1 //===---- ScheduleDAG.cpp - Implement the ScheduleDAG class ---------------===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by James M. Laskey and is distributed under the
6 // University of Illinois Open Source 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 "sched"
17 #include "llvm/CodeGen/MachineConstantPool.h"
18 #include "llvm/CodeGen/MachineFunction.h"
19 #include "llvm/CodeGen/ScheduleDAG.h"
20 #include "llvm/CodeGen/SSARegMap.h"
21 #include "llvm/Target/TargetMachine.h"
22 #include "llvm/Target/TargetInstrInfo.h"
23 #include "llvm/Target/TargetInstrItineraries.h"
24 #include "llvm/Target/TargetLowering.h"
25 #include "llvm/Support/Debug.h"
26 #include "llvm/Constant.h"
31 /// CountResults - The results of target nodes have register or immediate
32 /// operands first, then an optional chain, and optional flag operands (which do
33 /// not go into the machine instrs.)
34 static unsigned CountResults(SDNode *Node) {
35 unsigned N = Node->getNumValues();
36 while (N && Node->getValueType(N - 1) == MVT::Flag)
38 if (N && Node->getValueType(N - 1) == MVT::Other)
39 --N; // Skip over chain result.
43 /// CountOperands The inputs to target nodes have any actual inputs first,
44 /// followed by an optional chain operand, then flag operands. Compute the
45 /// number of actual operands that will go into the machine instr.
46 static unsigned CountOperands(SDNode *Node) {
47 unsigned N = Node->getNumOperands();
48 while (N && Node->getOperand(N - 1).getValueType() == MVT::Flag)
50 if (N && Node->getOperand(N - 1).getValueType() == MVT::Other)
51 --N; // Ignore chain if it exists.
55 /// PrepareNodeInfo - Set up the basic minimum node info for scheduling.
57 void ScheduleDAG::PrepareNodeInfo() {
58 // Allocate node information
59 Info = new NodeInfo[NodeCount];
62 for (SelectionDAG::allnodes_iterator I = DAG.allnodes_begin(),
63 E = DAG.allnodes_end(); I != E; ++I, ++i) {
64 // Fast reference to node schedule info
65 NodeInfo* NI = &Info[i];
70 // Set pending visit count
71 NI->setPending(I->use_size());
75 /// IdentifyGroups - Put flagged nodes into groups.
77 void ScheduleDAG::IdentifyGroups() {
78 for (unsigned i = 0, N = NodeCount; i < N; i++) {
79 NodeInfo* NI = &Info[i];
80 SDNode *Node = NI->Node;
82 // For each operand (in reverse to only look at flags)
83 for (unsigned N = Node->getNumOperands(); 0 < N--;) {
85 SDOperand Op = Node->getOperand(N);
86 // No more flags to walk
87 if (Op.getValueType() != MVT::Flag) break;
89 AddToGroup(getNI(Op.Val), NI);
90 // Let everyone else know
96 static unsigned CreateVirtualRegisters(MachineInstr *MI,
99 const TargetInstrDescriptor &II) {
100 // Create the result registers for this node and add the result regs to
101 // the machine instruction.
102 const TargetOperandInfo *OpInfo = II.OpInfo;
103 unsigned ResultReg = RegMap->createVirtualRegister(OpInfo[0].RegClass);
104 MI->addRegOperand(ResultReg, MachineOperand::Def);
105 for (unsigned i = 1; i != NumResults; ++i) {
106 assert(OpInfo[i].RegClass && "Isn't a register operand!");
107 MI->addRegOperand(RegMap->createVirtualRegister(OpInfo[i].RegClass),
108 MachineOperand::Def);
113 /// AddOperand - Add the specified operand to the specified machine instr. II
114 /// specifies the instruction information for the node, and IIOpNum is the
115 /// operand number (in the II) that we are adding. IIOpNum and II are used for
117 void ScheduleDAG::AddOperand(MachineInstr *MI, SDOperand Op,
119 const TargetInstrDescriptor *II) {
120 if (Op.isTargetOpcode()) {
121 // Note that this case is redundant with the final else block, but we
122 // include it because it is the most common and it makes the logic
124 assert(Op.getValueType() != MVT::Other &&
125 Op.getValueType() != MVT::Flag &&
126 "Chain and flag operands should occur at end of operand list!");
128 // Get/emit the operand.
129 unsigned VReg = getVR(Op);
130 MI->addRegOperand(VReg, MachineOperand::Use);
132 // Verify that it is right.
133 assert(MRegisterInfo::isVirtualRegister(VReg) && "Not a vreg?");
135 assert(II->OpInfo[IIOpNum].RegClass &&
136 "Don't have operand info for this instruction!");
137 assert(RegMap->getRegClass(VReg) == II->OpInfo[IIOpNum].RegClass &&
138 "Register class of operand and regclass of use don't agree!");
140 } else if (ConstantSDNode *C =
141 dyn_cast<ConstantSDNode>(Op)) {
142 MI->addZeroExtImm64Operand(C->getValue());
143 } else if (RegisterSDNode*R =
144 dyn_cast<RegisterSDNode>(Op)) {
145 MI->addRegOperand(R->getReg(), MachineOperand::Use);
146 } else if (GlobalAddressSDNode *TGA =
147 dyn_cast<GlobalAddressSDNode>(Op)) {
148 MI->addGlobalAddressOperand(TGA->getGlobal(), false, TGA->getOffset());
149 } else if (BasicBlockSDNode *BB =
150 dyn_cast<BasicBlockSDNode>(Op)) {
151 MI->addMachineBasicBlockOperand(BB->getBasicBlock());
152 } else if (FrameIndexSDNode *FI =
153 dyn_cast<FrameIndexSDNode>(Op)) {
154 MI->addFrameIndexOperand(FI->getIndex());
155 } else if (ConstantPoolSDNode *CP =
156 dyn_cast<ConstantPoolSDNode>(Op)) {
157 int Offset = CP->getOffset();
158 unsigned Align = CP->getAlignment();
159 // MachineConstantPool wants an explicit alignment.
161 if (CP->get()->getType() == Type::DoubleTy)
162 Align = 3; // always 8-byte align doubles.
164 Align = TM.getTargetData()
165 .getTypeAlignmentShift(CP->get()->getType());
168 unsigned Idx = ConstPool->getConstantPoolIndex(CP->get(), Align);
169 MI->addConstantPoolIndexOperand(Idx, Offset);
170 } else if (ExternalSymbolSDNode *ES =
171 dyn_cast<ExternalSymbolSDNode>(Op)) {
172 MI->addExternalSymbolOperand(ES->getSymbol(), false);
174 assert(Op.getValueType() != MVT::Other &&
175 Op.getValueType() != MVT::Flag &&
176 "Chain and flag operands should occur at end of operand list!");
177 unsigned VReg = getVR(Op);
178 MI->addRegOperand(VReg, MachineOperand::Use);
180 // Verify that it is right.
181 assert(MRegisterInfo::isVirtualRegister(VReg) && "Not a vreg?");
183 assert(II->OpInfo[IIOpNum].RegClass &&
184 "Don't have operand info for this instruction!");
185 assert(RegMap->getRegClass(VReg) == II->OpInfo[IIOpNum].RegClass &&
186 "Register class of operand and regclass of use don't agree!");
193 /// EmitNode - Generate machine code for an node and needed dependencies.
195 void ScheduleDAG::EmitNode(NodeInfo *NI) {
196 unsigned VRBase = 0; // First virtual register for node
197 SDNode *Node = NI->Node;
199 // If machine instruction
200 if (Node->isTargetOpcode()) {
201 unsigned Opc = Node->getTargetOpcode();
202 const TargetInstrDescriptor &II = TII->get(Opc);
204 unsigned NumResults = CountResults(Node);
205 unsigned NodeOperands = CountOperands(Node);
206 unsigned NumMIOperands = NodeOperands + NumResults;
208 assert((unsigned(II.numOperands) == NumMIOperands || II.numOperands == -1)&&
209 "#operands for dag node doesn't match .td file!");
212 // Create the new machine instruction.
213 MachineInstr *MI = new MachineInstr(Opc, NumMIOperands, true, true);
215 // Add result register values for things that are defined by this
218 // If the node is only used by a CopyToReg and the dest reg is a vreg, use
219 // the CopyToReg'd destination register instead of creating a new vreg.
220 if (NumResults == 1) {
221 for (SDNode::use_iterator UI = Node->use_begin(), E = Node->use_end();
224 if (Use->getOpcode() == ISD::CopyToReg &&
225 Use->getOperand(2).Val == Node) {
226 unsigned Reg = cast<RegisterSDNode>(Use->getOperand(1))->getReg();
227 if (MRegisterInfo::isVirtualRegister(Reg)) {
229 MI->addRegOperand(Reg, MachineOperand::Def);
236 // Otherwise, create new virtual registers.
237 if (NumResults && VRBase == 0)
238 VRBase = CreateVirtualRegisters(MI, NumResults, RegMap, II);
240 // Emit all of the actual operands of this instruction, adding them to the
241 // instruction as appropriate.
242 for (unsigned i = 0; i != NodeOperands; ++i)
243 AddOperand(MI, Node->getOperand(i), i+NumResults, &II);
245 // Now that we have emitted all operands, emit this instruction itself.
246 if ((II.Flags & M_USES_CUSTOM_DAG_SCHED_INSERTION) == 0) {
247 BB->insert(BB->end(), MI);
249 // Insert this instruction into the end of the basic block, potentially
250 // taking some custom action.
251 BB = DAG.getTargetLoweringInfo().InsertAtEndOfBasicBlock(MI, BB);
254 switch (Node->getOpcode()) {
257 assert(0 && "This target-independent node should have been selected!");
258 case ISD::EntryToken: // fall thru
259 case ISD::TokenFactor:
261 case ISD::CopyToReg: {
262 unsigned InReg = getVR(Node->getOperand(2));
263 unsigned DestReg = cast<RegisterSDNode>(Node->getOperand(1))->getReg();
264 if (InReg != DestReg) // Coallesced away the copy?
265 MRI->copyRegToReg(*BB, BB->end(), DestReg, InReg,
266 RegMap->getRegClass(InReg));
269 case ISD::CopyFromReg: {
270 unsigned SrcReg = cast<RegisterSDNode>(Node->getOperand(1))->getReg();
271 if (MRegisterInfo::isVirtualRegister(SrcReg)) {
272 VRBase = SrcReg; // Just use the input register directly!
276 // If the node is only used by a CopyToReg and the dest reg is a vreg, use
277 // the CopyToReg'd destination register instead of creating a new vreg.
278 for (SDNode::use_iterator UI = Node->use_begin(), E = Node->use_end();
281 if (Use->getOpcode() == ISD::CopyToReg &&
282 Use->getOperand(2).Val == Node) {
283 unsigned DestReg = cast<RegisterSDNode>(Use->getOperand(1))->getReg();
284 if (MRegisterInfo::isVirtualRegister(DestReg)) {
291 // Figure out the register class to create for the destreg.
292 const TargetRegisterClass *TRC = 0;
294 TRC = RegMap->getRegClass(VRBase);
297 // Pick the register class of the right type that contains this physreg.
298 for (MRegisterInfo::regclass_iterator I = MRI->regclass_begin(),
299 E = MRI->regclass_end(); I != E; ++I)
300 if ((*I)->hasType(Node->getValueType(0)) &&
301 (*I)->contains(SrcReg)) {
305 assert(TRC && "Couldn't find register class for reg copy!");
307 // Create the reg, emit the copy.
308 VRBase = RegMap->createVirtualRegister(TRC);
310 MRI->copyRegToReg(*BB, BB->end(), VRBase, SrcReg, TRC);
313 case ISD::INLINEASM: {
314 unsigned NumOps = Node->getNumOperands();
315 if (Node->getOperand(NumOps-1).getValueType() == MVT::Flag)
316 --NumOps; // Ignore the flag operand.
318 // Create the inline asm machine instruction.
320 new MachineInstr(BB, TargetInstrInfo::INLINEASM, (NumOps-2)/2+1);
322 // Add the asm string as an external symbol operand.
324 cast<ExternalSymbolSDNode>(Node->getOperand(1))->getSymbol();
325 MI->addExternalSymbolOperand(AsmStr, false);
327 // Add all of the operand registers to the instruction.
328 for (unsigned i = 2; i != NumOps;) {
329 unsigned Flags = cast<ConstantSDNode>(Node->getOperand(i))->getValue();
330 unsigned NumVals = Flags >> 3;
332 MI->addZeroExtImm64Operand(Flags);
333 ++i; // Skip the ID value.
336 default: assert(0 && "Bad flags!");
337 case 1: // Use of register.
338 for (; NumVals; --NumVals, ++i) {
339 unsigned Reg = cast<RegisterSDNode>(Node->getOperand(i))->getReg();
340 MI->addMachineRegOperand(Reg, MachineOperand::Use);
343 case 2: // Def of register.
344 for (; NumVals; --NumVals, ++i) {
345 unsigned Reg = cast<RegisterSDNode>(Node->getOperand(i))->getReg();
346 MI->addMachineRegOperand(Reg, MachineOperand::Def);
349 case 3: { // Immediate.
350 assert(NumVals == 1 && "Unknown immediate value!");
351 uint64_t Val = cast<ConstantSDNode>(Node->getOperand(i))->getValue();
352 MI->addZeroExtImm64Operand(Val);
356 case 4: // Addressing mode.
357 // The addressing mode has been selected, just add all of the
358 // operands to the machine instruction.
359 for (; NumVals; --NumVals, ++i)
360 AddOperand(MI, Node->getOperand(i), 0, 0);
369 assert(NI->VRBase == 0 && "Node emitted out of order - early");
373 void ScheduleDAG::EmitNoop() {
374 TII->insertNoop(*BB, BB->end());
377 /// EmitAll - Emit all nodes in schedule sorted order.
379 void ScheduleDAG::EmitAll() {
380 // For each node in the ordering
381 for (unsigned i = 0, N = Ordering.size(); i < N; i++) {
382 // Get the scheduling info
383 NodeInfo *NI = Ordering[i];
384 if (NI->isInGroup()) {
385 NodeGroupIterator NGI(Ordering[i]);
386 while (NodeInfo *NI = NGI.next()) EmitNode(NI);
393 /// isFlagDefiner - Returns true if the node defines a flag result.
394 static bool isFlagDefiner(SDNode *A) {
395 unsigned N = A->getNumValues();
396 return N && A->getValueType(N - 1) == MVT::Flag;
399 /// isFlagUser - Returns true if the node uses a flag result.
401 static bool isFlagUser(SDNode *A) {
402 unsigned N = A->getNumOperands();
403 return N && A->getOperand(N - 1).getValueType() == MVT::Flag;
406 /// printNI - Print node info.
408 void ScheduleDAG::printNI(std::ostream &O, NodeInfo *NI) const {
410 SDNode *Node = NI->Node;
412 << std::hex << Node << std::dec
413 << ", Lat=" << NI->Latency
414 << ", Slot=" << NI->Slot
415 << ", ARITY=(" << Node->getNumOperands() << ","
416 << Node->getNumValues() << ")"
417 << " " << Node->getOperationName(&DAG);
418 if (isFlagDefiner(Node)) O << "<#";
419 if (isFlagUser(Node)) O << ">#";
423 /// printChanges - Hilight changes in order caused by scheduling.
425 void ScheduleDAG::printChanges(unsigned Index) const {
427 // Get the ordered node count
428 unsigned N = Ordering.size();
429 // Determine if any changes
432 NodeInfo *NI = Ordering[i];
433 if (NI->Preorder != i) break;
437 std::cerr << Index << ". New Ordering\n";
439 for (i = 0; i < N; i++) {
440 NodeInfo *NI = Ordering[i];
441 std::cerr << " " << NI->Preorder << ". ";
442 printNI(std::cerr, NI);
444 if (NI->isGroupDominator()) {
445 NodeGroup *Group = NI->Group;
446 for (NIIterator NII = Group->group_begin(), E = Group->group_end();
449 printNI(std::cerr, *NII);
455 std::cerr << Index << ". No Changes\n";
460 /// print - Print ordering to specified output stream.
462 void ScheduleDAG::print(std::ostream &O) const {
466 for (unsigned i = 0, N = Ordering.size(); i < N; i++) {
467 NodeInfo *NI = Ordering[i];
470 if (NI->isGroupDominator()) {
471 NodeGroup *Group = NI->Group;
472 for (NIIterator NII = Group->group_begin(), E = Group->group_end();
483 void ScheduleDAG::dump(const char *tag) const {
484 std::cerr << tag; dump();
487 void ScheduleDAG::dump() const {
491 /// Run - perform scheduling.
493 MachineBasicBlock *ScheduleDAG::Run() {
494 TII = TM.getInstrInfo();
495 MRI = TM.getRegisterInfo();
496 RegMap = BB->getParent()->getSSARegMap();
497 ConstPool = BB->getParent()->getConstantPool();
500 NodeCount = std::distance(DAG.allnodes_begin(), DAG.allnodes_end());
501 // Set up minimum info for scheduling
503 // Construct node groups for flagged nodes
511 /// CountInternalUses - Returns the number of edges between the two nodes.
513 static unsigned CountInternalUses(NodeInfo *D, NodeInfo *U) {
515 for (unsigned M = U->Node->getNumOperands(); 0 < M--;) {
516 SDOperand Op = U->Node->getOperand(M);
517 if (Op.Val == D->Node) N++;
523 //===----------------------------------------------------------------------===//
524 /// Add - Adds a definer and user pair to a node group.
526 void ScheduleDAG::AddToGroup(NodeInfo *D, NodeInfo *U) {
527 // Get current groups
528 NodeGroup *DGroup = D->Group;
529 NodeGroup *UGroup = U->Group;
530 // If both are members of groups
531 if (DGroup && UGroup) {
532 // There may have been another edge connecting
533 if (DGroup == UGroup) return;
534 // Add the pending users count
535 DGroup->addPending(UGroup->getPending());
536 // For each member of the users group
537 NodeGroupIterator UNGI(U);
538 while (NodeInfo *UNI = UNGI.next() ) {
541 // For each member of the definers group
542 NodeGroupIterator DNGI(D);
543 while (NodeInfo *DNI = DNGI.next() ) {
544 // Remove internal edges
545 DGroup->addPending(-CountInternalUses(DNI, UNI));
548 // Merge the two lists
549 DGroup->group_insert(DGroup->group_end(),
550 UGroup->group_begin(), UGroup->group_end());
552 // Make user member of definers group
554 // Add users uses to definers group pending
555 DGroup->addPending(U->Node->use_size());
556 // For each member of the definers group
557 NodeGroupIterator DNGI(D);
558 while (NodeInfo *DNI = DNGI.next() ) {
559 // Remove internal edges
560 DGroup->addPending(-CountInternalUses(DNI, U));
562 DGroup->group_push_back(U);
564 // Make definer member of users group
566 // Add definers uses to users group pending
567 UGroup->addPending(D->Node->use_size());
568 // For each member of the users group
569 NodeGroupIterator UNGI(U);
570 while (NodeInfo *UNI = UNGI.next() ) {
571 // Remove internal edges
572 UGroup->addPending(-CountInternalUses(D, UNI));
574 UGroup->group_insert(UGroup->group_begin(), D);
576 D->Group = U->Group = DGroup = new NodeGroup();
577 DGroup->addPending(D->Node->use_size() + U->Node->use_size() -
578 CountInternalUses(D, U));
579 DGroup->group_push_back(D);
580 DGroup->group_push_back(U);
585 TailNG->Next = DGroup;