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<p class="MsoNormal"><span style="color:#1F497D">FYI, reference to the relevant part of the OpenCL spec:
<a href="https://www.khronos.org/registry/OpenCL/specs/opencl-2.0-openclc.pdf#105">
https://www.khronos.org/registry/OpenCL/specs/opencl-2.0-openclc.pdf#105</a><o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">From the OpenCL side this proposal seems to make sense generally. I am not quite clear though what would happen with the scopes other than synch_scope_single_thread.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Do you need to extend the IR language to accommodate that too in addition to ‘singlethread’ flag you already use?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Cheers,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Anastasia<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><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""> Liu, Yaxun (Sam) [mailto:Yaxun.Liu@amd.com]
<br>
<b>Sent:</b> 17 January 2017 17:16<br>
<b>To:</b> cfe-dev (cfe-dev@lists.llvm.org)<br>
<b>Cc:</b> Sumner, Brian; Tye, Tony; Zhuravlyov, Konstantin; Anastasia Stulova; Bader, Alexey (alexey.bader@intel.com)<br>
<b>Subject:</b> [RFC] Support synchronisation scope in Clang atomic builtin functions<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p style="mso-margin-top-alt:0cm;margin-right:0cm;margin-bottom:9.0pt;margin-left:0cm;background:white">
<span lang="EN-US" style="font-size:10.0pt;font-family:"Segoe UI","sans-serif";color:black">OpenCL 2.0 atomic builtin functions have a scope argument which is ideally represented as synchronization scope argument in LLVM atomic instructions.<o:p></o:p></span></p>
<p style="mso-margin-top-alt:0cm;margin-right:0cm;margin-bottom:9.0pt;margin-left:0cm;background:white;font-variant-ligatures: normal;font-variant-caps: normal;orphans: 2;widows: 2;-webkit-text-stroke-width: 0px;word-spacing:0px">
<span lang="EN-US" style="font-size:10.0pt;font-family:"Segoe UI","sans-serif";color:black">Clang supports translating Clang atomic builtin functions to LLVM atomic instructions. However it currently does not support synchronization scope of LLVM atomic instructions.
Without this, users have to use LLVM assembly code to implement OpenCL atomic builtin functions.<o:p></o:p></span></p>
<p style="mso-margin-top-alt:0cm;margin-right:0cm;margin-bottom:9.0pt;margin-left:0cm;background:white;font-variant-ligatures: normal;font-variant-caps: normal;orphans: 2;widows: 2;-webkit-text-stroke-width: 0px;word-spacing:0px">
<span lang="EN-US" style="font-size:10.0pt;font-family:"Segoe UI","sans-serif";color:black">I have a patch (<a href="https://reviews.llvm.org/D28691">https://reviews.llvm.org/D28691</a> ) which allows Clang atomic builtin functions to accept an optional synchronization
scope argument, so that they can be used to implement OpenCL atomic builtin functions.<o:p></o:p></span></p>
<p style="mso-margin-top-alt:0cm;margin-right:0cm;margin-bottom:9.0pt;margin-left:0cm;background:white;font-variant-ligatures: normal;font-variant-caps: normal;orphans: 2;widows: 2;-webkit-text-stroke-width: 0px;word-spacing:0px">
<span lang="EN-US" style="font-size:10.0pt;font-family:"Segoe UI","sans-serif";color:black">This patch will not just benefits OpenCL. It will benefit any languages which need to generate atomic instructions with synchronization scopes. For languages not using
synchronization scopes there is no functional change, since the synchronization scope argument is optional, and its default value generates the same LLVM instruction as before.<o:p></o:p></span></p>
<p style="mso-margin-top-alt:0cm;margin-right:0cm;margin-bottom:9.0pt;margin-left:0cm;background:white">
<span lang="EN-US" style="font-size:10.0pt;font-family:"Segoe UI","sans-serif";color:black">Your comments are welcome.<span style="background:white"><o:p></o:p></span></span></p>
<p style="mso-margin-top-alt:0cm;margin-right:0cm;margin-bottom:9.0pt;margin-left:0cm;background:white">
<span lang="EN-US" style="font-size:10.0pt;font-family:"Segoe UI","sans-serif";color:black;background:white">Thanks.<o:p></o:p></span></p>
<p style="mso-margin-top-alt:0cm;margin-right:0cm;margin-bottom:9.0pt;margin-left:0cm;background:white">
<span lang="EN-US" style="font-size:10.0pt;font-family:"Segoe UI","sans-serif";color:black;background:white">Sam</span><span lang="EN-US" style="font-size:10.0pt;font-family:"Segoe UI","sans-serif";color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
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