llvm dev - Jan 2018 - X86 new registers not being allocated

Hi all,

I have a bunch of new registers set up in X86RegisterInfo.td, the important
part being

def PR128 : RegisterClass<"X86", [i128],
                           128, (sequence "POI%u", 0, 7)>;

def VR128 : RegisterClass<"X86", [v4f32, v2f64, v16i8, v8i16,
v4i32, v2i64],
                          128, (add PR128, FR32)>;

I have an entry in X86ISelLowering.cpp:

addRegisterClass(MVT::i128, &X86::PR128RegClass);

and in findRepresentativeClass():

case MVT::i128:
    RRC =  &X86::PR128RegClass;

But even though my nodes have MVT::i128 value type, they get allocated to
XMM registers. I have, of course, removed i128 from FR128. What am I
missing?

Thanks,
Barbora

-- 
----------------
Barbora Murinová
The University of Edinburgh
SK: +421905718390
UK: +447477833795
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Hi Barbora,

What is important for using new registers is to have instructions that are
“compatible" with them.

In a nutshell, if you don’t have any instruction that uses your new register
class, then it won’t be used. Basically, it is useless to have a value living in
a container you cannot address.

Cheers,
-Quentin
> On Jan 21, 2018, at 4:29 PM, Barbora Murinová via llvm-dev <llvm-dev at
lists.llvm.org> wrote:
> 
> Hi all,
> 
> I have a bunch of new registers set up in X86RegisterInfo.td, the important
part being
> 
> def PR128 : RegisterClass<"X86", [i128],
>                            128, (sequence "POI%u", 0, 7)>;   
> 
> def VR128 : RegisterClass<"X86", [v4f32, v2f64, v16i8, v8i16,
v4i32, v2i64],
>                           128, (add PR128, FR32)>;
> 
> I have an entry in X86ISelLowering.cpp:
> 
> addRegisterClass(MVT::i128, &X86::PR128RegClass); 
> 
> and in findRepresentativeClass(): 
> 
> case MVT::i128:
>     RRC =  &X86::PR128RegClass;
> 
> But even though my nodes have MVT::i128 value type, they get allocated to
XMM registers. I have, of course, removed i128 from FR128. What am I missing?
> 
> Thanks,
> Barbora
> 
> -- 
> ----------------
> Barbora Murinová
> The University of Edinburgh
> SK: +421905718390
> UK: +447477833795
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
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