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<p class="MsoNormal">Thanks Kavon.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">What news of CpsCall in LLVM? That seems crucial.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I didn’t know of an effort to use a different SP register. I seriously doubt that, with GHC’s use of zillions of small, heap-allocated stacks that move around during GHC, we’ll be able to leverage profiling or debugging tools in a serious
way. But perhaps I need education.<o:p></o:p></p>
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<p class="MsoNormal">Simon<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><b><span lang="EN-US">From:</span></b><span lang="EN-US"> ghc-devs <ghc-devs-bounces@haskell.org>
<b>On Behalf Of </b>Kavon Farvardin<br>
<b>Sent:</b> 04 December 2019 19:32<br>
<b>To:</b> Ben Gamari <ben@smart-cactus.org><br>
<b>Cc:</b> GHC developers <ghc-devs@haskell.org><br>
<b>Subject:</b> Re: new llvm IR callbr instruction useful for proc-point splitting?<o:p></o:p></span></p>
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<p class="MsoNormal">Hi Ben,<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">The Wiki now has a link to the Google Doc that Michal and I were working on to compile all of the notes into one place.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">The key progress made on this front has been in evaluating the trade-offs of the design space being considered by GHC, but tested within Manticore.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">I'm drafting a message today for the LLVM mailing list regarding one of our first options: defining a GHC ABI to redefine which stack-pointer register is used. <o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Once we have additional answers to the question "how much effort is it to add a GHC ABI to LLVM?", we can then then start a discussion on whether GHC wants to change instead by moving to a native stack-pointer register (to take advantage
of existing debugging and profiling tools, etc).<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Ideally, we would then make a decision on which option to take and someone (perhaps a GSoC student with mentorship from myself and others) with spare time can work on it.<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">Kavon<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">On Wed, 2019-12-04 at 11:38 -0500, Ben Gamari wrote:<o:p></o:p></p>
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<pre>Kavon Farvardin <<a href="mailto:kavon@farvard.in">kavon@farvard.in</a>> writes:<o:p></o:p></pre>
<pre><o:p> </o:p></pre>
<pre>Yes, callbr is part of the discussion on removing proc-point splitting! <o:p></o:p></pre>
<pre>Soon there will be an announcement about a new working group dedicated to LLVM<o:p></o:p></pre>
<pre>issues such as this one on this mailing list. Anyone interested is welcome to<o:p></o:p></pre>
<pre>join our meetings.<o:p></o:p></pre>
<pre>We're currently gathering our notes together first, but you can have a look here<o:p></o:p></pre>
<pre>for a preview: <o:p></o:p></pre>
<pre><a href="https://gitlab.haskell.org/ghc/ghc/wikis/commentary/compiler/LLVM-Backend-Optimization">https://gitlab.haskell.org/ghc/ghc/wikis/commentary/compiler/LLVM-Backend-Optimization</a><o:p></o:p></pre>
<pre><o:p> </o:p></pre>
<pre>Hi Kavon,<o:p></o:p></pre>
<pre><o:p> </o:p></pre>
<pre>What ever happened to this? It came up during the GHC call and we<o:p></o:p></pre>
<pre>realized that none of us knew what the state of the proposal was. Is<o:p></o:p></pre>
<pre>this Wiki page still reflective of the current state of play?<o:p></o:p></pre>
<pre><o:p> </o:p></pre>
<pre>Cheers,<o:p></o:p></pre>
<pre><o:p> </o:p></pre>
<pre>- Ben<o:p></o:p></pre>
<pre><o:p> </o:p></pre>
<pre><o:p> </o:p></pre>
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