Re: [RFH] - Less than optimal code compiling 252.eon -O2 for x86

[fjahanian <fjahanian@apple.com>]

On Jun 24, 2005, at 5:06 PM, Steven Bosscher wrote:

> On Saturday 25 June 2005 01:48, fjahanian wrote:
>
>> On Jun 24, 2005, at 3:16 PM, Andrew Pinski wrote:
>>
>>> I wonder why combine can do the simplification though which is why
>>> still
>>> produce good code for the simple testcase:
>>> void f1(double *d,float *f2)
>>> {
>>>   *f2 = 0.0;
>>>   *d = 0.0;
>>> }
>>>
>>
>> It is hard to reproduce the simple test case, exhibiting the same
>> problem (-O1 producing better code than -O2). Yes, small test cases
>> move the desired simplification to other phases.
>>
>
> It often helps if you know what function your poorer code is in.  You
> could e.g. try to make the .optimized dump of that function compilable
> and see if the problem shows up there again.  Then work your way down
> to something small.

Yes, I am planning to do this. My first question was though if the  
RTL generated by -O2, which does not get simplified, is correct and  
should be optimized in one of the rtl optimizers. If not, then focus  
shifts to tree optimizers.

- Thanks ,fariborz

>
> Gr.
> Steven
>
>