Re: [PR65768] Check rtx_cost when propagating constant

[Kugan <kugan dot vivekanandarajah at linaro dot org>]

On 30/05/15 14:54, Jeff Law wrote:
> On 05/29/2015 12:32 AM, Kugan wrote:
>>>>>
>>>>>      PR target/65768
>>>>>      * cprop.c (try_replace_reg): Check cost of constants before
>>>>> propagating.
>>> I should have also noted, fresh bootstrap & regression test is needed
>>> too.
>>
>> Thanks Jeff for the comments. I did a fresh bootstrap and regression
>> testing on x86_64-linux-gnu with no new regression. I will wait for
>> you ACK.
> Can you address the 3 issues in my prior message?  I'll include them
> here for clarity:
> 
> -- 
> 
> The "const_p" variable is poorly named, though I can kindof see how you
> settled on it.  Maybe "check_rtx_costs" or something along those lines
> would be better.
> 
> The comment for the second hunk would probably be better as:
> 
> /* If TO is a constant, check the cost of the set after propagation
>    to the cost of the set before the propagation.  If the cost is
>    higher, then do not replace FROM with TO.  */
> 
> 
> You should try to produce a testcase where this change shows a code
> generation improvement.    Given we're checking target costs, that test
> will naturally be target specific.  But please do try.
> 
> So with the two nits fixed and a testcase, I think this can go forward.
> -- 
> 

Thanks Jeff and apologies for missing your previous email. I have now
fixed the comments as you suggested and changed the PR target/65768
testcase such that it tests this case.

I will commit it if there is no objections to this.

Thanks,
Kugan

gcc/ChangeLog:

2015-06-01  Kugan Vivekanandarajah  <kuganv@linaro.org>
	    Zhenqiang Chen  <zhenqiang.chen@linaro.org>

	PR target/65768
	* cprop.c (try_replace_reg): Check cost of constants before propagating.


gcc/testsuite/ChangeLog:

2015-06-01  Kugan Vivekanandarajah  <kuganv@linaro.org>

	PR target/65768
	* gcc.target/arm/maskdata.c: Remove -fno-gcse.

Attachment: cprop.txt
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