[llvm-commits] [llvm] r75308 - in /llvm/trunk: include/llvm/CodeGen/ValueTypes.h include/llvm/CodeGen/ValueTypes.td lib/VMCore/ValueTypes.cpp utils/TableGen/CodeGenTarget.cpp

[Duncan Sands]

Hi Bob,

>>> +      v24i8          =  18,   // 24 x i8
>>> +      v32i8          =  19,   // 32 x i8
>>> +      v48i8          =  20,   // 48 x i8
>> type legalization could be taught to exploit this by
>> (for example) splitting a v96i8 into two v48i8, or
>> by widening v20i8 to v24i8.  Currently it doesn't do
>> this - should it be taught to do it?  Also, if you
>> *don't* want this to happen then that might cause
>> problems later if some platform has a native type such
>> as v3i8 where they do want the type exploited for
>> splitting and widening.  Then there would need to be
>> some kind of mechanism for telling the type legalizer
>> which types are really usable and which ones are fake.
> 
> I can see no reason why type legalization should not produce these  
> types by splitting or widening, but at least for now, I don't think  
> implementing that is a priority.

similar functionality is needed for type legalization of integers to
support platforms that have (for example) 24 bit registers.  On the
level of the type legalizer I think support for this (for both integers
and vectors) can be added quite easily, though I'm not planning to do it
any time soon.

Ciao,

Duncan.