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Hi,
I have the following code that works well :
#pragma unrollfor(uint i = 0; i < MLT_SAMPLING_TASK_PER_SAMPLER; i++, taskId++){clTask task = tasks[taskId];clMLTSample sample = task.mltSample;if (sample.requestNewMLTSample && sample.score > bestScore){bestScore = sample.score;bestScoreTaskId = taskId;}}#pragma unroll for(uint i = 0; i < MLT_SAMPLING_TASK_PER_SAMPLER; i++, taskId++) { clTask task = tasks[taskId]; clMLTSample sample = task.mltSample; if (sample.requestNewMLTSample && sample.score > bestScore) { bestScore = sample.score; bestScoreTaskId = taskId; } }
But when I replace 2 lines with (to minimize the memory access) I got an access violation !
clMLTSample sample = tasks[taskId].mltSample;
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Is this OpenCL or Host code? From the looks of it it looks like a host code so it has nothing to do with Intel OpenCL SDK.
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No, it is OpenCL kernel code !!!!
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No reaction from the Intel Team ?
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Hello,
I'm not sure it's legal to use #pragma unroll in OpenCL C code. Does the problem persist when you remove those instructions?
Doron Singer
I'm not sure it's legal to use #pragma unroll in OpenCL C code. Does the problem persist when you remove those instructions?
Doron Singer
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It is something that I have found on the Intel pages... so at least for the Intel SDK it should work.
Anyway, I have test without... and I still have the crash :-(
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Good. Next question: What is a "clTask"? Is it a typedef to an OpenCL native type, or is it some user-defined struct?
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clTask is a typedef to a struct.
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I'm not sure the assignment operator is defined for structs in C. You can use the printf extension to make sure the struct doesn't contain garbage data after the assignment.
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Assignment operation for structs is very much defined in C (http://en.wikipedia.org/wiki/Struct_%28C_programming_language%29#Assignment).
These 2 pieces of code are identical in their functionality for a good compiler. Lazy compiler might allocate space from stack for clTask task but those days are long gone.
These 2 pieces of code are identical in their functionality for a good compiler. Lazy compiler might allocate space from stack for clTask task but those days are long gone.
clTask task = tasks[taskId];
clMLTSample sample = task.mltSample;
clMLTSample sample = tasks[taskId].mltSample;
If the only difference between working and non working version are those pieces of code then this indeed is a bug in Intel's implementation.
clMLTSample sample = tasks[taskId].mltSample;
If the only difference between working and non working version are those pieces of code then this indeed is a bug in Intel's implementation.
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In that case, we'll look into this.
Thanks for reporting (in case it's not obvious from my posts, I'm not on the compiler side of things :))
Doron
Thanks for reporting (in case it's not obvious from my posts, I'm not on the compiler side of things :))
Doron

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