p (src, 1))
+		  if (set != 0
+		      && REG_P (SET_DEST (set))
+		      && REGNO (SET_DEST (set)) >= FIRST_PSEUDO_REGISTER)
 		    {
-		      set_reg_known_value (regno, src);
-		      set_reg_known_equiv_p (regno, false);
+		      unsigned int regno = REGNO (SET_DEST (set));
+		      rtx src = SET_SRC (set);
+		      rtx t;
+
+		      note = find_reg_equal_equiv_note (insn);
+		      if (note && REG_NOTE_KIND (note) == REG_EQUAL
+			  && DF_REG_DEF_COUNT (regno) != 1)
+			note = NULL_RTX;
+
+		      if (note != NULL_RTX
+			  && GET_CODE (XEXP (note, 0)) != EXPR_LIST
+			  && ! rtx_varies_p (XEXP (note, 0), 1)
+			  && ! reg_overlap_mentioned_p (SET_DEST (set),
+							XEXP (note, 0)))
+			{
+			  set_reg_known_value (regno, XEXP (note, 0));
+			  set_reg_known_equiv_p (regno,
+						 REG_NOTE_KIND (note) == REG_EQUIV);
+			}
+		      else if (DF_REG_DEF_COUNT (regno) == 1
+			       && GET_CODE (src) == PLUS
+			       && REG_P (XEXP (src, 0))
+			       && (t = get_reg_known_value (REGNO (XEXP (src, 0))))
+			       && CONST_INT_P (XEXP (src, 1)))
+			{
+			  t = plus_constant (GET_MODE (src), t,
+					     INTVAL (XEXP (src, 1)));
+			  set_reg_known_value (regno, t);
+			  set_reg_known_equiv_p (regno, false);
+			}
+		      else if (DF_REG_DEF_COUNT (regno) == 1
+			       && ! rtx_varies_p (src, 1))
+			{
+			  set_reg_known_value (regno, src);
+			  set_reg_known_equiv_p (regno, false);
+			}
 		    }
 		}
+	      else if (NOTE_P (insn)
+		       && NOTE_KIND (insn) == NOTE_INSN_FUNCTION_BEG)
+		copying_arguments = false;
 	    }
-	  else if (NOTE_P (insn)
-		   && NOTE_KIND (insn) == NOTE_INSN_FUNCTION_BEG)
-	    copying_arguments = false;
 	}
 
       /* Now propagate values from new_reg_base_value to reg_base_value.  */
@@ -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);