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llvm-mirror/lib/Target/Mips/MipsSEFrameLowering.cpp
Tomas Matheson 3153790303 [NFC][CodeGen] Tidy up TargetRegisterInfo stack realignment functions 
Currently needsStackRealignment returns false if canRealignStack returns false.
This means that the behavior of needsStackRealignment does not correspond to
it's name and description; a function might need stack realignment, but if it
is not possible then this function returns false. Furthermore,
needsStackRealignment is not virtual and therefore some backends have made use
of canRealignStack to indicate whether a function needs stack realignment.

This patch attempts to clarify the situation by separating them and introducing
new names:

 - shouldRealignStack - true if there is any reason the stack should be
   realigned

 - canRealignStack - true if we are still able to realign the stack (e.g. we
   can still reserve/have reserved a frame pointer)

 - hasStackRealignment = shouldRealignStack && canRealignStack (not target
   customisable)

Targets can now override shouldRealignStack to indicate that stack realignment
is required.

This change will make it easier in a future change to handle the case where we
need to realign the stack but can't do so (for example when the register
allocator creates an aligned spill after the frame pointer has been
eliminated).

Differential Revision: https://reviews.llvm.org/D98716

Change-Id: Ib9a4d21728bf9d08a545b4365418d3ffe1af4d87
2021-03-30 17:31:39 +01:00

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//===- MipsSEFrameLowering.cpp - Mips32/64 Frame Information --------------===//
//
// 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 Mips32/64 implementation of TargetFrameLowering class.
//
//===----------------------------------------------------------------------===//
#include "MipsSEFrameLowering.h"
#include "MCTargetDesc/MipsABIInfo.h"
#include "MipsMachineFunction.h"
#include "MipsRegisterInfo.h"
#include "MipsSEInstrInfo.h"
#include "MipsSubtarget.h"
#include "llvm/ADT/BitVector.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/StringSwitch.h"
#include "llvm/CodeGen/MachineBasicBlock.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/CodeGen/MachineOperand.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/RegisterScavenging.h"
#include "llvm/CodeGen/TargetInstrInfo.h"
#include "llvm/CodeGen/TargetRegisterInfo.h"
#include "llvm/CodeGen/TargetSubtargetInfo.h"
#include "llvm/IR/DebugLoc.h"
#include "llvm/IR/Function.h"
#include "llvm/MC/MCDwarf.h"
#include "llvm/MC/MCRegisterInfo.h"
#include "llvm/MC/MachineLocation.h"
#include "llvm/Support/CodeGen.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/MathExtras.h"
#include <cassert>
#include <cstdint>
#include <utility>
#include <vector>
using namespace llvm;
static std::pair<unsigned, unsigned> getMFHiLoOpc(unsigned Src) {
if (Mips::ACC64RegClass.contains(Src))
return std::make_pair((unsigned)Mips::PseudoMFHI,
(unsigned)Mips::PseudoMFLO);
if (Mips::ACC64DSPRegClass.contains(Src))
return std::make_pair((unsigned)Mips::MFHI_DSP, (unsigned)Mips::MFLO_DSP);
if (Mips::ACC128RegClass.contains(Src))
return std::make_pair((unsigned)Mips::PseudoMFHI64,
(unsigned)Mips::PseudoMFLO64);
return std::make_pair(0, 0);
}
namespace {
/// Helper class to expand pseudos.
class ExpandPseudo {
public:
ExpandPseudo(MachineFunction &MF);
bool expand();
private:
using Iter = MachineBasicBlock::iterator;
bool expandInstr(MachineBasicBlock &MBB, Iter I);
void expandLoadCCond(MachineBasicBlock &MBB, Iter I);
void expandStoreCCond(MachineBasicBlock &MBB, Iter I);
void expandLoadACC(MachineBasicBlock &MBB, Iter I, unsigned RegSize);
void expandStoreACC(MachineBasicBlock &MBB, Iter I, unsigned MFHiOpc,
unsigned MFLoOpc, unsigned RegSize);
bool expandCopy(MachineBasicBlock &MBB, Iter I);
bool expandCopyACC(MachineBasicBlock &MBB, Iter I, unsigned MFHiOpc,
unsigned MFLoOpc);
bool expandBuildPairF64(MachineBasicBlock &MBB,
MachineBasicBlock::iterator I, bool FP64) const;
bool expandExtractElementF64(MachineBasicBlock &MBB,
MachineBasicBlock::iterator I, bool FP64) const;
MachineFunction &MF;
MachineRegisterInfo &MRI;
const MipsSubtarget &Subtarget;
const MipsSEInstrInfo &TII;
const MipsRegisterInfo &RegInfo;
};
} // end anonymous namespace
ExpandPseudo::ExpandPseudo(MachineFunction &MF_)
: MF(MF_), MRI(MF.getRegInfo()),
Subtarget(static_cast<const MipsSubtarget &>(MF.getSubtarget())),
TII(*static_cast<const MipsSEInstrInfo *>(Subtarget.getInstrInfo())),
RegInfo(*Subtarget.getRegisterInfo()) {}
bool ExpandPseudo::expand() {
bool Expanded = false;
for (auto &MBB : MF) {
for (Iter I = MBB.begin(), End = MBB.end(); I != End;)
Expanded |= expandInstr(MBB, I++);
}
return Expanded;
}
bool ExpandPseudo::expandInstr(MachineBasicBlock &MBB, Iter I) {
switch(I->getOpcode()) {
case Mips::LOAD_CCOND_DSP:
expandLoadCCond(MBB, I);
break;
case Mips::STORE_CCOND_DSP:
expandStoreCCond(MBB, I);
break;
case Mips::LOAD_ACC64:
case Mips::LOAD_ACC64DSP:
expandLoadACC(MBB, I, 4);
break;
case Mips::LOAD_ACC128:
expandLoadACC(MBB, I, 8);
break;
case Mips::STORE_ACC64:
expandStoreACC(MBB, I, Mips::PseudoMFHI, Mips::PseudoMFLO, 4);
break;
case Mips::STORE_ACC64DSP:
expandStoreACC(MBB, I, Mips::MFHI_DSP, Mips::MFLO_DSP, 4);
break;
case Mips::STORE_ACC128:
expandStoreACC(MBB, I, Mips::PseudoMFHI64, Mips::PseudoMFLO64, 8);
break;
case Mips::BuildPairF64:
if (expandBuildPairF64(MBB, I, false))
MBB.erase(I);
return false;
case Mips::BuildPairF64_64:
if (expandBuildPairF64(MBB, I, true))
MBB.erase(I);
return false;
case Mips::ExtractElementF64:
if (expandExtractElementF64(MBB, I, false))
MBB.erase(I);
return false;
case Mips::ExtractElementF64_64:
if (expandExtractElementF64(MBB, I, true))
MBB.erase(I);
return false;
case TargetOpcode::COPY:
if (!expandCopy(MBB, I))
return false;
break;
default:
return false;
}
MBB.erase(I);
return true;
}
void ExpandPseudo::expandLoadCCond(MachineBasicBlock &MBB, Iter I) {
// load $vr, FI
// copy ccond, $vr
assert(I->getOperand(0).isReg() && I->getOperand(1).isFI());
const TargetRegisterClass *RC = RegInfo.intRegClass(4);
Register VR = MRI.createVirtualRegister(RC);
Register Dst = I->getOperand(0).getReg(), FI = I->getOperand(1).getIndex();
TII.loadRegFromStack(MBB, I, VR, FI, RC, &RegInfo, 0);
BuildMI(MBB, I, I->getDebugLoc(), TII.get(TargetOpcode::COPY), Dst)
.addReg(VR, RegState::Kill);
}
void ExpandPseudo::expandStoreCCond(MachineBasicBlock &MBB, Iter I) {
// copy $vr, ccond
// store $vr, FI
assert(I->getOperand(0).isReg() && I->getOperand(1).isFI());
const TargetRegisterClass *RC = RegInfo.intRegClass(4);
Register VR = MRI.createVirtualRegister(RC);
Register Src = I->getOperand(0).getReg(), FI = I->getOperand(1).getIndex();
BuildMI(MBB, I, I->getDebugLoc(), TII.get(TargetOpcode::COPY), VR)
.addReg(Src, getKillRegState(I->getOperand(0).isKill()));
TII.storeRegToStack(MBB, I, VR, true, FI, RC, &RegInfo, 0);
}
void ExpandPseudo::expandLoadACC(MachineBasicBlock &MBB, Iter I,
unsigned RegSize) {
// load $vr0, FI
// copy lo, $vr0
// load $vr1, FI + 4
// copy hi, $vr1
assert(I->getOperand(0).isReg() && I->getOperand(1).isFI());
const TargetRegisterClass *RC = RegInfo.intRegClass(RegSize);
Register VR0 = MRI.createVirtualRegister(RC);
Register VR1 = MRI.createVirtualRegister(RC);
Register Dst = I->getOperand(0).getReg(), FI = I->getOperand(1).getIndex();
Register Lo = RegInfo.getSubReg(Dst, Mips::sub_lo);
Register Hi = RegInfo.getSubReg(Dst, Mips::sub_hi);
DebugLoc DL = I->getDebugLoc();
const MCInstrDesc &Desc = TII.get(TargetOpcode::COPY);
TII.loadRegFromStack(MBB, I, VR0, FI, RC, &RegInfo, 0);
BuildMI(MBB, I, DL, Desc, Lo).addReg(VR0, RegState::Kill);
TII.loadRegFromStack(MBB, I, VR1, FI, RC, &RegInfo, RegSize);
BuildMI(MBB, I, DL, Desc, Hi).addReg(VR1, RegState::Kill);
}
void ExpandPseudo::expandStoreACC(MachineBasicBlock &MBB, Iter I,
unsigned MFHiOpc, unsigned MFLoOpc,
unsigned RegSize) {
// mflo $vr0, src
// store $vr0, FI
// mfhi $vr1, src
// store $vr1, FI + 4
assert(I->getOperand(0).isReg() && I->getOperand(1).isFI());
const TargetRegisterClass *RC = RegInfo.intRegClass(RegSize);
Register VR0 = MRI.createVirtualRegister(RC);
Register VR1 = MRI.createVirtualRegister(RC);
Register Src = I->getOperand(0).getReg(), FI = I->getOperand(1).getIndex();
unsigned SrcKill = getKillRegState(I->getOperand(0).isKill());
DebugLoc DL = I->getDebugLoc();
BuildMI(MBB, I, DL, TII.get(MFLoOpc), VR0).addReg(Src);
TII.storeRegToStack(MBB, I, VR0, true, FI, RC, &RegInfo, 0);
BuildMI(MBB, I, DL, TII.get(MFHiOpc), VR1).addReg(Src, SrcKill);
TII.storeRegToStack(MBB, I, VR1, true, FI, RC, &RegInfo, RegSize);
}
bool ExpandPseudo::expandCopy(MachineBasicBlock &MBB, Iter I) {
Register Src = I->getOperand(1).getReg();
std::pair<unsigned, unsigned> Opcodes = getMFHiLoOpc(Src);
if (!Opcodes.first)
return false;
return expandCopyACC(MBB, I, Opcodes.first, Opcodes.second);
}
bool ExpandPseudo::expandCopyACC(MachineBasicBlock &MBB, Iter I,
unsigned MFHiOpc, unsigned MFLoOpc) {
// mflo $vr0, src
// copy dst_lo, $vr0
// mfhi $vr1, src
// copy dst_hi, $vr1
unsigned Dst = I->getOperand(0).getReg(), Src = I->getOperand(1).getReg();
const TargetRegisterClass *DstRC = RegInfo.getMinimalPhysRegClass(Dst);
unsigned VRegSize = RegInfo.getRegSizeInBits(*DstRC) / 16;
const TargetRegisterClass *RC = RegInfo.intRegClass(VRegSize);
Register VR0 = MRI.createVirtualRegister(RC);
Register VR1 = MRI.createVirtualRegister(RC);
unsigned SrcKill = getKillRegState(I->getOperand(1).isKill());
Register DstLo = RegInfo.getSubReg(Dst, Mips::sub_lo);
Register DstHi = RegInfo.getSubReg(Dst, Mips::sub_hi);
DebugLoc DL = I->getDebugLoc();
BuildMI(MBB, I, DL, TII.get(MFLoOpc), VR0).addReg(Src);
BuildMI(MBB, I, DL, TII.get(TargetOpcode::COPY), DstLo)
.addReg(VR0, RegState::Kill);
BuildMI(MBB, I, DL, TII.get(MFHiOpc), VR1).addReg(Src, SrcKill);
BuildMI(MBB, I, DL, TII.get(TargetOpcode::COPY), DstHi)
.addReg(VR1, RegState::Kill);
return true;
}
/// This method expands the same instruction that MipsSEInstrInfo::
/// expandBuildPairF64 does, for the case when ABI is fpxx and mthc1 is not
/// available and the case where the ABI is FP64A. It is implemented here
/// because frame indexes are eliminated before MipsSEInstrInfo::
/// expandBuildPairF64 is called.
bool ExpandPseudo::expandBuildPairF64(MachineBasicBlock &MBB,
MachineBasicBlock::iterator I,
bool FP64) const {
// For fpxx and when mthc1 is not available, use:
// spill + reload via ldc1
//
// The case where dmtc1 is available doesn't need to be handled here
// because it never creates a BuildPairF64 node.
//
// The FP64A ABI (fp64 with nooddspreg) must also use a spill/reload sequence
// for odd-numbered double precision values (because the lower 32-bits is
// transferred with mtc1 which is redirected to the upper half of the even
// register). Unfortunately, we have to make this decision before register
// allocation so for now we use a spill/reload sequence for all
// double-precision values in regardless of being an odd/even register.
//
// For the cases that should be covered here MipsSEISelDAGToDAG adds $sp as
// implicit operand, so other passes (like ShrinkWrapping) are aware that
// stack is used.
if (I->getNumOperands() == 4 && I->getOperand(3).isReg()
&& I->getOperand(3).getReg() == Mips::SP) {
Register DstReg = I->getOperand(0).getReg();
Register LoReg = I->getOperand(1).getReg();
Register HiReg = I->getOperand(2).getReg();
// It should be impossible to have FGR64 on MIPS-II or MIPS32r1 (which are
// the cases where mthc1 is not available). 64-bit architectures and
// MIPS32r2 or later can use FGR64 though.
assert(Subtarget.isGP64bit() || Subtarget.hasMTHC1() ||
!Subtarget.isFP64bit());
const TargetRegisterClass *RC = &Mips::GPR32RegClass;
const TargetRegisterClass *RC2 =
FP64 ? &Mips::FGR64RegClass : &Mips::AFGR64RegClass;
// We re-use the same spill slot each time so that the stack frame doesn't
// grow too much in functions with a large number of moves.
int FI = MF.getInfo<MipsFunctionInfo>()->getMoveF64ViaSpillFI(MF, RC2);
if (!Subtarget.isLittle())
std::swap(LoReg, HiReg);
TII.storeRegToStack(MBB, I, LoReg, I->getOperand(1).isKill(), FI, RC,
&RegInfo, 0);
TII.storeRegToStack(MBB, I, HiReg, I->getOperand(2).isKill(), FI, RC,
&RegInfo, 4);
TII.loadRegFromStack(MBB, I, DstReg, FI, RC2, &RegInfo, 0);
return true;
}
return false;
}
/// This method expands the same instruction that MipsSEInstrInfo::
/// expandExtractElementF64 does, for the case when ABI is fpxx and mfhc1 is not
/// available and the case where the ABI is FP64A. It is implemented here
/// because frame indexes are eliminated before MipsSEInstrInfo::
/// expandExtractElementF64 is called.
bool ExpandPseudo::expandExtractElementF64(MachineBasicBlock &MBB,
MachineBasicBlock::iterator I,
bool FP64) const {
const MachineOperand &Op1 = I->getOperand(1);
const MachineOperand &Op2 = I->getOperand(2);
if ((Op1.isReg() && Op1.isUndef()) || (Op2.isReg() && Op2.isUndef())) {
Register DstReg = I->getOperand(0).getReg();
BuildMI(MBB, I, I->getDebugLoc(), TII.get(Mips::IMPLICIT_DEF), DstReg);
return true;
}
// For fpxx and when mfhc1 is not available, use:
// spill + reload via ldc1
//
// The case where dmfc1 is available doesn't need to be handled here
// because it never creates a ExtractElementF64 node.
//
// The FP64A ABI (fp64 with nooddspreg) must also use a spill/reload sequence
// for odd-numbered double precision values (because the lower 32-bits is
// transferred with mfc1 which is redirected to the upper half of the even
// register). Unfortunately, we have to make this decision before register
// allocation so for now we use a spill/reload sequence for all
// double-precision values in regardless of being an odd/even register.
//
// For the cases that should be covered here MipsSEISelDAGToDAG adds $sp as
// implicit operand, so other passes (like ShrinkWrapping) are aware that
// stack is used.
if (I->getNumOperands() == 4 && I->getOperand(3).isReg()
&& I->getOperand(3).getReg() == Mips::SP) {
Register DstReg = I->getOperand(0).getReg();
Register SrcReg = Op1.getReg();
unsigned N = Op2.getImm();
int64_t Offset = 4 * (Subtarget.isLittle() ? N : (1 - N));
// It should be impossible to have FGR64 on MIPS-II or MIPS32r1 (which are
// the cases where mfhc1 is not available). 64-bit architectures and
// MIPS32r2 or later can use FGR64 though.
assert(Subtarget.isGP64bit() || Subtarget.hasMTHC1() ||
!Subtarget.isFP64bit());
const TargetRegisterClass *RC =
FP64 ? &Mips::FGR64RegClass : &Mips::AFGR64RegClass;
const TargetRegisterClass *RC2 = &Mips::GPR32RegClass;
// We re-use the same spill slot each time so that the stack frame doesn't
// grow too much in functions with a large number of moves.
int FI = MF.getInfo<MipsFunctionInfo>()->getMoveF64ViaSpillFI(MF, RC);
TII.storeRegToStack(MBB, I, SrcReg, Op1.isKill(), FI, RC, &RegInfo, 0);
TII.loadRegFromStack(MBB, I, DstReg, FI, RC2, &RegInfo, Offset);
return true;
}
return false;
}
MipsSEFrameLowering::MipsSEFrameLowering(const MipsSubtarget &STI)
: MipsFrameLowering(STI, STI.getStackAlignment()) {}
void MipsSEFrameLowering::emitPrologue(MachineFunction &MF,
MachineBasicBlock &MBB) const {
MachineFrameInfo &MFI = MF.getFrameInfo();
MipsFunctionInfo *MipsFI = MF.getInfo<MipsFunctionInfo>();
const MipsSEInstrInfo &TII =
*static_cast<const MipsSEInstrInfo *>(STI.getInstrInfo());
const MipsRegisterInfo &RegInfo =
*static_cast<const MipsRegisterInfo *>(STI.getRegisterInfo());
MachineBasicBlock::iterator MBBI = MBB.begin();
DebugLoc dl;
MipsABIInfo ABI = STI.getABI();
unsigned SP = ABI.GetStackPtr();
unsigned FP = ABI.GetFramePtr();
unsigned ZERO = ABI.GetNullPtr();
unsigned MOVE = ABI.GetGPRMoveOp();
unsigned ADDiu = ABI.GetPtrAddiuOp();
unsigned AND = ABI.IsN64() ? Mips::AND64 : Mips::AND;
const TargetRegisterClass *RC = ABI.ArePtrs64bit() ?
&Mips::GPR64RegClass : &Mips::GPR32RegClass;
// First, compute final stack size.
uint64_t StackSize = MFI.getStackSize();
// No need to allocate space on the stack.
if (StackSize == 0 && !MFI.adjustsStack()) return;
MachineModuleInfo &MMI = MF.getMMI();
const MCRegisterInfo *MRI = MMI.getContext().getRegisterInfo();
// Adjust stack.
TII.adjustStackPtr(SP, -StackSize, MBB, MBBI);
// emit ".cfi_def_cfa_offset StackSize"
unsigned CFIIndex =
MF.addFrameInst(MCCFIInstruction::cfiDefCfaOffset(nullptr, StackSize));
BuildMI(MBB, MBBI, dl, TII.get(TargetOpcode::CFI_INSTRUCTION))
.addCFIIndex(CFIIndex);
if (MF.getFunction().hasFnAttribute("interrupt"))
emitInterruptPrologueStub(MF, MBB);
const std::vector<CalleeSavedInfo> &CSI = MFI.getCalleeSavedInfo();
if (!CSI.empty()) {
// Find the instruction past the last instruction that saves a callee-saved
// register to the stack.
for (unsigned i = 0; i < CSI.size(); ++i)
++MBBI;
// Iterate over list of callee-saved registers and emit .cfi_offset
// directives.
for (std::vector<CalleeSavedInfo>::const_iterator I = CSI.begin(),
E = CSI.end(); I != E; ++I) {
int64_t Offset = MFI.getObjectOffset(I->getFrameIdx());
unsigned Reg = I->getReg();
// If Reg is a double precision register, emit two cfa_offsets,
// one for each of the paired single precision registers.
if (Mips::AFGR64RegClass.contains(Reg)) {
unsigned Reg0 =
MRI->getDwarfRegNum(RegInfo.getSubReg(Reg, Mips::sub_lo), true);
unsigned Reg1 =
MRI->getDwarfRegNum(RegInfo.getSubReg(Reg, Mips::sub_hi), true);
if (!STI.isLittle())
std::swap(Reg0, Reg1);
unsigned CFIIndex = MF.addFrameInst(
MCCFIInstruction::createOffset(nullptr, Reg0, Offset));
BuildMI(MBB, MBBI, dl, TII.get(TargetOpcode::CFI_INSTRUCTION))
.addCFIIndex(CFIIndex);
CFIIndex = MF.addFrameInst(
MCCFIInstruction::createOffset(nullptr, Reg1, Offset + 4));
BuildMI(MBB, MBBI, dl, TII.get(TargetOpcode::CFI_INSTRUCTION))
.addCFIIndex(CFIIndex);
} else if (Mips::FGR64RegClass.contains(Reg)) {
unsigned Reg0 = MRI->getDwarfRegNum(Reg, true);
unsigned Reg1 = MRI->getDwarfRegNum(Reg, true) + 1;
if (!STI.isLittle())
std::swap(Reg0, Reg1);
unsigned CFIIndex = MF.addFrameInst(
MCCFIInstruction::createOffset(nullptr, Reg0, Offset));
BuildMI(MBB, MBBI, dl, TII.get(TargetOpcode::CFI_INSTRUCTION))
.addCFIIndex(CFIIndex);
CFIIndex = MF.addFrameInst(
MCCFIInstruction::createOffset(nullptr, Reg1, Offset + 4));
BuildMI(MBB, MBBI, dl, TII.get(TargetOpcode::CFI_INSTRUCTION))
.addCFIIndex(CFIIndex);
} else {
// Reg is either in GPR32 or FGR32.
unsigned CFIIndex = MF.addFrameInst(MCCFIInstruction::createOffset(
nullptr, MRI->getDwarfRegNum(Reg, true), Offset));
BuildMI(MBB, MBBI, dl, TII.get(TargetOpcode::CFI_INSTRUCTION))
.addCFIIndex(CFIIndex);
}
}
}
if (MipsFI->callsEhReturn()) {
// Insert instructions that spill eh data registers.
for (int I = 0; I < 4; ++I) {
if (!MBB.isLiveIn(ABI.GetEhDataReg(I)))
MBB.addLiveIn(ABI.GetEhDataReg(I));
TII.storeRegToStackSlot(MBB, MBBI, ABI.GetEhDataReg(I), false,
MipsFI->getEhDataRegFI(I), RC, &RegInfo);
}
// Emit .cfi_offset directives for eh data registers.
for (int I = 0; I < 4; ++I) {
int64_t Offset = MFI.getObjectOffset(MipsFI->getEhDataRegFI(I));
unsigned Reg = MRI->getDwarfRegNum(ABI.GetEhDataReg(I), true);
unsigned CFIIndex = MF.addFrameInst(
MCCFIInstruction::createOffset(nullptr, Reg, Offset));
BuildMI(MBB, MBBI, dl, TII.get(TargetOpcode::CFI_INSTRUCTION))
.addCFIIndex(CFIIndex);
}
}
// if framepointer enabled, set it to point to the stack pointer.
if (hasFP(MF)) {
// Insert instruction "move $fp, $sp" at this location.
BuildMI(MBB, MBBI, dl, TII.get(MOVE), FP).addReg(SP).addReg(ZERO)
.setMIFlag(MachineInstr::FrameSetup);
// emit ".cfi_def_cfa_register $fp"
unsigned CFIIndex = MF.addFrameInst(MCCFIInstruction::createDefCfaRegister(
nullptr, MRI->getDwarfRegNum(FP, true)));
BuildMI(MBB, MBBI, dl, TII.get(TargetOpcode::CFI_INSTRUCTION))
.addCFIIndex(CFIIndex);
if (RegInfo.hasStackRealignment(MF)) {
// addiu $Reg, $zero, -MaxAlignment
// andi $sp, $sp, $Reg
Register VR = MF.getRegInfo().createVirtualRegister(RC);
assert((Log2(MFI.getMaxAlign()) < 16) &&
"Function's alignment size requirement is not supported.");
int64_t MaxAlign = -(int64_t)MFI.getMaxAlign().value();
BuildMI(MBB, MBBI, dl, TII.get(ADDiu), VR).addReg(ZERO).addImm(MaxAlign);
BuildMI(MBB, MBBI, dl, TII.get(AND), SP).addReg(SP).addReg(VR);
if (hasBP(MF)) {
// move $s7, $sp
unsigned BP = STI.isABI_N64() ? Mips::S7_64 : Mips::S7;
BuildMI(MBB, MBBI, dl, TII.get(MOVE), BP)
.addReg(SP)
.addReg(ZERO);
}
}
}
}
void MipsSEFrameLowering::emitInterruptPrologueStub(
MachineFunction &MF, MachineBasicBlock &MBB) const {
MipsFunctionInfo *MipsFI = MF.getInfo<MipsFunctionInfo>();
MachineBasicBlock::iterator MBBI = MBB.begin();
DebugLoc DL = MBBI != MBB.end() ? MBBI->getDebugLoc() : DebugLoc();
// Report an error the target doesn't support Mips32r2 or later.
// The epilogue relies on the use of the "ehb" to clear execution
// hazards. Pre R2 Mips relies on an implementation defined number
// of "ssnop"s to clear the execution hazard. Support for ssnop hazard
// clearing is not provided so reject that configuration.
if (!STI.hasMips32r2())
report_fatal_error(
"\"interrupt\" attribute is not supported on pre-MIPS32R2 or "
"MIPS16 targets.");
// The GP register contains the "user" value, so we cannot perform
// any gp relative loads until we restore the "kernel" or "system" gp
// value. Until support is written we shall only accept the static
// relocation model.
if ((STI.getRelocationModel() != Reloc::Static))
report_fatal_error("\"interrupt\" attribute is only supported for the "
"static relocation model on MIPS at the present time.");
if (!STI.isABI_O32() || STI.hasMips64())
report_fatal_error("\"interrupt\" attribute is only supported for the "
"O32 ABI on MIPS32R2+ at the present time.");
// Perform ISR handling like GCC
StringRef IntKind =
MF.getFunction().getFnAttribute("interrupt").getValueAsString();
const TargetRegisterClass *PtrRC = &Mips::GPR32RegClass;
// EIC interrupt handling needs to read the Cause register to disable
// interrupts.
if (IntKind == "eic") {
// Coprocessor registers are always live per se.
MBB.addLiveIn(Mips::COP013);
BuildMI(MBB, MBBI, DL, STI.getInstrInfo()->get(Mips::MFC0), Mips::K0)
.addReg(Mips::COP013)
.addImm(0)
.setMIFlag(MachineInstr::FrameSetup);
BuildMI(MBB, MBBI, DL, STI.getInstrInfo()->get(Mips::EXT), Mips::K0)
.addReg(Mips::K0)
.addImm(10)
.addImm(6)
.setMIFlag(MachineInstr::FrameSetup);
}
// Fetch and spill EPC
MBB.addLiveIn(Mips::COP014);
BuildMI(MBB, MBBI, DL, STI.getInstrInfo()->get(Mips::MFC0), Mips::K1)
.addReg(Mips::COP014)
.addImm(0)
.setMIFlag(MachineInstr::FrameSetup);
STI.getInstrInfo()->storeRegToStack(MBB, MBBI, Mips::K1, false,
MipsFI->getISRRegFI(0), PtrRC,
STI.getRegisterInfo(), 0);
// Fetch and Spill Status
MBB.addLiveIn(Mips::COP012);
BuildMI(MBB, MBBI, DL, STI.getInstrInfo()->get(Mips::MFC0), Mips::K1)
.addReg(Mips::COP012)
.addImm(0)
.setMIFlag(MachineInstr::FrameSetup);
STI.getInstrInfo()->storeRegToStack(MBB, MBBI, Mips::K1, false,
MipsFI->getISRRegFI(1), PtrRC,
STI.getRegisterInfo(), 0);
// Build the configuration for disabling lower priority interrupts. Non EIC
// interrupts need to be masked off with zero, EIC from the Cause register.
unsigned InsPosition = 8;
unsigned InsSize = 0;
unsigned SrcReg = Mips::ZERO;
// If the interrupt we're tied to is the EIC, switch the source for the
// masking off interrupts to the cause register.
if (IntKind == "eic") {
SrcReg = Mips::K0;
InsPosition = 10;
InsSize = 6;
} else
InsSize = StringSwitch<unsigned>(IntKind)
.Case("sw0", 1)
.Case("sw1", 2)
.Case("hw0", 3)
.Case("hw1", 4)
.Case("hw2", 5)
.Case("hw3", 6)
.Case("hw4", 7)
.Case("hw5", 8)
.Default(0);
assert(InsSize != 0 && "Unknown interrupt type!");
BuildMI(MBB, MBBI, DL, STI.getInstrInfo()->get(Mips::INS), Mips::K1)
.addReg(SrcReg)
.addImm(InsPosition)
.addImm(InsSize)
.addReg(Mips::K1)
.setMIFlag(MachineInstr::FrameSetup);
// Mask off KSU, ERL, EXL
BuildMI(MBB, MBBI, DL, STI.getInstrInfo()->get(Mips::INS), Mips::K1)
.addReg(Mips::ZERO)
.addImm(1)
.addImm(4)
.addReg(Mips::K1)
.setMIFlag(MachineInstr::FrameSetup);
// Disable the FPU as we are not spilling those register sets.
if (!STI.useSoftFloat())
BuildMI(MBB, MBBI, DL, STI.getInstrInfo()->get(Mips::INS), Mips::K1)
.addReg(Mips::ZERO)
.addImm(29)
.addImm(1)
.addReg(Mips::K1)
.setMIFlag(MachineInstr::FrameSetup);
// Set the new status
BuildMI(MBB, MBBI, DL, STI.getInstrInfo()->get(Mips::MTC0), Mips::COP012)
.addReg(Mips::K1)
.addImm(0)
.setMIFlag(MachineInstr::FrameSetup);
}
void MipsSEFrameLowering::emitEpilogue(MachineFunction &MF,
MachineBasicBlock &MBB) const {
MachineBasicBlock::iterator MBBI = MBB.getFirstTerminator();
MachineFrameInfo &MFI = MF.getFrameInfo();
MipsFunctionInfo *MipsFI = MF.getInfo<MipsFunctionInfo>();
const MipsSEInstrInfo &TII =
*static_cast<const MipsSEInstrInfo *>(STI.getInstrInfo());
const MipsRegisterInfo &RegInfo =
*static_cast<const MipsRegisterInfo *>(STI.getRegisterInfo());
DebugLoc DL = MBBI != MBB.end() ? MBBI->getDebugLoc() : DebugLoc();
MipsABIInfo ABI = STI.getABI();
unsigned SP = ABI.GetStackPtr();
unsigned FP = ABI.GetFramePtr();
unsigned ZERO = ABI.GetNullPtr();
unsigned MOVE = ABI.GetGPRMoveOp();
// if framepointer enabled, restore the stack pointer.
if (hasFP(MF)) {
// Find the first instruction that restores a callee-saved register.
MachineBasicBlock::iterator I = MBBI;
for (unsigned i = 0; i < MFI.getCalleeSavedInfo().size(); ++i)
--I;
// Insert instruction "move $sp, $fp" at this location.
BuildMI(MBB, I, DL, TII.get(MOVE), SP).addReg(FP).addReg(ZERO);
}
if (MipsFI->callsEhReturn()) {
const TargetRegisterClass *RC =
ABI.ArePtrs64bit() ? &Mips::GPR64RegClass : &Mips::GPR32RegClass;
// Find first instruction that restores a callee-saved register.
MachineBasicBlock::iterator I = MBBI;
for (unsigned i = 0; i < MFI.getCalleeSavedInfo().size(); ++i)
--I;
// Insert instructions that restore eh data registers.
for (int J = 0; J < 4; ++J) {
TII.loadRegFromStackSlot(MBB, I, ABI.GetEhDataReg(J),
MipsFI->getEhDataRegFI(J), RC, &RegInfo);
}
}
if (MF.getFunction().hasFnAttribute("interrupt"))
emitInterruptEpilogueStub(MF, MBB);
// Get the number of bytes from FrameInfo
uint64_t StackSize = MFI.getStackSize();
if (!StackSize)
return;
// Adjust stack.
TII.adjustStackPtr(SP, StackSize, MBB, MBBI);
}
void MipsSEFrameLowering::emitInterruptEpilogueStub(
MachineFunction &MF, MachineBasicBlock &MBB) const {
MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr();
MipsFunctionInfo *MipsFI = MF.getInfo<MipsFunctionInfo>();
DebugLoc DL = MBBI != MBB.end() ? MBBI->getDebugLoc() : DebugLoc();
// Perform ISR handling like GCC
const TargetRegisterClass *PtrRC = &Mips::GPR32RegClass;
// Disable Interrupts.
BuildMI(MBB, MBBI, DL, STI.getInstrInfo()->get(Mips::DI), Mips::ZERO);
BuildMI(MBB, MBBI, DL, STI.getInstrInfo()->get(Mips::EHB));
// Restore EPC
STI.getInstrInfo()->loadRegFromStackSlot(MBB, MBBI, Mips::K1,
MipsFI->getISRRegFI(0), PtrRC,
STI.getRegisterInfo());
BuildMI(MBB, MBBI, DL, STI.getInstrInfo()->get(Mips::MTC0), Mips::COP014)
.addReg(Mips::K1)
.addImm(0);
// Restore Status
STI.getInstrInfo()->loadRegFromStackSlot(MBB, MBBI, Mips::K1,
MipsFI->getISRRegFI(1), PtrRC,
STI.getRegisterInfo());
BuildMI(MBB, MBBI, DL, STI.getInstrInfo()->get(Mips::MTC0), Mips::COP012)
.addReg(Mips::K1)
.addImm(0);
}
StackOffset
MipsSEFrameLowering::getFrameIndexReference(const MachineFunction &MF, int FI,
Register &FrameReg) const {
const MachineFrameInfo &MFI = MF.getFrameInfo();
MipsABIInfo ABI = STI.getABI();
if (MFI.isFixedObjectIndex(FI))
FrameReg = hasFP(MF) ? ABI.GetFramePtr() : ABI.GetStackPtr();
else
FrameReg = hasBP(MF) ? ABI.GetBasePtr() : ABI.GetStackPtr();
return StackOffset::getFixed(MFI.getObjectOffset(FI) + MFI.getStackSize() -
getOffsetOfLocalArea() +
MFI.getOffsetAdjustment());
}
bool MipsSEFrameLowering::spillCalleeSavedRegisters(
MachineBasicBlock &MBB, MachineBasicBlock::iterator MI,
ArrayRef<CalleeSavedInfo> CSI, const TargetRegisterInfo *TRI) const {
MachineFunction *MF = MBB.getParent();
const TargetInstrInfo &TII = *STI.getInstrInfo();
for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
// Add the callee-saved register as live-in. Do not add if the register is
// RA and return address is taken, because it has already been added in
// method MipsTargetLowering::lowerRETURNADDR.
// It's killed at the spill, unless the register is RA and return address
// is taken.
unsigned Reg = CSI[i].getReg();
bool IsRAAndRetAddrIsTaken = (Reg == Mips::RA || Reg == Mips::RA_64)
&& MF->getFrameInfo().isReturnAddressTaken();
if (!IsRAAndRetAddrIsTaken)
MBB.addLiveIn(Reg);
// ISRs require HI/LO to be spilled into kernel registers to be then
// spilled to the stack frame.
bool IsLOHI = (Reg == Mips::LO0 || Reg == Mips::LO0_64 ||
Reg == Mips::HI0 || Reg == Mips::HI0_64);
const Function &Func = MBB.getParent()->getFunction();
if (IsLOHI && Func.hasFnAttribute("interrupt")) {
DebugLoc DL = MI->getDebugLoc();
unsigned Op = 0;
if (!STI.getABI().ArePtrs64bit()) {
Op = (Reg == Mips::HI0) ? Mips::MFHI : Mips::MFLO;
Reg = Mips::K0;
} else {
Op = (Reg == Mips::HI0) ? Mips::MFHI64 : Mips::MFLO64;
Reg = Mips::K0_64;
}
BuildMI(MBB, MI, DL, TII.get(Op), Mips::K0)
.setMIFlag(MachineInstr::FrameSetup);
}
// Insert the spill to the stack frame.
bool IsKill = !IsRAAndRetAddrIsTaken;
const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
TII.storeRegToStackSlot(MBB, MI, Reg, IsKill,
CSI[i].getFrameIdx(), RC, TRI);
}
return true;
}
bool
MipsSEFrameLowering::hasReservedCallFrame(const MachineFunction &MF) const {
const MachineFrameInfo &MFI = MF.getFrameInfo();
// Reserve call frame if the size of the maximum call frame fits into 16-bit
// immediate field and there are no variable sized objects on the stack.
// Make sure the second register scavenger spill slot can be accessed with one
// instruction.
return isInt<16>(MFI.getMaxCallFrameSize() + getStackAlignment()) &&
!MFI.hasVarSizedObjects();
}
/// Mark \p Reg and all registers aliasing it in the bitset.
static void setAliasRegs(MachineFunction &MF, BitVector &SavedRegs,
unsigned Reg) {
const TargetRegisterInfo *TRI = MF.getSubtarget().getRegisterInfo();
for (MCRegAliasIterator AI(Reg, TRI, true); AI.isValid(); ++AI)
SavedRegs.set(*AI);
}
void MipsSEFrameLowering::determineCalleeSaves(MachineFunction &MF,
BitVector &SavedRegs,
RegScavenger *RS) const {
TargetFrameLowering::determineCalleeSaves(MF, SavedRegs, RS);
const TargetRegisterInfo *TRI = MF.getSubtarget().getRegisterInfo();
MipsFunctionInfo *MipsFI = MF.getInfo<MipsFunctionInfo>();
MipsABIInfo ABI = STI.getABI();
unsigned RA = ABI.IsN64() ? Mips::RA_64 : Mips::RA;
unsigned FP = ABI.GetFramePtr();
unsigned BP = ABI.IsN64() ? Mips::S7_64 : Mips::S7;
// Mark $ra and $fp as used if function has dedicated frame pointer.
if (hasFP(MF)) {
setAliasRegs(MF, SavedRegs, RA);
setAliasRegs(MF, SavedRegs, FP);
}
// Mark $s7 as used if function has dedicated base pointer.
if (hasBP(MF))
setAliasRegs(MF, SavedRegs, BP);
// Create spill slots for eh data registers if function calls eh_return.
if (MipsFI->callsEhReturn())
MipsFI->createEhDataRegsFI(MF);
// Create spill slots for Coprocessor 0 registers if function is an ISR.
if (MipsFI->isISR())
MipsFI->createISRRegFI(MF);
// Expand pseudo instructions which load, store or copy accumulators.
// Add an emergency spill slot if a pseudo was expanded.
if (ExpandPseudo(MF).expand()) {
// The spill slot should be half the size of the accumulator. If target have
// general-purpose registers 64 bits wide, it should be 64-bit, otherwise
// it should be 32-bit.
const TargetRegisterClass &RC = STI.isGP64bit() ?
Mips::GPR64RegClass : Mips::GPR32RegClass;
int FI = MF.getFrameInfo().CreateStackObject(TRI->getSpillSize(RC),
TRI->getSpillAlign(RC), false);
RS->addScavengingFrameIndex(FI);
}
// Set scavenging frame index if necessary.
uint64_t MaxSPOffset = estimateStackSize(MF);
// MSA has a minimum offset of 10 bits signed. If there is a variable
// sized object on the stack, the estimation cannot account for it.
if (isIntN(STI.hasMSA() ? 10 : 16, MaxSPOffset) &&
!MF.getFrameInfo().hasVarSizedObjects())
return;
const TargetRegisterClass &RC =
ABI.ArePtrs64bit() ? Mips::GPR64RegClass : Mips::GPR32RegClass;
int FI = MF.getFrameInfo().CreateStackObject(TRI->getSpillSize(RC),
TRI->getSpillAlign(RC), false);
RS->addScavengingFrameIndex(FI);
}
const MipsFrameLowering *
llvm::createMipsSEFrameLowering(const MipsSubtarget &ST) {
return new MipsSEFrameLowering(ST);
}
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