getting the right boolean type

[Andrew MacLeod]

On 11/09/2017 10:16 AM, Richard Biener wrote:
> On Thu, Nov 9, 2017 at 3:44 PM, Andrew MacLeod <amacleod@redhat.com> wrote:
>> I'm a little confused.  In gimple I need to do a comparison between 2
>> values, and I create a boolean_type_node result.
>> I then combine it with an existing condition, but fortran is crapping out on
>> me because the boolean_type I created is not
>> compatible with the boolean type is has already created for a different
>> condition:
>>
>> Its not exactly this situation, but the idea is similar:
>>
>>   _65 = _37 != 0;    <<-- in the IL
>>   _77 = _34 != 0;    <<-- Im creating this
>>
>>   and something like
>>
>>     (_65 != _77)
>>
>>   Craps out on me because the types are incompatible.
>>
>> The expression created by fortran assigned to _65 is of type:
>> logical(kind=4)
>> and mine, _77 created with boolean_type_node, is logical(kind=1)
>>
>> I was under the impression that using boolean_type_node would give me the
>> right kind of boolean for that language, but apparently I was mistaken.
>>
>> If I don't have the context of the type of _65,  how am I suppose to get the
>> right boolean type for _77 when I create it? I don't want to cast it to the
>> right logical kind, Id like to just get it right.   I haven't stumbled
>> across any hooks or other obvious thing...
>>
>> I feel like I am missing something obvious...  :-P
> You should already know the boolean type from the existing comparison in the IL.
> That is, you shouldn't generate conditions out of thin air, do you?  That is,
> there isn't a "single" boolean type a random hook would tell you.
>
> Richard.
Yeah, I do actually generate them from thin air :-)   That why I said it 
wasnt exactly that situation.  All I have is 2 arbitrary things that are 
being compared, and then eventually I sometimes end up combining it with 
an existing boolean.  I dont know in advance that I will need to combine 
it. I chose boolean_type_node because I thought it was the default.

I presume fortran is using SImode because it works better, or there is 
some other subtle difference?  so even if I wasn't eventually combining 
it with a logical, and I was using the default  QImode, I would generate 
less than ideal code?  Is there not a way for the optimizers to pick the 
preferred type?

Andrew