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 { }.
Thanks,
Richard.
> 2016-05-19 Marek Polacek <pola...@redhat.com>
>
> PR tree-optimization/71031
> * tree-vrp.c (extract_range_from_binary_expr_1): Drop to varying for
> min overflow or max underflow and remove an assert.
>
> * 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..791d738 100644
> --- gcc/tree-vrp.c
> +++ gcc/tree-vrp.c
> @@ -2525,14 +2525,19 @@ extract_range_from_binary_expr_1 (value_range *vr,
> set_value_range_to_varying (vr);
> return;
> }
> + else if ((min_ovf == 1 && max_ovf == 0)
> + || (min_ovf == 0 && max_ovf == -1))
> + {
> + /* Min overflow or max underflow, drop to VR_VARYING. */
> + set_value_range_to_varying (vr);
> + return;
> + }
> else
> {
> /* 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)
>
> Marek
>
>
--
Richard Biener <rguent...@suse.de>
SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB
21284 (AG Nuernberg)
