re PR tree-optimization/52548 (missed PRE optimization when function call follows to-be hoisted variable)

2012-03-22  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/52548
	* tree-ssa-pre.c (valid_in_sets): Remove handling of invalidation
	because of clobbers.
	(prune_clobbered_mems): New function.
	(compute_antic_aux): Use it to prune ANTIC_OUT.
	(compute_partial_antic_aux): Use it to prune PA_IN.
	(compute_avail): Only insert expressions into EXP_GEN that
	are not invalidated when translated up to the beginning of
	the block.

	* gcc.dg/tree-ssa/ssa-pre-29.c: New testcase.

From-SVN: r185691

gcc/ChangeLog

@@ -1,3 +1,15 @@
+2012-03-22  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/52548
+	* tree-ssa-pre.c (valid_in_sets): Remove handling of invalidation
+	because of clobbers.
+	(prune_clobbered_mems): New function.
+	(compute_antic_aux): Use it to prune ANTIC_OUT.
+	(compute_partial_antic_aux): Use it to prune PA_IN.
+	(compute_avail): Only insert expressions into EXP_GEN that
+	are not invalidated when translated up to the beginning of
+	the block.
+
 2012-03-22  Richard Guenther  <rguenther@suse.de>
 
 	PR tree-optimization/52638

gcc/testsuite/ChangeLog

@@ -1,3 +1,8 @@
+2012-03-22  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/52548
+	* gcc.dg/tree-ssa/ssa-pre-29.c: New testcase.
+
 2012-03-22  Bernhard Reutner-Fischer  <aldot@gcc.gnu.org>
 
 	* lib/fortran-modules.exp (list-module-names-1): Remove

gcc/testsuite/gcc.dg/tree-ssa/ssa-pre-29.c

@@ -0,0 +1,21 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-pre-details" } */
+
+int flag, hoist, y, z;
+
+void
+foo (void)
+{
+  if (flag)
+    y = hoist + 4;
+  else
+    flag = 888;
+  z = hoist + 4;
+  bark ();
+}
+
+/* We should see the partial redundancy of hoist + 4, not being confused
+   about bark () possibly clobbering hoist.  */
+
+/* { dg-final { scan-tree-dump "Replaced hoist" "pre" } } */
+/* { dg-final { cleanup-tree-dump "pre" } } */

gcc/tree-ssa-pre.c

@@ -2123,16 +2123,7 @@ valid_in_sets (bitmap_set_t set1, bitmap_set_t set2, pre_expr expr,
 	    if (!vro_valid_in_sets (set1, set2, vro))
 	      return false;
 	  }
-	if (ref->vuse)
+	return true;
-	  {
-	    gimple def_stmt = SSA_NAME_DEF_STMT (ref->vuse);
-	    if (!gimple_nop_p (def_stmt)
-		&& gimple_bb (def_stmt) != block
-		&& !dominated_by_p (CDI_DOMINATORS,
-				    block, gimple_bb (def_stmt)))
-	      return false;
-	  }
-	return !value_dies_in_block_x (expr, block);
       }
     default:
       gcc_unreachable ();
@@ -2179,6 +2170,38 @@ clean (bitmap_set_t set, basic_block block)
   VEC_free (pre_expr, heap, exprs);
 }
 
+/* Clean the set of expressions that are no longer valid in SET because
+   they are clobbered in BLOCK.  */
+
+static void
+prune_clobbered_mems (bitmap_set_t set, basic_block block)
+{
+  VEC (pre_expr, heap) *exprs = sorted_array_from_bitmap_set (set);
+  pre_expr expr;
+  int i;
+
+  FOR_EACH_VEC_ELT (pre_expr, exprs, i, expr)
+    {
+      vn_reference_t ref;
+      if (expr->kind != REFERENCE)
+	continue;
+
+      ref = PRE_EXPR_REFERENCE (expr);
+      if (ref->vuse)
+	{
+	  gimple def_stmt = SSA_NAME_DEF_STMT (ref->vuse);
+	  if (!gimple_nop_p (def_stmt)
+	      && ((gimple_bb (def_stmt) != block
+		   && !dominated_by_p (CDI_DOMINATORS,
+				       block, gimple_bb (def_stmt)))
+		  || (gimple_bb (def_stmt) == block
+		      && value_dies_in_block_x (expr, block))))
+	    bitmap_remove_from_set (set, expr);
+	}
+    }
+  VEC_free (pre_expr, heap, exprs);
+}
+
 static sbitmap has_abnormal_preds;
 
 /* List of blocks that may have changed during ANTIC computation and
@@ -2320,6 +2343,10 @@ compute_antic_aux (basic_block block, bool block_has_abnormal_pred_edge)
       VEC_free (basic_block, heap, worklist);
     }
 
+  /* Prune expressions that are clobbered in block and thus become
+     invalid if translated from ANTIC_OUT to ANTIC_IN.  */
+  prune_clobbered_mems (ANTIC_OUT, block);
+
   /* Generate ANTIC_OUT - TMP_GEN.  */
   S = bitmap_set_subtract (ANTIC_OUT, TMP_GEN (block));
 
@@ -2474,6 +2501,10 @@ compute_partial_antic_aux (basic_block block,
       VEC_free (basic_block, heap, worklist);
     }
 
+  /* Prune expressions that are clobbered in block and thus become
+     invalid if translated from PA_OUT to PA_IN.  */
+  prune_clobbered_mems (PA_OUT, block);
+
   /* PA_IN starts with PA_OUT - TMP_GEN.
      Then we subtract things from ANTIC_IN.  */
   PA_IN (block) = bitmap_set_subtract (PA_OUT, TMP_GEN (block));
@@ -4027,6 +4058,16 @@ compute_avail (void)
 		    if (vro->op2 && TREE_CODE (vro->op2) == SSA_NAME)
 		      add_to_exp_gen (block, vro->op2);
 		  }
+
+		/* If the value of the call is not invalidated in
+		   this block until it is computed, add the expression
+		   to EXP_GEN.  */
+		if (!gimple_vuse (stmt)
+		    || gimple_code
+		         (SSA_NAME_DEF_STMT (gimple_vuse (stmt))) == GIMPLE_PHI
+		    || gimple_bb (SSA_NAME_DEF_STMT
+				    (gimple_vuse (stmt))) != block)
+		  {
 		    result = (pre_expr) pool_alloc (pre_expr_pool);
 		    result->kind = REFERENCE;
 		    result->id = 0;
@@ -4036,6 +4077,7 @@ compute_avail (void)
 		    add_to_value (get_expr_value_id (result), result);
 		    if (!in_fre)
 		      bitmap_value_insert_into_set (EXP_GEN (block), result);
+		  }
 		continue;
 	      }
 
@@ -4095,6 +4137,32 @@ compute_avail (void)
 			  if (vro->op2 && TREE_CODE (vro->op2) == SSA_NAME)
 			    add_to_exp_gen (block, vro->op2);
 			}
+
+		      /* If the value of the reference is not invalidated in
+			 this block until it is computed, add the expression
+			 to EXP_GEN.  */
+		      if (gimple_vuse (stmt))
+			{
+			  gimple def_stmt;
+			  bool ok = true;
+			  def_stmt = SSA_NAME_DEF_STMT (gimple_vuse (stmt));
+			  while (!gimple_nop_p (def_stmt)
+				 && gimple_code (def_stmt) != GIMPLE_PHI
+				 && gimple_bb (def_stmt) == block)
+			    {
+			      if (stmt_may_clobber_ref_p
+				    (def_stmt, gimple_assign_rhs1 (stmt)))
+				{
+				  ok = false;
+				  break;
+				}
+			      def_stmt
+				= SSA_NAME_DEF_STMT (gimple_vuse (def_stmt));
+			    }
+			  if (!ok)
+			    continue;
+			}
+
 		      result = (pre_expr) pool_alloc (pre_expr_pool);
 		      result->kind = REFERENCE;
 		      result->id = 0;