//===-- SystemZFrameLowering.cpp - Frame lowering for SystemZ -------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
#include "SystemZFrameLowering.h"
#include "SystemZCallingConv.h"
#include "SystemZInstrBuilder.h"
#include "SystemZInstrInfo.h"
#include "SystemZMachineFunctionInfo.h"
#include "SystemZRegisterInfo.h"
#include "SystemZSubtarget.h"
#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/RegisterScavenging.h"
#include "llvm/IR/Function.h"
using namespace llvm;
namespace {
// The ABI-defined register save slots, relative to the CFA (i.e.
// incoming stack pointer + SystemZMC::CallFrameSize).
static const TargetFrameLowering::SpillSlot SpillOffsetTable[] = {
{ SystemZ::R2D, 0x10 },
{ SystemZ::R3D, 0x18 },
{ SystemZ::R4D, 0x20 },
{ SystemZ::R5D, 0x28 },
{ SystemZ::R6D, 0x30 },
{ SystemZ::R7D, 0x38 },
{ SystemZ::R8D, 0x40 },
{ SystemZ::R9D, 0x48 },
{ SystemZ::R10D, 0x50 },
{ SystemZ::R11D, 0x58 },
{ SystemZ::R12D, 0x60 },
{ SystemZ::R13D, 0x68 },
{ SystemZ::R14D, 0x70 },
{ SystemZ::R15D, 0x78 },
{ SystemZ::F0D, 0x80 },
{ SystemZ::F2D, 0x88 },
{ SystemZ::F4D, 0x90 },
{ SystemZ::F6D, 0x98 }
};
} // end anonymous namespace
SystemZFrameLowering::SystemZFrameLowering()
: TargetFrameLowering(TargetFrameLowering::StackGrowsDown, Align(8),
0, Align(8), false /* StackRealignable */),
RegSpillOffsets(0) {
// Due to the SystemZ ABI, the DWARF CFA (Canonical Frame Address) is not
// equal to the incoming stack pointer, but to incoming stack pointer plus
// 160. Instead of using a Local Area Offset, the Register save area will
// be occupied by fixed frame objects, and all offsets are actually
// relative to CFA.
// Create a mapping from register number to save slot offset.
// These offsets are relative to the start of the register save area.
RegSpillOffsets.grow(SystemZ::NUM_TARGET_REGS);
for (unsigned I = 0, E = array_lengthof(SpillOffsetTable); I != E; ++I)
RegSpillOffsets[SpillOffsetTable[I].Reg] = SpillOffsetTable[I].Offset;
}
static bool usePackedStack(MachineFunction &MF) {
bool HasPackedStackAttr = MF.getFunction().hasFnAttribute("packed-stack");
bool IsVarArg = MF.getFunction().isVarArg();
bool CallConv = MF.getFunction().getCallingConv() != CallingConv::GHC;
bool BackChain = MF.getFunction().hasFnAttribute("backchain");
bool FramAddressTaken = MF.getFrameInfo().isFrameAddressTaken();
if (HasPackedStackAttr && BackChain)
report_fatal_error("packed-stack with backchain is currently unsupported.");
return HasPackedStackAttr && !IsVarArg && CallConv && !BackChain &&
!FramAddressTaken;
}
bool SystemZFrameLowering::
assignCalleeSavedSpillSlots(MachineFunction &MF,
const TargetRegisterInfo *TRI,
std::vector<CalleeSavedInfo> &CSI) const {
SystemZMachineFunctionInfo *ZFI = MF.getInfo<SystemZMachineFunctionInfo>();
MachineFrameInfo &MFFrame = MF.getFrameInfo();
bool IsVarArg = MF.getFunction().isVarArg();
if (CSI.empty())
return true; // Early exit if no callee saved registers are modified!
unsigned LowGPR = 0;
unsigned HighGPR = SystemZ::R15D;
int StartSPOffset = SystemZMC::CallFrameSize;
int CurrOffset;
if (!usePackedStack(MF)) {
for (auto &CS : CSI) {
unsigned Reg = CS.getReg();
int Offset = RegSpillOffsets[Reg];
if (Offset) {
if (SystemZ::GR64BitRegClass.contains(Reg) && StartSPOffset > Offset) {
LowGPR = Reg;
StartSPOffset = Offset;
}
Offset -= SystemZMC::CallFrameSize;
int FrameIdx = MFFrame.CreateFixedSpillStackObject(8, Offset);
CS.setFrameIdx(FrameIdx);
} else
CS.setFrameIdx(INT32_MAX);
}
// Save the range of call-saved registers, for use by the
// prologue/epilogue inserters.
ZFI->setRestoreGPRRegs(LowGPR, HighGPR, StartSPOffset);
if (IsVarArg) {
// Also save the GPR varargs, if any. R6D is call-saved, so would
// already be included, but we also need to handle the call-clobbered
// argument registers.
unsigned FirstGPR = ZFI->getVarArgsFirstGPR();
if (FirstGPR < SystemZ::NumArgGPRs) {
unsigned Reg = SystemZ::ArgGPRs[FirstGPR];
int Offset = RegSpillOffsets[Reg];
if (StartSPOffset > Offset) {
LowGPR = Reg; StartSPOffset = Offset;
}
}
}
ZFI->setSpillGPRRegs(LowGPR, HighGPR, StartSPOffset);
CurrOffset = -SystemZMC::CallFrameSize;
} else {
// Packed stack: put all the GPRs at the top of the Register save area.
uint32_t LowGR64Num = UINT32_MAX;
for (auto &CS : CSI) {
unsigned Reg = CS.getReg();
if (SystemZ::GR64BitRegClass.contains(Reg)) {
unsigned GR64Num = SystemZMC::getFirstReg(Reg);
int Offset = -8 * (15 - GR64Num + 1);
if (LowGR64Num > GR64Num) {
LowGR64Num = GR64Num;
StartSPOffset = SystemZMC::CallFrameSize + Offset;
}
int FrameIdx = MFFrame.CreateFixedSpillStackObject(8, Offset);
CS.setFrameIdx(FrameIdx);
} else
CS.setFrameIdx(INT32_MAX);
}
if (LowGR64Num < UINT32_MAX)
LowGPR = SystemZMC::GR64Regs[LowGR64Num];
// Save the range of call-saved registers, for use by the
// prologue/epilogue inserters.
ZFI->setRestoreGPRRegs(LowGPR, HighGPR, StartSPOffset);
ZFI->setSpillGPRRegs(LowGPR, HighGPR, StartSPOffset);
CurrOffset = LowGPR ? -(SystemZMC::CallFrameSize - StartSPOffset) : 0;
}
// Create fixed stack objects for the remaining registers.
for (auto &CS : CSI) {
if (CS.getFrameIdx() != INT32_MAX)
continue;
unsigned Reg = CS.getReg();
const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
unsigned Size = TRI->getSpillSize(*RC);
CurrOffset -= Size;
assert(CurrOffset % 8 == 0 &&
"8-byte alignment required for for all register save slots");
int FrameIdx = MFFrame.CreateFixedSpillStackObject(Size, CurrOffset);
CS.setFrameIdx(FrameIdx);
}
return true;
}
void SystemZFrameLowering::determineCalleeSaves(MachineFunction &MF,
BitVector &SavedRegs,
RegScavenger *RS) const {
TargetFrameLowering::determineCalleeSaves(MF, SavedRegs, RS);
MachineFrameInfo &MFFrame = MF.getFrameInfo();
const TargetRegisterInfo *TRI = MF.getSubtarget().getRegisterInfo();
bool HasFP = hasFP(MF);
SystemZMachineFunctionInfo *MFI = MF.getInfo<SystemZMachineFunctionInfo>();
bool IsVarArg = MF.getFunction().isVarArg();
// va_start stores incoming FPR varargs in the normal way, but delegates
// the saving of incoming GPR varargs to spillCalleeSavedRegisters().
// Record these pending uses, which typically include the call-saved
// argument register R6D.
if (IsVarArg)
for (unsigned I = MFI->getVarArgsFirstGPR(); I < SystemZ::NumArgGPRs; ++I)
SavedRegs.set(SystemZ::ArgGPRs[I]);
// If there are any landing pads, entering them will modify r6/r7.
if (!MF.getLandingPads().empty()) {
SavedRegs.set(SystemZ::R6D);
SavedRegs.set(SystemZ::R7D);
}
// If the function requires a frame pointer, record that the hard
// frame pointer will be clobbered.
if (HasFP)
SavedRegs.set(SystemZ::R11D);
// If the function calls other functions, record that the return
// address register will be clobbered.
if (MFFrame.hasCalls())
SavedRegs.set(SystemZ::R14D);
// If we are saving GPRs other than the stack pointer, we might as well
// save and restore the stack pointer at the same time, via STMG and LMG.
// This allows the deallocation to be done by the LMG, rather than needing
// a separate %r15 addition.
const MCPhysReg *CSRegs = TRI->getCalleeSavedRegs(&MF);
for (unsigned I = 0; CSRegs[I]; ++I) {
unsigned Reg = CSRegs[I];
if (SystemZ::GR64BitRegClass.contains(Reg) && SavedRegs.test(Reg)) {
SavedRegs.set(SystemZ::R15D);
break;
}
}
}
// Add GPR64 to the save instruction being built by MIB, which is in basic
// block MBB. IsImplicit says whether this is an explicit operand to the
// instruction, or an implicit one that comes between the explicit start
// and end registers.
static void addSavedGPR(MachineBasicBlock &MBB, MachineInstrBuilder &MIB,
unsigned GPR64, bool IsImplicit) {
const TargetRegisterInfo *RI =
MBB.getParent()->getSubtarget().getRegisterInfo();
Register GPR32 = RI->getSubReg(GPR64, SystemZ::subreg_l32);
bool IsLive = MBB.isLiveIn(GPR64) || MBB.isLiveIn(GPR32);
if (!IsLive || !IsImplicit) {
MIB.addReg(GPR64, getImplRegState(IsImplicit) | getKillRegState(!IsLive));
if (!IsLive)
MBB.addLiveIn(GPR64);
}
}
bool SystemZFrameLowering::
spillCalleeSavedRegisters(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MBBI,
const std::vector<CalleeSavedInfo> &CSI,
const TargetRegisterInfo *TRI) const {
if (CSI.empty())
return false;
MachineFunction &MF = *MBB.getParent();
const TargetInstrInfo *TII = MF.getSubtarget().getInstrInfo();
SystemZMachineFunctionInfo *ZFI = MF.getInfo<SystemZMachineFunctionInfo>();
bool IsVarArg = MF.getFunction().isVarArg();
DebugLoc DL;
// Save GPRs
SystemZ::GPRRegs SpillGPRs = ZFI->getSpillGPRRegs();
if (SpillGPRs.LowGPR) {
assert(SpillGPRs.LowGPR != SpillGPRs.HighGPR &&
"Should be saving %r15 and something else");
// Build an STMG instruction.
MachineInstrBuilder MIB = BuildMI(MBB, MBBI, DL, TII->get(SystemZ::STMG));
// Add the explicit register operands.
addSavedGPR(MBB, MIB, SpillGPRs.LowGPR, false);
addSavedGPR(MBB, MIB, SpillGPRs.HighGPR, false);
// Add the address.
MIB.addReg(SystemZ::R15D).addImm(SpillGPRs.GPROffset);
// Make sure all call-saved GPRs are included as operands and are
// marked as live on entry.
for (unsigned I = 0, E = CSI.size(); I != E; ++I) {
unsigned Reg = CSI[I].getReg();
if (SystemZ::GR64BitRegClass.contains(Reg))
addSavedGPR(MBB, MIB, Reg, true);
}
// ...likewise GPR varargs.
if (IsVarArg)
for (unsigned I = ZFI->getVarArgsFirstGPR(); I < SystemZ::NumArgGPRs; ++I)
addSavedGPR(MBB, MIB, SystemZ::ArgGPRs[I], true);
}
// Save FPRs/VRs in the normal TargetInstrInfo way.
for (unsigned I = 0, E = CSI.size(); I != E; ++I) {
unsigned Reg = CSI[I].getReg();
if (SystemZ::FP64BitRegClass.contains(Reg)) {
MBB.addLiveIn(Reg);
TII->storeRegToStackSlot(MBB, MBBI, Reg, true, CSI[I].getFrameIdx(),
&SystemZ::FP64BitRegClass, TRI);
}
if (SystemZ::VR128BitRegClass.contains(Reg)) {
MBB.addLiveIn(Reg);
TII->storeRegToStackSlot(MBB, MBBI, Reg, true, CSI[I].getFrameIdx(),
&SystemZ::VR128BitRegClass, TRI);
}
}
return true;
}
bool SystemZFrameLowering::
restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MBBI,
std::vector<CalleeSavedInfo> &CSI,
const TargetRegisterInfo *TRI) const {
if (CSI.empty())
return false;
MachineFunction &MF = *MBB.getParent();
const TargetInstrInfo *TII = MF.getSubtarget().getInstrInfo();
SystemZMachineFunctionInfo *ZFI = MF.getInfo<SystemZMachineFunctionInfo>();
bool HasFP = hasFP(MF);
DebugLoc DL = MBBI != MBB.end() ? MBBI->getDebugLoc() : DebugLoc();
// Restore FPRs/VRs in the normal TargetInstrInfo way.
for (unsigned I = 0, E = CSI.size(); I != E; ++I) {
unsigned Reg = CSI[I].getReg();
if (SystemZ::FP64BitRegClass.contains(Reg))
TII->loadRegFromStackSlot(MBB, MBBI, Reg, CSI[I].getFrameIdx(),
&SystemZ::FP64BitRegClass, TRI);
if (SystemZ::VR128BitRegClass.contains(Reg))
TII->loadRegFromStackSlot(MBB, MBBI, Reg, CSI[I].getFrameIdx(),
&SystemZ::VR128BitRegClass, TRI);
}
// Restore call-saved GPRs (but not call-clobbered varargs, which at
// this point might hold return values).
SystemZ::GPRRegs RestoreGPRs = ZFI->getRestoreGPRRegs();
if (RestoreGPRs.LowGPR) {
// If we saved any of %r2-%r5 as varargs, we should also be saving
// and restoring %r6. If we're saving %r6 or above, we should be
// restoring it too.
assert(RestoreGPRs.LowGPR != RestoreGPRs.HighGPR &&
"Should be loading %r15 and something else");
// Build an LMG instruction.
MachineInstrBuilder MIB = BuildMI(MBB, MBBI, DL, TII->get(SystemZ::LMG));
// Add the explicit register operands.
MIB.addReg(RestoreGPRs.LowGPR, RegState::Define);
MIB.addReg(RestoreGPRs.HighGPR, RegState::Define);
// Add the address.
MIB.addReg(HasFP ? SystemZ::R11D : SystemZ::R15D);
MIB.addImm(RestoreGPRs.GPROffset);
// Do a second scan adding regs as being defined by instruction
for (unsigned I = 0, E = CSI.size(); I != E; ++I) {
unsigned Reg = CSI[I].getReg();
if (Reg != RestoreGPRs.LowGPR && Reg != RestoreGPRs.HighGPR &&
SystemZ::GR64BitRegClass.contains(Reg))
MIB.addReg(Reg, RegState::ImplicitDefine);
}
}
return true;
}
void SystemZFrameLowering::
processFunctionBeforeFrameFinalized(MachineFunction &MF,
RegScavenger *RS) const {
MachineFrameInfo &MFFrame = MF.getFrameInfo();
if (!usePackedStack(MF))
// Always create the full incoming register save area.
getOrCreateFramePointerSaveIndex(MF);
// Get the size of our stack frame to be allocated ...
uint64_t StackSize = (MFFrame.estimateStackSize(MF) +
SystemZMC::CallFrameSize);
// ... and the maximum offset we may need to reach into the
// caller's frame to access the save area or stack arguments.
int64_t MaxArgOffset = 0;
for (int I = MFFrame.getObjectIndexBegin(); I != 0; ++I)
if (MFFrame.getObjectOffset(I) >= 0) {
int64_t ArgOffset = MFFrame.getObjectOffset(I) +
MFFrame.getObjectSize(I);
MaxArgOffset = std::max(MaxArgOffset, ArgOffset);
}
uint64_t MaxReach = StackSize + MaxArgOffset;
if (!isUInt<12>(MaxReach)) {
// We may need register scavenging slots if some parts of the frame
// are outside the reach of an unsigned 12-bit displacement.
// Create 2 for the case where both addresses in an MVC are
// out of range.
RS->addScavengingFrameIndex(MFFrame.CreateStackObject(8, 8, false));
RS->addScavengingFrameIndex(MFFrame.CreateStackObject(8, 8, false));
}
}
// Emit instructions before MBBI (in MBB) to add NumBytes to Reg.
static void emitIncrement(MachineBasicBlock &MBB,
MachineBasicBlock::iterator &MBBI,
const DebugLoc &DL,
unsigned Reg, int64_t NumBytes,
const TargetInstrInfo *TII) {
while (NumBytes) {
unsigned Opcode;
int64_t ThisVal = NumBytes;
if (isInt<16>(NumBytes))
Opcode = SystemZ::AGHI;
else {
Opcode = SystemZ::AGFI;
// Make sure we maintain 8-byte stack alignment.
int64_t MinVal = -uint64_t(1) << 31;
int64_t MaxVal = (int64_t(1) << 31) - 8;
if (ThisVal < MinVal)
ThisVal = MinVal;
else if (ThisVal > MaxVal)
ThisVal = MaxVal;
}
MachineInstr *MI = BuildMI(MBB, MBBI, DL, TII->get(Opcode), Reg)
.addReg(Reg).addImm(ThisVal);
// The CC implicit def is dead.
MI->getOperand(3).setIsDead();
NumBytes -= ThisVal;
}
}
void SystemZFrameLowering::emitPrologue(MachineFunction &MF,
MachineBasicBlock &MBB) const {
assert(&MF.front() == &MBB && "Shrink-wrapping not yet supported");
MachineFrameInfo &MFFrame = MF.getFrameInfo();
auto *ZII =
static_cast<const SystemZInstrInfo *>(MF.getSubtarget().getInstrInfo());
SystemZMachineFunctionInfo *ZFI = MF.getInfo<SystemZMachineFunctionInfo>();
MachineBasicBlock::iterator MBBI = MBB.begin();
MachineModuleInfo &MMI = MF.getMMI();
const MCRegisterInfo *MRI = MMI.getContext().getRegisterInfo();
const std::vector<CalleeSavedInfo> &CSI = MFFrame.getCalleeSavedInfo();
bool HasFP = hasFP(MF);
// In GHC calling convention C stack space, including the ABI-defined
// 160-byte base area, is (de)allocated by GHC itself. This stack space may
// be used by LLVM as spill slots for the tail recursive GHC functions. Thus
// do not allocate stack space here, too.
if (MF.getFunction().getCallingConv() == CallingConv::GHC) {
if (MFFrame.getStackSize() > 2048 * sizeof(long)) {
report_fatal_error(
"Pre allocated stack space for GHC function is too small");
}
if (HasFP) {
report_fatal_error(
"In GHC calling convention a frame pointer is not supported");
}
MFFrame.setStackSize(MFFrame.getStackSize() + SystemZMC::CallFrameSize);
return;
}
// Debug location must be unknown since the first debug location is used
// to determine the end of the prologue.
DebugLoc DL;
// The current offset of the stack pointer from the CFA.
int64_t SPOffsetFromCFA = -SystemZMC::CFAOffsetFromInitialSP;
if (ZFI->getSpillGPRRegs().LowGPR) {
// Skip over the GPR saves.
if (MBBI != MBB.end() && MBBI->getOpcode() == SystemZ::STMG)
++MBBI;
else
llvm_unreachable("Couldn't skip over GPR saves");
// Add CFI for the GPR saves.
for (auto &Save : CSI) {
unsigned Reg = Save.getReg();
if (SystemZ::GR64BitRegClass.contains(Reg)) {
int FI = Save.getFrameIdx();
int64_t Offset = MFFrame.getObjectOffset(FI);
unsigned CFIIndex = MF.addFrameInst(MCCFIInstruction::createOffset(
nullptr, MRI->getDwarfRegNum(Reg, true), Offset));
BuildMI(MBB, MBBI, DL, ZII->get(TargetOpcode::CFI_INSTRUCTION))
.addCFIIndex(CFIIndex);
}
}
}
uint64_t StackSize = MFFrame.getStackSize();
// We need to allocate the ABI-defined 160-byte base area whenever
// we allocate stack space for our own use and whenever we call another
// function.
bool HasStackObject = false;
for (unsigned i = 0, e = MFFrame.getObjectIndexEnd(); i != e; ++i)
if (!MFFrame.isDeadObjectIndex(i)) {
HasStackObject = true;
break;
}
if (HasStackObject || MFFrame.hasCalls())
StackSize += SystemZMC::CallFrameSize;
// Don't allocate the incoming reg save area.
StackSize = StackSize > SystemZMC::CallFrameSize
? StackSize - SystemZMC::CallFrameSize
: 0;
MFFrame.setStackSize(StackSize);
if (StackSize) {
// Determine if we want to store a backchain.
bool StoreBackchain = MF.getFunction().hasFnAttribute("backchain");
// If we need backchain, save current stack pointer. R1 is free at this
// point.
if (StoreBackchain)
BuildMI(MBB, MBBI, DL, ZII->get(SystemZ::LGR))
.addReg(SystemZ::R1D, RegState::Define).addReg(SystemZ::R15D);
// Allocate StackSize bytes.
int64_t Delta = -int64_t(StackSize);
emitIncrement(MBB, MBBI, DL, SystemZ::R15D, Delta, ZII);
// Add CFI for the allocation.
unsigned CFIIndex = MF.addFrameInst(
MCCFIInstruction::createDefCfaOffset(nullptr, SPOffsetFromCFA + Delta));
BuildMI(MBB, MBBI, DL, ZII->get(TargetOpcode::CFI_INSTRUCTION))
.addCFIIndex(CFIIndex);
SPOffsetFromCFA += Delta;
if (StoreBackchain)
BuildMI(MBB, MBBI, DL, ZII->get(SystemZ::STG))
.addReg(SystemZ::R1D, RegState::Kill).addReg(SystemZ::R15D).addImm(0)
.addReg(0);
}
if (HasFP) {
// Copy the base of the frame to R11.
BuildMI(MBB, MBBI, DL, ZII->get(SystemZ::LGR), SystemZ::R11D)
.addReg(SystemZ::R15D);
// Add CFI for the new frame location.
unsigned HardFP = MRI->getDwarfRegNum(SystemZ::R11D, true);
unsigned CFIIndex = MF.addFrameInst(
MCCFIInstruction::createDefCfaRegister(nullptr, HardFP));
BuildMI(MBB, MBBI, DL, ZII->get(TargetOpcode::CFI_INSTRUCTION))
.addCFIIndex(CFIIndex);
// Mark the FramePtr as live at the beginning of every block except
// the entry block. (We'll have marked R11 as live on entry when
// saving the GPRs.)
for (auto I = std::next(MF.begin()), E = MF.end(); I != E; ++I)
I->addLiveIn(SystemZ::R11D);
}
// Skip over the FPR/VR saves.
SmallVector<unsigned, 8> CFIIndexes;
for (auto &Save : CSI) {
unsigned Reg = Save.getReg();
if (SystemZ::FP64BitRegClass.contains(Reg)) {
if (MBBI != MBB.end() &&
(MBBI->getOpcode() == SystemZ::STD ||
MBBI->getOpcode() == SystemZ::STDY))
++MBBI;
else
llvm_unreachable("Couldn't skip over FPR save");
} else if (SystemZ::VR128BitRegClass.contains(Reg)) {
if (MBBI != MBB.end() &&
MBBI->getOpcode() == SystemZ::VST)
++MBBI;
else
llvm_unreachable("Couldn't skip over VR save");
} else
continue;
// Add CFI for the this save.
unsigned DwarfReg = MRI->getDwarfRegNum(Reg, true);
unsigned IgnoredFrameReg;
int64_t Offset =
getFrameIndexReference(MF, Save.getFrameIdx(), IgnoredFrameReg);
unsigned CFIIndex = MF.addFrameInst(MCCFIInstruction::createOffset(
nullptr, DwarfReg, SPOffsetFromCFA + Offset));
CFIIndexes.push_back(CFIIndex);
}
// Complete the CFI for the FPR/VR saves, modelling them as taking effect
// after the last save.
for (auto CFIIndex : CFIIndexes) {
BuildMI(MBB, MBBI, DL, ZII->get(TargetOpcode::CFI_INSTRUCTION))
.addCFIIndex(CFIIndex);
}
}
void SystemZFrameLowering::emitEpilogue(MachineFunction &MF,
MachineBasicBlock &MBB) const {
MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr();
auto *ZII =
static_cast<const SystemZInstrInfo *>(MF.getSubtarget().getInstrInfo());
SystemZMachineFunctionInfo *ZFI = MF.getInfo<SystemZMachineFunctionInfo>();
MachineFrameInfo &MFFrame = MF.getFrameInfo();
// See SystemZFrameLowering::emitPrologue
if (MF.getFunction().getCallingConv() == CallingConv::GHC)
return;
// Skip the return instruction.
assert(MBBI->isReturn() && "Can only insert epilogue into returning blocks");
uint64_t StackSize = MFFrame.getStackSize();
if (ZFI->getRestoreGPRRegs().LowGPR) {
--MBBI;
unsigned Opcode = MBBI->getOpcode();
if (Opcode != SystemZ::LMG)
llvm_unreachable("Expected to see callee-save register restore code");
unsigned AddrOpNo = 2;
DebugLoc DL = MBBI->getDebugLoc();
uint64_t Offset = StackSize + MBBI->getOperand(AddrOpNo + 1).getImm();
unsigned NewOpcode = ZII->getOpcodeForOffset(Opcode, Offset);
// If the offset is too large, use the largest stack-aligned offset
// and add the rest to the base register (the stack or frame pointer).
if (!NewOpcode) {
uint64_t NumBytes = Offset - 0x7fff8;
emitIncrement(MBB, MBBI, DL, MBBI->getOperand(AddrOpNo).getReg(),
NumBytes, ZII);
Offset -= NumBytes;
NewOpcode = ZII->getOpcodeForOffset(Opcode, Offset);
assert(NewOpcode && "No restore instruction available");
}
MBBI->setDesc(ZII->get(NewOpcode));
MBBI->getOperand(AddrOpNo + 1).ChangeToImmediate(Offset);
} else if (StackSize) {
DebugLoc DL = MBBI->getDebugLoc();
emitIncrement(MBB, MBBI, DL, SystemZ::R15D, StackSize, ZII);
}
}
bool SystemZFrameLowering::hasFP(const MachineFunction &MF) const {
return (MF.getTarget().Options.DisableFramePointerElim(MF) ||
MF.getFrameInfo().hasVarSizedObjects() ||
MF.getInfo<SystemZMachineFunctionInfo>()->getManipulatesSP());
}
bool
SystemZFrameLowering::hasReservedCallFrame(const MachineFunction &MF) const {
// The ABI requires us to allocate 160 bytes of stack space for the callee,
// with any outgoing stack arguments being placed above that. It seems
// better to make that area a permanent feature of the frame even if
// we're using a frame pointer.
return true;
}
int SystemZFrameLowering::getFrameIndexReference(const MachineFunction &MF,
int FI,
unsigned &FrameReg) const {
// Our incoming SP is actually SystemZMC::CallFrameSize below the CFA, so
// add that difference here.
int64_t Offset =
TargetFrameLowering::getFrameIndexReference(MF, FI, FrameReg);
return Offset + SystemZMC::CallFrameSize;
}
MachineBasicBlock::iterator SystemZFrameLowering::
eliminateCallFramePseudoInstr(MachineFunction &MF,
MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI) const {
switch (MI->getOpcode()) {
case SystemZ::ADJCALLSTACKDOWN:
case SystemZ::ADJCALLSTACKUP:
assert(hasReservedCallFrame(MF) &&
"ADJSTACKDOWN and ADJSTACKUP should be no-ops");
return MBB.erase(MI);
break;
default:
llvm_unreachable("Unexpected call frame instruction");
}
}
int SystemZFrameLowering::
getOrCreateFramePointerSaveIndex(MachineFunction &MF) const {
SystemZMachineFunctionInfo *ZFI = MF.getInfo<SystemZMachineFunctionInfo>();
int FI = ZFI->getFramePointerSaveIndex();
if (!FI) {
MachineFrameInfo &MFFrame = MF.getFrameInfo();
FI = MFFrame.CreateFixedObject(8, -SystemZMC::CallFrameSize, false);
ZFI->setFramePointerSaveIndex(FI);
}
return FI;
}