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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:KO">Hi Ben,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:KO"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:KO">As the error message mentioned, the first operand of SUBXri needs to be GPR64sp register class. The ANDXri one is GPR64.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:KO">In order to align the register classes, you can use constrainRegClass with the SrcReg and it will constraint the register class to GPR64common which
is common between GPR64sp and GPR64.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:KO"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:KO">JinGu Kang<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:KO"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> llvm-dev <llvm-dev-bounces@lists.llvm.org>
<b>On Behalf Of </b>Ben Shi via llvm-dev<br>
<b>Sent:</b> 03 October 2021 15:46<br>
<b>To:</b> llvm-dev <llvm-dev@lists.llvm.org><br>
<b>Subject:</b> [llvm-dev] Help: A Question about AArch64 Register Class<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p style="margin:0cm"><span style="font-size:10.5pt;font-family:"Courier New";color:black">Hello, </span><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p></o:p></span></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Courier New";color:black">I am modifying the new committed pass "aarch64-mi-peephole-opt", but get unexpected errors.</span><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Courier New";color:black">My code:</span><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Courier New";color:black"> const TargetRegisterClass *RC =</span><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Courier New";color:black"> (RegSize == 32) ? &AArch64::GPR32spRegClass : &AArch64::GPR64spRegClass;</span><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Courier New";color:black"> Register DstReg = MI.getOperand(0).getReg();</span><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Courier New";color:black"> Register SrcReg = MI.getOperand(1).getReg();</span><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Courier New";color:black"> Register TmpReg = MRI->createVirtualRegister(RC);</span><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Courier New";color:black"> BuildMI(*MBB, MI, DL, TII->get(AArch64::SUBXri), TmpReg)</span><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Courier New";color:black"> .addReg(SrcReg)</span><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Courier New";color:black"> .addImm(Imm)</span><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Courier New";color:black"> .addImm(12);</span><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Courier New";color:black"> </span><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Courier New";color:black">But when I tried to compile a simple function with
</span><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Courier New";color:black">"llc a.ll -mtriple=aarch64 -verify-machineinstrs", I got errors like</span><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Courier New";color:black"> </span><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Courier New";color:black">*** Bad machine code: Illegal virtual register for instruction ***</span><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Courier New";color:black">- function: add_two_parts_imm_i64</span><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Courier New";color:black">- basic block: %bb.0 (0x561f681b0410)</span><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Courier New";color:black">- instruction: %3:gpr64common = SUBXri %0:gpr64, 2730, 12</span><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Courier New";color:black">- operand 1: %0:gpr64</span><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Courier New";color:black">Expected a GPR64sp register, but got a GPR64 register</span><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Courier New";color:black">LLVM ERROR: Found 1 machine code errors.</span><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Courier New";color:black"> </span><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Courier New";color:black">But if I changed to Opcode from SUBXri to ANDXri, then the errors were eliminated.</span><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Courier New";color:black"> </span><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Courier New";color:black">What is difference between ANDXri and SUBXri? (also ADDXri has the same errors)</span><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Courier New";color:black">What should I do to avoid the errors with Opcode SUBXri/ADDXri ?</span><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Courier New";color:black"> </span><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Courier New";color:black">Ben Shi</span><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Courier New";color:black"> </span><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.5pt;font-family:"Courier New";color:black"> </span><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:black"><o:p></o:p></span></p>
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