re PR tree-optimization/86066 (wrong code for bit-field manipulation at -Os)

	PR tree-optimization/86066
	* gimple-ssa-store-merging.c (process_store): Do not bypass BIT_NOT_EXPR
	for BIT_INSERT_EXPR stores.

From-SVN: r261232

gcc/ChangeLog

+2018-06-06  Eric Botcazou  <ebotcazou@adacore.com>
+
+	PR tree-optimization/86066
+	* gimple-ssa-store-merging.c (process_store): Do not bypass BIT_NOT_EXPR
+	for BIT_INSERT_EXPR stores.
+
 2018-06-06  Richard Biener  <rguenther@suse.de>
 
 	PR tree-optimization/86062

gcc/gimple-ssa-store-merging.c

@@ -4333,7 +4333,9 @@ pass_store_merging::process_store (gimple *stmt)
 	  && const_bitsize <= 64)
 	{
 	  /* Bypass a conversion to the bit-field type.  */
-	  if (is_gimple_assign (def_stmt) && CONVERT_EXPR_CODE_P (rhs_code))
+	  if (!bit_not_p
+	      && is_gimple_assign (def_stmt)
+	      && CONVERT_EXPR_CODE_P (rhs_code))
 	    {
 	      tree rhs1 = gimple_assign_rhs1 (def_stmt);
 	      if (TREE_CODE (rhs1) == SSA_NAME
@@ -4341,6 +4343,7 @@ pass_store_merging::process_store (gimple *stmt)
 		rhs = rhs1;
 	    }
 	  rhs_code = BIT_INSERT_EXPR;
+	  bit_not_p = false;
 	  ops[0].val = rhs;
 	  ops[0].base_addr = NULL_TREE;
 	  ops[1].base_addr = NULL_TREE;

gcc/testsuite/ChangeLog

+2018-06-06  Eric Botcazou  <ebotcazou@adacore.com>
+
+	* gcc.dg/torture/pr86066.c: New test.
+
 2018-06-06  Richard Biener  <rguenther@suse.de>
 
 	PR tree-optimization/86062

gcc/testsuite/gcc.dg/torture/pr86066.c

+/* PR tree-optimization/86066 */
+/* Testcase by Zhendong Su <Zhendong Su> */
+
+struct A
+{
+  int b:2;
+  int c:2;
+  unsigned d:8;
+};
+
+int main ()
+{
+  struct A t = { 0, 0, 2 };
+ L:
+  t.d = ~(~(~0 % t.d) % 2);
+  if (!t.d)
+    goto L;
+  return 0;
+}