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Instruction selection via pattern matching on instruction trees using BURG.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Vikram S. Adve
344
lib/CodeGen/MachineInstr.cpp
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344
lib/CodeGen/MachineInstr.cpp
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// $Id$
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//***************************************************************************
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// File:
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// MachineInstr.cpp
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//
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// Purpose:
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//
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//
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// Strategy:
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//
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// History:
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// 7/2/01 - Vikram Adve - Created
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//**************************************************************************/
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//************************** System Include Files **************************/
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#include <strstream.h>
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#include <string>
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#include <vector>
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//*************************** User Include Files ***************************/
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#include "llvm/Type.h"
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#include "llvm/DerivedTypes.h"
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#include "llvm/ConstPoolVals.h"
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#include "llvm/Value.h"
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#include "llvm/Instruction.h"
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#include "llvm/Codegen/InstrForest.h"
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#include "llvm/Codegen/MachineInstr.h"
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//************************ Class Implementations **************************/
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bool
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MachineInstrInfo::constantFitsInImmedField(int64_t intValue) const
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{
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// First, check if opCode has an immed field.
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bool isSignExtended;
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uint64_t maxImmedValue = this->maxImmedConstant(isSignExtended);
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if (maxImmedValue != 0)
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{
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// Now check if the constant fits
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if (intValue <= (int64_t) maxImmedValue &&
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intValue >= -((int64_t) maxImmedValue+1))
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return true;
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}
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return false;
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}
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MachineInstr::MachineInstr(MachineOpCode _opCode,
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OpCodeMask _opCodeMask)
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: opCode(_opCode),
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opCodeMask(_opCodeMask),
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operands(TargetMachineInstrInfo[_opCode].numOperands)
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{
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}
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MachineInstr::~MachineInstr()
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{
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}
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void
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MachineInstr::SetMachineOperand(unsigned int i,
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MachineOperand::MachineOperandType operandType,
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Value* _val)
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{
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assert(i < TargetMachineInstrInfo[opCode].numOperands);
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operands[i].Initialize(operandType, _val);
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}
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void
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MachineInstr::SetMachineOperand(unsigned int i,
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MachineOperand::MachineOperandType operandType,
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int64_t intValue)
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{
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assert(i < TargetMachineInstrInfo[opCode].numOperands);
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operands[i].InitializeConst(operandType, intValue);
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}
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void
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MachineInstr::SetMachineOperand(unsigned int i,
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unsigned int regNum)
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{
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assert(i < TargetMachineInstrInfo[opCode].numOperands);
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operands[i].InitializeReg(regNum);
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}
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void
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MachineInstr::dump(unsigned int indent)
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{
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for (unsigned i=0; i < indent; i++)
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cout << " ";
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cout << *this;
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}
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ostream&
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operator<< (ostream& os, const MachineInstr& minstr)
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{
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os << TargetMachineInstrInfo[minstr.opCode].opCodeString;
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for (unsigned i=0, N=minstr.getNumOperands(); i < N; i++)
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os << "\t" << minstr.getOperand(i);
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return os;
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}
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ostream&
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operator<< (ostream& os, const MachineOperand& mop)
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{
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strstream regInfo;
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if (mop.machineOperandType == MachineOperand::MO_Register)
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{
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if (mop.vregType == MachineOperand::MO_VirtualReg)
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regInfo << "(val " << mop.value << ")" << ends;
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else
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regInfo << "(" << mop.regNum << ")" << ends;
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}
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else if (mop.machineOperandType == MachineOperand::MO_CCRegister)
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regInfo << "(val " << mop.value << ")" << ends;
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switch(mop.machineOperandType)
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{
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case MachineOperand::MO_Register:
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os << "%reg" << regInfo.str();
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free(regInfo.str());
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break;
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case MachineOperand::MO_CCRegister:
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os << "%ccreg" << regInfo.str();
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free(regInfo.str());
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break;
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case MachineOperand::MO_SignExtendedImmed:
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os << mop.immedVal;
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break;
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case MachineOperand::MO_UnextendedImmed:
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os << mop.immedVal;
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break;
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case MachineOperand::MO_PCRelativeDisp:
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os << "%disp(label " << mop.value << ")";
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break;
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default:
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assert(0 && "Unrecognized operand type");
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break;
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}
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return os;
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}
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//---------------------------------------------------------------------------
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// Target-independent utility routines for creating machine instructions
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//---------------------------------------------------------------------------
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//------------------------------------------------------------------------
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// Function Set2OperandsFromInstr
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// Function Set3OperandsFromInstr
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//
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// For the common case of 2- and 3-operand arithmetic/logical instructions,
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// set the m/c instr. operands directly from the VM instruction's operands.
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// Check whether the first or second operand is 0 and can use a dedicated "0" register.
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// Check whether the second operand should use an immediate field or register.
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// (First and third operands are never immediates for such instructions.)
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//
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// Arguments:
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// canDiscardResult: Specifies that the result operand can be discarded
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// by using the dedicated "0"
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//
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// op1position, op2position and resultPosition: Specify in which position
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// in the machine instruction the 3 operands (arg1, arg2
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// and result) should go.
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//
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// RETURN VALUE: unsigned int flags, where
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// flags & 0x01 => operand 1 is constant and needs a register
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// flags & 0x02 => operand 2 is constant and needs a register
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//------------------------------------------------------------------------
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void
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Set2OperandsFromInstr(MachineInstr* minstr,
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InstructionNode* vmInstrNode,
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const TargetMachine& targetMachine,
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bool canDiscardResult,
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int op1Position,
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int resultPosition)
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{
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Set3OperandsFromInstr(minstr, vmInstrNode, targetMachine,
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canDiscardResult, op1Position,
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/*op2Position*/ -1, resultPosition);
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}
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unsigned
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Set3OperandsFromInstrJUNK(MachineInstr* minstr,
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InstructionNode* vmInstrNode,
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const TargetMachine& targetMachine,
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bool canDiscardResult,
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int op1Position,
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int op2Position,
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int resultPosition)
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{
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assert(op1Position >= 0);
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assert(resultPosition >= 0);
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unsigned returnFlags = 0x0;
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// Check if operand 1 is 0 and if so, try to use the register that gives 0, if any.
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Value* op1Value = vmInstrNode->leftChild()->getValue();
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bool isValidConstant;
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int64_t intValue = GetConstantValueAsSignedInt(op1Value, isValidConstant);
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if (isValidConstant && intValue == 0 && targetMachine.zeroRegNum >= 0)
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minstr->SetMachineOperand(op1Position, /*regNum*/ targetMachine.zeroRegNum);
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else
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{
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if (op1Value->getValueType() == Value::ConstantVal)
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{// value is constant and must be loaded from constant pool
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returnFlags = returnFlags | (1 << op1Position);
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}
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minstr->SetMachineOperand(op1Position, MachineOperand::MO_Register,
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op1Value);
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}
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// Check if operand 2 (if any) fits in the immediate field of the instruction,
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// of if it is 0 and can use a dedicated machine register
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if (op2Position >= 0)
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{
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Value* op2Value = vmInstrNode->rightChild()->getValue();
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int64_t immedValue;
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MachineOperand::VirtualRegisterType vregType;
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unsigned int machineRegNum;
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MachineOperand::MachineOperandType
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op2type = ChooseRegOrImmed(op2Value, minstr->getOpCode(),targetMachine,
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/*canUseImmed*/ true,
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vregType, machineRegNum, immedValue);
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if (op2type == MachineOperand::MO_Register)
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{
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if (vregType == MachineOperand::MO_MachineReg)
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minstr->SetMachineOperand(op2Position, machineRegNum);
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else
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{
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if (op2Value->getValueType() == Value::ConstantVal)
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{// value is constant and must be loaded from constant pool
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returnFlags = returnFlags | (1 << op2Position);
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}
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minstr->SetMachineOperand(op2Position, op2type, op2Value);
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}
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}
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else
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minstr->SetMachineOperand(op2Position, op2type, immedValue);
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}
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// If operand 3 (result) can be discarded, use a dead register if one exists
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if (canDiscardResult && targetMachine.zeroRegNum >= 0)
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minstr->SetMachineOperand(resultPosition, targetMachine.zeroRegNum);
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else
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minstr->SetMachineOperand(resultPosition, MachineOperand::MO_Register,
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vmInstrNode->getValue());
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return returnFlags;
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}
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void
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Set3OperandsFromInstr(MachineInstr* minstr,
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InstructionNode* vmInstrNode,
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const TargetMachine& targetMachine,
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bool canDiscardResult,
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int op1Position,
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int op2Position,
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int resultPosition)
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{
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assert(op1Position >= 0);
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assert(resultPosition >= 0);
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// operand 1
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minstr->SetMachineOperand(op1Position, MachineOperand::MO_Register,
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vmInstrNode->leftChild()->getValue());
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// operand 2 (if any)
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if (op2Position >= 0)
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minstr->SetMachineOperand(op2Position, MachineOperand::MO_Register,
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vmInstrNode->rightChild()->getValue());
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// result operand: if it can be discarded, use a dead register if one exists
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if (canDiscardResult && targetMachine.zeroRegNum >= 0)
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minstr->SetMachineOperand(resultPosition, targetMachine.zeroRegNum);
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else
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minstr->SetMachineOperand(resultPosition, MachineOperand::MO_Register,
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vmInstrNode->getValue());
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}
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MachineOperand::MachineOperandType
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ChooseRegOrImmed(Value* val,
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MachineOpCode opCode,
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const TargetMachine& targetMachine,
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bool canUseImmed,
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MachineOperand::VirtualRegisterType& getVRegType,
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unsigned int& getMachineRegNum,
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int64_t& getImmedValue)
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{
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MachineOperand::MachineOperandType opType = MachineOperand::MO_Register;
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getVRegType = MachineOperand::MO_VirtualReg;
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getMachineRegNum = 0;
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getImmedValue = 0;
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// Check for the common case first: argument is not constant
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//
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if (val->getValueType() != Value::ConstantVal)
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return opType;
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// Now get the constant value and check if it fits in the IMMED field.
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// Take advantage of the fact that the max unsigned value will rarely
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// fit into any IMMED field and ignore that case (i.e., cast smaller
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// unsigned constants to signed).
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//
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bool isValidConstant;
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int64_t intValue = GetConstantValueAsSignedInt(val, isValidConstant);
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if (isValidConstant)
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{
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if (intValue == 0 && targetMachine.zeroRegNum >= 0)
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{
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getVRegType = MachineOperand::MO_MachineReg;
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getMachineRegNum = targetMachine.zeroRegNum;
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}
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else if (canUseImmed &&
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targetMachine.machineInstrInfo[opCode].constantFitsInImmedField(intValue))
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{
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opType = MachineOperand::MO_SignExtendedImmed;
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getImmedValue = intValue;
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}
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}
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return opType;
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}
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