re PR tree-optimization/81555 (Wrong code at -O1)

PR tree-optimization/81555
	PR tree-optimization/81556
	* tree-ssa-reassoc.c (rewrite_expr_tree): Add NEXT_CHANGED argument,
	if true, force CHANGED for the recursive invocation.
	(reassociate_bb): Remember original length of ops array, pass
	len != orig_len as NEXT_CHANGED in rewrite_expr_tree call.

	* gcc.c-torture/execute/pr81555.c: New test.
	* gcc.c-torture/execute/pr81556.c: New test.

From-SVN: r250609

gcc/ChangeLog

@@ -1,5 +1,12 @@
 2017-07-27  Jakub Jelinek  <jakub@redhat.com>
 
+	PR tree-optimization/81555
+	PR tree-optimization/81556
+	* tree-ssa-reassoc.c (rewrite_expr_tree): Add NEXT_CHANGED argument,
+	if true, force CHANGED for the recursive invocation.
+	(reassociate_bb): Remember original length of ops array, pass
+	len != orig_len as NEXT_CHANGED in rewrite_expr_tree call.
+
 	* attribs.c (decl_attributes): Imply noinline, noclone and no_icf
 	attributes for noipa attribute.  For naked attribute use
 	lookup_attribute first before lookup_attribute_spec.

gcc/testsuite/ChangeLog

@@ -1,5 +1,10 @@
 2017-07-27  Jakub Jelinek  <jakub@redhat.com>
 
+	PR tree-optimization/81555
+	PR tree-optimization/81556
+	* gcc.c-torture/execute/pr81555.c: New test.
+	* gcc.c-torture/execute/pr81556.c: New test.
+
 	* gcc.dg/attr-noipa.c: New test.
 	* gcc.dg/ipa/ipa-pta-18.c: New test.
 	* gcc.dg/ipa/ipa-sra-11.c: New test.

gcc/testsuite/gcc.c-torture/execute/pr81555.c

@@ -0,0 +1,24 @@
+/* PR tree-optimization/81555 */
+
+unsigned int a = 1, d = 0xfaeU, e = 0xe376U;
+_Bool b = 0, f = 1;
+unsigned char g = 1;
+
+void
+foo (void)
+{
+  _Bool c = a != b;
+  if (c)
+    f = 0;
+  if (e & c & (unsigned char)d & c)
+    g = 0;
+}
+
+int
+main ()
+{
+  foo ();
+  if (f || g != 1)
+    __builtin_abort ();
+  return 0;
+}

gcc/testsuite/gcc.c-torture/execute/pr81556.c

@@ -0,0 +1,23 @@
+/* PR tree-optimization/81556 */
+
+unsigned long long int b = 0xb82ff73c5c020599ULL;
+unsigned long long int c = 0xd4e8188733a29d8eULL;
+unsigned long long int d = 2, f = 1, g = 0, h = 0;
+unsigned long long int e = 0xf27771784749f32bULL;
+
+__attribute__((noinline, noclone)) void
+foo (void)
+{
+  _Bool a = d > 1;
+  g = f % ((d > 1) << 9);
+  h = a & (e & (a & b & c));
+}
+
+int
+main ()
+{
+  foo ();
+  if (g != 1 || h != 0)
+    __builtin_abort ();
+  return 0;
+}

gcc/tree-ssa-reassoc.c

@@ -4205,11 +4205,15 @@ insert_stmt_before_use (gimple *stmt, gimple *stmt_to_insert)
 
 /* Recursively rewrite our linearized statements so that the operators
    match those in OPS[OPINDEX], putting the computation in rank
-   order.  Return new lhs.  */
+   order.  Return new lhs.
+   CHANGED is true if we shouldn't reuse the lhs SSA_NAME both in
+   the current stmt and during recursive invocations.
+   NEXT_CHANGED is true if we shouldn't reuse the lhs SSA_NAME in
+   recursive invocations.  */
 
 static tree
 rewrite_expr_tree (gimple *stmt, unsigned int opindex,
-		   vec<operand_entry *> ops, bool changed)
+		   vec<operand_entry *> ops, bool changed, bool next_changed)
 {
   tree rhs1 = gimple_assign_rhs1 (stmt);
   tree rhs2 = gimple_assign_rhs2 (stmt);
@@ -4300,7 +4304,8 @@ rewrite_expr_tree (gimple *stmt, unsigned int opindex,
      be the non-leaf side.  */
   tree new_rhs1
     = rewrite_expr_tree (SSA_NAME_DEF_STMT (rhs1), opindex + 1, ops,
-			 changed || oe->op != rhs2);
+			 changed || oe->op != rhs2 || next_changed,
+			 false);
 
   if (oe->op != rhs2 || new_rhs1 != rhs1)
     {
@@ -5654,6 +5659,7 @@ reassociate_bb (basic_block bb)
 	      gimple_set_visited (stmt, true);
 	      linearize_expr_tree (&ops, stmt, true, true);
 	      ops.qsort (sort_by_operand_rank);
+	      int orig_len = ops.length ();
 	      optimize_ops_list (rhs_code, &ops);
 	      if (undistribute_ops_list (rhs_code, &ops,
 					 loop_containing_stmt (stmt)))
@@ -5744,7 +5750,8 @@ reassociate_bb (basic_block bb)
 
 		      new_lhs = rewrite_expr_tree (stmt, 0, ops,
 						   powi_result != NULL
-						   || negate_result);
+						   || negate_result,
+						   len != orig_len);
                     }
 
 		  /* If we combined some repeated factors into a