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//===- llvm/CodeGen/GlobalISel/InstructionSelector.cpp -----------*- C++ -*-==//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
/// \file
/// This file implements the InstructionSelector class.
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/GlobalISel/InstructionSelector.h"
#include "llvm/CodeGen/GlobalISel/RegisterBankInfo.h"
#include "llvm/CodeGen/GlobalISel/Utils.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/IR/Constants.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetRegisterInfo.h"
#define DEBUG_TYPE "instructionselector"
using namespace llvm;
InstructionSelector::InstructionSelector() {}
bool InstructionSelector::constrainSelectedInstRegOperands(
MachineInstr &I, const TargetInstrInfo &TII, const TargetRegisterInfo &TRI,
const RegisterBankInfo &RBI) const {
MachineBasicBlock &MBB = *I.getParent();
MachineFunction &MF = *MBB.getParent();
MachineRegisterInfo &MRI = MF.getRegInfo();
for (unsigned OpI = 0, OpE = I.getNumExplicitOperands(); OpI != OpE; ++OpI) {
MachineOperand &MO = I.getOperand(OpI);
// There's nothing to be done on non-register operands.
if (!MO.isReg())
continue;
DEBUG(dbgs() << "Converting operand: " << MO << '\n');
assert(MO.isReg() && "Unsupported non-reg operand");
unsigned Reg = MO.getReg();
// Physical registers don't need to be constrained.
if (TRI.isPhysicalRegister(Reg))
continue;
// Register operands with a value of 0 (e.g. predicate operands) don't need
// to be constrained.
if (Reg == 0)
continue;
// If the operand is a vreg, we should constrain its regclass, and only
// insert COPYs if that's impossible.
// constrainOperandRegClass does that for us.
MO.setReg(constrainOperandRegClass(MF, TRI, MRI, TII, RBI, I, I.getDesc(),
Reg, OpI));
// Tie uses to defs as indicated in MCInstrDesc.
if (MO.isUse()) {
int DefIdx = I.getDesc().getOperandConstraint(OpI, MCOI::TIED_TO);
if (DefIdx != -1)
I.tieOperands(DefIdx, OpI);
}
}
return true;
}
bool InstructionSelector::isOperandImmEqual(
const MachineOperand &MO, int64_t Value,
const MachineRegisterInfo &MRI) const {
if (MO.getReg())
if (auto VRegVal = getConstantVRegVal(MO.getReg(), MRI))
return *VRegVal == Value;
return false;
}
bool InstructionSelector::isObviouslySafeToFold(MachineInstr &MI) const {
return !MI.mayLoadOrStore() && !MI.hasUnmodeledSideEffects() &&
MI.implicit_operands().begin() == MI.implicit_operands().end();
}
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