[LLVMdev] lowering and non legal types in fast-isel

Eric Christopher echristo at gmail.com
Tue Sep 9 15:02:05 PDT 2014


Look at how the calling convention code does it when it legalizes :)

-eric

On Tue, Sep 9, 2014 at 2:28 PM, Reed Kotler <reed.kotler at imgtec.com> wrote:

>  How would you return a pair of registers then?
>
> For example, If I lower 64 bit integer and materialize a constant, i need
> to return a pair of 32 registers.
>
>
> On 09/09/2014 01:49 PM, Eric Christopher wrote:
>
> You can do everything from legalize it yourself, or just add code to
> select it and legalize it in your backend during instruction selection.
> fast-isel now has support for completely avoiding the target independent
> version of the code.
>
>  -eric
>
> On Sun, Aug 31, 2014 at 10:41 AM, Reed Kotler <Reed.Kotler at imgtec.com>
> wrote:
>
>> I understand that but falling back makes the compilation slower.
>>
>> I'm wondering what could be done to remove this restriction about
>> fast-isel not being able to
>> handle non legal types.
>>
>>
>> ________________________________________
>> From: Anton Korobeynikov [anton at korobeynikov.info]
>> Sent: Sunday, August 31, 2014 12:55 AM
>> To: Reed Kotler
>> Cc: LLVMdev at cs.uiuc.edu
>> Subject: Re: [LLVMdev] lowering and non legal types in fast-isel
>>
>> Fastisel should fallback to usual selector in the cases it cannot
>> handle. So, for illegal types as well.
>>
>> On Sun, Aug 31, 2014 at 1:42 AM, reed kotler <rkotler at mips.com> wrote:
>> > Fast-isel is not equipped in general to deal with non legal types.
>> >
>> > It would seem that an llvm assembler pass run after clang  but before
>> llvm
>> > could do the lowering though.
>> >
>> > Any thoughts?
>> >
>> > Reed
>> >
>> > _______________________________________________
>> > LLVM Developers mailing list
>> > LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>> > http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>
>>
>>
>> --
>> With best regards, Anton Korobeynikov
>> Faculty of Mathematics and Mechanics, Saint Petersburg State University
>>
>> _______________________________________________
>> LLVM Developers mailing list
>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>
>
>
>
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