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llvm-project/llvm/lib/Target/SystemZ/SystemZFrameLowering.cpp

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//=====- SystemZFrameLowering.cpp - SystemZ Frame Information ------*- C++ -*-====//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains the SystemZ implementation of TargetFrameLowering class.
//
//===----------------------------------------------------------------------===//
#include "SystemZFrameLowering.h"
#include "SystemZInstrBuilder.h"
#include "SystemZInstrInfo.h"
#include "SystemZMachineFunctionInfo.h"
#include "llvm/Function.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Target/TargetOptions.h"
#include "llvm/Support/CommandLine.h"
using namespace llvm;
SystemZFrameLowering::SystemZFrameLowering(const SystemZSubtarget &sti)
: TargetFrameLowering(TargetFrameLowering::StackGrowsDown, 8, -160), STI(sti) {
// Fill the spill offsets map
static const unsigned SpillOffsTab[][2] = {
{ 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 }
};
RegSpillOffsets.grow(SystemZ::NUM_TARGET_REGS);
for (unsigned i = 0, e = array_lengthof(SpillOffsTab); i != e; ++i)
RegSpillOffsets[SpillOffsTab[i][0]] = SpillOffsTab[i][1];
}
/// needsFP - Return true if the specified function should have a dedicated
/// frame pointer register. This is true if the function has variable sized
/// allocas or if frame pointer elimination is disabled.
bool SystemZFrameLowering::hasFP(const MachineFunction &MF) const {
const MachineFrameInfo *MFI = MF.getFrameInfo();
return DisableFramePointerElim(MF) || MFI->hasVarSizedObjects();
}
/// emitSPUpdate - Emit a series of instructions to increment / decrement the
/// stack pointer by a constant value.
static
void emitSPUpdate(MachineBasicBlock &MBB, MachineBasicBlock::iterator &MBBI,
int64_t NumBytes, const TargetInstrInfo &TII) {
unsigned Opc; uint64_t Chunk;
bool isSub = NumBytes < 0;
uint64_t Offset = isSub ? -NumBytes : NumBytes;
if (Offset >= (1LL << 15) - 1) {
Opc = SystemZ::ADD64ri32;
Chunk = (1LL << 31) - 1;
} else {
Opc = SystemZ::ADD64ri16;
Chunk = (1LL << 15) - 1;
}
DebugLoc DL = MBBI != MBB.end() ? MBBI->getDebugLoc() : DebugLoc();
while (Offset) {
uint64_t ThisVal = (Offset > Chunk) ? Chunk : Offset;
MachineInstr *MI =
BuildMI(MBB, MBBI, DL, TII.get(Opc), SystemZ::R15D)
.addReg(SystemZ::R15D).addImm(isSub ? -ThisVal : ThisVal);
// The PSW implicit def is dead.
MI->getOperand(3).setIsDead();
Offset -= ThisVal;
}
}
void SystemZFrameLowering::emitPrologue(MachineFunction &MF) const {
MachineBasicBlock &MBB = MF.front(); // Prolog goes in entry BB
MachineFrameInfo *MFI = MF.getFrameInfo();
const SystemZInstrInfo &TII =
*static_cast<const SystemZInstrInfo*>(MF.getTarget().getInstrInfo());
SystemZMachineFunctionInfo *SystemZMFI =
MF.getInfo<SystemZMachineFunctionInfo>();
MachineBasicBlock::iterator MBBI = MBB.begin();
DebugLoc DL = MBBI != MBB.end() ? MBBI->getDebugLoc() : DebugLoc();
// Get the number of bytes to allocate from the FrameInfo.
// Note that area for callee-saved stuff is already allocated, thus we need to
// 'undo' the stack movement.
uint64_t StackSize = MFI->getStackSize();
StackSize -= SystemZMFI->getCalleeSavedFrameSize();
uint64_t NumBytes = StackSize - getOffsetOfLocalArea();
// Skip the callee-saved push instructions.
while (MBBI != MBB.end() &&
(MBBI->getOpcode() == SystemZ::MOV64mr ||
MBBI->getOpcode() == SystemZ::MOV64mrm))
++MBBI;
if (MBBI != MBB.end())
DL = MBBI->getDebugLoc();
// adjust stack pointer: R15 -= numbytes
if (StackSize || MFI->hasCalls()) {
assert(MF.getRegInfo().isPhysRegUsed(SystemZ::R15D) &&
"Invalid stack frame calculation!");
emitSPUpdate(MBB, MBBI, -(int64_t)NumBytes, TII);
}
if (hasFP(MF)) {
// Update R11 with the new base value...
BuildMI(MBB, MBBI, DL, TII.get(SystemZ::MOV64rr), SystemZ::R11D)
.addReg(SystemZ::R15D);
// Mark the FramePtr as live-in in every block except the entry.
for (MachineFunction::iterator I = llvm::next(MF.begin()), E = MF.end();
I != E; ++I)
I->addLiveIn(SystemZ::R11D);
}
}
void SystemZFrameLowering::emitEpilogue(MachineFunction &MF,
MachineBasicBlock &MBB) const {
const MachineFrameInfo *MFI = MF.getFrameInfo();
MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr();
const SystemZInstrInfo &TII =
*static_cast<const SystemZInstrInfo*>(MF.getTarget().getInstrInfo());
SystemZMachineFunctionInfo *SystemZMFI =
MF.getInfo<SystemZMachineFunctionInfo>();
unsigned RetOpcode = MBBI->getOpcode();
switch (RetOpcode) {
case SystemZ::RET: break; // These are ok
default:
assert(0 && "Can only insert epilog into returning blocks");
}
// Get the number of bytes to allocate from the FrameInfo
// Note that area for callee-saved stuff is already allocated, thus we need to
// 'undo' the stack movement.
uint64_t StackSize =
MFI->getStackSize() - SystemZMFI->getCalleeSavedFrameSize();
uint64_t NumBytes = StackSize - getOffsetOfLocalArea();
// Skip the final terminator instruction.
while (MBBI != MBB.begin()) {
MachineBasicBlock::iterator PI = prior(MBBI);
--MBBI;
if (!PI->getDesc().isTerminator())
break;
}
// During callee-saved restores emission stack frame was not yet finialized
// (and thus - the stack size was unknown). Tune the offset having full stack
// size in hands.
if (StackSize || MFI->hasCalls()) {
assert((MBBI->getOpcode() == SystemZ::MOV64rmm ||
MBBI->getOpcode() == SystemZ::MOV64rm) &&
"Expected to see callee-save register restore code");
assert(MF.getRegInfo().isPhysRegUsed(SystemZ::R15D) &&
"Invalid stack frame calculation!");
unsigned i = 0;
MachineInstr &MI = *MBBI;
while (!MI.getOperand(i).isImm()) {
++i;
assert(i < MI.getNumOperands() && "Unexpected restore code!");
}
uint64_t Offset = NumBytes + MI.getOperand(i).getImm();
// If Offset does not fit into 20-bit signed displacement field we need to
// emit some additional code...
if (Offset > 524287) {
// Fold the displacement into load instruction as much as possible.
NumBytes = Offset - 524287;
Offset = 524287;
emitSPUpdate(MBB, MBBI, NumBytes, TII);
}
MI.getOperand(i).ChangeToImmediate(Offset);
}
}
int SystemZFrameLowering::getFrameIndexOffset(const MachineFunction &MF,
int FI) const {
const MachineFrameInfo *MFI = MF.getFrameInfo();
const SystemZMachineFunctionInfo *SystemZMFI =
MF.getInfo<SystemZMachineFunctionInfo>();
int Offset = MFI->getObjectOffset(FI) + MFI->getOffsetAdjustment();
uint64_t StackSize = MFI->getStackSize();
// Fixed objects are really located in the "previous" frame.
if (FI < 0)
StackSize -= SystemZMFI->getCalleeSavedFrameSize();
Offset += StackSize - getOffsetOfLocalArea();
// Skip the register save area if we generated the stack frame.
if (StackSize || MFI->hasCalls())
Offset -= getOffsetOfLocalArea();
return Offset;
}
bool
SystemZFrameLowering::spillCalleeSavedRegisters(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI,
const std::vector<CalleeSavedInfo> &CSI,
const TargetRegisterInfo *TRI) const {
if (CSI.empty())
return false;
DebugLoc DL;
if (MI != MBB.end()) DL = MI->getDebugLoc();
MachineFunction &MF = *MBB.getParent();
const TargetInstrInfo &TII = *MF.getTarget().getInstrInfo();
SystemZMachineFunctionInfo *MFI = MF.getInfo<SystemZMachineFunctionInfo>();
unsigned CalleeFrameSize = 0;
// Scan the callee-saved and find the bounds of register spill area.
unsigned LowReg = 0, HighReg = 0, StartOffset = -1U, EndOffset = 0;
for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
unsigned Reg = CSI[i].getReg();
if (!SystemZ::FP64RegClass.contains(Reg)) {
unsigned Offset = RegSpillOffsets[Reg];
CalleeFrameSize += 8;
if (StartOffset > Offset) {
LowReg = Reg; StartOffset = Offset;
}
if (EndOffset < Offset) {
HighReg = Reg; EndOffset = RegSpillOffsets[Reg];
}
}
}
// Save information for epilogue inserter.
MFI->setCalleeSavedFrameSize(CalleeFrameSize);
MFI->setLowReg(LowReg); MFI->setHighReg(HighReg);
// Save GPRs
if (StartOffset) {
// Build a store instruction. Use STORE MULTIPLE instruction if there are many
// registers to store, otherwise - just STORE.
MachineInstrBuilder MIB =
BuildMI(MBB, MI, DL, TII.get((LowReg == HighReg ?
SystemZ::MOV64mr : SystemZ::MOV64mrm)));
// Add store operands.
MIB.addReg(SystemZ::R15D).addImm(StartOffset);
if (LowReg == HighReg)
MIB.addReg(0);
MIB.addReg(LowReg, RegState::Kill);
if (LowReg != HighReg)
MIB.addReg(HighReg, RegState::Kill);
// Do a second scan adding regs as being killed by instruction
for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
unsigned Reg = CSI[i].getReg();
// Add the callee-saved register as live-in. It's killed at the spill.
MBB.addLiveIn(Reg);
if (Reg != LowReg && Reg != HighReg)
MIB.addReg(Reg, RegState::ImplicitKill);
}
}
// Save FPRs
for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
unsigned Reg = CSI[i].getReg();
if (SystemZ::FP64RegClass.contains(Reg)) {
MBB.addLiveIn(Reg);
TII.storeRegToStackSlot(MBB, MI, Reg, true, CSI[i].getFrameIdx(),
&SystemZ::FP64RegClass, TRI);
}
}
return true;
}
bool
SystemZFrameLowering::restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI,
const std::vector<CalleeSavedInfo> &CSI,
const TargetRegisterInfo *TRI) const {
if (CSI.empty())
return false;
DebugLoc DL;
if (MI != MBB.end()) DL = MI->getDebugLoc();
MachineFunction &MF = *MBB.getParent();
const TargetInstrInfo &TII = *MF.getTarget().getInstrInfo();
SystemZMachineFunctionInfo *MFI = MF.getInfo<SystemZMachineFunctionInfo>();
// Restore FP registers
for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
unsigned Reg = CSI[i].getReg();
if (SystemZ::FP64RegClass.contains(Reg))
TII.loadRegFromStackSlot(MBB, MI, Reg, CSI[i].getFrameIdx(),
&SystemZ::FP64RegClass, TRI);
}
// Restore GP registers
unsigned LowReg = MFI->getLowReg(), HighReg = MFI->getHighReg();
unsigned StartOffset = RegSpillOffsets[LowReg];
if (StartOffset) {
// Build a load instruction. Use LOAD MULTIPLE instruction if there are many
// registers to load, otherwise - just LOAD.
MachineInstrBuilder MIB =
BuildMI(MBB, MI, DL, TII.get((LowReg == HighReg ?
SystemZ::MOV64rm : SystemZ::MOV64rmm)));
// Add store operands.
MIB.addReg(LowReg, RegState::Define);
if (LowReg != HighReg)
MIB.addReg(HighReg, RegState::Define);
MIB.addReg(hasFP(MF) ? SystemZ::R11D : SystemZ::R15D);
MIB.addImm(StartOffset);
if (LowReg == HighReg)
MIB.addReg(0);
// 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 != LowReg && Reg != HighReg)
MIB.addReg(Reg, RegState::ImplicitDefine);
}
}
return true;
}
void
SystemZFrameLowering::processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
RegScavenger *RS) const {
// Determine whether R15/R14 will ever be clobbered inside the function. And
// if yes - mark it as 'callee' saved.
MachineFrameInfo *FFI = MF.getFrameInfo();
MachineRegisterInfo &MRI = MF.getRegInfo();
// Check whether high FPRs are ever used, if yes - we need to save R15 as
// well.
static const unsigned HighFPRs[] = {
SystemZ::F8L, SystemZ::F9L, SystemZ::F10L, SystemZ::F11L,
SystemZ::F12L, SystemZ::F13L, SystemZ::F14L, SystemZ::F15L,
SystemZ::F8S, SystemZ::F9S, SystemZ::F10S, SystemZ::F11S,
SystemZ::F12S, SystemZ::F13S, SystemZ::F14S, SystemZ::F15S,
};
bool HighFPRsUsed = false;
for (unsigned i = 0, e = array_lengthof(HighFPRs); i != e; ++i)
HighFPRsUsed |= MRI.isPhysRegUsed(HighFPRs[i]);
if (FFI->hasCalls())
/* FIXME: function is varargs */
/* FIXME: function grabs RA */
/* FIXME: function calls eh_return */
MRI.setPhysRegUsed(SystemZ::R14D);
if (HighFPRsUsed ||
FFI->hasCalls() ||
FFI->getObjectIndexEnd() != 0 || // Contains automatic variables
FFI->hasVarSizedObjects() // Function calls dynamic alloca's
/* FIXME: function is varargs */)
MRI.setPhysRegUsed(SystemZ::R15D);
}
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