[Bug tree-optimization/79576] [7 Regression] ICE in gimple_stmt_nonnegative_warnv_p in gcc/gimple-fold.c:6979

[rguenther at suse dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79576

--- Comment #1 from rguenther at suse dot de <rguenther at suse dot de> ---
On Fri, 17 Feb 2017, marxin at gcc dot gnu.org wrote:

> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79576
> 
>             Bug ID: 79576
>            Summary: [7 Regression] ICE in gimple_stmt_nonnegative_warnv_p
>                     in gcc/gimple-fold.c:6979
>            Product: gcc
>            Version: unknown
>             Status: UNCONFIRMED
>           Keywords: ice-on-valid-code
>           Severity: normal
>           Priority: P3
>          Component: tree-optimization
>           Assignee: unassigned at gcc dot gnu.org
>           Reporter: marxin at gcc dot gnu.org
>                 CC: kugan at gcc dot gnu.org, rguenth at gcc dot gnu.org
>   Target Milestone: ---
> 
> Running following test-case:
> 
> $ cat ice.c
> a, b;
> c ()
> {
>   int d = 0;
>   for (;;)
>     if (b)
>       while (a)
>         d++;
> }
> $ gcc
> /home/marxin/Programming/gcc/gcc/testsuite/gcc.c-torture/execute/pr24716.c
> --param max-ssa-name-query-depth=10000000 -O2
         ^^^^^^^^^^^^^^^

"doctor it hurts" -- "don't do that then"

due to the --param and its low default we do not bother to do any
cycles detection (it would be costly like allocating a bitmap).

I suppose we should define a maximum for this param then, like ... 5?
(due to no limiting in search width this can be highly exponential)