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<p class="MsoNormal"><span style="color:#1F497D">Hello Neil.<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">Out of the solutions mentioned in the comments<o:p></o:p></span></p>
<p class="MsoNormal" style="text-indent:.5in"><span style="color:#1F497D"><a href="https://reviews.llvm.org/D5389">https://reviews.llvm.org/D5389</a> by beanz<o:p></o:p></span></p>
<p class="MsoNormal" style="text-indent:.5in"><span style="color:#1F497D"><a href="https://reviews.llvm.org/D53424#1273950">https://reviews.llvm.org/D53424#1273950</a> by delcypher<o:p></o:p></span></p>
<p class="MsoNormal" style="text-indent:.5in"><span style="color:#1F497D"><a href="https://reviews.llvm.org/D53424">https://reviews.llvm.org/D53424</a> by yrouban<o:p></o:p></span></p>
<p class="MsoNormal" style="text-indent:.5in"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">none has got future community agreement on further development.<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"><a href="https://reviews.llvm.org/D53424">https://reviews.llvm.org/D53424</a> seems to be simple and gives a new use model (thread specific redefinition) for all existing cl::opts. This scares those who have
another development direction in mind, because such new use model will have to be handled in future. In other words, this *<b>increases technical debt</b>*.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">On the other hand I see the other ideas to be hardly applicable to all cl::opts at once: they have to be changed for every single cl::opt and it could not be done automatically or with a script.<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">It seems we stack but I agree with you, we need something to go further.<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"><span style="color:#1F497D">Thanks.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">-Yevgeny Rouban<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b>From:</b> llvm-dev <llvm-dev-bounces@lists.llvm.org> <b>On Behalf Of
</b>Neil Henning via llvm-dev<br>
<b>Sent:</b> Thursday, December 13, 2018 6:07 PM<br>
<b>To:</b> llvm-dev@lists.llvm.org<br>
<b>Subject:</b> Re: [llvm-dev] [RFC] Enable thread specific cl::opt values for multi-threaded support<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p>Hey all,<o:p></o:p></p>
<p>Trying to revive the RFC thread here - we have a need for this functionality (or some similar mechanism that lets us have a per-thread or per-context setting for options).<o:p></o:p></p>
<p>Is there any scope for getting something in that enables our (AMD's) graphics drivers and Azul to make use of it, in the short term, even if it's not the perfect solution that everyone desires?<o:p></o:p></p>
<p>Cheers,<o:p></o:p></p>
<p>-Neil.<o:p></o:p></p>
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<p class="MsoNormal">On 08/11/2018 07:50, Yevgeny Rouban via llvm-dev wrote:<o:p></o:p></p>
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<p class="MsoNormal">Hello Chris.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">> One of the perennial problems with cl::opt is that ...<o:p></o:p></p>
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<p class="MsoNormal">My RFC does not change the way the options are initialized and registered. So the static initialization problem is not made worse by this RFC.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">> Personally I very much prefer the idea of having *Context objects be responsible for options rather than thread-local storage ...<o:p></o:p></p>
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<p class="MsoNormal">This RFC defines a *Context* for options. In the patch the class is called ContextValues. Essentially, it is similar to *Context objects*.<o:p></o:p></p>
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<p class="MsoNormal">With the RFC we will be able to make further changes for specific options to get them from any specific Context, not only from the thread local one. The thread local is proposed as the default context to keep unchanged all places where
cl::opts are accessed.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">If we have a flag:<o:p></o:p></p>
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<p class="MsoNormal"><span style="font-family:"Courier New"">static cl::opt<bool> SomeFlag; // static global</span><o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Flag access code looks like the following:<o:p></o:p></p>
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<p class="MsoNormal"><span style="font-family:"Courier New"">if ( SomeFlag ) ... // global flag access</span><o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">With the RFC (thread specific cl::opt values) this code being unchanged becomes equivalent to:<o:p></o:p></p>
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<p class="MsoNormal"><span style="font-family:"Courier New"">if ( SomeFlag.getValue(<span class="gmail-n">cl</span><span class="gmail-o">::</span><span class="gmail-n">ContextValues</span><span class="gmail-o">::</span><span class="gmail-n">GetThreadOptionContext()</span>)
) ... // thread local flag access with fallback to global flag access</span> <o:p>
</o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Then we can manually change this source to:<o:p></o:p></p>
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<p class="MsoNormal"><span style="font-family:"Courier New"">if ( SomeFlag.getValue(SomeSpecificContext) ) ... // context specific flag access with fallback to thread local flag access</span>
<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">In this example SomeSpecificContext can be specific to LLVMContext, Pass, ...<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Thanks.<o:p></o:p></p>
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<p class="MsoNormal">-Yevgeny Rouban<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><br>
<br>
<o:p></o:p></p>
<pre>_______________________________________________<o:p></o:p></pre>
<pre>LLVM Developers mailing list<o:p></o:p></pre>
<pre><a href="mailto:llvm-dev@lists.llvm.org">llvm-dev@lists.llvm.org</a><o:p></o:p></pre>
<pre><a href="http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev">http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev</a><o:p></o:p></pre>
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