[PATCH] AArch64: Enable subregister liveness tracking.

[Eric Christopher]

Sure thing. Up to you.

On Thu, Mar 19, 2015, 5:12 PM Matthias Braun <matze at braunis.de> wrote:

>
> On Mar 19, 2015, at 4:46 PM, Eric Christopher <echristo at gmail.com> wrote:
>
>
>
> On Thu, Mar 19, 2015 at 4:33 PM Matthias Braun <matze at braunis.de> wrote:
>
>> Hi t.p.northover, qcolombet,
>>
>> Splitting this into an own commit to get some visibility.
>>
>> After doing some extensive benchmarking wiht llvm test-suite, I see no
>> correctness or compiletime changes. I see some very slight benchmark
>> runtime improvements (which may or may not be noise). The only noticeable
>> regression is in a benchmark were literally 6 lines of assembly changed for
>> the better, so that must be cache issues.
>>
>> REPOSITORY
>>   rL LLVM
>>
>> http://reviews.llvm.org/D8474
>>
>> Files:
>>   lib/Target/AArch64/AArch64Subtarget.h
>>
>> Index: lib/Target/AArch64/AArch64Subtarget.h
>> ===================================================================
>> --- lib/Target/AArch64/AArch64Subtarget.h
>> +++ lib/Target/AArch64/AArch64Subtarget.h
>> @@ -91,6 +91,7 @@
>>    bool enablePostMachineScheduler() const override {
>>      return isCortexA53() || isCortexA57();
>>    }
>> +  bool enableSubRegLiveness() const override { return true; }
>>
>>
> Drive by feedback:
>
> Most of AArch64 is option controlled for this sort of thing. Did you want
> to add an option with init(true) for this?
>
> Personally no preference, but thought I'd bring it up.
>
>
> In this case there is already the global -enable-subreg-liveness=false
> switch available, so I think there is no need for an additional aarch64
> option.
>
> - Matthias
>
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