[llvm-commits] [llvm] r142439 - /llvm/trunk/lib/Target/X86/X86TargetMachine.cpp

Eli Friedman eli.friedman at gmail.com
Tue Oct 18 16:14:24 PDT 2011


On Tue, Oct 18, 2011 at 4:11 PM, Eric Christopher <echristo at apple.com> wrote:
>
> On Oct 18, 2011, at 4:11 PM, Bruno Cardoso Lopes wrote:
>
>> Hi Eli,
>>
>> On Tue, Oct 18, 2011 at 9:05 PM, Eli Friedman <eli.friedman at gmail.com> wrote:
>>> On Tue, Oct 18, 2011 at 3:50 PM, Eric Christopher <echristo at apple.com> wrote:
>>>> Author: echristo
>>>> Date: Tue Oct 18 17:50:17 2011
>>>> New Revision: 142439
>>>>
>>>> URL: http://llvm.org/viewvc/llvm-project?rev=142439&view=rev
>>>> Log:
>>>> Turn on the vzeroupper pass by default.
>>>>
>>>> I'll remove/rename the option in a few days.
>>>
>>> Is the VZEROUPPER pass really ready?  I was under the impression it
>>> was missing some rather important functionality (e.g. it inserts
>>> VZEROUPPER calls into modules which don't use the ymm registers at
>>> all).
>>
>> The actual approach of this pass is very naive, I have a updated patch
>> for improving it significantly. I've tested locally but haven't had
>> the time yet to run it
>> with all the singlesource+multisource on the testsuite, that's why I
>> haven't comited yet.
>>
>> I think this shouldn't be enabled by default yet, since I fix some issues on the
>> upcoming patch.
>
> OK. I can disable it.
>
> I didn't see any issues, can you be a bit more forthcoming?

There isn't really anything wrong with it; it just inserts a bunch of
unnecessary VZEROUPPER instructions.

-Eli




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