[PATCH] [TTI] Add a new hook to TargetTransformInfo to query the target if a load of a constant should be converted to simply the constant itself.

[Juergen Ributzka]

Here is the updated patch.
-Juergen



On Jan 27, 2014, at 4:32 PM, Hal Finkel <hfinkel at anl.gov> wrote:

> ----- Original Message -----
>> From: "Chandler Carruth" <chandlerc at google.com>
>> To: "Juergen Ributzka" <juergen at apple.com>
>> Cc: "LLVM Commits" <llvm-commits at cs.uiuc.edu>
>> Sent: Monday, January 27, 2014 6:26:27 PM
>> Subject: Re: [PATCH] [TTI] Add a new hook to TargetTransformInfo to query the	target if a load of a constant should
>> be converted to simply the	constant itself.
>> 
>> 
>> 
>> Why is this going into the TargetTransformInfo which is for use by
>> IR-level analysis routines when its only caller is in the
>> SelectionDAG? The SelectionDAG can query TargetLowering directly.
>> 
> 
> I agree, this should be in TargetLowering. Otherwise, this seems reasonable to me.
> 
> -Hal
> 
>> 
>> 
>> On Mon, Jan 27, 2014 at 4:20 PM, Juergen Ributzka < juergen at apple.com
>>> wrote:
>> 
>> 
>> Hi Hal
>> 
>> this is the new target hook we talked about before. I also added Evan
>> and Nadav, because I had to modify the ARM and X86 backend.
>> 
>> Before this patch we used getIntImmCost to determine if a load of a
>> constant should be converted to just a constant, but the threshold
>> for this was set to an arbitrary value. This value works well for
>> the two targets (ARM and X86) that implement this target-hook, but
>> it isn't target-independent at all.
>> 
>> Now targets have the possibility to decide directly if this
>> optimization should be performed. The default value is set to false
>> to preserve the current behavior.
>> 
>> Please review.
>> 
>> Thanks
>> 
>> -Juergen
>> 
>> 
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>> 
>> 
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> 
> -- 
> Hal Finkel
> Assistant Computational Scientist
> Leadership Computing Facility
> Argonne National Laboratory

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