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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>I think you can make the 32bit and 64bit types legal (using addRegisterClass) and use setOperationAction(Expand) for all the operations for which you don’t have native support.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> llvm-dev [mailto:llvm-dev-bounces@lists.llvm.org] <b>On Behalf Of </b>Miguel Inigo J. Manalac via llvm-dev<br><b>Sent:</b> Thursday, February 6, 2020 2:27 AM<br><b>To:</b> llvm-dev@lists.llvm.org<br><b>Subject:</b> [llvm-dev] LLVM Backend Legalize Phase<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><div><div><div><div><p class=gmaildefault style='mso-margin-top-alt:0in;margin-right:0in;margin-bottom:11.25pt;margin-left:0in;line-height:14.65pt;vertical-align:baseline'><span lang=EN-PH style='font-size:11.5pt;font-family:"Verdana","sans-serif";color:black'>Hello llvm-dev,<o:p></o:p></span></p><p class=gmaildefault style='mso-margin-top-alt:0in;margin-right:0in;margin-bottom:11.25pt;margin-left:0in;line-height:14.65pt;vertical-align:baseline'><span lang=EN-PH style='font-size:11.5pt;font-family:"Verdana","sans-serif";color:black'><o:p> </o:p></span></p><p class=gmaildefault style='mso-margin-top-alt:0in;margin-right:0in;margin-bottom:11.25pt;margin-left:0in;line-height:14.65pt;vertical-align:baseline'><span lang=EN-PH style='font-size:11.5pt;font-family:"Verdana","sans-serif";color:#242729'>Our team is currently creating an LLVM backend for embedded systems. We're seeking for an advice on the best/correct way to implement our register classes in the Legalize Phase. As an overview, our backend has 8-bit, 16-bit, 32-bit, and 64-bit register classes. Our instruction set consist mostly of 8-bit and 16-bit instructions. The 32-bit and 64-bit instructions are commonly used in memory access operations. </span><span lang=EN-PH style='font-size:11.5pt;color:#242729'><o:p></o:p></span></p><p class=gmaildefault style='mso-margin-top-alt:0in;margin-right:0in;margin-bottom:11.25pt;margin-left:0in;line-height:14.65pt;vertical-align:baseline;box-sizing:border-box;font-size-adjust:none;font-stretch:normal;word-spacing:0px'><span lang=EN-PH style='font-size:11.5pt;font-family:"Verdana","sans-serif";color:#242729'>The LLVM Backend reference we used is the AVR. In their implementation, 8-bit and 16-bit register classes were added with the addRegisterClass function (They only have up to 16-bit registers) in their TargetLowering. With this, 32-bit and 64-bit operations are automatically split into its equivalent 8/16-bit operations in the DAG after the Legalize Phase.</span><span lang=EN-PH style='font-size:11.5pt;color:#242729'><o:p></o:p></span></p><p class=gmaildefault style='mso-margin-top-alt:0in;margin-right:0in;margin-bottom:11.25pt;margin-left:0in;line-height:14.65pt;vertical-align:baseline;box-sizing:border-box;font-size-adjust:none;font-stretch:normal;word-spacing:0px'><span lang=EN-PH style='font-size:11.5pt;font-family:"Verdana","sans-serif";color:#242729'>For the LLVM Backend we are currently developing, in one hand, adding the 32-bit and 64-bit register classes would output DAG nodes containing 32/64-bit operations. This would require us to create pseudo instructions in the TableGen for expansion to its 8/16-bit equivalent operations. On the other hand, not adding these register classes would have the same behavior with the AVR.</span><span lang=EN-PH style='font-size:11.5pt;color:#242729'><o:p></o:p></span></p><p class=gmaildefault style='mso-margin-top-alt:0in;margin-right:0in;margin-bottom:11.25pt;margin-left:0in;line-height:14.65pt;vertical-align:baseline;box-sizing:border-box;font-size-adjust:none;font-stretch:normal;word-spacing:0px'><span lang=EN-PH style='font-size:11.5pt;font-family:"Verdana","sans-serif";color:#242729'>We are unaware of the consequences of both cases. We have only tested this with load and store operations for now. We have not verified if the DAG output are also correct for other operations. What should we consider in deciding what to use in our implementation?</span><span lang=EN-PH style='font-size:11.5pt;color:#242729'><o:p></o:p></span></p><p class=gmaildefault style='mso-margin-top-alt:0in;margin-right:0in;margin-bottom:11.25pt;margin-left:0in;line-height:14.65pt;vertical-align:baseline;box-sizing:border-box;font-size-adjust:none;font-stretch:normal;word-spacing:0px'><span lang=EN-PH style='font-size:11.5pt;font-family:"Verdana","sans-serif";color:#242729'>Thank you very much in advance for your efforts and help!</span><span lang=EN-PH style='font-size:11.5pt;color:#242729'><o:p></o:p></span></p><p class=gmaildefault style='mso-margin-top-alt:0in;margin-right:0in;margin-bottom:11.25pt;margin-left:0in;line-height:14.65pt;vertical-align:baseline;box-sizing:border-box;font-size-adjust:none;font-stretch:normal;word-spacing:0px'><span lang=EN-PH style='font-size:11.5pt;font-family:"Verdana","sans-serif";color:#242729'>Best,</span><span lang=EN-PH style='font-size:11.5pt;color:#242729'><o:p></o:p></span></p><p class=gmaildefault style='mso-margin-top-alt:0in;margin-right:0in;margin-bottom:11.25pt;margin-left:0in;line-height:14.65pt;vertical-align:baseline;box-sizing:border-box;font-size-adjust:none;font-stretch:normal;word-spacing:0px'><span lang=EN-PH style='font-size:11.5pt;font-family:"Verdana","sans-serif";color:#242729'>Igie</span><span lang=EN-PH style='font-size:11.5pt;color:#242729'><o:p></o:p></span></p></div></div></div></div><p class=MsoNormal><span lang=EN-PH>JAPANESE: </span><span style='font-family:"MS Gothic"'>このメールは、宛先に書かれている方のみに送信することを意図しております。誤ってそれ以外の方に送信された場合は、申し訳ございませんが、送信者までお知らせいただき、受信されたメールを削除していただきますようお願いいたします。また、コンピュータ・ウィルスの混入等によってメールの欠落・不整合・遅滞等が発生し、何らのご不便をおかけすることが生じても弊社はその責任を負いません。</span><span lang=EN-PH> ENGLISH: This e-mail is intended for the person(s) to which it is addressed. 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