[llvm-commits] [PATCH] Add Pattern ID Information

[Evan Cheng]

On Aug 4, 2011, at 6:35 AM, David A. Greene wrote:

> Chris Lattner <clattner at apple.com> writes:
> 
>> On Aug 3, 2011, at 4:38 PM, David Greene wrote:
>>> I've got a patch series ready to implement support for printing asm comments
>>> about instruction selection.  For example:
>>> 
>>>       incq    %rdx                    # test.c:38
>>>                                       #  Src: (add:i64 GR64:i64:$src, 1:i64)
>>>                                       #  Dst: (INC64r:i64 GR64:i64:$src)
>> 
>> Out of curiosity, how is this any better than just listing the
>> 'INC64r' opcode?  We already have that accessible and don't need to
>> add anything to MachineInstr to get it.
> 
> Because sometimes multiple patterns map to an instruction.  Think of
> Pat<> patterns.  It's helpful to know which pattern matched to generate
> the instruction.
> 
>>> This is really helpful for tracking down isel issues and was invaluable during
>>> AVX implementation and tuning.  So I want to get this in before I start doing
>>> the heavy-duty AVX merging.
>> 
>> What merging do you anticipate?  Mainline supports almost all of AVX,
>> there are just a few bugs left and missed optimizations.
> 
> There are a lot of bugs and missed optimizations.  I have a couple
> years' worth of bug fixing and tuning plus a complete reorganization of
> the SIMD specification so that adding stuff like AVX2 will be trivial.

There have a been quite a bit of activity in this area recently. Matt Pharr has filed a lot of AVX bugs and Bruno has been churning through them. Have you checked how many of your bug fixes are still necessary?

Evan

> 
>                              -Dave
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