<div dir="ltr">Do you have some examples you can share? I would be interested in taking a look to see what we can do to help improve the performance of NVPTX, especially relative to equivalent OpenCL code.</div><div class="gmail_extra"><br><div class="gmail_quote">On Tue, Jan 13, 2015 at 4:01 PM, Jonathan Ragan-Kelley <span dir="ltr"><<a href="mailto:jrk@csail.mit.edu" target="_blank">jrk@csail.mit.edu</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><u></u>
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<span></span><span><div>Thanks, all.</div>
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<div>I didn’t realize a 7.0 RC was public and changed to 3.4—I will go down that road for now, though I’ll probably also look into integrating variants of the SPIR converter in the future.</div><span class="">
<blockquote class="gmail_quote"><div dir="ltr"><div>Another possibility is to skip libnvvm altogether and use LLVM's NVPTX target. This is of course harder since you have to configure the passes yourself instead of just calling a few C functions, but it does give you more control over the optimization pipeline and gives you full visibility into the compiler. Unfortunately, there are some NVVM-specific optimizations missing upstream that we are not able to contribute back.</div></div></blockquote>
</span><div>I appreciate the suggestion, but this is actually for a project which has been using NVPTX for years. The problem is that we see (dramatically) better performance from our OpenCL backend (via CL C source kernels) on NVIDIA hardware simply because kernels actually get optimized through the full NVCC-style stack. Based on related experience in other projects, I expect NVVM to provide a similar or greater bump over NVPTX. In short, I’d *love* to stick with NVPTX and the open source stack in LLVM trunk, but until it provides competitive performance on real programs (which, in my experience so far, it ~never does), it’s unfortunately not a strong alternative.</div></span>
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</blockquote></div><br><br clear="all"><div><br></div>-- <br><div class="gmail_signature"><br><div>Thanks,</div><div><br></div><div>Justin Holewinski</div></div>
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