Re: [COMMITTED] process transitive inferred ranges in pre_fold_stmt.

[Andrew MacLeod <amacleod@redhat.com>]

On 11/11/22 16:56, Bernhard Reutner-Fischer wrote:
> On Fri, 11 Nov 2022 11:17:17 -0500
> Andrew MacLeod via Gcc-patches <gcc-patches@gcc.gnu.org> wrote:
>
>> diff --git a/gcc/tree-vrp.cc b/gcc/tree-vrp.cc
>> index 3393c73a7db..a474d9d11e5 100644
>> --- a/gcc/tree-vrp.cc
>> +++ b/gcc/tree-vrp.cc
>> @@ -4485,6 +4486,7 @@ public:
>>       for (gphi_iterator gsi = gsi_start_phis (bb); !gsi_end_p (gsi);
>>   	 gsi_next (&gsi))
>>         m_ranger->register_inferred_ranges (gsi.phi ());
>> +    m_last_bb_stmt = last_stmt (bb);
>>     }
>>   
>>     void post_fold_bb (basic_block bb) override
>> @@ -4497,19 +4499,14 @@ public:
>>     void pre_fold_stmt (gimple *stmt) override
>>     {
>>       m_pta->visit_stmt (stmt);
>> +    // If this is the last stmt and there are inferred ranges, reparse the
>> +    // block for transitive inferred ranges that occur earlier in the block.
>> +    if (stmt == m_last_bb_stmt)
>> +      m_ranger->register_transitive_inferred_ranges (gimple_bb (stmt));
>>     }
> So of course it doesn't really matter what that stmt was, a non_debug
> is as good as a debug one AFAIU, it's just a marker, as good as any SSA
> version or id, i suppose. So gsi_last_nondebug_bb(bb) is not strictly
> needed, fine.
It is important. It needs to be the last non-debug statement so that we 
can properly feed values into the final stmt of the block.. be it a 
conditional, switch or a return.
>
> But since it's last_stmt(), do you have an opinion on 1) in
> https://gcc.gnu.org/pipermail/gcc-help/2021-November/140908.html
> by chance, as you seem to use it..

Not really.  It possible that there is a slightly more efficient way to 
do it, not sure how measurable it would be.  Patches always welcome :-)

Andrew