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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">Thanks. Looks like we can do this for only __multi3. Other TImode functions (e.g. __divti3, __modti3, etc.) are not defined on 32-bit. I am not sure if any optimizations could
cause those to be generated. AFAICT there is no fall back support (like what is there for MUL) in the Legalizer for wide SDIV, etc. See below:
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas">void DAGTypeLegalizer::ExpandIntRes_SDIV(SDNode *N,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas"> SDValue &Lo, SDValue &Hi) {<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas"> EVT VT = N->getValueType(0);<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas"> SDLoc dl(N);<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas"> SDValue Ops[2] = { N->getOperand(0), N->getOperand(1) };<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas"> if (TLI.getOperationAction(ISD::SDIVREM, VT) == TargetLowering::Custom) {<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas"> SDValue Res = DAG.getNode(ISD::SDIVREM, dl, DAG.getVTList(VT, VT), Ops);<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas"> SplitInteger(Res.getValue(0), Lo, Hi);<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas"> return;<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas"> }<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas"> RTLIB::Libcall LC = RTLIB::UNKNOWN_LIBCALL;<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas"> if (VT == MVT::i16)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas"> LC = RTLIB::SDIV_I16;<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas"> else if (VT == MVT::i32)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas"> LC = RTLIB::SDIV_I32;<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas"> else if (VT == MVT::i64)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas"> LC = RTLIB::SDIV_I64;<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas"> else if (VT == MVT::i128)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas"> LC = RTLIB::SDIV_I128;<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas"> assert(LC != RTLIB::UNKNOWN_LIBCALL && "Unsupported SDIV!");<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas"> SplitInteger(TLI.makeLibCall(DAG, LC, VT, Ops, true, dl).first, Lo, Hi);<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:Consolas">}<o:p></o:p></span></p>
<p class="MsoNormal"><a name="_MailEndCompose"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"><o:p> </o:p></span></a></p>
<span style="mso-bookmark:_MailEndCompose"></span>
<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"> Craig Topper [mailto:craig.topper@gmail.com]
<br>
<b>Sent:</b> Friday, October 6, 2017 11:13 PM<br>
<b>To:</b> Riyaz Puthiyapurayil <Riyaz.Puthiyapurayil@synopsys.com><br>
<b>Cc:</b> llvm-dev@lists.llvm.org<br>
<b>Subject:</b> Re: [llvm-dev] Bug 20871 -- is there a fix or work around?<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">That seems like a valid fix to me.<o:p></o:p></p>
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<o:p></o:p></p>
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<p class="MsoNormal">~Craig<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, Oct 6, 2017 at 9:45 PM, Riyaz Puthiyapurayil via llvm-dev <<a href="mailto:llvm-dev@lists.llvm.org" target="_blank">llvm-dev@lists.llvm.org</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">Ignore the suggested fix in my earlier post. How about this?<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:Consolas">diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:Consolas">index 20c81c3..b8ebf42 100644</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:Consolas">--- a/lib/Target/X86/X86ISelLowering.cpp</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:Consolas">+++ b/lib/Target/X86/X86ISelLowering.cpp</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:Consolas">@@ -1632,10 +1632,11 @@ X86TargetLowering::X86TargetLowering(const X86TargetMachine &TM,</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:Consolas"> if (!Subtarget.is64Bit()) {</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:Consolas"> // These libcalls are not available in 32-bit.</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:Consolas"> setLibcallName(RTLIB::SHL_I128, nullptr);</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:Consolas"> setLibcallName(RTLIB::SRL_I128, nullptr);</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:Consolas"> setLibcallName(RTLIB::SRA_I128, nullptr);</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><b><span style="font-family:Consolas;color:#00B050">+ setLibcallName(RTLIB::MUL_I128, nullptr);</span></b><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:Consolas"> }</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:Consolas"> // Combine sin / cos into one node or libcall if possible.</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:Consolas"> if (Subtarget.hasSinCos()) {</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:Consolas"> setLibcallName(RTLIB::SINCOS_F32, "sincosf");</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:Consolas"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><i><span style="font-family:Consolas">This will make the Legalizer choose the brute force approach below:</span></i><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:Consolas"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:Consolas">void DAGTypeLegalizer::ExpandIntRes_MUL(SDNode *N,</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:Consolas"> SDValue &Lo, SDValue &Hi) {</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:Consolas">...</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:Consolas"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:Consolas">
<b>if (LC == RTLIB::UNKNOWN_LIBCALL || !TLI.getLibcallName(LC)) {</b></span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:Consolas"> // We'll expand the multiplication by brute force because we have no other</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:Consolas"> // options. This is a trivially-generalized version of the code from</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:Consolas"> // Hacker's Delight (itself derived from Knuth's Algorithm M from section</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-family:Consolas"> // 4.3.1).</span><o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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