1 //===---- ScheduleDAG.cpp - Implement the ScheduleDAG class ---------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This implements a simple two pass scheduler. The first pass attempts to push
11 // backward any lengthy instructions and critical paths. The second pass packs
12 // instructions into semi-optimal time slots.
14 //===----------------------------------------------------------------------===//
16 #define DEBUG_TYPE "pre-RA-sched"
17 #include "llvm/Type.h"
18 #include "llvm/CodeGen/ScheduleDAG.h"
19 #include "llvm/CodeGen/MachineConstantPool.h"
20 #include "llvm/CodeGen/MachineFunction.h"
21 #include "llvm/CodeGen/MachineRegisterInfo.h"
22 #include "llvm/Target/TargetData.h"
23 #include "llvm/Target/TargetMachine.h"
24 #include "llvm/Target/TargetInstrInfo.h"
25 #include "llvm/Target/TargetLowering.h"
26 #include "llvm/Support/Debug.h"
27 #include "llvm/Support/MathExtras.h"
30 ScheduleDAG::ScheduleDAG(SelectionDAG &dag, MachineBasicBlock *bb,
31 const TargetMachine &tm)
32 : DAG(dag), BB(bb), TM(tm), RegInfo(BB->getParent()->getRegInfo()) {
33 TII = TM.getInstrInfo();
34 MF = &DAG.getMachineFunction();
35 MRI = TM.getRegisterInfo();
36 ConstPool = BB->getParent()->getConstantPool();
39 /// CheckForPhysRegDependency - Check if the dependency between def and use of
40 /// a specified operand is a physical register dependency. If so, returns the
41 /// register and the cost of copying the register.
42 static void CheckForPhysRegDependency(SDNode *Def, SDNode *Use, unsigned Op,
43 const MRegisterInfo *MRI,
44 const TargetInstrInfo *TII,
45 unsigned &PhysReg, int &Cost) {
46 if (Op != 2 || Use->getOpcode() != ISD::CopyToReg)
49 unsigned Reg = cast<RegisterSDNode>(Use->getOperand(1))->getReg();
50 if (MRegisterInfo::isVirtualRegister(Reg))
53 unsigned ResNo = Use->getOperand(2).ResNo;
54 if (Def->isTargetOpcode()) {
55 const TargetInstrDesc &II = TII->get(Def->getTargetOpcode());
56 if (ResNo >= II.getNumDefs() &&
57 II.ImplicitDefs[ResNo - II.getNumDefs()] == Reg) {
59 const TargetRegisterClass *RC =
60 MRI->getPhysicalRegisterRegClass(Def->getValueType(ResNo), Reg);
61 Cost = RC->getCopyCost();
66 SUnit *ScheduleDAG::Clone(SUnit *Old) {
67 SUnit *SU = NewSUnit(Old->Node);
68 for (unsigned i = 0, e = SU->FlaggedNodes.size(); i != e; ++i)
69 SU->FlaggedNodes.push_back(SU->FlaggedNodes[i]);
70 SU->InstanceNo = SUnitMap[Old->Node].size();
71 SU->Latency = Old->Latency;
72 SU->isTwoAddress = Old->isTwoAddress;
73 SU->isCommutable = Old->isCommutable;
74 SU->hasPhysRegDefs = Old->hasPhysRegDefs;
75 SUnitMap[Old->Node].push_back(SU);
80 /// BuildSchedUnits - Build SUnits from the selection dag that we are input.
81 /// This SUnit graph is similar to the SelectionDAG, but represents flagged
82 /// together nodes with a single SUnit.
83 void ScheduleDAG::BuildSchedUnits() {
84 // Reserve entries in the vector for each of the SUnits we are creating. This
85 // ensure that reallocation of the vector won't happen, so SUnit*'s won't get
87 SUnits.reserve(std::distance(DAG.allnodes_begin(), DAG.allnodes_end()));
89 for (SelectionDAG::allnodes_iterator NI = DAG.allnodes_begin(),
90 E = DAG.allnodes_end(); NI != E; ++NI) {
91 if (isPassiveNode(NI)) // Leaf node, e.g. a TargetImmediate.
94 // If this node has already been processed, stop now.
95 if (SUnitMap[NI].size()) continue;
97 SUnit *NodeSUnit = NewSUnit(NI);
99 // See if anything is flagged to this node, if so, add them to flagged
100 // nodes. Nodes can have at most one flag input and one flag output. Flags
101 // are required the be the last operand and result of a node.
103 // Scan up, adding flagged preds to FlaggedNodes.
105 if (N->getNumOperands() &&
106 N->getOperand(N->getNumOperands()-1).getValueType() == MVT::Flag) {
108 N = N->getOperand(N->getNumOperands()-1).Val;
109 NodeSUnit->FlaggedNodes.push_back(N);
110 SUnitMap[N].push_back(NodeSUnit);
111 } while (N->getNumOperands() &&
112 N->getOperand(N->getNumOperands()-1).getValueType()== MVT::Flag);
113 std::reverse(NodeSUnit->FlaggedNodes.begin(),
114 NodeSUnit->FlaggedNodes.end());
117 // Scan down, adding this node and any flagged succs to FlaggedNodes if they
118 // have a user of the flag operand.
120 while (N->getValueType(N->getNumValues()-1) == MVT::Flag) {
121 SDOperand FlagVal(N, N->getNumValues()-1);
123 // There are either zero or one users of the Flag result.
124 bool HasFlagUse = false;
125 for (SDNode::use_iterator UI = N->use_begin(), E = N->use_end();
127 if (FlagVal.isOperand(*UI)) {
129 NodeSUnit->FlaggedNodes.push_back(N);
130 SUnitMap[N].push_back(NodeSUnit);
134 if (!HasFlagUse) break;
137 // Now all flagged nodes are in FlaggedNodes and N is the bottom-most node.
140 SUnitMap[N].push_back(NodeSUnit);
142 ComputeLatency(NodeSUnit);
145 // Pass 2: add the preds, succs, etc.
146 for (unsigned su = 0, e = SUnits.size(); su != e; ++su) {
147 SUnit *SU = &SUnits[su];
148 SDNode *MainNode = SU->Node;
150 if (MainNode->isTargetOpcode()) {
151 unsigned Opc = MainNode->getTargetOpcode();
152 const TargetInstrDesc &TID = TII->get(Opc);
153 for (unsigned i = 0; i != TID.getNumOperands(); ++i) {
154 if (TID.getOperandConstraint(i, TOI::TIED_TO) != -1) {
155 SU->isTwoAddress = true;
159 if (TID.isCommutable())
160 SU->isCommutable = true;
163 // Find all predecessors and successors of the group.
164 // Temporarily add N to make code simpler.
165 SU->FlaggedNodes.push_back(MainNode);
167 for (unsigned n = 0, e = SU->FlaggedNodes.size(); n != e; ++n) {
168 SDNode *N = SU->FlaggedNodes[n];
169 if (N->isTargetOpcode() &&
170 TII->get(N->getTargetOpcode()).getImplicitDefs() &&
171 CountResults(N) > TII->get(N->getTargetOpcode()).getNumDefs())
172 SU->hasPhysRegDefs = true;
174 for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i) {
175 SDNode *OpN = N->getOperand(i).Val;
176 if (isPassiveNode(OpN)) continue; // Not scheduled.
177 SUnit *OpSU = SUnitMap[OpN].front();
178 assert(OpSU && "Node has no SUnit!");
179 if (OpSU == SU) continue; // In the same group.
181 MVT::ValueType OpVT = N->getOperand(i).getValueType();
182 assert(OpVT != MVT::Flag && "Flagged nodes should be in same sunit!");
183 bool isChain = OpVT == MVT::Other;
185 unsigned PhysReg = 0;
187 // Determine if this is a physical register dependency.
188 CheckForPhysRegDependency(OpN, N, i, MRI, TII, PhysReg, Cost);
189 SU->addPred(OpSU, isChain, false, PhysReg, Cost);
193 // Remove MainNode from FlaggedNodes again.
194 SU->FlaggedNodes.pop_back();
200 void ScheduleDAG::ComputeLatency(SUnit *SU) {
201 const InstrItineraryData &InstrItins = TM.getInstrItineraryData();
203 // Compute the latency for the node. We use the sum of the latencies for
204 // all nodes flagged together into this SUnit.
205 if (InstrItins.isEmpty()) {
206 // No latency information.
210 if (SU->Node->isTargetOpcode()) {
211 unsigned SchedClass =
212 TII->get(SU->Node->getTargetOpcode()).getSchedClass();
213 InstrStage *S = InstrItins.begin(SchedClass);
214 InstrStage *E = InstrItins.end(SchedClass);
216 SU->Latency += S->Cycles;
218 for (unsigned i = 0, e = SU->FlaggedNodes.size(); i != e; ++i) {
219 SDNode *FNode = SU->FlaggedNodes[i];
220 if (FNode->isTargetOpcode()) {
221 unsigned SchedClass =TII->get(FNode->getTargetOpcode()).getSchedClass();
222 InstrStage *S = InstrItins.begin(SchedClass);
223 InstrStage *E = InstrItins.end(SchedClass);
225 SU->Latency += S->Cycles;
231 void ScheduleDAG::CalculateDepths() {
232 std::vector<std::pair<SUnit*, unsigned> > WorkList;
233 for (unsigned i = 0, e = SUnits.size(); i != e; ++i)
234 if (SUnits[i].Preds.empty())
235 WorkList.push_back(std::make_pair(&SUnits[i], 0U));
237 while (!WorkList.empty()) {
238 SUnit *SU = WorkList.back().first;
239 unsigned Depth = WorkList.back().second;
241 if (SU->Depth == 0 || Depth > SU->Depth) {
243 for (SUnit::succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
245 WorkList.push_back(std::make_pair(I->Dep, Depth+1));
250 void ScheduleDAG::CalculateHeights() {
251 std::vector<std::pair<SUnit*, unsigned> > WorkList;
252 SUnit *Root = SUnitMap[DAG.getRoot().Val].front();
253 WorkList.push_back(std::make_pair(Root, 0U));
255 while (!WorkList.empty()) {
256 SUnit *SU = WorkList.back().first;
257 unsigned Height = WorkList.back().second;
259 if (SU->Height == 0 || Height > SU->Height) {
261 for (SUnit::pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
263 WorkList.push_back(std::make_pair(I->Dep, Height+1));
268 /// CountResults - The results of target nodes have register or immediate
269 /// operands first, then an optional chain, and optional flag operands (which do
270 /// not go into the machine instrs.)
271 unsigned ScheduleDAG::CountResults(SDNode *Node) {
272 unsigned N = Node->getNumValues();
273 while (N && Node->getValueType(N - 1) == MVT::Flag)
275 if (N && Node->getValueType(N - 1) == MVT::Other)
276 --N; // Skip over chain result.
280 /// CountOperands The inputs to target nodes have any actual inputs first,
281 /// followed by an optional chain operand, then flag operands. Compute the
282 /// number of actual operands that will go into the machine instr.
283 unsigned ScheduleDAG::CountOperands(SDNode *Node) {
284 unsigned N = Node->getNumOperands();
285 while (N && Node->getOperand(N - 1).getValueType() == MVT::Flag)
287 if (N && Node->getOperand(N - 1).getValueType() == MVT::Other)
288 --N; // Ignore chain if it exists.
292 static const TargetRegisterClass *getInstrOperandRegClass(
293 const MRegisterInfo *MRI,
294 const TargetInstrInfo *TII,
295 const TargetInstrDesc &II,
297 if (Op >= II.getNumOperands()) {
298 assert(II.isVariadic() && "Invalid operand # of instruction");
301 if (II.OpInfo[Op].isLookupPtrRegClass())
302 return TII->getPointerRegClass();
303 return MRI->getRegClass(II.OpInfo[Op].RegClass);
306 void ScheduleDAG::EmitCopyFromReg(SDNode *Node, unsigned ResNo,
307 unsigned InstanceNo, unsigned SrcReg,
308 DenseMap<SDOperand, unsigned> &VRBaseMap) {
310 if (MRegisterInfo::isVirtualRegister(SrcReg)) {
311 // Just use the input register directly!
313 VRBaseMap.erase(SDOperand(Node, ResNo));
314 bool isNew = VRBaseMap.insert(std::make_pair(SDOperand(Node,ResNo),SrcReg));
315 assert(isNew && "Node emitted out of order - early");
319 // If the node is only used by a CopyToReg and the dest reg is a vreg, use
320 // the CopyToReg'd destination register instead of creating a new vreg.
321 bool MatchReg = true;
322 for (SDNode::use_iterator UI = Node->use_begin(), E = Node->use_end();
326 if (Use->getOpcode() == ISD::CopyToReg &&
327 Use->getOperand(2).Val == Node &&
328 Use->getOperand(2).ResNo == ResNo) {
329 unsigned DestReg = cast<RegisterSDNode>(Use->getOperand(1))->getReg();
330 if (MRegisterInfo::isVirtualRegister(DestReg)) {
333 } else if (DestReg != SrcReg)
336 for (unsigned i = 0, e = Use->getNumOperands(); i != e; ++i) {
337 SDOperand Op = Use->getOperand(i);
338 if (Op.Val != Node || Op.ResNo != ResNo)
340 MVT::ValueType VT = Node->getValueType(Op.ResNo);
341 if (VT != MVT::Other && VT != MVT::Flag)
350 const TargetRegisterClass *TRC = 0;
351 // Figure out the register class to create for the destreg.
353 TRC = RegInfo.getRegClass(VRBase);
355 TRC = MRI->getPhysicalRegisterRegClass(Node->getValueType(ResNo), SrcReg);
357 // If all uses are reading from the src physical register and copying the
358 // register is either impossible or very expensive, then don't create a copy.
359 if (MatchReg && TRC->getCopyCost() < 0) {
362 // Create the reg, emit the copy.
363 VRBase = RegInfo.createVirtualRegister(TRC);
364 TII->copyRegToReg(*BB, BB->end(), VRBase, SrcReg, TRC, TRC);
368 VRBaseMap.erase(SDOperand(Node, ResNo));
369 bool isNew = VRBaseMap.insert(std::make_pair(SDOperand(Node,ResNo), VRBase));
370 assert(isNew && "Node emitted out of order - early");
373 void ScheduleDAG::CreateVirtualRegisters(SDNode *Node,
375 const TargetInstrDesc &II,
376 DenseMap<SDOperand, unsigned> &VRBaseMap) {
377 for (unsigned i = 0; i < II.getNumDefs(); ++i) {
378 // If the specific node value is only used by a CopyToReg and the dest reg
379 // is a vreg, use the CopyToReg'd destination register instead of creating
382 for (SDNode::use_iterator UI = Node->use_begin(), E = Node->use_end();
385 if (Use->getOpcode() == ISD::CopyToReg &&
386 Use->getOperand(2).Val == Node &&
387 Use->getOperand(2).ResNo == i) {
388 unsigned Reg = cast<RegisterSDNode>(Use->getOperand(1))->getReg();
389 if (MRegisterInfo::isVirtualRegister(Reg)) {
391 MI->addOperand(MachineOperand::CreateReg(Reg, true));
397 // Create the result registers for this node and add the result regs to
398 // the machine instruction.
400 const TargetRegisterClass *RC = getInstrOperandRegClass(MRI, TII, II, i);
401 assert(RC && "Isn't a register operand!");
402 VRBase = RegInfo.createVirtualRegister(RC);
403 MI->addOperand(MachineOperand::CreateReg(VRBase, true));
406 bool isNew = VRBaseMap.insert(std::make_pair(SDOperand(Node,i), VRBase));
407 assert(isNew && "Node emitted out of order - early");
411 /// getVR - Return the virtual register corresponding to the specified result
412 /// of the specified node.
413 static unsigned getVR(SDOperand Op, DenseMap<SDOperand, unsigned> &VRBaseMap) {
414 DenseMap<SDOperand, unsigned>::iterator I = VRBaseMap.find(Op);
415 assert(I != VRBaseMap.end() && "Node emitted out of order - late");
420 /// AddOperand - Add the specified operand to the specified machine instr. II
421 /// specifies the instruction information for the node, and IIOpNum is the
422 /// operand number (in the II) that we are adding. IIOpNum and II are used for
424 void ScheduleDAG::AddOperand(MachineInstr *MI, SDOperand Op,
426 const TargetInstrDesc *II,
427 DenseMap<SDOperand, unsigned> &VRBaseMap) {
428 if (Op.isTargetOpcode()) {
429 // Note that this case is redundant with the final else block, but we
430 // include it because it is the most common and it makes the logic
432 assert(Op.getValueType() != MVT::Other &&
433 Op.getValueType() != MVT::Flag &&
434 "Chain and flag operands should occur at end of operand list!");
436 // Get/emit the operand.
437 unsigned VReg = getVR(Op, VRBaseMap);
438 const TargetInstrDesc &TID = MI->getDesc();
439 bool isOptDef = (IIOpNum < TID.getNumOperands())
440 ? (TID.OpInfo[IIOpNum].isOptionalDef()) : false;
441 MI->addOperand(MachineOperand::CreateReg(VReg, isOptDef));
443 // Verify that it is right.
444 assert(MRegisterInfo::isVirtualRegister(VReg) && "Not a vreg?");
446 const TargetRegisterClass *RC =
447 getInstrOperandRegClass(MRI, TII, *II, IIOpNum);
448 assert(RC && "Don't have operand info for this instruction!");
449 const TargetRegisterClass *VRC = RegInfo.getRegClass(VReg);
451 cerr << "Register class of operand and regclass of use don't agree!\n";
453 cerr << "Operand = " << IIOpNum << "\n";
454 cerr << "Op->Val = "; Op.Val->dump(&DAG); cerr << "\n";
455 cerr << "MI = "; MI->print(cerr);
456 cerr << "VReg = " << VReg << "\n";
457 cerr << "VReg RegClass size = " << VRC->getSize()
458 << ", align = " << VRC->getAlignment() << "\n";
459 cerr << "Expected RegClass size = " << RC->getSize()
460 << ", align = " << RC->getAlignment() << "\n";
462 cerr << "Fatal error, aborting.\n";
466 } else if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(Op)) {
467 MI->addOperand(MachineOperand::CreateImm(C->getValue()));
468 } else if (RegisterSDNode *R = dyn_cast<RegisterSDNode>(Op)) {
469 MI->addOperand(MachineOperand::CreateReg(R->getReg(), false));
470 } else if (GlobalAddressSDNode *TGA = dyn_cast<GlobalAddressSDNode>(Op)) {
471 MI->addOperand(MachineOperand::CreateGA(TGA->getGlobal(),TGA->getOffset()));
472 } else if (BasicBlockSDNode *BB = dyn_cast<BasicBlockSDNode>(Op)) {
473 MI->addOperand(MachineOperand::CreateMBB(BB->getBasicBlock()));
474 } else if (FrameIndexSDNode *FI = dyn_cast<FrameIndexSDNode>(Op)) {
475 MI->addOperand(MachineOperand::CreateFI(FI->getIndex()));
476 } else if (JumpTableSDNode *JT = dyn_cast<JumpTableSDNode>(Op)) {
477 MI->addOperand(MachineOperand::CreateJTI(JT->getIndex()));
478 } else if (ConstantPoolSDNode *CP = dyn_cast<ConstantPoolSDNode>(Op)) {
479 int Offset = CP->getOffset();
480 unsigned Align = CP->getAlignment();
481 const Type *Type = CP->getType();
482 // MachineConstantPool wants an explicit alignment.
484 Align = TM.getTargetData()->getPreferredTypeAlignmentShift(Type);
486 // Alignment of vector types. FIXME!
487 Align = TM.getTargetData()->getABITypeSize(Type);
488 Align = Log2_64(Align);
493 if (CP->isMachineConstantPoolEntry())
494 Idx = ConstPool->getConstantPoolIndex(CP->getMachineCPVal(), Align);
496 Idx = ConstPool->getConstantPoolIndex(CP->getConstVal(), Align);
497 MI->addOperand(MachineOperand::CreateCPI(Idx, Offset));
498 } else if (ExternalSymbolSDNode *ES = dyn_cast<ExternalSymbolSDNode>(Op)) {
499 MI->addOperand(MachineOperand::CreateES(ES->getSymbol()));
501 assert(Op.getValueType() != MVT::Other &&
502 Op.getValueType() != MVT::Flag &&
503 "Chain and flag operands should occur at end of operand list!");
504 unsigned VReg = getVR(Op, VRBaseMap);
505 MI->addOperand(MachineOperand::CreateReg(VReg, false));
507 // Verify that it is right.
508 assert(MRegisterInfo::isVirtualRegister(VReg) && "Not a vreg?");
510 const TargetRegisterClass *RC =
511 getInstrOperandRegClass(MRI, TII, *II, IIOpNum);
512 assert(RC && "Don't have operand info for this instruction!");
513 assert(RegInfo.getRegClass(VReg) == RC &&
514 "Register class of operand and regclass of use don't agree!");
520 // Returns the Register Class of a subregister
521 static const TargetRegisterClass *getSubRegisterRegClass(
522 const TargetRegisterClass *TRC,
524 // Pick the register class of the subregister
525 MRegisterInfo::regclass_iterator I = TRC->subregclasses_begin() + SubIdx-1;
526 assert(I < TRC->subregclasses_end() &&
527 "Invalid subregister index for register class");
531 static const TargetRegisterClass *getSuperregRegisterClass(
532 const TargetRegisterClass *TRC,
535 // Pick the register class of the superegister for this type
536 for (MRegisterInfo::regclass_iterator I = TRC->superregclasses_begin(),
537 E = TRC->superregclasses_end(); I != E; ++I)
538 if ((*I)->hasType(VT) && getSubRegisterRegClass(*I, SubIdx) == TRC)
540 assert(false && "Couldn't find the register class");
544 /// EmitSubregNode - Generate machine code for subreg nodes.
546 void ScheduleDAG::EmitSubregNode(SDNode *Node,
547 DenseMap<SDOperand, unsigned> &VRBaseMap) {
549 unsigned Opc = Node->getTargetOpcode();
550 if (Opc == TargetInstrInfo::EXTRACT_SUBREG) {
551 // If the node is only used by a CopyToReg and the dest reg is a vreg, use
552 // the CopyToReg'd destination register instead of creating a new vreg.
553 for (SDNode::use_iterator UI = Node->use_begin(), E = Node->use_end();
556 if (Use->getOpcode() == ISD::CopyToReg &&
557 Use->getOperand(2).Val == Node) {
558 unsigned DestReg = cast<RegisterSDNode>(Use->getOperand(1))->getReg();
559 if (MRegisterInfo::isVirtualRegister(DestReg)) {
566 unsigned SubIdx = cast<ConstantSDNode>(Node->getOperand(1))->getValue();
568 // TODO: If the node is a use of a CopyFromReg from a physical register
569 // fold the extract into the copy now
571 // Create the extract_subreg machine instruction.
573 new MachineInstr(BB, TII->get(TargetInstrInfo::EXTRACT_SUBREG));
575 // Figure out the register class to create for the destreg.
576 unsigned VReg = getVR(Node->getOperand(0), VRBaseMap);
577 const TargetRegisterClass *TRC = RegInfo.getRegClass(VReg);
578 const TargetRegisterClass *SRC = getSubRegisterRegClass(TRC, SubIdx);
581 // Grab the destination register
582 const TargetRegisterClass *DRC = 0;
583 DRC = RegInfo.getRegClass(VRBase);
585 "Source subregister and destination must have the same class");
588 VRBase = RegInfo.createVirtualRegister(SRC);
591 // Add def, source, and subreg index
592 MI->addOperand(MachineOperand::CreateReg(VRBase, true));
593 AddOperand(MI, Node->getOperand(0), 0, 0, VRBaseMap);
594 MI->addOperand(MachineOperand::CreateImm(SubIdx));
596 } else if (Opc == TargetInstrInfo::INSERT_SUBREG) {
597 assert((Node->getNumOperands() == 2 || Node->getNumOperands() == 3) &&
598 "Malformed insert_subreg node");
599 bool isUndefInput = (Node->getNumOperands() == 2);
604 SubReg = getVR(Node->getOperand(0), VRBaseMap);
605 SubIdx = cast<ConstantSDNode>(Node->getOperand(1))->getValue();
607 SubReg = getVR(Node->getOperand(1), VRBaseMap);
608 SubIdx = cast<ConstantSDNode>(Node->getOperand(2))->getValue();
611 // TODO: Add tracking info to MachineRegisterInfo of which vregs are subregs
612 // to allow coalescing in the allocator
614 // If the node is only used by a CopyToReg and the dest reg is a vreg, use
615 // the CopyToReg'd destination register instead of creating a new vreg.
616 // If the CopyToReg'd destination register is physical, then fold the
617 // insert into the copy
618 for (SDNode::use_iterator UI = Node->use_begin(), E = Node->use_end();
621 if (Use->getOpcode() == ISD::CopyToReg &&
622 Use->getOperand(2).Val == Node) {
623 unsigned DestReg = cast<RegisterSDNode>(Use->getOperand(1))->getReg();
624 if (MRegisterInfo::isVirtualRegister(DestReg)) {
631 // Create the insert_subreg machine instruction.
633 new MachineInstr(BB, TII->get(TargetInstrInfo::INSERT_SUBREG));
635 // Figure out the register class to create for the destreg.
636 const TargetRegisterClass *TRC = 0;
638 TRC = RegInfo.getRegClass(VRBase);
640 TRC = getSuperregRegisterClass(RegInfo.getRegClass(SubReg), SubIdx,
641 Node->getValueType(0));
642 assert(TRC && "Couldn't determine register class for insert_subreg");
643 VRBase = RegInfo.createVirtualRegister(TRC); // Create the reg
646 MI->addOperand(MachineOperand::CreateReg(VRBase, true));
647 AddOperand(MI, Node->getOperand(0), 0, 0, VRBaseMap);
649 AddOperand(MI, Node->getOperand(1), 0, 0, VRBaseMap);
650 MI->addOperand(MachineOperand::CreateImm(SubIdx));
652 assert(0 && "Node is not a subreg insert or extract");
654 bool isNew = VRBaseMap.insert(std::make_pair(SDOperand(Node,0), VRBase));
655 assert(isNew && "Node emitted out of order - early");
658 /// EmitNode - Generate machine code for an node and needed dependencies.
660 void ScheduleDAG::EmitNode(SDNode *Node, unsigned InstanceNo,
661 DenseMap<SDOperand, unsigned> &VRBaseMap) {
662 // If machine instruction
663 if (Node->isTargetOpcode()) {
664 unsigned Opc = Node->getTargetOpcode();
666 // Handle subreg insert/extract specially
667 if (Opc == TargetInstrInfo::EXTRACT_SUBREG ||
668 Opc == TargetInstrInfo::INSERT_SUBREG) {
669 EmitSubregNode(Node, VRBaseMap);
673 const TargetInstrDesc &II = TII->get(Opc);
675 unsigned NumResults = CountResults(Node);
676 unsigned NodeOperands = CountOperands(Node);
677 unsigned NumMIOperands = NodeOperands + NumResults;
678 bool HasPhysRegOuts = (NumResults > II.getNumDefs()) &&
679 II.getImplicitDefs() != 0;
681 assert((II.getNumOperands() == NumMIOperands ||
682 HasPhysRegOuts || II.isVariadic()) &&
683 "#operands for dag node doesn't match .td file!");
686 // Create the new machine instruction.
687 MachineInstr *MI = new MachineInstr(II);
689 // Add result register values for things that are defined by this
692 CreateVirtualRegisters(Node, MI, II, VRBaseMap);
694 // Emit all of the actual operands of this instruction, adding them to the
695 // instruction as appropriate.
696 for (unsigned i = 0; i != NodeOperands; ++i)
697 AddOperand(MI, Node->getOperand(i), i+II.getNumDefs(), &II, VRBaseMap);
699 // Commute node if it has been determined to be profitable.
700 if (CommuteSet.count(Node)) {
701 MachineInstr *NewMI = TII->commuteInstruction(MI);
703 DOUT << "Sched: COMMUTING FAILED!\n";
705 DOUT << "Sched: COMMUTED TO: " << *NewMI;
713 // Now that we have emitted all operands, emit this instruction itself.
714 if (Opc == TargetInstrInfo::LABEL &&
715 !BB->empty() && &MF->front() == BB) {
716 // If we are inserting a LABEL and this happens to be the first label in
717 // the entry block, it is the "function start" label. Make sure there are
718 // no other instructions before it.
719 unsigned NumLabels = 0;
720 MachineBasicBlock::iterator MBBI = BB->begin();
721 while (MBBI != BB->end()) {
722 if (MBBI->getOpcode() == TargetInstrInfo::LABEL) {
729 BB->insert(BB->begin(), MI);
732 } else if (II.usesCustomDAGSchedInsertionHook())
733 // Insert this instruction into the basic block using a target
734 // specific inserter which may returns a new basic block.
735 BB = DAG.getTargetLoweringInfo().EmitInstrWithCustomInserter(MI, BB);
739 // Additional results must be an physical register def.
740 if (HasPhysRegOuts) {
741 for (unsigned i = II.getNumDefs(); i < NumResults; ++i) {
742 unsigned Reg = II.getImplicitDefs()[i - II.getNumDefs()];
743 if (Node->hasAnyUseOfValue(i))
744 EmitCopyFromReg(Node, i, InstanceNo, Reg, VRBaseMap);
748 switch (Node->getOpcode()) {
753 assert(0 && "This target-independent node should have been selected!");
754 case ISD::EntryToken: // fall thru
755 case ISD::TokenFactor:
758 case ISD::CopyToReg: {
760 if (RegisterSDNode *R = dyn_cast<RegisterSDNode>(Node->getOperand(2)))
763 InReg = getVR(Node->getOperand(2), VRBaseMap);
764 unsigned DestReg = cast<RegisterSDNode>(Node->getOperand(1))->getReg();
765 if (InReg != DestReg) {// Coalesced away the copy?
766 const TargetRegisterClass *TRC = 0;
767 // Get the target register class
768 if (MRegisterInfo::isVirtualRegister(InReg))
769 TRC = RegInfo.getRegClass(InReg);
772 MRI->getPhysicalRegisterRegClass(Node->getOperand(2).getValueType(),
774 TII->copyRegToReg(*BB, BB->end(), DestReg, InReg, TRC, TRC);
778 case ISD::CopyFromReg: {
779 unsigned SrcReg = cast<RegisterSDNode>(Node->getOperand(1))->getReg();
780 EmitCopyFromReg(Node, 0, InstanceNo, SrcReg, VRBaseMap);
783 case ISD::INLINEASM: {
784 unsigned NumOps = Node->getNumOperands();
785 if (Node->getOperand(NumOps-1).getValueType() == MVT::Flag)
786 --NumOps; // Ignore the flag operand.
788 // Create the inline asm machine instruction.
790 new MachineInstr(BB, TII->get(TargetInstrInfo::INLINEASM));
792 // Add the asm string as an external symbol operand.
794 cast<ExternalSymbolSDNode>(Node->getOperand(1))->getSymbol();
795 MI->addOperand(MachineOperand::CreateES(AsmStr));
797 // Add all of the operand registers to the instruction.
798 for (unsigned i = 2; i != NumOps;) {
799 unsigned Flags = cast<ConstantSDNode>(Node->getOperand(i))->getValue();
800 unsigned NumVals = Flags >> 3;
802 MI->addOperand(MachineOperand::CreateImm(Flags));
803 ++i; // Skip the ID value.
806 default: assert(0 && "Bad flags!");
807 case 1: // Use of register.
808 for (; NumVals; --NumVals, ++i) {
809 unsigned Reg = cast<RegisterSDNode>(Node->getOperand(i))->getReg();
810 MI->addOperand(MachineOperand::CreateReg(Reg, false));
813 case 2: // Def of register.
814 for (; NumVals; --NumVals, ++i) {
815 unsigned Reg = cast<RegisterSDNode>(Node->getOperand(i))->getReg();
816 MI->addOperand(MachineOperand::CreateReg(Reg, true));
819 case 3: { // Immediate.
820 for (; NumVals; --NumVals, ++i) {
821 if (ConstantSDNode *CS =
822 dyn_cast<ConstantSDNode>(Node->getOperand(i))) {
823 MI->addOperand(MachineOperand::CreateImm(CS->getValue()));
824 } else if (GlobalAddressSDNode *GA =
825 dyn_cast<GlobalAddressSDNode>(Node->getOperand(i))) {
826 MI->addOperand(MachineOperand::CreateGA(GA->getGlobal(),
829 BasicBlockSDNode *BB =cast<BasicBlockSDNode>(Node->getOperand(i));
830 MI->addOperand(MachineOperand::CreateMBB(BB->getBasicBlock()));
835 case 4: // Addressing mode.
836 // The addressing mode has been selected, just add all of the
837 // operands to the machine instruction.
838 for (; NumVals; --NumVals, ++i)
839 AddOperand(MI, Node->getOperand(i), 0, 0, VRBaseMap);
849 void ScheduleDAG::EmitNoop() {
850 TII->insertNoop(*BB, BB->end());
853 void ScheduleDAG::EmitCrossRCCopy(SUnit *SU, DenseMap<SUnit*, unsigned> &VRBaseMap) {
854 for (SUnit::const_pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
856 if (I->isCtrl) continue; // ignore chain preds
858 // Copy to physical register.
859 DenseMap<SUnit*, unsigned>::iterator VRI = VRBaseMap.find(I->Dep);
860 assert(VRI != VRBaseMap.end() && "Node emitted out of order - late");
861 // Find the destination physical register.
863 for (SUnit::const_succ_iterator II = SU->Succs.begin(),
864 EE = SU->Succs.end(); II != EE; ++II) {
870 assert(I->Reg && "Unknown physical register!");
871 TII->copyRegToReg(*BB, BB->end(), Reg, VRI->second,
872 SU->CopyDstRC, SU->CopySrcRC);
874 // Copy from physical register.
875 assert(I->Reg && "Unknown physical register!");
876 unsigned VRBase = RegInfo.createVirtualRegister(SU->CopyDstRC);
877 bool isNew = VRBaseMap.insert(std::make_pair(SU, VRBase));
878 assert(isNew && "Node emitted out of order - early");
879 TII->copyRegToReg(*BB, BB->end(), VRBase, I->Reg,
880 SU->CopyDstRC, SU->CopySrcRC);
886 /// EmitSchedule - Emit the machine code in scheduled order.
887 void ScheduleDAG::EmitSchedule() {
888 // If this is the first basic block in the function, and if it has live ins
889 // that need to be copied into vregs, emit the copies into the top of the
890 // block before emitting the code for the block.
891 if (&MF->front() == BB) {
892 for (MachineRegisterInfo::livein_iterator LI = RegInfo.livein_begin(),
893 E = RegInfo.livein_end(); LI != E; ++LI)
895 const TargetRegisterClass *RC = RegInfo.getRegClass(LI->second);
896 TII->copyRegToReg(*MF->begin(), MF->begin()->end(), LI->second,
902 // Finally, emit the code for all of the scheduled instructions.
903 DenseMap<SDOperand, unsigned> VRBaseMap;
904 DenseMap<SUnit*, unsigned> CopyVRBaseMap;
905 for (unsigned i = 0, e = Sequence.size(); i != e; i++) {
906 if (SUnit *SU = Sequence[i]) {
907 for (unsigned j = 0, ee = SU->FlaggedNodes.size(); j != ee; ++j)
908 EmitNode(SU->FlaggedNodes[j], SU->InstanceNo, VRBaseMap);
910 EmitNode(SU->Node, SU->InstanceNo, VRBaseMap);
912 EmitCrossRCCopy(SU, CopyVRBaseMap);
914 // Null SUnit* is a noop.
920 /// dump - dump the schedule.
921 void ScheduleDAG::dumpSchedule() const {
922 for (unsigned i = 0, e = Sequence.size(); i != e; i++) {
923 if (SUnit *SU = Sequence[i])
926 cerr << "**** NOOP ****\n";
931 /// Run - perform scheduling.
933 MachineBasicBlock *ScheduleDAG::Run() {
938 /// SUnit - Scheduling unit. It's an wrapper around either a single SDNode or
939 /// a group of nodes flagged together.
940 void SUnit::dump(const SelectionDAG *G) const {
941 cerr << "SU(" << NodeNum << "): ";
945 cerr << "CROSS RC COPY ";
947 if (FlaggedNodes.size() != 0) {
948 for (unsigned i = 0, e = FlaggedNodes.size(); i != e; i++) {
950 FlaggedNodes[i]->dump(G);
956 void SUnit::dumpAll(const SelectionDAG *G) const {
959 cerr << " # preds left : " << NumPredsLeft << "\n";
960 cerr << " # succs left : " << NumSuccsLeft << "\n";
961 cerr << " Latency : " << Latency << "\n";
962 cerr << " Depth : " << Depth << "\n";
963 cerr << " Height : " << Height << "\n";
965 if (Preds.size() != 0) {
966 cerr << " Predecessors:\n";
967 for (SUnit::const_succ_iterator I = Preds.begin(), E = Preds.end();
973 cerr << I->Dep << " - SU(" << I->Dep->NodeNum << ")";
979 if (Succs.size() != 0) {
980 cerr << " Successors:\n";
981 for (SUnit::const_succ_iterator I = Succs.begin(), E = Succs.end();
987 cerr << I->Dep << " - SU(" << I->Dep->NodeNum << ")";