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llvm-project/llvm/lib/CodeGen/SelectionDAG/ScheduleDAG.cpp

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//===---- ScheduleDAG.cpp - Implement the ScheduleDAG class ---------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This implements a simple two pass scheduler. The first pass attempts to push
// backward any lengthy instructions and critical paths. The second pass packs
// instructions into semi-optimal time slots.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "pre-RA-sched"
#include "llvm/Constants.h"
#include "llvm/Type.h"
#include "llvm/CodeGen/ScheduleDAG.h"
#include "llvm/CodeGen/MachineConstantPool.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetLowering.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/MathExtras.h"
using namespace llvm;
STATISTIC(NumCommutes, "Number of instructions commuted");
ScheduleDAG::ScheduleDAG(SelectionDAG &dag, MachineBasicBlock *bb,
const TargetMachine &tm)
: DAG(dag), BB(bb), TM(tm), RegInfo(BB->getParent()->getRegInfo()) {
TII = TM.getInstrInfo();
MF = &DAG.getMachineFunction();
TRI = TM.getRegisterInfo();
ConstPool = BB->getParent()->getConstantPool();
}
/// CheckForPhysRegDependency - Check if the dependency between def and use of
/// a specified operand is a physical register dependency. If so, returns the
/// register and the cost of copying the register.
static void CheckForPhysRegDependency(SDNode *Def, SDNode *Use, unsigned Op,
const TargetRegisterInfo *TRI,
const TargetInstrInfo *TII,
unsigned &PhysReg, int &Cost) {
if (Op != 2 || Use->getOpcode() != ISD::CopyToReg)
return;
unsigned Reg = cast<RegisterSDNode>(Use->getOperand(1))->getReg();
if (TargetRegisterInfo::isVirtualRegister(Reg))
return;
unsigned ResNo = Use->getOperand(2).ResNo;
if (Def->isTargetOpcode()) {
const TargetInstrDesc &II = TII->get(Def->getTargetOpcode());
if (ResNo >= II.getNumDefs() &&
II.ImplicitDefs[ResNo - II.getNumDefs()] == Reg) {
PhysReg = Reg;
const TargetRegisterClass *RC =
TRI->getPhysicalRegisterRegClass(Def->getValueType(ResNo), Reg);
Cost = RC->getCopyCost();
}
}
}
SUnit *ScheduleDAG::Clone(SUnit *Old) {
SUnit *SU = NewSUnit(Old->Node);
for (unsigned i = 0, e = SU->FlaggedNodes.size(); i != e; ++i)
SU->FlaggedNodes.push_back(SU->FlaggedNodes[i]);
SU->InstanceNo = SUnitMap[Old->Node].size();
SU->Latency = Old->Latency;
SU->isTwoAddress = Old->isTwoAddress;
SU->isCommutable = Old->isCommutable;
SU->hasPhysRegDefs = Old->hasPhysRegDefs;
SUnitMap[Old->Node].push_back(SU);
return SU;
}
/// BuildSchedUnits - Build SUnits from the selection dag that we are input.
/// This SUnit graph is similar to the SelectionDAG, but represents flagged
/// together nodes with a single SUnit.
void ScheduleDAG::BuildSchedUnits() {
// Reserve entries in the vector for each of the SUnits we are creating. This
// ensure that reallocation of the vector won't happen, so SUnit*'s won't get
// invalidated.
SUnits.reserve(std::distance(DAG.allnodes_begin(), DAG.allnodes_end()));
for (SelectionDAG::allnodes_iterator NI = DAG.allnodes_begin(),
E = DAG.allnodes_end(); NI != E; ++NI) {
if (isPassiveNode(NI)) // Leaf node, e.g. a TargetImmediate.
continue;
// If this node has already been processed, stop now.
if (SUnitMap[NI].size()) continue;
SUnit *NodeSUnit = NewSUnit(NI);
// See if anything is flagged to this node, if so, add them to flagged
// nodes. Nodes can have at most one flag input and one flag output. Flags
// are required the be the last operand and result of a node.
// Scan up, adding flagged preds to FlaggedNodes.
SDNode *N = NI;
if (N->getNumOperands() &&
N->getOperand(N->getNumOperands()-1).getValueType() == MVT::Flag) {
do {
N = N->getOperand(N->getNumOperands()-1).Val;
NodeSUnit->FlaggedNodes.push_back(N);
SUnitMap[N].push_back(NodeSUnit);
} while (N->getNumOperands() &&
N->getOperand(N->getNumOperands()-1).getValueType()== MVT::Flag);
std::reverse(NodeSUnit->FlaggedNodes.begin(),
NodeSUnit->FlaggedNodes.end());
}
// Scan down, adding this node and any flagged succs to FlaggedNodes if they
// have a user of the flag operand.
N = NI;
while (N->getValueType(N->getNumValues()-1) == MVT::Flag) {
SDOperand FlagVal(N, N->getNumValues()-1);
// There are either zero or one users of the Flag result.
bool HasFlagUse = false;
for (SDNode::use_iterator UI = N->use_begin(), E = N->use_end();
UI != E; ++UI)
if (FlagVal.isOperand(*UI)) {
HasFlagUse = true;
NodeSUnit->FlaggedNodes.push_back(N);
SUnitMap[N].push_back(NodeSUnit);
N = *UI;
break;
}
if (!HasFlagUse) break;
}
// Now all flagged nodes are in FlaggedNodes and N is the bottom-most node.
// Update the SUnit
NodeSUnit->Node = N;
SUnitMap[N].push_back(NodeSUnit);
ComputeLatency(NodeSUnit);
}
// Pass 2: add the preds, succs, etc.
for (unsigned su = 0, e = SUnits.size(); su != e; ++su) {
SUnit *SU = &SUnits[su];
SDNode *MainNode = SU->Node;
if (MainNode->isTargetOpcode()) {
unsigned Opc = MainNode->getTargetOpcode();
const TargetInstrDesc &TID = TII->get(Opc);
for (unsigned i = 0; i != TID.getNumOperands(); ++i) {
if (TID.getOperandConstraint(i, TOI::TIED_TO) != -1) {
SU->isTwoAddress = true;
break;
}
}
if (TID.isCommutable())
SU->isCommutable = true;
}
// Find all predecessors and successors of the group.
// Temporarily add N to make code simpler.
SU->FlaggedNodes.push_back(MainNode);
for (unsigned n = 0, e = SU->FlaggedNodes.size(); n != e; ++n) {
SDNode *N = SU->FlaggedNodes[n];
if (N->isTargetOpcode() &&
TII->get(N->getTargetOpcode()).getImplicitDefs() &&
CountResults(N) > TII->get(N->getTargetOpcode()).getNumDefs())
SU->hasPhysRegDefs = true;
for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i) {
SDNode *OpN = N->getOperand(i).Val;
if (isPassiveNode(OpN)) continue; // Not scheduled.
SUnit *OpSU = SUnitMap[OpN].front();
assert(OpSU && "Node has no SUnit!");
if (OpSU == SU) continue; // In the same group.
MVT::ValueType OpVT = N->getOperand(i).getValueType();
assert(OpVT != MVT::Flag && "Flagged nodes should be in same sunit!");
bool isChain = OpVT == MVT::Other;
unsigned PhysReg = 0;
int Cost = 1;
// Determine if this is a physical register dependency.
CheckForPhysRegDependency(OpN, N, i, TRI, TII, PhysReg, Cost);
SU->addPred(OpSU, isChain, false, PhysReg, Cost);
}
}
// Remove MainNode from FlaggedNodes again.
SU->FlaggedNodes.pop_back();
}
return;
}
void ScheduleDAG::ComputeLatency(SUnit *SU) {
const InstrItineraryData &InstrItins = TM.getInstrItineraryData();
// Compute the latency for the node. We use the sum of the latencies for
// all nodes flagged together into this SUnit.
if (InstrItins.isEmpty()) {
// No latency information.
SU->Latency = 1;
} else {
SU->Latency = 0;
if (SU->Node->isTargetOpcode()) {
unsigned SchedClass =
TII->get(SU->Node->getTargetOpcode()).getSchedClass();
InstrStage *S = InstrItins.begin(SchedClass);
InstrStage *E = InstrItins.end(SchedClass);
for (; S != E; ++S)
SU->Latency += S->Cycles;
}
for (unsigned i = 0, e = SU->FlaggedNodes.size(); i != e; ++i) {
SDNode *FNode = SU->FlaggedNodes[i];
if (FNode->isTargetOpcode()) {
unsigned SchedClass =TII->get(FNode->getTargetOpcode()).getSchedClass();
InstrStage *S = InstrItins.begin(SchedClass);
InstrStage *E = InstrItins.end(SchedClass);
for (; S != E; ++S)
SU->Latency += S->Cycles;
}
}
}
}
void ScheduleDAG::CalculateDepths() {
std::vector<std::pair<SUnit*, unsigned> > WorkList;
for (unsigned i = 0, e = SUnits.size(); i != e; ++i)
if (SUnits[i].Preds.empty())
WorkList.push_back(std::make_pair(&SUnits[i], 0U));
while (!WorkList.empty()) {
SUnit *SU = WorkList.back().first;
unsigned Depth = WorkList.back().second;
WorkList.pop_back();
if (SU->Depth == 0 || Depth > SU->Depth) {
SU->Depth = Depth;
for (SUnit::succ_iterator I = SU->Succs.begin(), E = SU->Succs.end();
I != E; ++I)
WorkList.push_back(std::make_pair(I->Dep, Depth+1));
}
}
}
void ScheduleDAG::CalculateHeights() {
std::vector<std::pair<SUnit*, unsigned> > WorkList;
SUnit *Root = SUnitMap[DAG.getRoot().Val].front();
WorkList.push_back(std::make_pair(Root, 0U));
while (!WorkList.empty()) {
SUnit *SU = WorkList.back().first;
unsigned Height = WorkList.back().second;
WorkList.pop_back();
if (SU->Height == 0 || Height > SU->Height) {
SU->Height = Height;
for (SUnit::pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
I != E; ++I)
WorkList.push_back(std::make_pair(I->Dep, Height+1));
}
}
}
/// CountResults - The results of target nodes have register or immediate
/// operands first, then an optional chain, and optional flag operands (which do
/// not go into the resulting MachineInstr).
unsigned ScheduleDAG::CountResults(SDNode *Node) {
unsigned N = Node->getNumValues();
while (N && Node->getValueType(N - 1) == MVT::Flag)
--N;
if (N && Node->getValueType(N - 1) == MVT::Other)
--N; // Skip over chain result.
return N;
}
/// CountOperands - The inputs to target nodes have any actual inputs first,
/// followed by special operands that describe memory references, then an
/// optional chain operand, then flag operands. Compute the number of
/// actual operands that will go into the resulting MachineInstr.
unsigned ScheduleDAG::CountOperands(SDNode *Node) {
unsigned N = ComputeMemOperandsEnd(Node);
while (N && isa<MemOperandSDNode>(Node->getOperand(N - 1).Val))
--N; // Ignore MemOperand nodes
return N;
}
/// ComputeMemOperandsEnd - Find the index one past the last MemOperandSDNode
/// operand
unsigned ScheduleDAG::ComputeMemOperandsEnd(SDNode *Node) {
unsigned N = Node->getNumOperands();
while (N && Node->getOperand(N - 1).getValueType() == MVT::Flag)
--N;
if (N && Node->getOperand(N - 1).getValueType() == MVT::Other)
--N; // Ignore chain if it exists.
return N;
}
static const TargetRegisterClass *getInstrOperandRegClass(
const TargetRegisterInfo *TRI,
const TargetInstrInfo *TII,
const TargetInstrDesc &II,
unsigned Op) {
if (Op >= II.getNumOperands()) {
assert(II.isVariadic() && "Invalid operand # of instruction");
return NULL;
}
if (II.OpInfo[Op].isLookupPtrRegClass())
return TII->getPointerRegClass();
return TRI->getRegClass(II.OpInfo[Op].RegClass);
}
void ScheduleDAG::EmitCopyFromReg(SDNode *Node, unsigned ResNo,
unsigned InstanceNo, unsigned SrcReg,
DenseMap<SDOperand, unsigned> &VRBaseMap) {
unsigned VRBase = 0;
if (TargetRegisterInfo::isVirtualRegister(SrcReg)) {
// Just use the input register directly!
if (InstanceNo > 0)
VRBaseMap.erase(SDOperand(Node, ResNo));
bool isNew = VRBaseMap.insert(std::make_pair(SDOperand(Node,ResNo),SrcReg));
assert(isNew && "Node emitted out of order - early");
return;
}
// If the node is only used by a CopyToReg and the dest reg is a vreg, use
// the CopyToReg'd destination register instead of creating a new vreg.
bool MatchReg = true;
for (SDNode::use_iterator UI = Node->use_begin(), E = Node->use_end();
UI != E; ++UI) {
SDNode *Use = *UI;
bool Match = true;
if (Use->getOpcode() == ISD::CopyToReg &&
Use->getOperand(2).Val == Node &&
Use->getOperand(2).ResNo == ResNo) {
unsigned DestReg = cast<RegisterSDNode>(Use->getOperand(1))->getReg();
if (TargetRegisterInfo::isVirtualRegister(DestReg)) {
VRBase = DestReg;
Match = false;
} else if (DestReg != SrcReg)
Match = false;
} else {
for (unsigned i = 0, e = Use->getNumOperands(); i != e; ++i) {
SDOperand Op = Use->getOperand(i);
if (Op.Val != Node || Op.ResNo != ResNo)
continue;
MVT::ValueType VT = Node->getValueType(Op.ResNo);
if (VT != MVT::Other && VT != MVT::Flag)
Match = false;
}
}
MatchReg &= Match;
if (VRBase)
break;
}
const TargetRegisterClass *TRC = 0;
// Figure out the register class to create for the destreg.
if (VRBase)
TRC = RegInfo.getRegClass(VRBase);
else
TRC = TRI->getPhysicalRegisterRegClass(Node->getValueType(ResNo), SrcReg);
// If all uses are reading from the src physical register and copying the
// register is either impossible or very expensive, then don't create a copy.
if (MatchReg && TRC->getCopyCost() < 0) {
VRBase = SrcReg;
} else {
// Create the reg, emit the copy.
VRBase = RegInfo.createVirtualRegister(TRC);
TII->copyRegToReg(*BB, BB->end(), VRBase, SrcReg, TRC, TRC);
}
if (InstanceNo > 0)
VRBaseMap.erase(SDOperand(Node, ResNo));
bool isNew = VRBaseMap.insert(std::make_pair(SDOperand(Node,ResNo), VRBase));
assert(isNew && "Node emitted out of order - early");
}
void ScheduleDAG::CreateVirtualRegisters(SDNode *Node,
MachineInstr *MI,
const TargetInstrDesc &II,
DenseMap<SDOperand, unsigned> &VRBaseMap) {
for (unsigned i = 0; i < II.getNumDefs(); ++i) {
// If the specific node value is only used by a CopyToReg and the dest reg
// is a vreg, use the CopyToReg'd destination register instead of creating
// a new vreg.
unsigned VRBase = 0;
for (SDNode::use_iterator UI = Node->use_begin(), E = Node->use_end();
UI != E; ++UI) {
SDNode *Use = *UI;
if (Use->getOpcode() == ISD::CopyToReg &&
Use->getOperand(2).Val == Node &&
Use->getOperand(2).ResNo == i) {
unsigned Reg = cast<RegisterSDNode>(Use->getOperand(1))->getReg();
if (TargetRegisterInfo::isVirtualRegister(Reg)) {
VRBase = Reg;
MI->addOperand(MachineOperand::CreateReg(Reg, true));
break;
}
}
}
// Create the result registers for this node and add the result regs to
// the machine instruction.
if (VRBase == 0) {
const TargetRegisterClass *RC = getInstrOperandRegClass(TRI, TII, II, i);
assert(RC && "Isn't a register operand!");
VRBase = RegInfo.createVirtualRegister(RC);
MI->addOperand(MachineOperand::CreateReg(VRBase, true));
}
bool isNew = VRBaseMap.insert(std::make_pair(SDOperand(Node,i), VRBase));
assert(isNew && "Node emitted out of order - early");
}
}
/// getVR - Return the virtual register corresponding to the specified result
/// of the specified node.
static unsigned getVR(SDOperand Op, DenseMap<SDOperand, unsigned> &VRBaseMap) {
DenseMap<SDOperand, unsigned>::iterator I = VRBaseMap.find(Op);
assert(I != VRBaseMap.end() && "Node emitted out of order - late");
return I->second;
}
/// AddOperand - Add the specified operand to the specified machine instr. II
/// specifies the instruction information for the node, and IIOpNum is the
/// operand number (in the II) that we are adding. IIOpNum and II are used for
/// assertions only.
void ScheduleDAG::AddOperand(MachineInstr *MI, SDOperand Op,
unsigned IIOpNum,
const TargetInstrDesc *II,
DenseMap<SDOperand, unsigned> &VRBaseMap) {
if (Op.isTargetOpcode()) {
// Note that this case is redundant with the final else block, but we
// include it because it is the most common and it makes the logic
// simpler here.
assert(Op.getValueType() != MVT::Other &&
Op.getValueType() != MVT::Flag &&
"Chain and flag operands should occur at end of operand list!");
// Get/emit the operand.
unsigned VReg = getVR(Op, VRBaseMap);
const TargetInstrDesc &TID = MI->getDesc();
bool isOptDef = (IIOpNum < TID.getNumOperands())
? (TID.OpInfo[IIOpNum].isOptionalDef()) : false;
MI->addOperand(MachineOperand::CreateReg(VReg, isOptDef));
// Verify that it is right.
assert(TargetRegisterInfo::isVirtualRegister(VReg) && "Not a vreg?");
if (II) {
const TargetRegisterClass *RC =
getInstrOperandRegClass(TRI, TII, *II, IIOpNum);
assert(RC && "Don't have operand info for this instruction!");
const TargetRegisterClass *VRC = RegInfo.getRegClass(VReg);
if (VRC != RC) {
cerr << "Register class of operand and regclass of use don't agree!\n";
#ifndef NDEBUG
cerr << "Operand = " << IIOpNum << "\n";
cerr << "Op->Val = "; Op.Val->dump(&DAG); cerr << "\n";
cerr << "MI = "; MI->print(cerr);
cerr << "VReg = " << VReg << "\n";
cerr << "VReg RegClass size = " << VRC->getSize()
<< ", align = " << VRC->getAlignment() << "\n";
cerr << "Expected RegClass size = " << RC->getSize()
<< ", align = " << RC->getAlignment() << "\n";
#endif
cerr << "Fatal error, aborting.\n";
abort();
}
}
} else if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(Op)) {
MI->addOperand(MachineOperand::CreateImm(C->getValue()));
} else if (ConstantFPSDNode *F = dyn_cast<ConstantFPSDNode>(Op)) {
const Type *FType = MVT::getTypeForValueType(Op.getValueType());
ConstantFP *CFP = ConstantFP::get(FType, F->getValueAPF());
MI->addOperand(MachineOperand::CreateFPImm(CFP));
} else if (RegisterSDNode *R = dyn_cast<RegisterSDNode>(Op)) {
MI->addOperand(MachineOperand::CreateReg(R->getReg(), false));
} else if (GlobalAddressSDNode *TGA = dyn_cast<GlobalAddressSDNode>(Op)) {
MI->addOperand(MachineOperand::CreateGA(TGA->getGlobal(),TGA->getOffset()));
} else if (BasicBlockSDNode *BB = dyn_cast<BasicBlockSDNode>(Op)) {
MI->addOperand(MachineOperand::CreateMBB(BB->getBasicBlock()));
} else if (FrameIndexSDNode *FI = dyn_cast<FrameIndexSDNode>(Op)) {
MI->addOperand(MachineOperand::CreateFI(FI->getIndex()));
} else if (JumpTableSDNode *JT = dyn_cast<JumpTableSDNode>(Op)) {
MI->addOperand(MachineOperand::CreateJTI(JT->getIndex()));
} else if (ConstantPoolSDNode *CP = dyn_cast<ConstantPoolSDNode>(Op)) {
int Offset = CP->getOffset();
unsigned Align = CP->getAlignment();
const Type *Type = CP->getType();
// MachineConstantPool wants an explicit alignment.
if (Align == 0) {
Align = TM.getTargetData()->getPreferredTypeAlignmentShift(Type);
if (Align == 0) {
// Alignment of vector types. FIXME!
Align = TM.getTargetData()->getABITypeSize(Type);
Align = Log2_64(Align);
}
}
unsigned Idx;
if (CP->isMachineConstantPoolEntry())
Idx = ConstPool->getConstantPoolIndex(CP->getMachineCPVal(), Align);
else
Idx = ConstPool->getConstantPoolIndex(CP->getConstVal(), Align);
MI->addOperand(MachineOperand::CreateCPI(Idx, Offset));
} else if (ExternalSymbolSDNode *ES = dyn_cast<ExternalSymbolSDNode>(Op)) {
MI->addOperand(MachineOperand::CreateES(ES->getSymbol()));
} else {
assert(Op.getValueType() != MVT::Other &&
Op.getValueType() != MVT::Flag &&
"Chain and flag operands should occur at end of operand list!");
unsigned VReg = getVR(Op, VRBaseMap);
MI->addOperand(MachineOperand::CreateReg(VReg, false));
// Verify that it is right.
assert(TargetRegisterInfo::isVirtualRegister(VReg) && "Not a vreg?");
if (II) {
const TargetRegisterClass *RC =
getInstrOperandRegClass(TRI, TII, *II, IIOpNum);
assert(RC && "Don't have operand info for this instruction!");
assert(RegInfo.getRegClass(VReg) == RC &&
"Register class of operand and regclass of use don't agree!");
}
}
}
void ScheduleDAG::AddMemOperand(MachineInstr *MI, const MemOperand &MO) {
MI->addMemOperand(MO);
}
// Returns the Register Class of a subregister
static const TargetRegisterClass *getSubRegisterRegClass(
const TargetRegisterClass *TRC,
unsigned SubIdx) {
// Pick the register class of the subregister
TargetRegisterInfo::regclass_iterator I =
TRC->subregclasses_begin() + SubIdx-1;
assert(I < TRC->subregclasses_end() &&
"Invalid subregister index for register class");
return *I;
}
static const TargetRegisterClass *getSuperregRegisterClass(
const TargetRegisterClass *TRC,
unsigned SubIdx,
MVT::ValueType VT) {
// Pick the register class of the superegister for this type
for (TargetRegisterInfo::regclass_iterator I = TRC->superregclasses_begin(),
E = TRC->superregclasses_end(); I != E; ++I)
if ((*I)->hasType(VT) && getSubRegisterRegClass(*I, SubIdx) == TRC)
return *I;
assert(false && "Couldn't find the register class");
return 0;
}
/// EmitSubregNode - Generate machine code for subreg nodes.
///
void ScheduleDAG::EmitSubregNode(SDNode *Node,
DenseMap<SDOperand, unsigned> &VRBaseMap) {
unsigned VRBase = 0;
unsigned Opc = Node->getTargetOpcode();
if (Opc == TargetInstrInfo::EXTRACT_SUBREG) {
// If the node is only used by a CopyToReg and the dest reg is a vreg, use
// the CopyToReg'd destination register instead of creating a new vreg.
for (SDNode::use_iterator UI = Node->use_begin(), E = Node->use_end();
UI != E; ++UI) {
SDNode *Use = *UI;
if (Use->getOpcode() == ISD::CopyToReg &&
Use->getOperand(2).Val == Node) {
unsigned DestReg = cast<RegisterSDNode>(Use->getOperand(1))->getReg();
if (TargetRegisterInfo::isVirtualRegister(DestReg)) {
VRBase = DestReg;
break;
}
}
}
unsigned SubIdx = cast<ConstantSDNode>(Node->getOperand(1))->getValue();
// TODO: If the node is a use of a CopyFromReg from a physical register
// fold the extract into the copy now
// Create the extract_subreg machine instruction.
MachineInstr *MI =
new MachineInstr(BB, TII->get(TargetInstrInfo::EXTRACT_SUBREG));
// Figure out the register class to create for the destreg.
unsigned VReg = getVR(Node->getOperand(0), VRBaseMap);
const TargetRegisterClass *TRC = RegInfo.getRegClass(VReg);
const TargetRegisterClass *SRC = getSubRegisterRegClass(TRC, SubIdx);
if (VRBase) {
// Grab the destination register
const TargetRegisterClass *DRC = 0;
DRC = RegInfo.getRegClass(VRBase);
assert(SRC && DRC && SRC == DRC &&
"Source subregister and destination must have the same class");
} else {
// Create the reg
assert(SRC && "Couldn't find source register class");
VRBase = RegInfo.createVirtualRegister(SRC);
}
// Add def, source, and subreg index
MI->addOperand(MachineOperand::CreateReg(VRBase, true));
AddOperand(MI, Node->getOperand(0), 0, 0, VRBaseMap);
MI->addOperand(MachineOperand::CreateImm(SubIdx));
} else if (Opc == TargetInstrInfo::INSERT_SUBREG) {
assert((Node->getNumOperands() == 2 || Node->getNumOperands() == 3) &&
"Malformed insert_subreg node");
bool isUndefInput = (Node->getNumOperands() == 2);
unsigned SubReg = 0;
unsigned SubIdx = 0;
if (isUndefInput) {
SubReg = getVR(Node->getOperand(0), VRBaseMap);
SubIdx = cast<ConstantSDNode>(Node->getOperand(1))->getValue();
} else {
SubReg = getVR(Node->getOperand(1), VRBaseMap);
SubIdx = cast<ConstantSDNode>(Node->getOperand(2))->getValue();
}
// TODO: Add tracking info to MachineRegisterInfo of which vregs are subregs
// to allow coalescing in the allocator
// If the node is only used by a CopyToReg and the dest reg is a vreg, use
// the CopyToReg'd destination register instead of creating a new vreg.
// If the CopyToReg'd destination register is physical, then fold the
// insert into the copy
for (SDNode::use_iterator UI = Node->use_begin(), E = Node->use_end();
UI != E; ++UI) {
SDNode *Use = *UI;
if (Use->getOpcode() == ISD::CopyToReg &&
Use->getOperand(2).Val == Node) {
unsigned DestReg = cast<RegisterSDNode>(Use->getOperand(1))->getReg();
if (TargetRegisterInfo::isVirtualRegister(DestReg)) {
VRBase = DestReg;
break;
}
}
}
// Create the insert_subreg machine instruction.
MachineInstr *MI =
new MachineInstr(BB, TII->get(TargetInstrInfo::INSERT_SUBREG));
// Figure out the register class to create for the destreg.
const TargetRegisterClass *TRC = 0;
if (VRBase) {
TRC = RegInfo.getRegClass(VRBase);
} else {
TRC = getSuperregRegisterClass(RegInfo.getRegClass(SubReg), SubIdx,
Node->getValueType(0));
assert(TRC && "Couldn't determine register class for insert_subreg");
VRBase = RegInfo.createVirtualRegister(TRC); // Create the reg
}
MI->addOperand(MachineOperand::CreateReg(VRBase, true));
AddOperand(MI, Node->getOperand(0), 0, 0, VRBaseMap);
if (!isUndefInput)
AddOperand(MI, Node->getOperand(1), 0, 0, VRBaseMap);
MI->addOperand(MachineOperand::CreateImm(SubIdx));
} else
assert(0 && "Node is not a subreg insert or extract");
bool isNew = VRBaseMap.insert(std::make_pair(SDOperand(Node,0), VRBase));
assert(isNew && "Node emitted out of order - early");
}
/// EmitNode - Generate machine code for an node and needed dependencies.
///
void ScheduleDAG::EmitNode(SDNode *Node, unsigned InstanceNo,
DenseMap<SDOperand, unsigned> &VRBaseMap) {
// If machine instruction
if (Node->isTargetOpcode()) {
unsigned Opc = Node->getTargetOpcode();
// Handle subreg insert/extract specially
if (Opc == TargetInstrInfo::EXTRACT_SUBREG ||
Opc == TargetInstrInfo::INSERT_SUBREG) {
EmitSubregNode(Node, VRBaseMap);
return;
}
const TargetInstrDesc &II = TII->get(Opc);
unsigned NumResults = CountResults(Node);
unsigned NodeOperands = CountOperands(Node);
unsigned MemOperandsEnd = ComputeMemOperandsEnd(Node);
unsigned NumMIOperands = NodeOperands + NumResults;
bool HasPhysRegOuts = (NumResults > II.getNumDefs()) &&
II.getImplicitDefs() != 0;
#ifndef NDEBUG
assert((II.getNumOperands() == NumMIOperands ||
HasPhysRegOuts || II.isVariadic()) &&
"#operands for dag node doesn't match .td file!");
#endif
// Create the new machine instruction.
MachineInstr *MI = new MachineInstr(II);
// Add result register values for things that are defined by this
// instruction.
if (NumResults)
CreateVirtualRegisters(Node, MI, II, VRBaseMap);
// Emit all of the actual operands of this instruction, adding them to the
// instruction as appropriate.
for (unsigned i = 0; i != NodeOperands; ++i)
AddOperand(MI, Node->getOperand(i), i+II.getNumDefs(), &II, VRBaseMap);
// Emit all of the memory operands of this instruction
for (unsigned i = NodeOperands; i != MemOperandsEnd; ++i)
AddMemOperand(MI, cast<MemOperandSDNode>(Node->getOperand(i))->MO);
// Commute node if it has been determined to be profitable.
if (CommuteSet.count(Node)) {
MachineInstr *NewMI = TII->commuteInstruction(MI);
if (NewMI == 0)
DOUT << "Sched: COMMUTING FAILED!\n";
else {
DOUT << "Sched: COMMUTED TO: " << *NewMI;
if (MI != NewMI) {
delete MI;
MI = NewMI;
}
++NumCommutes;
}
}
if (II.usesCustomDAGSchedInsertionHook())
// Insert this instruction into the basic block using a target
// specific inserter which may returns a new basic block.
BB = DAG.getTargetLoweringInfo().EmitInstrWithCustomInserter(MI, BB);
else
BB->push_back(MI);
// Additional results must be an physical register def.
if (HasPhysRegOuts) {
for (unsigned i = II.getNumDefs(); i < NumResults; ++i) {
unsigned Reg = II.getImplicitDefs()[i - II.getNumDefs()];
if (Node->hasAnyUseOfValue(i))
EmitCopyFromReg(Node, i, InstanceNo, Reg, VRBaseMap);
}
}
} else {
switch (Node->getOpcode()) {
default:
#ifndef NDEBUG
Node->dump(&DAG);
#endif
assert(0 && "This target-independent node should have been selected!");
case ISD::EntryToken: // fall thru
case ISD::TokenFactor:
case ISD::LABEL:
case ISD::DECLARE:
case ISD::SRCVALUE:
break;
case ISD::CopyToReg: {
unsigned InReg;
if (RegisterSDNode *R = dyn_cast<RegisterSDNode>(Node->getOperand(2)))
InReg = R->getReg();
else
InReg = getVR(Node->getOperand(2), VRBaseMap);
unsigned DestReg = cast<RegisterSDNode>(Node->getOperand(1))->getReg();
if (InReg != DestReg) {// Coalesced away the copy?
const TargetRegisterClass *TRC = 0;
// Get the target register class
if (TargetRegisterInfo::isVirtualRegister(InReg))
TRC = RegInfo.getRegClass(InReg);
else
TRC =
TRI->getPhysicalRegisterRegClass(Node->getOperand(2).getValueType(),
InReg);
TII->copyRegToReg(*BB, BB->end(), DestReg, InReg, TRC, TRC);
}
break;
}
case ISD::CopyFromReg: {
unsigned SrcReg = cast<RegisterSDNode>(Node->getOperand(1))->getReg();
EmitCopyFromReg(Node, 0, InstanceNo, SrcReg, VRBaseMap);
break;
}
case ISD::INLINEASM: {
unsigned NumOps = Node->getNumOperands();
if (Node->getOperand(NumOps-1).getValueType() == MVT::Flag)
--NumOps; // Ignore the flag operand.
// Create the inline asm machine instruction.
MachineInstr *MI =
new MachineInstr(BB, TII->get(TargetInstrInfo::INLINEASM));
// Add the asm string as an external symbol operand.
const char *AsmStr =
cast<ExternalSymbolSDNode>(Node->getOperand(1))->getSymbol();
MI->addOperand(MachineOperand::CreateES(AsmStr));
// Add all of the operand registers to the instruction.
for (unsigned i = 2; i != NumOps;) {
unsigned Flags = cast<ConstantSDNode>(Node->getOperand(i))->getValue();
unsigned NumVals = Flags >> 3;
MI->addOperand(MachineOperand::CreateImm(Flags));
++i; // Skip the ID value.
switch (Flags & 7) {
default: assert(0 && "Bad flags!");
case 1: // Use of register.
for (; NumVals; --NumVals, ++i) {
unsigned Reg = cast<RegisterSDNode>(Node->getOperand(i))->getReg();
MI->addOperand(MachineOperand::CreateReg(Reg, false));
}
break;
case 2: // Def of register.
for (; NumVals; --NumVals, ++i) {
unsigned Reg = cast<RegisterSDNode>(Node->getOperand(i))->getReg();
MI->addOperand(MachineOperand::CreateReg(Reg, true));
}
break;
case 3: { // Immediate.
for (; NumVals; --NumVals, ++i) {
if (ConstantSDNode *CS =
dyn_cast<ConstantSDNode>(Node->getOperand(i))) {
MI->addOperand(MachineOperand::CreateImm(CS->getValue()));
} else if (GlobalAddressSDNode *GA =
dyn_cast<GlobalAddressSDNode>(Node->getOperand(i))) {
MI->addOperand(MachineOperand::CreateGA(GA->getGlobal(),
GA->getOffset()));
} else {
BasicBlockSDNode *BB =cast<BasicBlockSDNode>(Node->getOperand(i));
MI->addOperand(MachineOperand::CreateMBB(BB->getBasicBlock()));
}
}
break;
}
case 4: // Addressing mode.
// The addressing mode has been selected, just add all of the
// operands to the machine instruction.
for (; NumVals; --NumVals, ++i)
AddOperand(MI, Node->getOperand(i), 0, 0, VRBaseMap);
break;
}
}
break;
}
}
}
}
void ScheduleDAG::EmitNoop() {
TII->insertNoop(*BB, BB->end());
}
void ScheduleDAG::EmitCrossRCCopy(SUnit *SU, DenseMap<SUnit*, unsigned> &VRBaseMap) {
for (SUnit::const_pred_iterator I = SU->Preds.begin(), E = SU->Preds.end();
I != E; ++I) {
if (I->isCtrl) continue; // ignore chain preds
if (!I->Dep->Node) {
// Copy to physical register.
DenseMap<SUnit*, unsigned>::iterator VRI = VRBaseMap.find(I->Dep);
assert(VRI != VRBaseMap.end() && "Node emitted out of order - late");
// Find the destination physical register.
unsigned Reg = 0;
for (SUnit::const_succ_iterator II = SU->Succs.begin(),
EE = SU->Succs.end(); II != EE; ++II) {
if (I->Reg) {
Reg = I->Reg;
break;
}
}
assert(I->Reg && "Unknown physical register!");
TII->copyRegToReg(*BB, BB->end(), Reg, VRI->second,
SU->CopyDstRC, SU->CopySrcRC);
} else {
// Copy from physical register.
assert(I->Reg && "Unknown physical register!");
unsigned VRBase = RegInfo.createVirtualRegister(SU->CopyDstRC);
bool isNew = VRBaseMap.insert(std::make_pair(SU, VRBase));
assert(isNew && "Node emitted out of order - early");
TII->copyRegToReg(*BB, BB->end(), VRBase, I->Reg,
SU->CopyDstRC, SU->CopySrcRC);
}
break;
}
}
/// EmitSchedule - Emit the machine code in scheduled order.
void ScheduleDAG::EmitSchedule() {
// If this is the first basic block in the function, and if it has live ins
// that need to be copied into vregs, emit the copies into the top of the
// block before emitting the code for the block.
if (&MF->front() == BB) {
for (MachineRegisterInfo::livein_iterator LI = RegInfo.livein_begin(),
E = RegInfo.livein_end(); LI != E; ++LI)
if (LI->second) {
const TargetRegisterClass *RC = RegInfo.getRegClass(LI->second);
TII->copyRegToReg(*MF->begin(), MF->begin()->end(), LI->second,
LI->first, RC, RC);
}
}
// Finally, emit the code for all of the scheduled instructions.
DenseMap<SDOperand, unsigned> VRBaseMap;
DenseMap<SUnit*, unsigned> CopyVRBaseMap;
for (unsigned i = 0, e = Sequence.size(); i != e; i++) {
if (SUnit *SU = Sequence[i]) {
for (unsigned j = 0, ee = SU->FlaggedNodes.size(); j != ee; ++j)
EmitNode(SU->FlaggedNodes[j], SU->InstanceNo, VRBaseMap);
if (SU->Node)
EmitNode(SU->Node, SU->InstanceNo, VRBaseMap);
else
EmitCrossRCCopy(SU, CopyVRBaseMap);
} else {
// Null SUnit* is a noop.
EmitNoop();
}
}
}
/// dump - dump the schedule.
void ScheduleDAG::dumpSchedule() const {
for (unsigned i = 0, e = Sequence.size(); i != e; i++) {
if (SUnit *SU = Sequence[i])
SU->dump(&DAG);
else
cerr << "**** NOOP ****\n";
}
}
/// Run - perform scheduling.
///
MachineBasicBlock *ScheduleDAG::Run() {
Schedule();
return BB;
}
/// SUnit - Scheduling unit. It's an wrapper around either a single SDNode or
/// a group of nodes flagged together.
void SUnit::dump(const SelectionDAG *G) const {
cerr << "SU(" << NodeNum << "): ";
if (Node)
Node->dump(G);
else
cerr << "CROSS RC COPY ";
cerr << "\n";
if (FlaggedNodes.size() != 0) {
for (unsigned i = 0, e = FlaggedNodes.size(); i != e; i++) {
cerr << " ";
FlaggedNodes[i]->dump(G);
cerr << "\n";
}
}
}
void SUnit::dumpAll(const SelectionDAG *G) const {
dump(G);
cerr << " # preds left : " << NumPredsLeft << "\n";
cerr << " # succs left : " << NumSuccsLeft << "\n";
cerr << " Latency : " << Latency << "\n";
cerr << " Depth : " << Depth << "\n";
cerr << " Height : " << Height << "\n";
if (Preds.size() != 0) {
cerr << " Predecessors:\n";
for (SUnit::const_succ_iterator I = Preds.begin(), E = Preds.end();
I != E; ++I) {
if (I->isCtrl)
cerr << " ch #";
else
cerr << " val #";
cerr << I->Dep << " - SU(" << I->Dep->NodeNum << ")";
if (I->isSpecial)
cerr << " *";
cerr << "\n";
}
}
if (Succs.size() != 0) {
cerr << " Successors:\n";
for (SUnit::const_succ_iterator I = Succs.begin(), E = Succs.end();
I != E; ++I) {
if (I->isCtrl)
cerr << " ch #";
else
cerr << " val #";
cerr << I->Dep << " - SU(" << I->Dep->NodeNum << ")";
if (I->isSpecial)
cerr << " *";
cerr << "\n";
}
}
cerr << "\n";
}
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