llvm-6502/lib/CodeGen/SelectionDAG/ScheduleDAG.cpp
Nate Begeman 37efe67645 JumpTable support! What this represents is working asm and jit support for
x86 and ppc for 100% dense switch statements when relocations are non-PIC.
This support will be extended and enhanced in the coming days to support
PIC, and less dense forms of jump tables.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@27947 91177308-0d34-0410-b5e6-96231b3b80d8
2006-04-22 18:53:45 +00:00

364 lines
14 KiB
C++

//===---- ScheduleDAG.cpp - Implement the ScheduleDAG class ---------------===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by James M. Laskey and 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.
//
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/ScheduleDAG.h"
#include "llvm/CodeGen/MachineConstantPool.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/SSARegMap.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetLowering.h"
#include "llvm/Support/MathExtras.h"
using namespace llvm;
/// 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 machine instrs.)
static unsigned 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 an optional chain operand, then flag operands. Compute the
/// number of actual operands that will go into the machine instr.
static unsigned CountOperands(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 unsigned CreateVirtualRegisters(MachineInstr *MI,
unsigned NumResults,
SSARegMap *RegMap,
const TargetInstrDescriptor &II) {
// Create the result registers for this node and add the result regs to
// the machine instruction.
const TargetOperandInfo *OpInfo = II.OpInfo;
unsigned ResultReg = RegMap->createVirtualRegister(OpInfo[0].RegClass);
MI->addRegOperand(ResultReg, MachineOperand::Def);
for (unsigned i = 1; i != NumResults; ++i) {
assert(OpInfo[i].RegClass && "Isn't a register operand!");
MI->addRegOperand(RegMap->createVirtualRegister(OpInfo[i].RegClass),
MachineOperand::Def);
}
return ResultReg;
}
/// getVR - Return the virtual register corresponding to the specified result
/// of the specified node.
static unsigned getVR(SDOperand Op, std::map<SDNode*, unsigned> &VRBaseMap) {
std::map<SDNode*, unsigned>::iterator I = VRBaseMap.find(Op.Val);
assert(I != VRBaseMap.end() && "Node emitted out of order - late");
return I->second + Op.ResNo;
}
/// 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 TargetInstrDescriptor *II,
std::map<SDNode*, 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);
MI->addRegOperand(VReg, MachineOperand::Use);
// Verify that it is right.
assert(MRegisterInfo::isVirtualRegister(VReg) && "Not a vreg?");
if (II) {
assert(II->OpInfo[IIOpNum].RegClass &&
"Don't have operand info for this instruction!");
assert(RegMap->getRegClass(VReg) == II->OpInfo[IIOpNum].RegClass &&
"Register class of operand and regclass of use don't agree!");
}
} else if (ConstantSDNode *C =
dyn_cast<ConstantSDNode>(Op)) {
MI->addZeroExtImm64Operand(C->getValue());
} else if (RegisterSDNode*R =
dyn_cast<RegisterSDNode>(Op)) {
MI->addRegOperand(R->getReg(), MachineOperand::Use);
} else if (GlobalAddressSDNode *TGA =
dyn_cast<GlobalAddressSDNode>(Op)) {
MI->addGlobalAddressOperand(TGA->getGlobal(), false, TGA->getOffset());
} else if (BasicBlockSDNode *BB =
dyn_cast<BasicBlockSDNode>(Op)) {
MI->addMachineBasicBlockOperand(BB->getBasicBlock());
} else if (FrameIndexSDNode *FI =
dyn_cast<FrameIndexSDNode>(Op)) {
MI->addFrameIndexOperand(FI->getIndex());
} else if (JumpTableSDNode *JT =
dyn_cast<JumpTableSDNode>(Op)) {
MI->addJumpTableIndexOperand(JT->getIndex());
} else if (ConstantPoolSDNode *CP =
dyn_cast<ConstantPoolSDNode>(Op)) {
int Offset = CP->getOffset();
unsigned Align = CP->getAlignment();
// MachineConstantPool wants an explicit alignment.
if (Align == 0) {
if (CP->get()->getType() == Type::DoubleTy)
Align = 3; // always 8-byte align doubles.
else {
Align = TM.getTargetData()
.getTypeAlignmentShift(CP->get()->getType());
if (Align == 0) {
// Alignment of packed types. FIXME!
Align = TM.getTargetData().getTypeSize(CP->get()->getType());
Align = Log2_64(Align);
}
}
}
unsigned Idx = ConstPool->getConstantPoolIndex(CP->get(), Align);
MI->addConstantPoolIndexOperand(Idx, Offset);
} else if (ExternalSymbolSDNode *ES =
dyn_cast<ExternalSymbolSDNode>(Op)) {
MI->addExternalSymbolOperand(ES->getSymbol(), false);
} 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->addRegOperand(VReg, MachineOperand::Use);
// Verify that it is right.
assert(MRegisterInfo::isVirtualRegister(VReg) && "Not a vreg?");
if (II) {
assert(II->OpInfo[IIOpNum].RegClass &&
"Don't have operand info for this instruction!");
assert(RegMap->getRegClass(VReg) == II->OpInfo[IIOpNum].RegClass &&
"Register class of operand and regclass of use don't agree!");
}
}
}
/// EmitNode - Generate machine code for an node and needed dependencies.
///
void ScheduleDAG::EmitNode(SDNode *Node,
std::map<SDNode*, unsigned> &VRBaseMap) {
unsigned VRBase = 0; // First virtual register for node
// If machine instruction
if (Node->isTargetOpcode()) {
unsigned Opc = Node->getTargetOpcode();
const TargetInstrDescriptor &II = TII->get(Opc);
unsigned NumResults = CountResults(Node);
unsigned NodeOperands = CountOperands(Node);
unsigned NumMIOperands = NodeOperands + NumResults;
#ifndef NDEBUG
assert((unsigned(II.numOperands) == NumMIOperands || II.numOperands == -1)&&
"#operands for dag node doesn't match .td file!");
#endif
// Create the new machine instruction.
MachineInstr *MI = new MachineInstr(Opc, NumMIOperands, true, true);
// Add result register values for things that are defined by this
// instruction.
// 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 (NumResults == 1) {
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 Reg = cast<RegisterSDNode>(Use->getOperand(1))->getReg();
if (MRegisterInfo::isVirtualRegister(Reg)) {
VRBase = Reg;
MI->addRegOperand(Reg, MachineOperand::Def);
break;
}
}
}
}
// Otherwise, create new virtual registers.
if (NumResults && VRBase == 0)
VRBase = CreateVirtualRegisters(MI, NumResults, RegMap, II);
// 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+NumResults, &II, VRBaseMap);
// Now that we have emitted all operands, emit this instruction itself.
if ((II.Flags & M_USES_CUSTOM_DAG_SCHED_INSERTION) == 0) {
BB->insert(BB->end(), MI);
} else {
// Insert this instruction into the end of the basic block, potentially
// taking some custom action.
BB = DAG.getTargetLoweringInfo().InsertAtEndOfBasicBlock(MI, BB);
}
} else {
switch (Node->getOpcode()) {
default:
Node->dump();
assert(0 && "This target-independent node should have been selected!");
case ISD::EntryToken: // fall thru
case ISD::TokenFactor:
break;
case ISD::CopyToReg: {
unsigned InReg = getVR(Node->getOperand(2), VRBaseMap);
unsigned DestReg = cast<RegisterSDNode>(Node->getOperand(1))->getReg();
if (InReg != DestReg) // Coalesced away the copy?
MRI->copyRegToReg(*BB, BB->end(), DestReg, InReg,
RegMap->getRegClass(InReg));
break;
}
case ISD::CopyFromReg: {
unsigned SrcReg = cast<RegisterSDNode>(Node->getOperand(1))->getReg();
if (MRegisterInfo::isVirtualRegister(SrcReg)) {
VRBase = SrcReg; // Just use the input register directly!
break;
}
// 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 (MRegisterInfo::isVirtualRegister(DestReg)) {
VRBase = DestReg;
break;
}
}
}
// Figure out the register class to create for the destreg.
const TargetRegisterClass *TRC = 0;
if (VRBase) {
TRC = RegMap->getRegClass(VRBase);
} else {
// Pick the register class of the right type that contains this physreg.
for (MRegisterInfo::regclass_iterator I = MRI->regclass_begin(),
E = MRI->regclass_end(); I != E; ++I)
if ((*I)->hasType(Node->getValueType(0)) &&
(*I)->contains(SrcReg)) {
TRC = *I;
break;
}
assert(TRC && "Couldn't find register class for reg copy!");
// Create the reg, emit the copy.
VRBase = RegMap->createVirtualRegister(TRC);
}
MRI->copyRegToReg(*BB, BB->end(), VRBase, SrcReg, TRC);
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, TargetInstrInfo::INLINEASM, (NumOps-2)/2+1);
// Add the asm string as an external symbol operand.
const char *AsmStr =
cast<ExternalSymbolSDNode>(Node->getOperand(1))->getSymbol();
MI->addExternalSymbolOperand(AsmStr, false);
// 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->addZeroExtImm64Operand(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->addMachineRegOperand(Reg, MachineOperand::Use);
}
break;
case 2: // Def of register.
for (; NumVals; --NumVals, ++i) {
unsigned Reg = cast<RegisterSDNode>(Node->getOperand(i))->getReg();
MI->addMachineRegOperand(Reg, MachineOperand::Def);
}
break;
case 3: { // Immediate.
assert(NumVals == 1 && "Unknown immediate value!");
uint64_t Val = cast<ConstantSDNode>(Node->getOperand(i))->getValue();
MI->addZeroExtImm64Operand(Val);
++i;
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;
}
}
}
assert(!VRBaseMap.count(Node) && "Node emitted out of order - early");
VRBaseMap[Node] = VRBase;
}
void ScheduleDAG::EmitNoop() {
TII->insertNoop(*BB, BB->end());
}
/// Run - perform scheduling.
///
MachineBasicBlock *ScheduleDAG::Run() {
TII = TM.getInstrInfo();
MRI = TM.getRegisterInfo();
RegMap = BB->getParent()->getSSARegMap();
ConstPool = BB->getParent()->getConstantPool();
Schedule();
return BB;
}