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Re: [Patch tree-ssa] RFC: Enable path threading for control variables (PR tree-optimization/54742).


On Fri, Jun 21, 2013 at 11:21 PM, Steve Ellcey <sellcey@mips.com> wrote:
> On Fri, 2013-06-21 at 17:43 +0100, James Greenhalgh wrote:
>
>> So to my mind, this is all far too tied up in pass ordering details to
>> resolve. Given that all the threading opportunities for my patch are found
>> in dom1 and how fragile the positioning of dom1 is, there is not a great
>> deal I can do to modify the ordering.
>>
>> The biggest improvement I could find comes from rerunning pass_ch
>> immediately after dom1, though I'm not sure what the cost of that
>> would be.
>>
>> I wonder if you or others have any thoughts on what the right thing to
>> do would be?
>>
>> > I am not sure if path threading in general is turned off for -Os but it
>> > probably should be.
>>
>> I agree, jump threading is on at -Os, path threading should not be.
>>
>> Thanks,
>> James
>
> I think that since it seems to be more a space issue then a time issue,
> the way you currently have it is reasonable.  As long as the
> optimization does not happen at -Os then I think we can probably live
> with the space increase.

I suppose with Jeffs recent work on jump-threading through paths
this case in handled and the patch in this thread is obsolete or can
be reworked?

Thanks,
Richard.

> Steve Ellcey
> sellcey@mips.com
>
>


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