[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.

[Chandler Carruth]

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.


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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