[llvm-commits] Turning off SSE codegen for x86-64?

[Evan Cheng]

On Jan 28, 2009, at 10:21 AM, Török Edwin wrote:

> On 2009-01-25 22:21, Torok Edwin wrote:
>> Author: edwin
>> Date: Sun Jan 25 14:21:24 2009
>> New Revision: 62972
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=62972&view=rev
>> Log:
>> revert this patch for now, because Codegen does still want to  
>> generate SSE code,
>> for example in the case of va-args. XFAIL associated tests.
>>
>
> Hi Evan,
>
> Can you please look at these bugreports and see if there is a way to
> solve both?
> http://llvm.org/bugs/show_bug.cgi?id=3402
> http://llvm.org/bugs/show_bug.cgi?id=3403
>
> My attempt to solve PR3402 (by allowing X86SSELevel to be 0 for  
> x86-64)
> caused PR3403, so I reverted that patch.
> Are there other placesin codegen (other than va_arg I found in PR3403)
> that assume x86sselevel > 0 without actually
> checking that flag?

Unfortunately there is no trivial fix for this. I think some  
vector_shuffle lowering code (and perhaps more) in X86ISelLowering.cpp  
assumes SSE2 is available in 64-bit mode. This will require someone  
walking through the code to fix all the cases.

Evan

>
>
> Turning off SSE codegen for x86-64 is needed to compile kernel code,
> like the Linux kernel.
>
> Best regards,
> --Edwin