[llvm-dev] RFC: Building GlobalISel by default

[Quentin Colombet via llvm-dev]

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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