On Mon, 3 Apr 2017, Marc Glisse wrote:
> On Mon, 3 Apr 2017, Richard Biener wrote:
>
> > --- 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))))))
>
> Why do we match
> (plus:c (convert1? @0) (convert2? (negate @1)))
> instead of the simpler
> (plus:c @0 (convert? (negate @1)))
Hmm, historic I believe - matching forwprop code 1:1. The convert on
@0 is not needed indeed.
> > /* A - (-B) -> A + B */
>
> Actually, I believe this transformation has issues as well, it seems possible
> to transform X-INT_MIN into X+INT_MIN if INT_MIN comes as
> (int)(-(unsigned)INT_MIN).
True. So the same fix applies to this variant.
I'm re-testing the following variant.
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. Simplify.
(A - (-B) -> A + B): Likewise.
* 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 246648)
+++ gcc/match.pd (working copy)
@@ -1148,19 +1148,31 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
/* Contract negates. */
/* A + (-B) -> A - B */
(simplify
- (plus:c (convert1? @0) (convert2? (negate @1)))
- /* Apply STRIP_NOPS on @0 and the negate. */
- (if (tree_nop_conversion_p (type, TREE_TYPE (@0))
- && tree_nop_conversion_p (type, TREE_TYPE (@1))
+ (plus:c @0 (convert? (negate @1)))
+ /* Apply STRIP_NOPS on the negate. */
+ (if (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)))
- (if (tree_nop_conversion_p (type, TREE_TYPE (@0))
- && tree_nop_conversion_p (type, TREE_TYPE (@1))
+ (minus @0 (convert? (negate @1)))
+ (if (tree_nop_conversion_p (type, TREE_TYPE (@1))
&& !TYPE_OVERFLOW_SANITIZED (type))
- (plus (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 (plus (convert:t1 @0) (convert:t1 @1))))))
/* -(-A) -> A */
(simplify
(negate (convert? (negate @1)))
Index: gcc/fold-const.c
===================================================================
--- gcc/fold-const.c (revision 246648)
+++ 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 (nonexistent)
+++ 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;
+}
