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Submitter Richard Guenther
Date Nov. 29, 2012, 1:48 p.m.
Message ID <alpine.LNX.2.00.1211291447090.8142@zhemvz.fhfr.qr>
Download mbox | patch
Permalink /patch/202752/
State New
Headers show

Comments

Richard Guenther - Nov. 29, 2012, 1:48 p.m.
When working on PR55124 I noticed we do some useless work in PRE.
This cleans it up and makes it more obvious what we do in compute_avail.

Bootstrapped and tested on x86_64-unknown-linux-gnu, applied to trunk.

Richard.

2012-11-29  Richard Biener  <rguenther@suse.de>

	* tree-ssa-pre.c (get_expr_value_id): Do not add expr
	to the set of value expressions here.
	(add_to_exp_gen, make_values_for_phi): Fold into ...
	(compute_avail): ... here, and avoid useless work.  Dump
	avail sets in processing order.
	(do_pre): Do not dump avail sets here.

Patch

Index: gcc/tree-ssa-pre.c
===================================================================
--- gcc/tree-ssa-pre.c	(revision 193932)
+++ gcc/tree-ssa-pre.c	(working copy)
@@ -612,28 +612,28 @@  bitmap_set_new (void)
 static unsigned int
 get_expr_value_id (pre_expr expr)
 {
+  unsigned int id;
   switch (expr->kind)
     {
     case CONSTANT:
-      {
-	unsigned int id;
-	id = get_constant_value_id (PRE_EXPR_CONSTANT (expr));
-	if (id == 0)
-	  {
-	    id = get_or_alloc_constant_value_id (PRE_EXPR_CONSTANT (expr));
-	    add_to_value (id, expr);
-	  }
-	return id;
-      }
+      id = get_or_alloc_constant_value_id (PRE_EXPR_CONSTANT (expr));
+      break;
     case NAME:
-      return VN_INFO (PRE_EXPR_NAME (expr))->value_id;
+      id = VN_INFO (PRE_EXPR_NAME (expr))->value_id;
+      break;
     case NARY:
-      return PRE_EXPR_NARY (expr)->value_id;
+      id = PRE_EXPR_NARY (expr)->value_id;
+      break;
     case REFERENCE:
-      return PRE_EXPR_REFERENCE (expr)->value_id;
+      id = PRE_EXPR_REFERENCE (expr)->value_id;
+      break;
     default:
       gcc_unreachable ();
     }
+  /* ???  We cannot assert that expr has a value-id (it can be 0), because
+     we assign value-ids only to expressions that have a result
+     in set_hashtable_value_ids.  */
+  return id;
 }
 
 /* Return a SCCVN valnum (SSA name or constant) for the PRE value-id VAL.  */
@@ -3624,48 +3624,6 @@  insert (void)
 }
 
 
-/* Add OP to EXP_GEN (block), and possibly to the maximal set.  */
-
-static void
-add_to_exp_gen (basic_block block, tree op)
-{
-  pre_expr result;
-
-  if (TREE_CODE (op) == SSA_NAME && ssa_undefined_value_p (op))
-    return;
-
-  result = get_or_alloc_expr_for_name (op);
-  bitmap_value_insert_into_set (EXP_GEN (block), result);
-}
-
-/* Create value ids for PHI in BLOCK.  */
-
-static void
-make_values_for_phi (gimple phi, basic_block block)
-{
-  tree result = gimple_phi_result (phi);
-  unsigned i;
-
-  /* We have no need for virtual phis, as they don't represent
-     actual computations.  */
-  if (virtual_operand_p (result))
-    return;
-
-  pre_expr e = get_or_alloc_expr_for_name (result);
-  add_to_value (get_expr_value_id (e), e);
-  bitmap_value_insert_into_set (AVAIL_OUT (block), e);
-  bitmap_insert_into_set (PHI_GEN (block), e);
-  for (i = 0; i < gimple_phi_num_args (phi); ++i)
-    {
-      tree arg = gimple_phi_arg_def (phi, i);
-      if (TREE_CODE (arg) == SSA_NAME)
-	{
-	  e = get_or_alloc_expr_for_name (arg);
-	  add_to_value (get_expr_value_id (e), e);
-	}
-    }
-}
-
 /* Compute the AVAIL set for all basic blocks.
 
    This function performs value numbering of the statements in each basic
@@ -3703,6 +3661,14 @@  compute_avail (void)
       bitmap_value_insert_into_set (AVAIL_OUT (ENTRY_BLOCK_PTR), e);
     }
 
+  if (dump_file && (dump_flags & TDF_DETAILS))
+    {
+      print_bitmap_set (dump_file, TMP_GEN (ENTRY_BLOCK_PTR),
+			"tmp_gen", ENTRY_BLOCK);
+      print_bitmap_set (dump_file, AVAIL_OUT (ENTRY_BLOCK_PTR),
+			"avail_out", ENTRY_BLOCK);
+    }
+
   /* Allocate the worklist.  */
   worklist = XNEWVEC (basic_block, n_basic_blocks);
 
@@ -3731,7 +3697,19 @@  compute_avail (void)
 
       /* Generate values for PHI nodes.  */
       for (gsi = gsi_start_phis (block); !gsi_end_p (gsi); gsi_next (&gsi))
-	make_values_for_phi (gsi_stmt (gsi), block);
+	{
+	  tree result = gimple_phi_result (gsi_stmt (gsi));
+
+	  /* We have no need for virtual phis, as they don't represent
+	     actual computations.  */
+	  if (virtual_operand_p (result))
+	    continue;
+
+	  pre_expr e = get_or_alloc_expr_for_name (result);
+	  add_to_value (get_expr_value_id (e), e);
+	  bitmap_value_insert_into_set (AVAIL_OUT (block), e);
+	  bitmap_insert_into_set (PHI_GEN (block), e);
+	}
 
       BB_MAY_NOTRETURN (block) = 0;
 
@@ -3775,7 +3753,12 @@  compute_avail (void)
 	    continue;
 
 	  FOR_EACH_SSA_TREE_OPERAND (op, stmt, iter, SSA_OP_USE)
-	    add_to_exp_gen (block, op);
+	    {
+	      if (ssa_undefined_value_p (op))
+		continue;
+	      pre_expr e = get_or_alloc_expr_for_name (op);
+	      bitmap_value_insert_into_set (EXP_GEN (block), e);
+	    }
 
 	  switch (gimple_code (stmt))
 	    {
@@ -3911,6 +3894,18 @@  compute_avail (void)
 	    }
 	}
 
+      if (dump_file && (dump_flags & TDF_DETAILS))
+	{
+	  print_bitmap_set (dump_file, EXP_GEN (block),
+			    "exp_gen", block->index);
+	  print_bitmap_set (dump_file, PHI_GEN (block),
+			    "phi_gen", block->index);
+	  print_bitmap_set (dump_file, TMP_GEN (block),
+			    "tmp_gen", block->index);
+	  print_bitmap_set (dump_file, AVAIL_OUT (block),
+			    "avail_out", block->index);
+	}
+
       /* Put the dominator children of BLOCK on the worklist of blocks
 	 to compute available sets for.  */
       for (son = first_dom_son (CDI_DOMINATORS, block);
@@ -4667,22 +4662,6 @@  do_pre (void)
   /* Collect and value number expressions computed in each basic block.  */
   compute_avail ();
 
-  if (dump_file && (dump_flags & TDF_DETAILS))
-    {
-      basic_block bb;
-      FOR_ALL_BB (bb)
-	{
-	  print_bitmap_set (dump_file, EXP_GEN (bb),
-			    "exp_gen", bb->index);
-	  print_bitmap_set (dump_file, PHI_GEN (bb),
-			    "phi_gen", bb->index);
-	  print_bitmap_set (dump_file, TMP_GEN (bb),
-			    "tmp_gen", bb->index);
-	  print_bitmap_set (dump_file, AVAIL_OUT (bb),
-			    "avail_out", bb->index);
-	}
-    }
-
   /* Insert can get quite slow on an incredibly large number of basic
      blocks due to some quadratic behavior.  Until this behavior is
      fixed, don't run it when he have an incredibly large number of