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POWhy dead code in OpenCL kernel influence result in Nvidia GTX550ti?
 

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  1. POWhy dead code in OpenCL kernel influence result in Nvidia GTX550ti?
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    <p>I am using OpenCL dev software of Nvidia on GTX550ti graphics card, and encounter a strange problem. (I am freshman for OpenCL).</p> <p>My kernel code is like this:</p> <pre><code>__kernel void kernel_name(...) { size_t d = get_local_id(0); char abc[8]; ... } </code></pre> <p>Actually, the <code>char abc[8]</code> is useless (dead code) for my case. But, if I have the <code>char abc[8]</code> in my kernel code, the result will be totally messy and the running time of kernel will be much longer (2095712 ns). If I comment out the <code>char abc[8]</code>, the result becomes correct, and the running time of kernel becomes shorter (697856 ns). The compiler of kernel won't wipe off the dead code?</p> <p>The above is just an explicit example that I can repeat. I also encounter more stranger case that one program gets different result when run at different time in totally the same environment.</p> <p>Is that related to memory allocation or..? Anyone can give me some advice on how to find the problem?</p> <p>By the way, oclDeviceQuery output information is listed as follows: Platform Version = OpenCL 1.1<br> CUDA 4.2.1,<br> SDK Revision = 7027912</p> <p>My OS is Windows XP.</p> <p>Today is 2012-07-17, and I think I have resolved this problem.</p> <ol> <li><p>don't use #include in kernel source file.</p></li> <li><p>don't use ultra length line (for example, you write program to generate some line data for kernel source file) in kernel source file.</p></li> </ol>
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