[llvm-dev] RFC: Building GlobalISel by default

Quentin Colombet via llvm-dev
Wed, 18 Jan 2017 04:40:53 -0000

Hi Philip,

> On Jan 13, 2017, at 9:21 PM, Philip Reames via llvm-dev <llvm-dev at
lists.llvm.org> wrote:
>
> I would lean towards doing this, but don't have an strong opinion
either way.
>
> Would it be possible (in another thread) to get a brief status report of
where we are with GlobalISEL overall?

Sure, I’ll do that. I’ll post the link when the mail is sent.

Thanks,
-Quentin

>
> Philip
>
>
> On 01/13/2017 05:54 PM, Quentin Colombet via llvm-dev wrote:
>> Hi all,
>>
>> Now, four backends (if I am counting right: X86, ARM, AArch64, AMDGPU)
are working on bringing-up GlobalISel, I’d like to switch the default of the
LLVM_BUILD_GLOBAL_ISEL variable in CMake, such that the framework gets built by
default.
>>
>> ** Impact of Flipping the Switch **
>>
>> * Upsides *
>>
>> For people developing on GlobalISel, it will:
>> - Simplify the CMake command to type :)
>> - Build/Test GlobalISel on all the LLVM bots
>>
>> For people not developing on GlobalISel, it will:
>> - Test that GlobalISel still works with your changes (make check will
test that for you)
>> - Allow you to play with it!
>>
>> Basically flipping the default CMake setting will give access to all
the ISel schemes that we have in LLVM, instead of just SDISel and FastISel.
>>
>> * Downsides *
>>
>> For people developing on GlobalISel, it will:
>> - Leave the status as it is now, meaning that mainly only people
working on GlobalISel look at the failures of GlobalISel specific bots
>>
>> For people not developing for GlobalISel, it will:
>> - Increase the compile time since the GlobalISel framework and the
related target specific parts will have to be built
>> - Increase the size of the binary (depending on what backend you pull)
>> - Require the setting of an additional CMake variable to disable it
(-DLLVM_BUILD_GLOBAL_ISEL=OFF)
>>
>>
>> What do people think?
>>
>> Thanks,
>> -Quentin
>> _______________________________________________
>> LLVM Developers mailing list
>> llvm-dev at lists.llvm.org
>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
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