<div dir="ltr">Yes, thank you, Simon. I had not occurred to me that an inlining could start working in a later phase due to loss of loop-breaker status, rather than the relationship between the current phase and the identifier's declared inlining phase.<div><br></div><div>-- Conal</div></div><div class="gmail_extra"><br><div class="gmail_quote">On Tue, Dec 6, 2016 at 6:02 AM, Simon Peyton Jones <span dir="ltr"><<a href="mailto:simonpj@microsoft.com" target="_blank">simonpj@microsoft.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div lang="EN-GB" link="blue" vlink="purple">
<div class="m_-6806254548404377450WordSection1"><span class="">
<p class="MsoNormal" style="margin-right:0cm;margin-bottom:6.0pt;margin-left:0cm">
* To access an unfolding, is `maybeUnfoldingTemplate (idUnfolding v)` the recommended recipe?<u></u><u></u></p>
</span><p class="MsoNormal"><span style="font-family:"Calibri",sans-serif">You can see by looking at the code that idUnfolding returns nothing for a loop breaker. You have to decide if that’s what you want; if not, use realIdUnfolding.<u></u><u></u></span></p><span class="">
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif"><u></u> <u></u></span></p>
<p class="MsoNormal" style="margin-right:0cm;margin-bottom:6.0pt;margin-left:0cm">
* Is it the case that this recipe succeeds (`Just`) in some compiler phases and not others?<u></u><u></u></p>
</span><p class="MsoNormal"><span style="font-family:"Calibri",sans-serif">It fails for loop breakers. An Id might be a loop breaker in some phases but not others; e.g. the loop might be broken by some optimisation.<u></u><u></u></span></p><span class="">
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif"><u></u> <u></u></span></p>
<p class="MsoNormal" style="margin-right:0cm;margin-bottom:6.0pt;margin-left:0cm">
* Before an Id is ready for general inlining by the simplifier, can I get the Id's unfolding another way so that I can substitute it early?<u></u><u></u></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif"><u></u> <u></u></span></p>
</span><p class="MsoNormal"><span style="font-family:"Calibri",sans-serif">realIdUnfolding always works. As the code shows<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif"><u></u> <u></u></span></p>
<p class="m_-6806254548404377450Code">idUnfolding :: Id -> Unfolding<u></u><u></u></p>
<p class="m_-6806254548404377450Code">-- Do not expose the unfolding of a loop breaker!<u></u><u></u></p>
<p class="m_-6806254548404377450Code">idUnfolding id<u></u><u></u></p>
<p class="m_-6806254548404377450Code"> | isStrongLoopBreaker (occInfo info) = NoUnfolding<u></u><u></u></p>
<p class="m_-6806254548404377450Code"> | otherwise <wbr> = unfoldingInfo info<u></u><u></u></p>
<p class="m_-6806254548404377450Code"> where<u></u><u></u></p>
<p class="m_-6806254548404377450Code"> info = idInfo id<u></u><u></u></p>
<p class="m_-6806254548404377450Code"><u></u> <u></u></p>
<p class="m_-6806254548404377450Code">realIdUnfolding :: Id -> Unfolding<u></u><u></u></p>
<p class="m_-6806254548404377450Code">-- Expose the unfolding if there is one, including for loop breakers<u></u><u></u></p>
<p class="m_-6806254548404377450Code">realIdUnfolding id = unfoldingInfo (idInfo id)<u></u><u></u></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif">Does that help?<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif">Simon<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif"><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif"><u></u> <u></u></span></p>
<div style="border:none;border-left:solid blue 1.5pt;padding:0cm 0cm 0cm 4.0pt">
<div>
<div style="border:none;border-top:solid #e1e1e1 1.0pt;padding:3.0pt 0cm 0cm 0cm">
<p class="MsoNormal"><b><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif"> <a href="mailto:conal.elliott@gmail.com" target="_blank">conal.elliott@gmail.com</a> [mailto:<a href="mailto:conal.elliott@gmail.com" target="_blank">conal.elliott@gmail.<wbr>com</a>]
<b>On Behalf Of </b>Conal Elliott<br>
<b>Sent:</b> 02 December 2016 18:13<br>
<b>To:</b> Simon Peyton Jones <<a href="mailto:simonpj@microsoft.com" target="_blank">simonpj@microsoft.com</a>><br>
<b>Cc:</b> <a href="mailto:ghc-devs@haskell.org" target="_blank">ghc-devs@haskell.org</a><br>
<b>Subject:</b> Re: How to inline early in a GHC plugin?<u></u><u></u></span></p>
</div>
</div><div><div class="h5">
<p class="MsoNormal"><u></u> <u></u></p>
<div>
<div>
<p class="MsoNormal" style="margin-right:0cm;margin-bottom:6.0pt;margin-left:0cm">
Thanks for the pointers, Simon. Some more specific questions:<u></u><u></u></p>
</div>
<div>
<p class="MsoNormal" style="margin-right:0cm;margin-bottom:6.0pt;margin-left:0cm">
<u></u> <u></u></p>
</div>
<div>
<p class="MsoNormal" style="margin-right:0cm;margin-bottom:6.0pt;margin-left:0cm">
* To access an unfolding, is `maybeUnfoldingTemplate (idUnfolding v)` the recommended recipe?<u></u><u></u></p>
</div>
<div>
<p class="MsoNormal" style="margin-right:0cm;margin-bottom:6.0pt;margin-left:0cm">
* Is it the case that this recipe succeeds (`Just`) in some compiler phases and not others?<u></u><u></u></p>
</div>
<div>
<p class="MsoNormal" style="margin-right:0cm;margin-bottom:6.0pt;margin-left:0cm">
If so, is this difference due to Ids being altered (presumably via `setUnfoldingInfo` being called between phases)?<u></u><u></u></p>
</div>
<div>
<p class="MsoNormal" style="margin-right:0cm;margin-bottom:6.0pt;margin-left:0cm">
* Before an Id is ready for general inlining by the simplifier, can I get the Id's unfolding another way so that I can substitute it early?<u></u><u></u></p>
</div>
<div>
<p class="MsoNormal" style="margin-right:0cm;margin-bottom:6.0pt;margin-left:0cm">
<u></u> <u></u></p>
</div>
<div>
<p class="MsoNormal" style="margin-right:0cm;margin-bottom:6.0pt;margin-left:0cm">
A short Skype chat might easily clear up my questions and confusions if you have time and inclination.<u></u><u></u></p>
</div>
<div>
<p class="MsoNormal" style="margin-right:0cm;margin-bottom:6.0pt;margin-left:0cm">
<u></u> <u></u></p>
</div>
<div>
<p class="MsoNormal" style="margin-right:0cm;margin-bottom:6.0pt;margin-left:0cm">
Regards, - Conal<u></u><u></u></p>
</div>
</div>
<div>
<p class="MsoNormal" style="margin-right:0cm;margin-bottom:6.0pt;margin-left:0cm">
<u></u> <u></u></p>
<div>
<p class="MsoNormal" style="margin-right:0cm;margin-bottom:6.0pt;margin-left:0cm">
On Fri, Dec 2, 2016 at 9:07 AM, Simon Peyton Jones <<a href="mailto:simonpj@microsoft.com" target="_blank">simonpj@microsoft.com</a>> wrote:<u></u><u></u></p>
<blockquote style="border:none;border-left:solid #cccccc 1.0pt;padding:0cm 0cm 0cm 6.0pt;margin-left:4.8pt;margin-right:0cm">
<div>
<div>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif">I don’t really understand your question clearly. So I’ll guess</span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif"> </span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif">Unfoldings are added to Ids in Simplify.completeBind (look for setUnfoldingInfo). Apart from INLINE pragmas, that’s about the only
place it happens. </span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif"> </span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif">Does that help?</span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif"> </span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif">S</span><u></u><u></u></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif"> </span><u></u><u></u></p>
<div style="border:none;border-left:solid blue 1.5pt;padding:0cm 0cm 0cm 4.0pt">
<div>
<div style="border:none;border-top:solid #e1e1e1 1.0pt;padding:3.0pt 0cm 0cm 0cm">
<p class="MsoNormal"><b><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif"> ghc-devs
[mailto:<a href="mailto:ghc-devs-bounces@haskell.org" target="_blank">ghc-devs-bounces@<wbr>haskell.org</a>]
<b>On Behalf Of </b>Conal Elliott<br>
<b>Sent:</b> 01 December 2016 21:51<br>
<b>To:</b> <a href="mailto:ghc-devs@haskell.org" target="_blank">ghc-devs@haskell.org</a><br>
<b>Subject:</b> How to inline early in a GHC plugin?</span><u></u><u></u></p>
</div>
</div>
<p class="MsoNormal"> <u></u><u></u></p>
<div>
<div>
<p class="MsoNormal" style="margin-bottom:6.0pt">I'm implementing a GHC plugin that installs a `BuiltInRule` that does the work, and I'd like to learn how to inline more flexibly. Given an identifier `v`, I'm using `maybeUnfoldingTemplate
(realIdUnfolding v)` to get a `Maybe CoreExpr`. Sometimes this recipe yields `Nothing` until a later compiler phase. Meanwhile, I guess my variable `v` has been replaced by one with inlining info. First, am I understanding this mechanism correctly? A GHC source
pointer to how inlining is made available would help me. Second, can I access the inlining info before it's made available to the rest of the simplifier?<u></u><u></u></p>
</div>
<div>
<p class="MsoNormal" style="margin-bottom:6.0pt"> <u></u><u></u></p>
</div>
<div>
<p class="MsoNormal" style="margin-bottom:6.0pt">Thanks, - Conal<u></u><u></u></p>
</div>
</div>
</div>
</div>
</div>
</blockquote>
</div>
<p class="MsoNormal"><u></u> <u></u></p>
</div>
</div></div></div>
</div>
</div>
</blockquote></div><br></div>