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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'>Andy, <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'> Thanks for that clarification. I’ll spend more time with it nonetheless to better understand it – my next goal is to add DFA to the overall equation… <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Also if it is any use to you at this point, it looks like we could benefit from moving class MachineSchedStrategy to ScheduleDAGInstrs.h.<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'>Thanks.<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'>Sergei<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:10.5pt;font-family:Consolas;color:#1F497D'>--<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.5pt;font-family:Consolas;color:#1F497D'>Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum.<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 style='border:none;border-left:solid blue 1.5pt;padding:0in 0in 0in 4.0pt'><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"'> Andrew Trick [mailto:atrick@apple.com] <br><b>Sent:</b> Wednesday, August 15, 2012 3:39 PM<br><b>To:</b> Sergei Larin<br><b>Cc:</b> llvm-commits@cs.uiuc.edu<br><b>Subject:</b> Re: [llvm-commits] [llvm] r157006 - in /llvm/trunk/lib/CodeGen: MachineScheduler.cpp RegisterPressure.cpp RegisterPressure.h<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 Aug 15, 2012, at 11:56 AM, Sergei Larin <<a href="mailto:slarin@codeaurora.org">slarin@codeaurora.org</a>> wrote:<o:p></o:p></p></div><p class=MsoNormal><br><br><o:p></o:p></p><div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Andy,</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> I am still at an earlier stage… I am trying to “port” VLIW scheduler to the “new” MI infrastructure. So far I simply copied default implementation and trying to make it work as is for my back end.</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>I currently have no reg pressure interface, so as a result the scheduler basically picks “NCAND” every time. I am trying to define these methods to enable reg pressure tracking:</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>// Get the weight in units of pressure for this register class.</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> virtual const RegClassWeight &getRegClassWeight(</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> const TargetRegisterClass *RC) const = 0;</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> /// Get the number of dimensions of register pressure.</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> virtual unsigned getNumRegPressureSets() const = 0;</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> /// Get the name of this register unit pressure set.</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> virtual const char *getRegPressureSetName(unsigned Idx) const = 0;</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> /// Get the register unit pressure limit for this dimension.</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> /// This limit must be adjusted dynamically for reserved registers.</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> virtual unsigned getRegPressureSetLimit(unsigned Idx) const = 0;</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> /// Get the dimensions of register pressure impacted by this register class.</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> /// Returns a -1 terminated array of pressure set IDs.</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> virtual const int *getRegClassPressureSets(</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> const TargetRegisterClass *RC) const = 0;</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>…but kind of uncertain about intent around getRegClassPressureSets – I am trying to read the code in RegisterPressure.cpp, but it sure would be much easier if I would know your intent…</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Here is what I gather so far, please tell me if I am wrong:</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>getRegClassWeight – should reflect how “expensive” a specific RC is.</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>getRegPressureSetLimit – is when I start to worry about register pressure (threshold of a sort).</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>getNumRegPressureSets – total number of sets(?)</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>getRegPressureSetName – their name…</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>But I am not sure what getRegClassPressureSets should produce…</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>One set per RC? Is it multiple sets per RC? If so, what is the heuristic for split? Calle/caller save etc?</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Anything else I am missing for full reg pressure tracking?</span><o:p></o:p></p></div></div></div><div><p class=MsoNormal><o:p> </o:p></p></div><p class=MsoNormal>You don't need to port anything.<o:p></o:p></p><div><p class=MsoNormal><o:p> </o:p></p><div><p class=MsoNormal>Pressure sets are meant to handle complex register files with overlapping register classes and subregisters. On Hexagon, it's very simple as you can see in HexagonGenRegisterInfo.inc.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><div><p class=MsoNormal>/// Get the weight in units of pressure for this register class.<o:p></o:p></p></div><div><p class=MsoNormal>const RegClassWeight &HexagonGenRegisterInfo::<o:p></o:p></p></div><div><p class=MsoNormal>getRegClassWeight(const TargetRegisterClass *RC) const {<o:p></o:p></p></div><div><p class=MsoNormal> static const RegClassWeight RCWeightTable[] = {<o:p></o:p></p></div><div><p class=MsoNormal> {1, 32}, <span class=apple-tab-span> </span>// IntRegs<o:p></o:p></p></div><div><p class=MsoNormal> {1, 8}, <span class=apple-tab-span> </span>// CRRegs<o:p></o:p></p></div><div><p class=MsoNormal> {1, 4}, <span class=apple-tab-span> </span>// PredRegs<o:p></o:p></p></div><div><p class=MsoNormal> {2, 32}, <span class=apple-tab-span> </span>// DoubleRegs<o:p></o:p></p></div><div><p class=MsoNormal> {0, 0} };<o:p></o:p></p></div><div><p class=MsoNormal> return RCWeightTable[RC->getID()];<o:p></o:p></p></div><div><p class=MsoNormal>}<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div></div><div><p class=MsoNormal>You can ask for the Set ID from a register class with:<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><div><p class=MsoNormal>const int* HexagonGenRegisterInfo::<o:p></o:p></p></div><div><p class=MsoNormal>getRegClassPressureSets(const TargetRegisterClass *RC) const {<o:p></o:p></p></div><div><p class=MsoNormal> static const int RCSetsTable[] = {<o:p></o:p></p></div><div><p class=MsoNormal> 0, -1, <span class=apple-tab-span> </span>// IntRegs<o:p></o:p></p></div><div><p class=MsoNormal> 1, -1, <span class=apple-tab-span> </span>// CRRegs<o:p></o:p></p></div><div><p class=MsoNormal> 2, -1, <span class=apple-tab-span> </span>// PredRegs<o:p></o:p></p></div><div><p class=MsoNormal> 0, -1, <span class=apple-tab-span> </span>// DoubleRegs<o:p></o:p></p></div><div><p class=MsoNormal> -1 };<o:p></o:p></p></div><div><p class=MsoNormal> static const unsigned RCSetStartTable[] = {<o:p></o:p></p></div><div><p class=MsoNormal> 0,2,4,6,0 };<o:p></o:p></p></div><div><p class=MsoNormal> unsigned SetListStart = RCSetStartTable[RC->getID()];<o:p></o:p></p></div><div><p class=MsoNormal> return &RCSetsTable[SetListStart];<o:p></o:p></p></div><div><p class=MsoNormal>}<o:p></o:p></p></div></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Just grab the first ID and assert that the next is -1.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Incidentally, register weight is not really the same as spill cost. Register weight really indicates the number of register units that may be contained within a register of that class.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>I still need to add some notion of spill cost to compareRPDelta to properly balance int vs. float spills...<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>-Andy<o:p></o:p></p></div></div></div></div></body></html>