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<p class="MsoNormal"><span style="mso-fareast-language:EN-US">What is the GlobalVecRegTy field doing?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Don’t you need an Int for the register number, like all the rest?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Generally, sounds good though<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">S<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span lang="EN-US">From:</span></b><span lang="EN-US"> Abhiroop Sarkar <asiamgenius@gmail.com>
<br>
<b>Sent:</b> 13 July 2018 14:07<br>
<b>To:</b> Simon Peyton Jones <simonpj@microsoft.com><br>
<b>Cc:</b> ghc-devs@haskell.org<br>
<b>Subject:</b> Re: Is it possible to enhance the vector STG registers(Xmm, Ymm, Zmm) with more information?<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Hello Simon,<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 for your response. I had written a patch[1] for this and the approach I took was quite similar to what you pointed out. <o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">data GlobalReg = ...<br>
| XmmReg <o:p></o:p></p>
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<p class="MsoNormal"> (Maybe (Length, Width))<o:p></o:p></p>
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<p class="MsoNormal"> (Maybe GlobalVecRegTy)<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">data GlobalVecRegTy = Integer | Float<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">-- Width and Length are already defined<o:p></o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">data Width = W8 | W16 | W32 .....<o:p></o:p></p>
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<p class="MsoNormal">type Length = Int <o:p></o:p></p>
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<p class="MsoNormal"><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 wrapped the types inside a `Maybe` because when initializing a GlobalReg (in the `activeStgRegs`[2] function), I was not sure what value to initialize the register with, so I used a `Nothing` when initializing. <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 see now in the case of `VanillaReg` it is initialized with the `VGcPtr` constructor: <span class="gmail-pl-ent"><span style="font-size:9.0pt;font-family:Consolas;color:#22863A;background:white">VanillaReg</span></span><span style="font-size:9.0pt;font-family:Consolas;color:#24292E;background:white">
</span><span class="gmail-pl-c1"><span style="font-size:9.0pt;font-family:Consolas;color:#005CC5;background:white">1</span></span><span style="font-size:9.0pt;font-family:Consolas;color:#24292E;background:white">
</span><span class="gmail-pl-ent"><span style="font-size:9.0pt;font-family:Consolas;color:#22863A;background:white">VGcPtr etc</span></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">I think I should modify my patch as well to remove the Maybe and initialize with some default Length, Width and GlobalRegTy. Thanks for the help.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;background:white">Abhiroop</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"><o:p> </o:p></p>
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<p class="MsoNormal">[1] <a href="https://phabricator.haskell.org/D4922">https://phabricator.haskell.org/D4922</a><o:p></o:p></p>
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<p class="MsoNormal">[2] <a href="https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fghc%2Fghc%2Fblob%2Fmaster%2Fincludes%2FCodeGen.Platform.hs%23L450&data=02%7C01%7Csimonpj%40microsoft.com%7Ccb18f3003224456cfd5b08d5e8c19b21%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636670840587296823&sdata=quBJxkG7r6a7ylFqrh4VMgP8y0P1i1Xc79Xj10kV9ts%3D&reserved=0">https://github.com/ghc/ghc/blob/master/includes/CodeGen.Platform.hs#L450-L623</a><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 Fri, Jul 13, 2018 at 10:58 AM Simon Peyton Jones <<a href="mailto:simonpj@microsoft.com">simonpj@microsoft.com</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt">Abhiroop</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt">Did anyone reply?</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt">My instinct is this. You want to use the same register (say Xmm reg 3) in different ways. We already have this for ‘VanillaReg’:</span><o:p></o:p></p>
<p class="m160898050108459242code">data GlobalReg<o:p></o:p></p>
<p class="m160898050108459242code"> = VanillaReg -- pointers, unboxed ints and chars<o:p></o:p></p>
<p class="m160898050108459242code"> Int -- its number<o:p></o:p></p>
<p class="m160898050108459242code"> VGcPtr<o:p></o:p></p>
<p class="m160898050108459242code"> | …<o:p></o:p></p>
<p class="m160898050108459242code"> <o:p></o:p></p>
<p class="m160898050108459242code">data VGcPtr = VGcPtr | VNonGcPtr <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt">We use VanillaReg for both pointers and non-pointers, so (VanillaReg 3 VGcPtr) is register 3 used as a pointer, and (VanillaReg 3 VNonGcPtr) is register
3 used as a non-pointer. And notice that globalRegType looks at this field to decide what type to return.</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt">I think you can do exactly the same: add a field to Xmm that explains how you are gong to divide it up. Would that work?</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt">Simon</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt"> </span><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><b><span lang="EN-US">From:</span></b><span lang="EN-US"> ghc-devs <<a href="mailto:ghc-devs-bounces@haskell.org" target="_blank">ghc-devs-bounces@haskell.org</a>>
<b>On Behalf Of </b>Abhiroop Sarkar<br>
<b>Sent:</b> 27 June 2018 22:32<br>
<b>To:</b> <a href="mailto:ghc-devs@haskell.org" target="_blank">ghc-devs@haskell.org</a><br>
<b>Subject:</b> Is it possible to enhance the vector STG registers(Xmm, Ymm, Zmm) with more information?</span><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;margin-bottom:6.0pt">Hello all,<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;margin-bottom:6.0pt"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;margin-bottom:6.0pt">I am currently working on adding support for SIMD operations to the native code generator. One of the roadblocks I faced recently was the definition of the `globalRegType` function in
"compiler/cmm/CmmExpr.hs". The `globalRegType` function maps the STG registers to the respective `CmmType` datatype.<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;margin-bottom:6.0pt"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;margin-bottom:6.0pt">For Xmm, Ymm, Zmm registers the function defines globalRegType like this: <a href="https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fghc%2Fghc%2Fblob%2Fmaster%2Fcompiler%2Fcmm%2FCmmExpr.hs%23L585-L587&data=02%7C01%7Csimonpj%40microsoft.com%7Ccb18f3003224456cfd5b08d5e8c19b21%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636670840587296823&sdata=Ct2zsaFgEsRTclglezuPAg05zlSWwuyU45KZrrzcZCc%3D&reserved=0" target="_blank">https://github.com/ghc/ghc/blob/master/compiler/cmm/CmmExpr.hs#L585-L587</a><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;margin-bottom:6.0pt"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;margin-bottom:6.0pt">Consider the case for an Xmm register, the above definition limits an Xmm register to hold only vectors of size 4. However we can store 2 64-bit Doubles or 16 Int8s or 8 Int16s and so
on<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;margin-bottom:6.0pt"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;margin-bottom:6.0pt">The function `globalRegType` is internally called by the function `cmmRegType` (<a href="https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fghc%2Fghc%2Fblob%2F838b69032566ce6ab3918d70e8d5e098d0bcee02%2Fcompiler%2Fcmm%2FCmmExpr.hs%23L275&data=02%7C01%7Csimonpj%40microsoft.com%7Ccb18f3003224456cfd5b08d5e8c19b21%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636670840587296823&sdata=yi3CN5tdL%2FEteEwBRH6Pt%2B3QB7Ji0sGWnnlE02eyMqk%3D&reserved=0" target="_blank">https://github.com/ghc/ghc/blob/838b69032566ce6ab3918d70e8d5e098d0bcee02/compiler/cmm/CmmExpr.hs#L275</a>)
which is itself used in a number of places in the x86 code generator.<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;margin-bottom:6.0pt"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;margin-bottom:6.0pt">In fact depending on the result of the `cmmRegType` function is another important function `cmmTypeFormat` defined in Format.hs whose result is used to print the actual assembly instruction.<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;margin-bottom:6.0pt"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;margin-bottom:6.0pt">I have extended all the other Format types to include VectorFormats, however this definition of the `globalRegType` seems incorrect to me. Looking at the signature of the function itself:<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;margin-bottom:6.0pt"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;margin-bottom:6.0pt">`globalRegType :: DynFlags -> GlobalReg -> CmmType`<br>
<br>
its actually difficult to predict the CmmType by just looking at the GlobalReg in case of Xmm, Ymm, Zmm. So thats why my original question how do I go about solving this. Should I modify the GlobalReg type to contain more information like Width and Length(for
Xmm, Ymm, Zmm) or do I somehow pass the length and width information to the globalRegType function?<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;margin-bottom:6.0pt"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;margin-bottom:6.0pt">Thanks<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;margin-bottom:6.0pt">Abhiroop Sakar<o:p></o:p></p>
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<p class="MsoNormal">-- <o:p></o:p></p>
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<p class="MsoNormal">Kloona - Coming Soon!<o:p></o:p></p>
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