[LLVMdev] [PATCH] Spill Comments

[Dan Gohman]

On Sep 14, 2009, at 10:32 AM, David Greene wrote:


> On Monday 14 September 2009 12:22, Dan Gohman wrote:
>
>> Hi Dave,
>>
>>
>>
>> On Sep 11, 2009, at 3:31 PM, David Greene wrote:
>>
>>> Attached is a patch to print asm comments for spill information.
>>>
>>> We've discussed the mechanisms before but I wanted to run the
>>>
>>> patch by everyone before I start to commit pieces.
>>>
>>
>>
>> The Offset->FrameIndex mapping seems rather heavy-weight, as
>>
>> any expense is incurred even when AsmVerbose is off.   Would it
>>
>> be possible to use MachineMemOperands instead? In theory,
>>
>> they should already be preserving the needed information.  If
>>
>> they're not sufficient, could they be improved?
>>
>
> Yeah, I'm not totally happy with that mapping either.  With
> MachineMemOperands, would that be the getOffset() method?  That's
> only for FPRel data, though.  What if frame pointer elimination has
> been run?
>
> I would love to get out from under the map if possible.

MachineMemOperands for spill slots use FixedStack PseudoSourceValues
as their base. There's a unique FixedStack PseudoSourceValue for each
fixed frame object, so it's independent of whether frame pointer
elimination has been done, and it's independent of the actual frame
offsets.

Dan