[llvm-commits] [llvm] r108735 - in /llvm/trunk: include/llvm/Target/TargetLowering.h lib/CodeGen/SelectionDAG/TargetLowering.cpp

[Evan Cheng]

On Jul 19, 2010, at 12:59 PM, Jakob Stoklund Olesen wrote:

> 
> On Jul 19, 2010, at 11:47 AM, Evan Cheng wrote:
> 
>> Author: evancheng
>> Date: Mon Jul 19 13:47:01 2010
>> New Revision: 108735
>> 
>> URL: http://llvm.org/viewvc/llvm-project?rev=108735&view=rev
>> Log:
>> Teach computeRegisterProperties() to compute "representative" register class for legal value types. A "representative" register class is the largest legal super-reg register class for a value type. e.g. On i386, GR32 is the rep register class for i8 / i16 / i32; on x86_64 it would be GR64.
>> 
>> This property will be used by the register pressure tracking instruction scheduler.
> 
> Hi Evan,
> 
> This looks a lot like you have x86 in mind.

No. What is x86? :-)

> 
> What is getRepRegClassFor(f32) going to return on ARM? QQQQ?

QQ and QQQQ are not legal during isel. It's Q. It's probably overly conservative for tracking. I'm still trying to figure that out.


> 
> How are you planning to deal with registers with more than one usable subregister?

I am not sure what you mean? It's ignore sub-register classes (e.g. QPR_VFP2).

Evan

> 
> /jakob
>