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

[Michael Ilseman]

On Feb 27, 2013, at 11:36 AM, Eric Christopher <echristo at gmail.com> wrote:

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> 
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> On Wed, Feb 27, 2013 at 11:32 AM, Michael Ilseman <milseman at apple.com> wrote:
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> On Feb 27, 2013, at 11:24 AM, Eric Christopher <echristo at gmail.com> wrote:
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>> 
>> 
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>> On Tue, Feb 26, 2013 at 8:37 PM, Michael Ilseman <milseman at apple.com> wrote:
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>> On Feb 26, 2013, at 3:30 PM, Eli Bendersky <eliben at google.com> wrote:
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>> > 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.
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>> Is there anything that's going to be using this any time soon? Something that doesn't use the target independent fast isel path?
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> 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? :)
> 

Reverted in r176204

> -eric 
> 

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