Re: [PATCH] Add verifier for leaked SSA names

[Richard Biener <richard dot guenther at gmail dot com>]

On Fri, Oct 2, 2015 at 5:24 PM, Jeff Law <law@redhat.com> wrote:
> On 10/02/2015 01:37 AM, Richard Biener wrote:
>>
>>
>> The following patch doesn't pass bootstrap & regtest.  It did at some
>> point though and its comment hints that fixing leaks after inlining
>> was too interesting a problem to solve ;)
>>
>> Thus patch is FYI.
>>
>> Richard.
>>
>> Index: tree-ssa.c
>> ===================================================================
>> --- tree-ssa.c  (revision 228320)
>> +++ tree-ssa.c  (working copy)
>> @@ -693,6 +693,16 @@ verify_def (basic_block bb, basic_block
>>         goto err;
>>       }
>>
>> +  if (bb == NULL
>> +      /* ???  Too many latent cases in the main opt pipeline.  But it's
>> +         worth to fix all cases before inlining as that reduces the
>> +        amount of garbage kept live.  */
>> +      && !cfun->after_inlining)
>> +    {
>> +      error ("removed STMT failed to release SSA name");
>> +      goto err;
>> +    }
>> +
>
> I was building the verification step into the ssa name manager. Essentially
> at the point where we flush from the pending to the free list, we should
> have a consistent state.

Yeah, though when SSA verifiers run the state should also be consistent
and we'd get to pinpoint the offending pass easier.

> Thus we ought to be able to walk the IL marking everything we can see,
> combine that with the contents of the freelist and the result ought to be
> every SSA_NAME ever created.
>
> Reality is somewhat different, of course.
>
> Yours takes a slightly different approach.  Ultimately if we get the leaks
> plugged, we might even consider using both.

Sure.  Note that the above is from simply walking all SSA names.

Richard.

> jeff
>
>
>