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Region Addressing in openCL kernel

Stephan1
Beginner
179 Views

Hi

The Intel OpenSource HD Graphics Programmer's Reference Manual Vol 4 Part 2 for HD 4000 describes the region adressing feature.

Is it possible to utilize register indrect region addressing in an openCL kernel on HD4000 ?

Best regards, Stephan

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2 Replies
Raghupathi_M_Intel
179 Views

Hi Stephan,

This is something that the compiler takes advantage of and the OCL kernel developer does not have control over. Hope that helps.

Raghu

Stephan1
Beginner
179 Views

Hi Raghu

Thank ypu a lot for the answer. Can we just wrap it up ?

I think twiddling uses direct region adressing, i.e. the element access in the region is coded.
Im am right ? E.g.:
float4 a, b;
a.s0123 = b.s3210;

(One could dissassemble the .ir to check the GPU asm, but I guess, this needs a certain VTune version ?)

Which opencl C code statement would lead to an indirect region adressing by the compiler ?
Some array access ? Here my untested idea:
float4 dst;
float4 src[ 16 ];
int4 idx = ... ; // values within range 0..15
dst = src[ idx ];

Yes, it could be done also with several fetches. Would the compiler combine those into one inderect region adressing ?
dst.s0 = src[ idx.s0 ];
dst.s1 = src[ idx.s1 ];

Best regards, Stephan

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