topic Optimization question in OpenCL* for CPU

Optimization question

Polar01 — Thu, 03 Mar 2011 15:29:05 GMT

I have a few question to know "how" I should write my methods. Can you tell me which one is the fast one ?

By example to pass values to a method :

1 - Passing float3 by pointer

void mymethod(float3* a, float3* b, float3* result)....

2 - Passing float3 directly

void mymethod(float3 a, float3 b, float3* result)....

3 - using "const" allowing the compiler to keep "a" and avoir a copy when entering into the method

void mymethod(const float3 a, const float3 b, float3* result)....

And to return values

1 - By pointer

void mymethod(float3* a, float3* b, float3* result)....

float3 a;

mymethod(&a);

2 - By value

float3 mymethod(float3* a, float3* b)....

float3 a = mythod(...);

jogshy — Thu, 10 Mar 2011 00:10:32 GMT

Good questions. I'm also interestered in this!

Evgeny_F_Intel — Fri, 11 Mar 2011 07:29:16 GMT

In most of the cases the compiler will perform in-lining, hence there is no much differences.

If for some reason the compiler can't perform in-lining the following method is preferred.

float3 mymethod(float3,float3);

In any case, I advise you to use the "Offline compiler" tool and look for thex86 assembly.