> On 1 Aug 2022, at 09:21, Richard Biener via Gcc-patches
> <gcc-patches@gcc.gnu.org> wrote:
>
> On Sun, 31 Jul 2022, Iain Sandoe wrote:
>
>> Hi Richi,
>>
>>> On 29 Jul 2022, at 09:54, Richard Biener via Gcc-patches
>>> <gcc-patches@gcc.gnu.org> wrote:
>>>
>>> The following makes the backward threader reject threads whose entry
>>> edge is probably never executed according to the profile. That in
>>> particular, for the testcase, avoids threading the irq == 1 check
>>> on the path where irq > 31, thereby avoiding spurious -Warray-bounds
>>> diagnostics
>>
>> This breaks bootstrap on i686-darwin{9,17} with what looks like a valid
>> warning (werrors on stage2)
>>
>> cc1plus … -O2 -Wall … is enough to.
>>
>> I can repeat it on a cross from x86_64-darwin19, so I can probably reduce
>> the .ii (it’s like 2M5 raw) and file a PR if you like - depends if the
>> solution might be obvious to you …
>
> Can you open a bugreport and attach full preprocessed source at start?
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106496
> Note at the start of the function we have
>
> if (m_path.length () <= 1)
> return false;
>
> so
>
> edge entry = find_edge (m_path[m_path.length () - 1],
> m_path[m_path.length () - 2]);
>
> is known to not access m_path out-of-bounds ...
yes, I saw that .. so I guess somehow that information is getting dropped.
thanks
Iain
>
> Thanks,
> Richard.
>
>>
>> thanks
>> Iain
>>
>> --------
>>
>> In file included from /src-local/gcc-master/gcc/hash-table.h:248,
>> from /src-local/gcc-master/gcc/coretypes.h:486,
>> from /src-local/gcc-master/gcc/tree-ssa-threadbackward.cc:22:
>> In member function ‘T& vec<T, A, vl_embed>::operator[](unsigned int) [with T
>> = basic_block_def*; A = va_heap]’,
>> inlined from ‘const T& vec<T>::operator[](unsigned int) const [with T =
>> basic_block_def*]’ at /src-local/gcc-master/gcc/vec.h:1486:20,
>> inlined from ‘bool back_threader_profitability::profitable_path_p(const
>> vec<basic_block_def*>&, tree, edge, bool*)’ at
>> /src-local/gcc-master/gcc/tree-ssa-threadbackward.cc:781:37:
>> /src-local/gcc-master/gcc/vec.h:890:19: warning: array subscript 4294967294
>> is above array bounds of ‘basic_block_def* [1]’ [-Warray-bounds]
>> 890 | return m_vecdata[ix];
>> | ~~~~~~~~~^
>> /src-local/gcc-master/gcc/vec.h: In member function ‘bool
>> back_threader_profitability::profitable_path_p(const vec<basic_block_def*>&,
>> tree, edge, bool*)’:
>> /src-local/gcc-master/gcc/vec.h:635:5: note: while referencing
>> ‘vec<basic_block_def*, va_heap, vl_embed>::m_vecdata’
>> 635 | T m_vecdata[1];
>> | ^~~~~~~~~
>>
>> =====
>
> --
> Richard Biener <rguent...@suse.de>
> SUSE Software Solutions Germany GmbH, Frankenstrasse 146, 90461 Nuernberg,
> Germany; GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman;
> HRB 36809 (AG Nuernberg)
