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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">>
</span>I like this idea, but it might not so easy to allocate spaces in global or local address space and tell sub-kernel to access them without draining the storage space. Maybe a memory manager is required. <o:p></o:p></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Yes, I see it as some sort of simplified global/local memory heap support would be required in implementation of enqueue_kernel on the device.
<o:p></o:p></span></p>
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<p class="MsoNormal"><b><span lang="EN-US" style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span lang="EN-US" style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> Bekket McClane [mailto:bekket.mcclane@gmail.com]
<br>
<b>Sent:</b> 21 March 2016 13:48<br>
<b>To:</b> David Chisnall<br>
<b>Cc:</b> cfe-dev@lists.llvm.org; Anastasia Stulova<br>
<b>Subject:</b> Re: [cfe-dev] About OpenCL 2.x Dynamic Parallelism<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:9.0pt;font-family:"Helvetica","sans-serif"">In [Objective-]C, If the block is expected to persist beyond the lifetime of the caller, then the callee is expected to call _Block_copy to promote it to the heap. The
compiler emits copy helpers (and descriptors for captured variables that have trivial copy semantics) that allow this to work with a little bit of support from the blocks runtime library.<br>
<br>
For OpenCL, you may want to generalise this slightly to provide different target address spaces for the copy,
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<p class="MsoNormal">I like this idea, but it might not so easy to allocate spaces in global or local address space and tell sub-kernel to access them without draining the storage space. Maybe a memory manager is required. <o:p></o:p></p>
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<o:p></o:p></p>
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<p class="MsoNormal"><span style="font-size:9.0pt;font-family:"Helvetica","sans-serif"">but note that for __block to work correctly the target address space must be readable (and writeable) in the context of the caller. If you do not support __block variables
then this is not an issue.</span><o:p></o:p></p>
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<p class="MsoNormal">Fortunately, OpenCL-C 2.x doesn’t allow __block attribute : )<o:p></o:p></p>
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<p class="MsoNormal"><span style="font-size:9.0pt;font-family:"Helvetica","sans-serif""><br>
It sounds as if OpenCL’s requirements are much simpler than [Objective-]C’s. I looked at implementing flattening for blocks a few years ago, but it becomes quite complex when a single variable is bound to multiple blocks and the potential performance improvements
did not justify the increased complexity. This is not an issue for you though.<br>
<br>
It sounds as if OpenCL’s blocks are actually far closer to C++ lambdas with a default copy capture than they are to [Objective-]C blocks. It might be cleaner and simpler to treat them as special syntax for lambdas than as special semantics for blocks</span><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-size:9.0pt;font-family:"Helvetica","sans-serif""><br>
David</span><o:p></o:p></p>
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<p class="MsoNormal">Cheers,<o:p></o:p></p>
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<p class="MsoNormal">McClane<o:p></o:p></p>
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