<div dir="ltr">Hi Rahul,<div><br></div><div>I see mention of the popcount instruction in nativeGen/X86/CodeGen.hs. In particular it looks like it only activates if sse4_2 is activated? Maybe all I need to do is activate this somehow?</div><div><br></div><div>Cheers,</div><div><br></div><div>-John</div><div><br><div class="gmail_quote"><div dir="ltr">On Wed, 23 Mar 2016 at 12:07 <<a href="mailto:rahulmutt@gmail.com">rahulmutt@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div lang="en-GB" style="background-color:rgb(255,255,255);line-height:initial"> <div style="width:100%;font-size:initial;font-family:Calibri,'Slate Pro',sans-serif,sans-serif;color:rgb(31,73,125);text-align:initial;background-color:rgb(255,255,255)">Hi John,</div><div style="width:100%;font-size:initial;font-family:Calibri,'Slate Pro',sans-serif,sans-serif;color:rgb(31,73,125);text-align:initial;background-color:rgb(255,255,255)"><br></div><div style="width:100%;font-size:initial;font-family:Calibri,'Slate Pro',sans-serif,sans-serif;color:rgb(31,73,125);text-align:initial;background-color:rgb(255,255,255)">ghc-prim is just a stub package generated for the purpose of documentation. All primops are defined in a low level language called Cmm in GHC. If you want to make it even faster, you'll need to learn Cmm and update the definition in GHC. If you want to a specialized implementation for x86 systems, you may need to modify the NCG (Native Code Generator) which requires a knowledge of assembly language.</div><div style="width:100%;font-size:initial;font-family:Calibri,'Slate Pro',sans-serif,sans-serif;color:rgb(31,73,125);text-align:initial;background-color:rgb(255,255,255)"><br></div><div style="width:100%;font-size:initial;font-family:Calibri,'Slate Pro',sans-serif,sans-serif;color:rgb(31,73,125);text-align:initial;background-color:rgb(255,255,255)">Hope that helps!</div><div style="width:100%;font-size:initial;font-family:Calibri,'Slate Pro',sans-serif,sans-serif;color:rgb(31,73,125);text-align:initial;background-color:rgb(255,255,255)">Rahul Muttineni</div> <div style="width:100%;font-size:initial;font-family:Calibri,'Slate Pro',sans-serif,sans-serif;color:rgb(31,73,125);text-align:initial;background-color:rgb(255,255,255)"><br style="display:initial"></div> <div style="font-size:initial;font-family:Calibri,'Slate Pro',sans-serif,sans-serif;color:rgb(31,73,125);text-align:initial;background-color:rgb(255,255,255)">Sent from my BlackBerry 10 smartphone.</div> <table width="100%" style="background-color:white;border-spacing:0px"> <tbody><tr><td colspan="2" style="font-size:initial;text-align:initial;background-color:rgb(255,255,255)"> <div style="border-style:solid none none;border-top-color:rgb(181,196,223);border-top-width:1pt;padding:3pt 0in 0in;font-family:Tahoma,'BB Alpha Sans','Slate Pro';font-size:10pt"> <div><b>From: </b>John Ky</div><div><b>Sent: </b>Wednesday 23 March 2016 4:40 AM</div><div><b>To: </b>The Haskell-Beginners Mailing List - Discussion of primarily beginner-level topics related to Haskell</div><div><b>Reply To: </b>The Haskell-Beginners Mailing List - Discussion of primarily beginner-level topics related to Haskell</div><div><b>Subject: </b>[Haskell-beginners] let x = x in x (GHC.Prim)</div></div></td></tr></tbody></table></div><div lang="en-GB" style="background-color:rgb(255,255,255);line-height:initial"><div style="border-style:solid none none;border-top-color:rgb(186,188,209);border-top-width:1pt;font-size:initial;text-align:initial;background-color:rgb(255,255,255)"></div><br><div><div dir="ltr">Hello Haskellers,<div><br></div><div>I'm trying to write a faster popCount function for x86 systems.<br></div><div><br></div><div>I tried cloning the ghc-prim package and repurposing it for my own needs, but it isn't working as hoped.</div><div><br></div><div>In particular, popCnt64# was implemented in GHC.Prim as:</div><div><br></div><div>popCnt64# = let x = x in x<br></div><div><br></div><div>Which shouldn't terminate. Yet when I call it, it magically finds the C implementation in hs_popcnt64 and returns the correct value.</div><div><br></div><div>My cloned project doesn't behave that way. Instead it doesn't terminate as I would expect.</div><div><br></div><div>Anyone know what's happening here, if there is a way to make this work or tell me if I'm going about this completely the wrong way?</div><div><br></div><div>Cheers,</div><div><br></div><div>-John</div><div><br></div></div>
<br></div></div><div lang="en-GB" style="background-color:rgb(255,255,255);line-height:initial"></div>
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