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//===-- LanaiRegisterInfo.cpp - Lanai Register Information ------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file contains the Lanai implementation of the TargetRegisterInfo class.
//
//===----------------------------------------------------------------------===//
#include "LanaiRegisterInfo.h"
#include "Lanai.h"
#include "LanaiSubtarget.h"
#include "llvm/ADT/BitVector.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/RegisterScavenging.h"
#include "llvm/CodeGen/TargetFrameLowering.h"
#include "llvm/CodeGen/TargetInstrInfo.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/Type.h"
#include "llvm/Support/ErrorHandling.h"
#define GET_REGINFO_TARGET_DESC
#include "LanaiGenRegisterInfo.inc"
using namespace llvm;
LanaiRegisterInfo::LanaiRegisterInfo() : LanaiGenRegisterInfo(Lanai::RCA) {}
const uint16_t *
LanaiRegisterInfo::getCalleeSavedRegs(const MachineFunction * /*MF*/) const {
return CSR_SaveList;
}
BitVector LanaiRegisterInfo::getReservedRegs(const MachineFunction &MF) const {
BitVector Reserved(getNumRegs());
Reserved.set(Lanai::R0);
Reserved.set(Lanai::R1);
Reserved.set(Lanai::PC);
Reserved.set(Lanai::R2);
Reserved.set(Lanai::SP);
Reserved.set(Lanai::R4);
Reserved.set(Lanai::FP);
Reserved.set(Lanai::R5);
Reserved.set(Lanai::RR1);
Reserved.set(Lanai::R10);
Reserved.set(Lanai::RR2);
Reserved.set(Lanai::R11);
Reserved.set(Lanai::RCA);
Reserved.set(Lanai::R15);
if (hasBasePointer(MF))
Reserved.set(getBaseRegister());
return Reserved;
}
bool LanaiRegisterInfo::requiresRegisterScavenging(
const MachineFunction & /*MF*/) const {
return true;
}
bool LanaiRegisterInfo::trackLivenessAfterRegAlloc(
const MachineFunction & /*MF*/) const {
return true;
}
static bool isALUArithLoOpcode(unsigned Opcode) {
switch (Opcode) {
case Lanai::ADD_I_LO:
case Lanai::SUB_I_LO:
case Lanai::ADD_F_I_LO:
case Lanai::SUB_F_I_LO:
case Lanai::ADDC_I_LO:
case Lanai::SUBB_I_LO:
case Lanai::ADDC_F_I_LO:
case Lanai::SUBB_F_I_LO:
return true;
default:
return false;
}
}
static unsigned getOppositeALULoOpcode(unsigned Opcode) {
switch (Opcode) {
case Lanai::ADD_I_LO:
return Lanai::SUB_I_LO;
case Lanai::SUB_I_LO:
return Lanai::ADD_I_LO;
case Lanai::ADD_F_I_LO:
return Lanai::SUB_F_I_LO;
case Lanai::SUB_F_I_LO:
return Lanai::ADD_F_I_LO;
case Lanai::ADDC_I_LO:
return Lanai::SUBB_I_LO;
case Lanai::SUBB_I_LO:
return Lanai::ADDC_I_LO;
case Lanai::ADDC_F_I_LO:
return Lanai::SUBB_F_I_LO;
case Lanai::SUBB_F_I_LO:
return Lanai::ADDC_F_I_LO;
default:
llvm_unreachable("Invalid ALU lo opcode");
}
}
static unsigned getRRMOpcodeVariant(unsigned Opcode) {
switch (Opcode) {
case Lanai::LDBs_RI:
return Lanai::LDBs_RR;
case Lanai::LDBz_RI:
return Lanai::LDBz_RR;
case Lanai::LDHs_RI:
return Lanai::LDHs_RR;
case Lanai::LDHz_RI:
return Lanai::LDHz_RR;
case Lanai::LDW_RI:
return Lanai::LDW_RR;
case Lanai::STB_RI:
return Lanai::STB_RR;
case Lanai::STH_RI:
return Lanai::STH_RR;
case Lanai::SW_RI:
return Lanai::SW_RR;
default:
llvm_unreachable("Opcode has no RRM variant");
}
}
void LanaiRegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II,
int SPAdj, unsigned FIOperandNum,
RegScavenger *RS) const {
assert(SPAdj == 0 && "Unexpected");
MachineInstr &MI = *II;
MachineFunction &MF = *MI.getParent()->getParent();
const TargetInstrInfo *TII = MF.getSubtarget().getInstrInfo();
const TargetFrameLowering *TFI = MF.getSubtarget().getFrameLowering();
bool HasFP = TFI->hasFP(MF);
DebugLoc DL = MI.getDebugLoc();
int FrameIndex = MI.getOperand(FIOperandNum).getIndex();
int Offset = MF.getFrameInfo().getObjectOffset(FrameIndex) +
MI.getOperand(FIOperandNum + 1).getImm();
// Addressable stack objects are addressed using neg. offsets from fp
// or pos. offsets from sp/basepointer
if (!HasFP || (needsStackRealignment(MF) && FrameIndex >= 0))
Offset += MF.getFrameInfo().getStackSize();
unsigned FrameReg = getFrameRegister(MF);
if (FrameIndex >= 0) {
if (hasBasePointer(MF))
FrameReg = getBaseRegister();
else if (needsStackRealignment(MF))
FrameReg = Lanai::SP;
}
// Replace frame index with a frame pointer reference.
// If the offset is small enough to fit in the immediate field, directly
// encode it.
// Otherwise scavenge a register and encode it into a MOVHI, OR_I_LO sequence.
if ((isSPLSOpcode(MI.getOpcode()) && !isInt<10>(Offset)) ||
!isInt<16>(Offset)) {
assert(RS && "Register scavenging must be on");
unsigned Reg = RS->FindUnusedReg(&Lanai::GPRRegClass);
if (!Reg)
Reg = RS->scavengeRegister(&Lanai::GPRRegClass, II, SPAdj);
assert(Reg && "Register scavenger failed");
bool HasNegOffset = false;
// ALU ops have unsigned immediate values. If the Offset is negative, we
// negate it here and reverse the opcode later.
if (Offset < 0) {
HasNegOffset = true;
Offset = -Offset;
}
if (!isInt<16>(Offset)) {
// Reg = hi(offset) | lo(offset)
BuildMI(*MI.getParent(), II, DL, TII->get(Lanai::MOVHI), Reg)
.addImm(static_cast<uint32_t>(Offset) >> 16);
BuildMI(*MI.getParent(), II, DL, TII->get(Lanai::OR_I_LO), Reg)
.addReg(Reg)
.addImm(Offset & 0xffffU);
} else {
// Reg = mov(offset)
BuildMI(*MI.getParent(), II, DL, TII->get(Lanai::ADD_I_LO), Reg)
.addImm(0)
.addImm(Offset);
}
// Reg = FrameReg OP Reg
if (MI.getOpcode() == Lanai::ADD_I_LO) {
BuildMI(*MI.getParent(), II, DL,
HasNegOffset ? TII->get(Lanai::SUB_R) : TII->get(Lanai::ADD_R),
MI.getOperand(0).getReg())
.addReg(FrameReg)
.addReg(Reg)
.addImm(LPCC::ICC_T);
MI.eraseFromParent();
return;
}
if (isSPLSOpcode(MI.getOpcode()) || isRMOpcode(MI.getOpcode())) {
MI.setDesc(TII->get(getRRMOpcodeVariant(MI.getOpcode())));
if (HasNegOffset) {
// Change the ALU op (operand 3) from LPAC::ADD (the default) to
// LPAC::SUB with the already negated offset.
assert((MI.getOperand(3).getImm() == LPAC::ADD) &&
"Unexpected ALU op in RRM instruction");
MI.getOperand(3).setImm(LPAC::SUB);
}
} else
llvm_unreachable("Unexpected opcode in frame index operation");
MI.getOperand(FIOperandNum).ChangeToRegister(FrameReg, /*isDef=*/false);
MI.getOperand(FIOperandNum + 1)
.ChangeToRegister(Reg, /*isDef=*/false, /*isImp=*/false,
/*isKill=*/true);
return;
}
// ALU arithmetic ops take unsigned immediates. If the offset is negative,
// we replace the instruction with one that inverts the opcode and negates
// the immediate.
if ((Offset < 0) && isALUArithLoOpcode(MI.getOpcode())) {
unsigned NewOpcode = getOppositeALULoOpcode(MI.getOpcode());
// We know this is an ALU op, so we know the operands are as follows:
// 0: destination register
// 1: source register (frame register)
// 2: immediate
BuildMI(*MI.getParent(), II, DL, TII->get(NewOpcode),
MI.getOperand(0).getReg())
.addReg(FrameReg)
.addImm(-Offset);
MI.eraseFromParent();
} else {
MI.getOperand(FIOperandNum).ChangeToRegister(FrameReg, /*isDef=*/false);
MI.getOperand(FIOperandNum + 1).ChangeToImmediate(Offset);
}
}
bool LanaiRegisterInfo::hasBasePointer(const MachineFunction &MF) const {
const MachineFrameInfo &MFI = MF.getFrameInfo();
// When we need stack realignment and there are dynamic allocas, we can't
// reference off of the stack pointer, so we reserve a base pointer.
if (needsStackRealignment(MF) && MFI.hasVarSizedObjects())
return true;
return false;
}
unsigned LanaiRegisterInfo::getRARegister() const { return Lanai::RCA; }
unsigned
LanaiRegisterInfo::getFrameRegister(const MachineFunction & /*MF*/) const {
return Lanai::FP;
}
unsigned LanaiRegisterInfo::getBaseRegister() const { return Lanai::R14; }
const uint32_t *
LanaiRegisterInfo::getCallPreservedMask(const MachineFunction & /*MF*/,
CallingConv::ID /*CC*/) const {
return CSR_RegMask;
}