[llvm] r176136 - Have a way for a target to opt-out of target-independent fast isel

[Eric Christopher]

On Wed, Feb 27, 2013 at 11:32 AM, Michael Ilseman <milseman at apple.com>wrote:

>
> On Feb 27, 2013, at 11:24 AM, Eric Christopher <echristo at gmail.com> wrote:
>
>
>
>
> On Tue, Feb 26, 2013 at 8:37 PM, Michael Ilseman <milseman at apple.com>wrote:
>
>>
>> On Feb 26, 2013, at 3:30 PM, Eli Bendersky <eliben at google.com> wrote:
>>
>> > Can you provide more background for this change? Is it being done for
>> > the sake of debugging? What are the intended use cases?
>> >
>>
>> Sure! Debugging can definitely be improved by this, but this also gives
>> targets more flexibility. Targets can fast-isel better code with more
>> coverage in some situations. For example, SelectOperator(), even when it
>> returns false, has side-effects and can schedule IR instructions to be
>> fast-iselled that otherwise never would. This becomes particularly
>> unfortunate when such instructions trigger the DAG slow-path.
>>
>>
> Is there anything that's going to be using this any time soon? Something
> that doesn't use the target independent fast isel path?
>
>
> There is an out-of-tree backend currently using it.
>

Seems a bit early to commit effectively dead code unless there's something
coming down soonish? :)

-eric
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