[LLVMdev] LLVM3.2 Backend for mips1 subtarget

Eric Christopher
Fri, 26 Apr 2013 10:27:16 -0000

My guess is he wants mips1 so that he doesn't have to worry about the
patented mips instructions?

At any rate, it will be a bit of work to enable a mips1 target and I
doubt many people are interested, so it'll definitely be up to him to
do the work.

-eric

On Fri, Apr 26, 2013 at 10:15 AM, Reed Kotler <rkotler at mips.com>
wrote:
> If you want to create a version for the mips1 subtarget, going back in time
> will probably be a lot of work for you.
>
> If you want to modify the current version you might try the following:
> 1) Create a Mips1 predicate and use that to disable instruction patterns
> that match using non Mips1 instructions.
> 2) Use soft-float
> 3) You would need to reenable some commented out code used to implement
> conditional move instructions on Mips1 . You will see that in the Mips Isel
> lowering class.
>
> We chose to not support Mips 1 a while back so this is about as much as I
> can help you on this.
>
> Why not just use the llvm 2.9 backend and clang front end?
>
> Reed
>
>
> On 04/25/2013 07:03 PM, Feng Liu wrote:
>>
>> Hi Everybody,
>>
>> I'm working a project which requires assembly code for mips1
>> architecture for simulation purpose. I checked the latest LLVM3.2
>> version and found that the backend has been removed. I tried to replace
>> the MIPS backed in LLVM3.2 by the old one in LLVM2.9 (which contains
>> mips1) and adjust some routines to get the backend compiled. However,
>> when llc is used to generate the assembly, there are some internal
>> faults such as very large physical register id in the register
>> allocation phase.
>>
>> Would anyone to give me some suggestions to bring the mips1 backend to
>> the latest LLVM version in this case? Thank you very much!
>>
>> Best,
>> Feng
>>
>>
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