On May 19, 2016 5:14:24 PM GMT+02:00, Marek Polacek <pola...@redhat.com> wrote:
>On Thu, May 19, 2016 at 03:54:05PM +0200, Richard Biener wrote:
>> On Thu, 19 May 2016, Marek Polacek wrote:
>>
>> > Since Bin's changes to the niter analysis in r231097, we find
>ourselves in
>> > a situation where extract_range_from_binary_expr is given [1, od_5]
>+ UINT_MAX
>> > on type unsigned. We combine the lower bounds, which is 1 +
>UINT_MAX = 0(OVF).
>> > We then combine the upper bounds, because the max_op0 is not a
>constant, the
>> > result of that is UINT_MAX. That results in min overflow -- and an
>assert is
>> > unhappy about that. As suggested in the PR, a safe thing would be
>to change
>> > the assert to dropping to varying.
>> >
>> > Bootstrapped/regtested on x86_64-linux, ok for trunk and 6?
>>
>> Ok if you leave the assert in (there is at least one unhandled case,
>> min_ovf == 1 && max_ovf == -1).
>>
>> Alternatively make the code match the comment and drop the
>> == 0 checks in your added condition. Which would suggest
>> to make the else { an else if (asserted condition) and common
>> the varying case to else { }.
>
>Oh, this is indeed better. So like this?
Yes.
Thanks,
Richard.
>Bootstrapped/regtested on x86_64-linux, ok for trunk and 6?
>
>2016-05-19 Marek Polacek <pola...@redhat.com>
>
> PR tree-optimization/71031
> * tree-vrp.c (extract_range_from_binary_expr_1): Turn assert into a
> condition and adjust the code a bit.
>
> * gcc.dg/tree-ssa/vrp100.c: New test.
>
>diff --git gcc/testsuite/gcc.dg/tree-ssa/vrp100.c
>gcc/testsuite/gcc.dg/tree-ssa/vrp100.c
>index e69de29..c0fe4b5 100644
>--- gcc/testsuite/gcc.dg/tree-ssa/vrp100.c
>+++ gcc/testsuite/gcc.dg/tree-ssa/vrp100.c
>@@ -0,0 +1,32 @@
>+/* PR tree-optimization/71031 */
>+/* { dg-do compile } */
>+/* { dg-options "-Os" } */
>+
>+int zj;
>+int **yr;
>+
>+void
>+nn (void)
>+{
>+ unsigned int od = 4;
>+
>+ for (;;)
>+ {
>+ int lk;
>+
>+ for (lk = 0; lk < 2; ++lk)
>+ {
>+ static int cm;
>+
>+ zj = 0;
>+ if (od == 0)
>+ return;
>+ ++od;
>+ for (cm = 0; cm < 2; ++cm)
>+ {
>+ --od;
>+ **yr = 0;
>+ }
>+ }
>+ }
>+}
>diff --git gcc/tree-vrp.c gcc/tree-vrp.c
>index 69e6248..92d889c 100644
>--- gcc/tree-vrp.c
>+++ gcc/tree-vrp.c
>@@ -2519,20 +2519,13 @@ extract_range_from_binary_expr_1 (value_range
>*vr,
> min = wide_int_to_tree (expr_type, tmin);
> max = wide_int_to_tree (expr_type, tmax);
> }
>- else if (min_ovf == -1 && max_ovf == 1)
>- {
>- /* Underflow and overflow, drop to VR_VARYING. */
>- set_value_range_to_varying (vr);
>- return;
>- }
>- else
>+ else if ((min_ovf == -1 && max_ovf == 0)
>+ || (max_ovf == 1 && min_ovf == 0))
> {
> /* Min underflow or max overflow. The range kind
> changes to VR_ANTI_RANGE. */
> bool covers = false;
> wide_int tem = tmin;
>- gcc_assert ((min_ovf == -1 && max_ovf == 0)
>- || (max_ovf == 1 && min_ovf == 0));
> type = VR_ANTI_RANGE;
> tmin = tmax + 1;
> if (wi::cmp (tmin, tmax, sgn) < 0)
>@@ -2551,6 +2544,12 @@ extract_range_from_binary_expr_1 (value_range
>*vr,
> min = wide_int_to_tree (expr_type, tmin);
> max = wide_int_to_tree (expr_type, tmax);
> }
>+ else
>+ {
>+ /* Other underflow and/or overflow, drop to VR_VARYING. */
>+ set_value_range_to_varying (vr);
>+ return;
>+ }
> }
> else
> {
>
> Marek
