re PR c/86617 (Volatile qualifier is ignored sometimes for unsigned char)

gcc:
2018-07-23  Bernd Edlinger  <bernd.edlinger@hotmail.de>

        PR c/86617
        * genmatch.c (dt_operand::gen_match_op): Avoid folding volatile values.

testsuite:
2018-07-23  Bernd Edlinger  <bernd.edlinger@hotmail.de>

        PR c/86617
        * gcc.dg/pr86617.c: New test.

From-SVN: r262933

gcc/ChangeLog

 2018-07-23  Bernd Edlinger  <bernd.edlinger@hotmail.de>
 
+	PR c/86617
+	* genmatch.c (dt_operand::gen_match_op): Avoid folding volatile values.
+
+2018-07-23  Bernd Edlinger  <bernd.edlinger@hotmail.de>
+
 	* gimple-fold.c (gimple_fold_builtin_printf): Don't create a not NUL
 	terminated STRING_CST object.
 

gcc/genmatch.c

@@ -2748,12 +2748,14 @@ dt_operand::gen_match_op (FILE *f, int indent, const char *opname, bool)
   char match_opname[20];
   match_dop->get_name (match_opname);
   if (value_match)
-    fprintf_indent (f, indent, "if (%s == %s || operand_equal_p (%s, %s, 0))\n",
-		    opname, match_opname, opname, match_opname);
+    fprintf_indent (f, indent, "if ((%s == %s && ! TREE_SIDE_EFFECTS (%s)) "
+		    "|| operand_equal_p (%s, %s, 0))\n",
+		    opname, match_opname, opname, opname, match_opname);
   else
-    fprintf_indent (f, indent, "if (%s == %s || (operand_equal_p (%s, %s, 0) "
+    fprintf_indent (f, indent, "if ((%s == %s && ! TREE_SIDE_EFFECTS (%s)) "
+		    "|| (operand_equal_p (%s, %s, 0) "
 		    "&& types_match (%s, %s)))\n",
-		    opname, match_opname, opname, match_opname,
+		    opname, match_opname, opname, opname, match_opname,
 		    opname, match_opname);
   fprintf_indent (f, indent + 2, "{\n");
   return 1;

gcc/testsuite/ChangeLog

+2018-07-23  Bernd Edlinger  <bernd.edlinger@hotmail.de>
+
+	PR c/86617
+	* gcc.dg/pr86617.c: New test.
+
 2018-07-23  Jakub Jelinek  <jakub@redhat.com>
 
 	PR c++/86569

gcc/testsuite/gcc.dg/pr86617.c

+/* { dg-options "-Os -fdump-rtl-final" } */
+
+volatile unsigned char u8;
+
+void test (void)
+{
+  u8 = u8 + u8;
+  u8 = u8 - u8;
+}
+
+/* { dg-final { scan-rtl-dump-times "mem/v" 6 "final" } } */