Shrink-wrap on povray

2012-11-20 Thread Zhenqiang Chen 
Hi,

I try ARM, MIPS, PowerPC and X86 on povray benchmark. No one can
shrink-wrap function Ray_In_Bound.

Here is:
bool Ray_In_Bound (RAY *Ray, OBJECT *Bounding_Object)
{
  ...
  for (Bound = Bounding_Object; Bound != NULL; Bound = Bound->Sibling)
  {...}
  return (true);
}
For ARM O2/O3, "Bound" is allocated to "r6" during ira. So there is copy

r6 = r1 before
testing Bound != NULL

The copy (using r6) blocks the shrink-wrap optimization since r6
should be saved. Need enhance shrink-wrap to handle this case.

Overall, for povray benchmark,
54 functions are shrink-wrapped for ARM;
59 functions are shrink-wrapped for X86;
25 functions are shrink-wrapped for MIPS;
26 functions are shrink-wrapped for PowerPC.

Thanks!
-Zhenqiang

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Re: Shrink-wrap on povray

2012-11-20 Thread Michael Hope 
On 20 November 2012 22:10, Zhenqiang Chen  wrote:
> Hi,
>
> I try ARM, MIPS, PowerPC and X86 on povray benchmark. No one can
> shrink-wrap function Ray_In_Bound.
>
> Here is:
> bool Ray_In_Bound (RAY *Ray, OBJECT *Bounding_Object)
> {
>   ...
>   for (Bound = Bounding_Object; Bound != NULL; Bound = Bound->Sibling)
>   {...}
>   return (true);
> }
> For ARM O2/O3, "Bound" is allocated to "r6" during ira. So there is copy
>
> r6 = r1 before
> testing Bound != NULL

Could you hack the benchmark to make the early exit explicit and see
if that changes the result?  That lets us know if improving shrink
wrap is worthwhile.

Something like:

 bool Ray_In_Bound (RAY *Ray, OBJECT *Bounding_Object)
 {
  if (Bounding_Object == NULL) return true;
   ...
   for (Bound = Bounding_Object; Bound != NULL; Bound = Bound->Sibling)
   {...}
   return (true);
}

-- Michael

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Re: Shrink-wrap on povray

2012-11-20 Thread Zhenqiang Chen 
On 21 November 2012 03:26, Michael Hope  wrote:
> On 20 November 2012 22:10, Zhenqiang Chen  wrote:
>> Hi,
>>
>> I try ARM, MIPS, PowerPC and X86 on povray benchmark. No one can
>> shrink-wrap function Ray_In_Bound.
>>
>> Here is:
>> bool Ray_In_Bound (RAY *Ray, OBJECT *Bounding_Object)
>> {
>>   ...
>>   for (Bound = Bounding_Object; Bound != NULL; Bound = Bound->Sibling)
>>   {...}
>>   return (true);
>> }
>> For ARM O2/O3, "Bound" is allocated to "r6" during ira. So there is copy
>>
>> r6 = r1 before
>> testing Bound != NULL
>
> Could you hack the benchmark to make the early exit explicit and see
> if that changes the result?  That lets us know if improving shrink
> wrap is worthwhile.
>
> Something like:
>
>  bool Ray_In_Bound (RAY *Ray, OBJECT *Bounding_Object)
>  {
>   if (Bounding_Object == NULL) return true;

I had tried it. The result is the same with the original one. (The
hack code is optimized)

Thanks!
-Zhenqiang

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