re PR tree-optimization/37542 (PRE doesn't simplify during phi-translation)

2008-11-02  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/37542
	* tree-ssa-pre.c (fully_constant_expression): Handle more cases.
	* tree-ssa-sccvn.c (vn_get_expr_for): Fix typo.
	(vn_nary_op_lookup_stmt): Adjust for unary reference trees.
	(vn_nary_op_insert_stmt): Likewise.
	(visit_use): Likewise.

	* gcc.dg/tree-ssa/ssa-pre-22.c: New testcase.
	* gcc.c-torture/compile/20081101-1.c: Likewise.

From-SVN: r141534

gcc/ChangeLog

+2008-11-02  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/37542
+	* tree-ssa-pre.c (fully_constant_expression): Handle more cases.
+	* tree-ssa-sccvn.c (vn_get_expr_for): Fix typo.
+	(vn_nary_op_lookup_stmt): Adjust for unary reference trees.
+	(vn_nary_op_insert_stmt): Likewise.
+	(visit_use): Likewise.
+
 2008-11-02  Anatoly Sokolov  <aesok@post.ru>
 
 	* config/avr/avr.md (UNSPEC_SWAP): Remove constants.

gcc/testsuite/ChangeLog

 2008-11-02  Richard Guenther  <rguenther@suse.de>
 
+	PR tree-optimization/37542
+	* gcc.dg/tree-ssa/ssa-pre-22.c: New testcase.
+	* gcc.c-torture/compile/20081101-1.c: Likewise.
+
+2008-11-02  Richard Guenther  <rguenther@suse.de>
+
 	PR tree-optimization/37991
 	* gcc.c-torture/compile/pr37991.c: New testcase.
 

gcc/testsuite/gcc.c-torture/compile/20081101-1.c

+int foo (int i, int b)
+{
+  int mask;
+  int result;
+  if (b)
+    mask = -1;
+  else
+    mask = 0;
+  result = i + 1;
+  result = result & mask;
+  return result;
+}

gcc/testsuite/gcc.dg/tree-ssa/ssa-pre-22.c

+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-pre-stats" } */
+
+int foo (int i, int b)
+{
+  int j = 1;
+  if (b)
+    j = i;
+  return j - i;
+}
+
+/* { dg-final { scan-tree-dump "Eliminated: 1" "pre" } } */
+/* { dg-final { cleanup-tree-dump "pre" } } */

gcc/tree-ssa-pre.c

@@ -1088,47 +1088,59 @@ fully_constant_expression (pre_expr e)
 	vn_nary_op_t nary = PRE_EXPR_NARY (e);
 	switch (TREE_CODE_CLASS (nary->opcode))
 	  {
+	  case tcc_expression:
+	    if (nary->opcode == TRUTH_NOT_EXPR)
+	      goto do_unary;
+	    if (nary->opcode != TRUTH_AND_EXPR
+		&& nary->opcode != TRUTH_OR_EXPR
+		&& nary->opcode != TRUTH_XOR_EXPR)
+	      return e;
+	    /* Fallthrough.  */
 	  case tcc_binary:
+	  case tcc_comparison:
 	    {
 	      /* We have to go from trees to pre exprs to value ids to
 		 constants.  */
 	      tree naryop0 = nary->op[0];
 	      tree naryop1 = nary->op[1];
-	      tree const0, const1, result;
-	      if (is_gimple_min_invariant (naryop0))
-		const0 = naryop0;
-	      else
+	      tree result;
+	      if (!is_gimple_min_invariant (naryop0))
 		{
 		  pre_expr rep0 = get_or_alloc_expr_for (naryop0);
 		  unsigned int vrep0 = get_expr_value_id (rep0);
-		  const0 = get_constant_for_value_id (vrep0);
+		  tree const0 = get_constant_for_value_id (vrep0);
+		  if (const0)
+		    naryop0 = fold_convert (TREE_TYPE (naryop0), const0);
 		}
-	      if (is_gimple_min_invariant (naryop1))
-		const1 = naryop1;
-	      else
+	      if (!is_gimple_min_invariant (naryop1))
 		{
 		  pre_expr rep1 = get_or_alloc_expr_for (naryop1);
 		  unsigned int vrep1 = get_expr_value_id (rep1);
-		  const1 = get_constant_for_value_id (vrep1);
-		}
-	      result = NULL;
-	      if (const0 && const1)
-		{
-		  tree type1 = TREE_TYPE (nary->op[0]);
-		  tree type2 = TREE_TYPE (nary->op[1]);
-		  const0 = fold_convert (type1, const0);
-		  const1 = fold_convert (type2, const1);
-		  result = fold_binary (nary->opcode, nary->type, const0,
-					const1);
+		  tree const1 = get_constant_for_value_id (vrep1);
+		  if (const1)
+		    naryop1 = fold_convert (TREE_TYPE (naryop1), const1);
 		}
+	      result = fold_binary (nary->opcode, nary->type,
+				    naryop0, naryop1);
 	      if (result && is_gimple_min_invariant (result))
 		return get_or_alloc_expr_for_constant (result);
+	      /* We might have simplified the expression to a
+		 SSA_NAME for example from x_1 * 1.  But we cannot
+		 insert a PHI for x_1 unconditionally as x_1 might
+		 not be available readily.  */
 	      return e;
 	    }
+	  case tcc_reference:
+	    if (nary->opcode != REALPART_EXPR
+		&& nary->opcode != IMAGPART_EXPR 
+		&& nary->opcode != VIEW_CONVERT_EXPR)
+	      return e;
+	    /* Fallthrough.  */
 	  case tcc_unary:
+do_unary:
 	    {
-	    /* We have to go from trees to pre exprs to value ids to
-	       constants.  */
+	      /* We have to go from trees to pre exprs to value ids to
+		 constants.  */
 	      tree naryop0 = nary->op[0];
 	      tree const0, result;
 	      if (is_gimple_min_invariant (naryop0))
@@ -1146,7 +1158,6 @@ fully_constant_expression (pre_expr e)
 		  const0 = fold_convert (type1, const0);
 		  result = fold_unary (nary->opcode, nary->type, const0);
 		}
-	      
 	      if (result && is_gimple_min_invariant (result))
 		return get_or_alloc_expr_for_constant (result);
 	      return e;

gcc/tree-ssa-sccvn.c

@@ -258,8 +258,8 @@ vn_get_expr_for (tree name)
     {
     case tcc_reference:
       if (gimple_assign_rhs_code (def_stmt) == VIEW_CONVERT_EXPR
-	  && gimple_assign_rhs_code (def_stmt) == REALPART_EXPR
-	  && gimple_assign_rhs_code (def_stmt) == IMAGPART_EXPR)
+	  || gimple_assign_rhs_code (def_stmt) == REALPART_EXPR
+	  || gimple_assign_rhs_code (def_stmt) == IMAGPART_EXPR)
 	expr = fold_build1 (gimple_assign_rhs_code (def_stmt),
 			    gimple_expr_type (def_stmt),
 			    TREE_OPERAND (gimple_assign_rhs1 (def_stmt), 0));
@@ -1281,6 +1281,10 @@ vn_nary_op_lookup_stmt (gimple stmt, vn_nary_op_t *vnresult)
   vno1.type = TREE_TYPE (gimple_assign_lhs (stmt));
   for (i = 0; i < vno1.length; ++i)
     vno1.op[i] = gimple_op (stmt, i + 1);
+  if (vno1.opcode == REALPART_EXPR
+      || vno1.opcode == IMAGPART_EXPR
+      || vno1.opcode == VIEW_CONVERT_EXPR)
+    vno1.op[0] = TREE_OPERAND (vno1.op[0], 0);
   vno1.hashcode = vn_nary_op_compute_hash (&vno1);
   slot = htab_find_slot_with_hash (current_info->nary, &vno1, vno1.hashcode,
 				   NO_INSERT);
@@ -1385,6 +1389,10 @@ vn_nary_op_insert_stmt (gimple stmt, tree result)
   vno1->type = TREE_TYPE (gimple_assign_lhs (stmt));
   for (i = 0; i < vno1->length; ++i)
     vno1->op[i] = gimple_op (stmt, i + 1);
+  if (vno1->opcode == REALPART_EXPR
+      || vno1->opcode == IMAGPART_EXPR
+      || vno1->opcode == VIEW_CONVERT_EXPR)
+    vno1->op[0] = TREE_OPERAND (vno1->op[0], 0);
   vno1->result = result;
   vno1->hashcode = vn_nary_op_compute_hash (vno1);
   slot = htab_find_slot_with_hash (current_info->nary, vno1, vno1->hashcode,
@@ -2380,8 +2388,18 @@ visit_use (tree use)
 		    case GIMPLE_SINGLE_RHS:
 		      switch (TREE_CODE_CLASS (gimple_assign_rhs_code (stmt)))
 			{
-			case tcc_declaration:
 			case tcc_reference:
+			  /* VOP-less references can go through unary case.  */
+			  if ((gimple_assign_rhs_code (stmt) == REALPART_EXPR
+			       || gimple_assign_rhs_code (stmt) == IMAGPART_EXPR
+			       || gimple_assign_rhs_code (stmt) == VIEW_CONVERT_EXPR )
+			      && TREE_CODE (TREE_OPERAND (gimple_assign_rhs1 (stmt), 0)) == SSA_NAME)
+			    {
+			      changed = visit_unary_op (lhs, stmt);
+			      break;
+			    }
+			  /* Fallthrough.  */
+			case tcc_declaration:
 			  changed = visit_reference_op_load
 			      (lhs, gimple_assign_rhs1 (stmt), stmt);
 			  break;