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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'>Yes, I tried to use CopyToReg/CopyFromReg to enforce the order. The issue is “Untyped” data type.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>The REG_SEQUENCE and EXTRACT_SUBREG has to use “Untyped” data type. However, CopyToReg/CopyFromReg doesn’t support such data type.<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'>And I explicitly add a glue edge between the Extract_subreg and inline asm:<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>SDValue E0 = SDValue(CurDAG->getMachineNode(TargetOpcode::EXTRACT_SUBREG,<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> dl, MVT::i32, MVT::Glue, PairedReg,<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> CurDAG->getTargetConstant(ARM::gsub_0, MVT::i32),<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> Chain.getValue(1) </span><span style='font-size:11.0pt;font-family:Wingdings;color:#1F497D'>è</span><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> Guarantees that this node is emitted after the linlineasm<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> ), 0);<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'>In other words, this node has the same effect as CopyFromReg.<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><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation</span><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p></o:p></span></p></div><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"'> Jakob Stoklund Olesen [mailto:stoklund@2pi.dk] <br><b>Sent:</b> Thursday, January 03, 2013 10:57 AM<br><b>To:</b> weimingz@codeaurora.org<br><b>Cc:</b> llvm-commits@cs.uiuc.edu; 'James Grosbach'; Evan Cheng<br><b>Subject:</b> Re: [llvm-commits] Fixing Bug 13662: paired register for inline asm with 64-bit data on ARM<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p><div><div><p class=MsoNormal>On Dec 19, 2012, at 4:22 PM, Weiming Zhao <<a href="mailto:weimingz@codeaurora.org">weimingz@codeaurora.org</a>> wrote:<o:p></o:p></p></div><p class=MsoNormal><br><br><o:p></o:p></p><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>The change to InstrEmitter is to let it support ExtractSubReg / RegSequence to be connected to RegisterNode and CopyFrom node to be connected to a SubReg SDNode.</span><o:p></o:p></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Normally, ExtractSubReg/RegSequence are only connected to a SDValue, but for inlineasem, we have to connect them to a VR.</span><o:p></o:p></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Existing inlineasm just emits multiple 32bit-typed VRs, it doesn’t need ExtractSubReg/RegSequence, so such scenarios are not encountered. </span><o:p></o:p></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Now, this issue is exposed . </span><o:p></o:p></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>So my patch let it handle more cases. It should be safe.</span><o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>It is important that you understand how data dependencies are modeled in SelectionDAG. They must be represented by DAG edges, and RegisterSDNode doesn't provide a DAG edge.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Calls and inline-asm nodes get their arguments from virtual or physical registers via RegisterSDNode arguments, but that only works because those registers are read or written by CopyToReg and/or CopyFromReg nodes that are *glued* to the call/asm nodes. The DAG edges carrying the data dependencies are provided by the CopyToReg / CopyFromReg nodes.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>You can't simply allow REG_SEQUENCE and EXTRACT_SUBREG to operate on RegisterSDNodes since there is no DAG edge providing the data dependency. It would be completely unsafe to allow such DAG constructs.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>It is also entirely unnecessary. You can feed your REG_SEQUENCE DAG edge into the CopyToReg node that is glued to an inline-asm node, and you can EXTRACT_SUBREG from a similarly glued CopyFromReg.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>/jakob<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div></div></div></body></html>