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<div class="moz-cite-prefix">On 1/14/20 10:37 AM, Jon Chesterfield via Openmp-dev wrote:<br>
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<div dir="ltr">Hello OpenMP dev,
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<div>A motivating example is atomicInc for amdgcn. There is ISA support for this so a good implementation folds to a single instruction. There is no corresponding clang intrinsic, though there is an llvm intrinsic.</div>
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<p>Do you mean a target-specific intrinsic, or a target-independent intrinsic?</p>
<p> -Hal<br>
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<div>I see the following options:</div>
<div>- Implement it in IR, linked into deviceRTL</div>
<div>- Inline assembly</div>
<div>- Delay implementation until the intrinsic can be added to clang</div>
<div>- Implement in terms of CAS</div>
<div>- Your suggestion here</div>
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<div>Adding atomicInc.ll to the source tree is the easy short term fix. It has drawbacks in terms of future ABI change, build complexity and limited precedent - libclc does this, but nowhere else.</div>
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<div>Inline assembly works (modulo getting the syntax right) and hits the right instruction.</div>
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<div>Implementing in terms of CAS means one can stay in HIP or OpenCL, but performance suffers.</div>
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<div>What would the you prefer out of these options?<br>
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<div>Thanks,</div>
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<div>Jon</div>
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<pre class="moz-signature" cols="72">--
Hal Finkel
Lead, Compiler Technology and Programming Languages
Leadership Computing Facility
Argonne National Laboratory</pre>
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