[PATCH] Fix PR80281

[Richard Biener]

The following fixes PR80281.

Bootstrapped on x86_64-unknown-linux-gnu, testing in progress.

Richard.

2017-04-03  Richard Biener  <rguent...@suse.de>

        PR middle-end/80281
        * match.pd (A + (-B) -> A - B): Make sure to preserve unsigned
        arithmetic done for the negate or the plus.
        * fold-const.c (split_tree): Make sure to not negate pointers.

        * gcc.dg/torture/pr80281.c: New testcase.

Index: gcc/match.pd
===================================================================
--- gcc/match.pd        (revision 246642)
+++ gcc/match.pd        (working copy)
@@ -1153,7 +1153,14 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
   (if (tree_nop_conversion_p (type, TREE_TYPE (@0))
        && tree_nop_conversion_p (type, TREE_TYPE (@1))
        && !TYPE_OVERFLOW_SANITIZED (type))
-   (minus (convert @0) (convert @1))))
+   (with
+    {
+     tree t1 = type;
+     if (INTEGRAL_TYPE_P (type)
+        && TYPE_OVERFLOW_WRAPS (type) != TYPE_OVERFLOW_WRAPS (TREE_TYPE (@1)))
+       t1 = TYPE_OVERFLOW_WRAPS (type) ? type : TREE_TYPE (@1);
+    }
+    (convert (minus (convert:t1 @0) (convert:t1 @1))))))
  /* A - (-B) -> A + B */
  (simplify
   (minus (convert1? @0) (convert2? (negate @1)))
Index: gcc/fold-const.c
===================================================================
--- gcc/fold-const.c    (revision 246642)
+++ gcc/fold-const.c    (working copy)
@@ -831,8 +831,12 @@ split_tree (location_t loc, tree in, tre
       /* Now do any needed negations.  */
       if (neg_litp_p)
        *minus_litp = *litp, *litp = 0;
-      if (neg_conp_p)
-       *conp = negate_expr (*conp);
+      if (neg_conp_p && *conp)
+       {
+         /* Convert to TYPE before negating.  */
+         *conp = fold_convert_loc (loc, type, *conp);
+         *conp = negate_expr (*conp);
+       }
       if (neg_var_p && var)
        {
          /* Convert to TYPE before negating.  */
@@ -859,7 +863,12 @@ split_tree (location_t loc, tree in, tre
        *minus_litp = *litp, *litp = 0;
       else if (*minus_litp)
        *litp = *minus_litp, *minus_litp = 0;
-      *conp = negate_expr (*conp);
+      if (*conp)
+       {
+         /* Convert to TYPE before negating.  */
+         *conp = fold_convert_loc (loc, type, *conp);
+         *conp = negate_expr (*conp);
+       }
       if (var)
        {
          /* Convert to TYPE before negating.  */
Index: gcc/testsuite/gcc.dg/torture/pr80281.c
===================================================================
--- gcc/testsuite/gcc.dg/torture/pr80281.c      (revision 0)
+++ gcc/testsuite/gcc.dg/torture/pr80281.c      (working copy)
@@ -0,0 +1,14 @@
+/* { dg-run } */
+/* { dg-require-effective-target int32plus } */
+
+int
+main ()
+{
+  volatile int a = 0;
+  long long b = 2147483648LL;
+  int c = a % 2;
+  int x = ((int) -b + c) % -2147483647;
+  if (x != -1)
+    __builtin_abort ();
+  return 0;
+}