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llvm-project/llvm/lib/Target/XCore/XCoreFrameLowering.cpp

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//===-- XCoreFrameLowering.cpp - Frame info for XCore Target --------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains XCore frame information that doesn't fit anywhere else
// cleanly...
//
//===----------------------------------------------------------------------===//
#include "XCoreFrameLowering.h"
#include "XCore.h"
#include "XCoreInstrInfo.h"
#include "XCoreMachineFunctionInfo.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/CodeGen/RegisterScavenging.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/Function.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Target/TargetOptions.h"
using namespace llvm;
static const unsigned FramePtr = XCore::R10;
static const int MaxImmU16 = (1<<16) - 1;
// helper functions. FIXME: Eliminate.
static inline bool isImmU6(unsigned val) {
return val < (1 << 6);
}
static inline bool isImmU16(unsigned val) {
return val < (1 << 16);
}
static void EmitDefCfaRegister(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MBBI, DebugLoc dl,
const TargetInstrInfo &TII,
MachineModuleInfo *MMI, unsigned DRegNum) {
MCSymbol *Label = MMI->getContext().CreateTempSymbol();
BuildMI(MBB, MBBI, dl, TII.get(XCore::PROLOG_LABEL)).addSym(Label);
MMI->addFrameInst(MCCFIInstruction::createDefCfaRegister(Label, DRegNum));
}
static void EmitDefCfaOffset(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MBBI, DebugLoc dl,
const TargetInstrInfo &TII,
MachineModuleInfo *MMI, int Offset) {
MCSymbol *Label = MMI->getContext().CreateTempSymbol();
BuildMI(MBB, MBBI, dl, TII.get(XCore::PROLOG_LABEL)).addSym(Label);
MMI->addFrameInst(MCCFIInstruction::createDefCfaOffset(Label, -Offset));
}
static void EmitCfiOffset(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MBBI, DebugLoc dl,
const TargetInstrInfo &TII, MachineModuleInfo *MMI,
unsigned DRegNum, int Offset, MCSymbol *Label) {
if (!Label) {
Label = MMI->getContext().CreateTempSymbol();
BuildMI(MBB, MBBI, dl, TII.get(XCore::PROLOG_LABEL)).addSym(Label);
}
MMI->addFrameInst(MCCFIInstruction::createOffset(Label, DRegNum, Offset));
}
/// The SP register is moved in steps of 'MaxImmU16' towards the bottom of the
/// frame. During these steps, it may be necessary to spill registers.
/// IfNeededExtSP emits the necessary EXTSP instructions to move the SP only
/// as far as to make 'OffsetFromBottom' reachable using an STWSP_lru6.
/// \param OffsetFromTop the spill offset from the top of the frame.
/// \param [in,out] Adjusted the current SP offset from the top of the frame.
static void IfNeededExtSP(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MBBI, DebugLoc dl,
const TargetInstrInfo &TII, MachineModuleInfo *MMI,
int OffsetFromTop, int &Adjusted, int FrameSize,
bool emitFrameMoves) {
while (OffsetFromTop > Adjusted) {
assert(Adjusted < FrameSize && "OffsetFromTop is beyond FrameSize");
int remaining = FrameSize - Adjusted;
int OpImm = (remaining > MaxImmU16) ? MaxImmU16 : remaining;
int Opcode = isImmU6(OpImm) ? XCore::EXTSP_u6 : XCore::EXTSP_lu6;
BuildMI(MBB, MBBI, dl, TII.get(Opcode)).addImm(OpImm);
Adjusted += OpImm;
if (emitFrameMoves)
EmitDefCfaOffset(MBB, MBBI, dl, TII, MMI, Adjusted*4);
}
}
/// The SP register is moved in steps of 'MaxImmU16' towards the top of the
/// frame. During these steps, it may be necessary to re-load registers.
/// IfNeededLDAWSP emits the necessary LDAWSP instructions to move the SP only
/// as far as to make 'OffsetFromTop' reachable using an LDAWSP_lru6.
/// \param OffsetFromTop the spill offset from the top of the frame.
/// \param [in,out] RemainingAdj the current SP offset from the top of the frame.
static void IfNeededLDAWSP(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MBBI, DebugLoc dl,
const TargetInstrInfo &TII, int OffsetFromTop,
int &RemainingAdj) {
while (OffsetFromTop < RemainingAdj - MaxImmU16) {
assert(RemainingAdj && "OffsetFromTop is beyond FrameSize");
int OpImm = (RemainingAdj > MaxImmU16) ? MaxImmU16 : RemainingAdj;
int Opcode = isImmU6(OpImm) ? XCore::LDAWSP_ru6 : XCore::LDAWSP_lru6;
BuildMI(MBB, MBBI, dl, TII.get(Opcode), XCore::SP).addImm(OpImm);
RemainingAdj -= OpImm;
}
}
/// Creates an ordered list of registers that are spilled
/// during the emitPrologue/emitEpilogue.
/// Registers are ordered according to their frame offset.
static void GetSpillList(SmallVectorImpl<std::pair<unsigned,int> > &SpillList,
MachineFrameInfo *MFI, XCoreFunctionInfo *XFI,
bool fetchLR, bool fetchFP) {
int LRSpillOffset = fetchLR? MFI->getObjectOffset(XFI->getLRSpillSlot()) : 0;
int FPSpillOffset = fetchFP? MFI->getObjectOffset(XFI->getFPSpillSlot()) : 0;
if (fetchLR && fetchFP && LRSpillOffset > FPSpillOffset) {
SpillList.push_back(std::pair<unsigned, int>(XCore::LR, LRSpillOffset));
fetchLR = false;
}
if (fetchFP)
SpillList.push_back(std::pair<unsigned, int>(FramePtr, FPSpillOffset));
if (fetchLR)
SpillList.push_back(std::pair<unsigned, int>(XCore::LR, LRSpillOffset));
}
//===----------------------------------------------------------------------===//
// XCoreFrameLowering:
//===----------------------------------------------------------------------===//
XCoreFrameLowering::XCoreFrameLowering(const XCoreSubtarget &sti)
: TargetFrameLowering(TargetFrameLowering::StackGrowsDown, 4, 0) {
// Do nothing
}
bool XCoreFrameLowering::hasFP(const MachineFunction &MF) const {
return MF.getTarget().Options.DisableFramePointerElim(MF) ||
MF.getFrameInfo()->hasVarSizedObjects();
}
void XCoreFrameLowering::emitPrologue(MachineFunction &MF) const {
MachineBasicBlock &MBB = MF.front(); // Prolog goes in entry BB
MachineBasicBlock::iterator MBBI = MBB.begin();
MachineFrameInfo *MFI = MF.getFrameInfo();
MachineModuleInfo *MMI = &MF.getMMI();
const MCRegisterInfo *MRI = MMI->getContext().getRegisterInfo();
const XCoreInstrInfo &TII =
*static_cast<const XCoreInstrInfo*>(MF.getTarget().getInstrInfo());
XCoreFunctionInfo *XFI = MF.getInfo<XCoreFunctionInfo>();
DebugLoc dl = MBBI != MBB.end() ? MBBI->getDebugLoc() : DebugLoc();
if (MFI->getMaxAlignment() > getStackAlignment())
report_fatal_error("emitPrologue unsupported alignment: "
+ Twine(MFI->getMaxAlignment()));
const AttributeSet &PAL = MF.getFunction()->getAttributes();
if (PAL.hasAttrSomewhere(Attribute::Nest))
BuildMI(MBB, MBBI, dl, TII.get(XCore::LDWSP_ru6), XCore::R11).addImm(0);
// Work out frame sizes.
// We will adjust the SP in stages towards the final FrameSize.
assert(MFI->getStackSize()%4 == 0 && "Misaligned frame size");
const int FrameSize = MFI->getStackSize() / 4;
int Adjusted = 0;
bool saveLR = XFI->getUsesLR();
bool UseENTSP = saveLR && FrameSize
&& (MFI->getObjectOffset(XFI->getLRSpillSlot()) == 0);
if (UseENTSP)
saveLR = false;
bool FP = hasFP(MF);
bool emitFrameMoves = XCoreRegisterInfo::needsFrameMoves(MF);
if (UseENTSP) {
// Allocate space on the stack at the same time as saving LR.
Adjusted = (FrameSize > MaxImmU16) ? MaxImmU16 : FrameSize;
int Opcode = isImmU6(Adjusted) ? XCore::ENTSP_u6 : XCore::ENTSP_lu6;
BuildMI(MBB, MBBI, dl, TII.get(Opcode)).addImm(Adjusted);
MBB.addLiveIn(XCore::LR);
if (emitFrameMoves) {
EmitDefCfaOffset(MBB, MBBI, dl, TII, MMI, Adjusted*4);
unsigned DRegNum = MRI->getDwarfRegNum(XCore::LR, true);
EmitCfiOffset(MBB, MBBI, dl, TII, MMI, DRegNum, 0, NULL);
}
}
// If necessary, save LR and FP to the stack, as we EXTSP.
SmallVector<std::pair<unsigned,int>,2> SpillList;
GetSpillList(SpillList, MFI, XFI, saveLR, FP);
for (unsigned i = 0, e = SpillList.size(); i != e; ++i) {
unsigned SpillReg = SpillList[i].first;
int SpillOffset = SpillList[i].second;
assert(SpillOffset % 4 == 0 && "Misaligned stack offset");
assert(SpillOffset <= 0 && "Unexpected positive stack offset");
int OffsetFromTop = - SpillOffset/4;
IfNeededExtSP(MBB, MBBI, dl, TII, MMI, OffsetFromTop, Adjusted, FrameSize,
emitFrameMoves);
int Offset = Adjusted - OffsetFromTop;
int Opcode = isImmU6(Offset) ? XCore::STWSP_ru6 : XCore::STWSP_lru6;
BuildMI(MBB, MBBI, dl, TII.get(Opcode)).addReg(SpillReg).addImm(Offset);
MBB.addLiveIn(SpillReg);
if (emitFrameMoves) {
unsigned DRegNum = MRI->getDwarfRegNum(SpillReg, true);
EmitCfiOffset(MBB, MBBI, dl, TII, MMI, DRegNum, SpillOffset, NULL);
}
}
// Complete any remaining Stack adjustment.
IfNeededExtSP(MBB, MBBI, dl, TII, MMI, FrameSize, Adjusted, FrameSize,
emitFrameMoves);
assert(Adjusted==FrameSize && "IfNeededExtSP has not completed adjustment");
if (FP) {
// Set the FP from the SP.
BuildMI(MBB, MBBI, dl, TII.get(XCore::LDAWSP_ru6), FramePtr).addImm(0);
if (emitFrameMoves)
EmitDefCfaRegister(MBB, MBBI, dl, TII, MMI,
MRI->getDwarfRegNum(FramePtr, true));
}
if (emitFrameMoves) {
// Frame moves for callee saved.
std::vector<std::pair<MCSymbol*, CalleeSavedInfo> >&SpillLabels =
XFI->getSpillLabels();
for (unsigned I = 0, E = SpillLabels.size(); I != E; ++I) {
MCSymbol *SpillLabel = SpillLabels[I].first;
CalleeSavedInfo &CSI = SpillLabels[I].second;
int Offset = MFI->getObjectOffset(CSI.getFrameIdx());
unsigned DRegNum = MRI->getDwarfRegNum(CSI.getReg(), true);
EmitCfiOffset(MBB, MBBI, dl, TII, MMI, DRegNum, Offset, SpillLabel);
}
}
}
void XCoreFrameLowering::emitEpilogue(MachineFunction &MF,
MachineBasicBlock &MBB) const {
MachineFrameInfo *MFI = MF.getFrameInfo();
MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr();
const XCoreInstrInfo &TII =
*static_cast<const XCoreInstrInfo*>(MF.getTarget().getInstrInfo());
XCoreFunctionInfo *XFI = MF.getInfo<XCoreFunctionInfo>();
DebugLoc dl = MBBI->getDebugLoc();
// Work out frame sizes.
// We will adjust the SP in stages towards the final FrameSize.
int RemainingAdj = MFI->getStackSize();
assert(RemainingAdj%4 == 0 && "Misaligned frame size");
RemainingAdj /= 4;
bool restoreLR = XFI->getUsesLR();
bool UseRETSP = restoreLR && RemainingAdj
&& (MFI->getObjectOffset(XFI->getLRSpillSlot()) == 0);
if (UseRETSP)
restoreLR = false;
bool FP = hasFP(MF);
if (FP) // Restore the stack pointer.
BuildMI(MBB, MBBI, dl, TII.get(XCore::SETSP_1r)).addReg(FramePtr);
// If necessary, restore LR and FP from the stack, as we EXTSP.
SmallVector<std::pair<unsigned,int>,2> SpillList;
GetSpillList(SpillList, MFI, XFI, restoreLR, FP);
unsigned i = SpillList.size();
while (i--) {
unsigned SpilledReg = SpillList[i].first;
int SpillOffset = SpillList[i].second;
assert(SpillOffset % 4 == 0 && "Misaligned stack offset");
assert(SpillOffset <= 0 && "Unexpected positive stack offset");
int OffsetFromTop = - SpillOffset/4;
IfNeededLDAWSP(MBB, MBBI, dl, TII, OffsetFromTop, RemainingAdj);
int Offset = RemainingAdj - OffsetFromTop;
int Opcode = isImmU6(Offset) ? XCore::LDWSP_ru6 : XCore::LDWSP_lru6;
BuildMI(MBB, MBBI, dl, TII.get(Opcode), SpilledReg).addImm(Offset);
}
if (RemainingAdj) {
// Complete all but one of the remaining Stack adjustments.
IfNeededLDAWSP(MBB, MBBI, dl, TII, 0, RemainingAdj);
if (UseRETSP) {
// Fold prologue into return instruction
assert(MBBI->getOpcode() == XCore::RETSP_u6
|| MBBI->getOpcode() == XCore::RETSP_lu6);
int Opcode = isImmU6(RemainingAdj) ? XCore::RETSP_u6 : XCore::RETSP_lu6;
MachineInstrBuilder MIB = BuildMI(MBB, MBBI, dl, TII.get(Opcode))
.addImm(RemainingAdj);
for (unsigned i = 3, e = MBBI->getNumOperands(); i < e; ++i)
MIB->addOperand(MBBI->getOperand(i)); // copy any variadic operands
MBB.erase(MBBI); // Erase the previous return instruction.
} else {
int Opcode = isImmU6(RemainingAdj) ? XCore::LDAWSP_ru6 :
XCore::LDAWSP_lru6;
BuildMI(MBB, MBBI, dl, TII.get(Opcode), XCore::SP).addImm(RemainingAdj);
// Don't erase the return instruction.
}
} // else Don't erase the return instruction.
}
bool XCoreFrameLowering::
spillCalleeSavedRegisters(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI,
const std::vector<CalleeSavedInfo> &CSI,
const TargetRegisterInfo *TRI) const {
if (CSI.empty())
return true;
MachineFunction *MF = MBB.getParent();
const TargetInstrInfo &TII = *MF->getTarget().getInstrInfo();
XCoreFunctionInfo *XFI = MF->getInfo<XCoreFunctionInfo>();
bool emitFrameMoves = XCoreRegisterInfo::needsFrameMoves(*MF);
DebugLoc DL;
if (MI != MBB.end())
DL = MI->getDebugLoc();
for (std::vector<CalleeSavedInfo>::const_iterator it = CSI.begin();
it != CSI.end(); ++it) {
// Add the callee-saved register as live-in. It's killed at the spill.
MBB.addLiveIn(it->getReg());
unsigned Reg = it->getReg();
const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
TII.storeRegToStackSlot(MBB, MI, Reg, true,
it->getFrameIdx(), RC, TRI);
if (emitFrameMoves) {
MCSymbol *SaveLabel = MF->getContext().CreateTempSymbol();
BuildMI(MBB, MI, DL, TII.get(XCore::PROLOG_LABEL)).addSym(SaveLabel);
XFI->getSpillLabels().push_back(std::make_pair(SaveLabel, *it));
}
}
return true;
}
bool XCoreFrameLowering::
restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI,
const std::vector<CalleeSavedInfo> &CSI,
const TargetRegisterInfo *TRI) const{
MachineFunction *MF = MBB.getParent();
const TargetInstrInfo &TII = *MF->getTarget().getInstrInfo();
bool AtStart = MI == MBB.begin();
MachineBasicBlock::iterator BeforeI = MI;
if (!AtStart)
--BeforeI;
for (std::vector<CalleeSavedInfo>::const_iterator it = CSI.begin();
it != CSI.end(); ++it) {
unsigned Reg = it->getReg();
const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
TII.loadRegFromStackSlot(MBB, MI, it->getReg(), it->getFrameIdx(),
RC, TRI);
assert(MI != MBB.begin() &&
"loadRegFromStackSlot didn't insert any code!");
// Insert in reverse order. loadRegFromStackSlot can insert multiple
// instructions.
if (AtStart)
MI = MBB.begin();
else {
MI = BeforeI;
++MI;
}
}
return true;
}
// This function eliminates ADJCALLSTACKDOWN,
// ADJCALLSTACKUP pseudo instructions
void XCoreFrameLowering::
eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
MachineBasicBlock::iterator I) const {
const XCoreInstrInfo &TII =
*static_cast<const XCoreInstrInfo*>(MF.getTarget().getInstrInfo());
if (!hasReservedCallFrame(MF)) {
// Turn the adjcallstackdown instruction into 'extsp <amt>' and the
// adjcallstackup instruction into 'ldaw sp, sp[<amt>]'
MachineInstr *Old = I;
uint64_t Amount = Old->getOperand(0).getImm();
if (Amount != 0) {
// We need to keep the stack aligned properly. To do this, we round the
// amount of space needed for the outgoing arguments up to the next
// alignment boundary.
unsigned Align = getStackAlignment();
Amount = (Amount+Align-1)/Align*Align;
assert(Amount%4 == 0);
Amount /= 4;
bool isU6 = isImmU6(Amount);
if (!isU6 && !isImmU16(Amount)) {
// FIX could emit multiple instructions in this case.
#ifndef NDEBUG
errs() << "eliminateCallFramePseudoInstr size too big: "
<< Amount << "\n";
#endif
llvm_unreachable(0);
}
MachineInstr *New;
if (Old->getOpcode() == XCore::ADJCALLSTACKDOWN) {
int Opcode = isU6 ? XCore::EXTSP_u6 : XCore::EXTSP_lu6;
New=BuildMI(MF, Old->getDebugLoc(), TII.get(Opcode))
.addImm(Amount);
} else {
assert(Old->getOpcode() == XCore::ADJCALLSTACKUP);
int Opcode = isU6 ? XCore::LDAWSP_ru6 : XCore::LDAWSP_lru6;
New=BuildMI(MF, Old->getDebugLoc(), TII.get(Opcode), XCore::SP)
.addImm(Amount);
}
// Replace the pseudo instruction with a new instruction...
MBB.insert(I, New);
}
}
MBB.erase(I);
}
void XCoreFrameLowering::
processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
RegScavenger *RS) const {
MachineFrameInfo *MFI = MF.getFrameInfo();
bool LRUsed = MF.getRegInfo().isPhysRegUsed(XCore::LR);
const TargetRegisterClass *RC = &XCore::GRRegsRegClass;
XCoreFunctionInfo *XFI = MF.getInfo<XCoreFunctionInfo>();
if (LRUsed) {
MF.getRegInfo().setPhysRegUnused(XCore::LR);
bool isVarArg = MF.getFunction()->isVarArg();
int FrameIdx;
if (! isVarArg) {
// A fixed offset of 0 allows us to save/restore LR using entsp/retsp.
FrameIdx = MFI->CreateFixedObject(RC->getSize(), 0, true);
} else {
FrameIdx = MFI->CreateStackObject(RC->getSize(), RC->getAlignment(),
false);
}
XFI->setUsesLR(FrameIdx);
XFI->setLRSpillSlot(FrameIdx);
}
// A callee save register is used to hold the FP.
// This needs saving / restoring in the epilogue / prologue.
if (hasFP(MF))
XFI->setFPSpillSlot(MFI->CreateStackObject(RC->getSize(),
RC->getAlignment(),
false));
}
void XCoreFrameLowering::
processFunctionBeforeFrameFinalized(MachineFunction &MF,
RegScavenger *RS) const {
assert(RS && "requiresRegisterScavenging failed");
MachineFrameInfo *MFI = MF.getFrameInfo();
const TargetRegisterClass *RC = &XCore::GRRegsRegClass;
XCoreFunctionInfo *XFI = MF.getInfo<XCoreFunctionInfo>();
// Reserve slots close to SP or frame pointer for Scavenging spills.
// When using SP for small frames, we don't need any scratch registers.
// When using SP for large frames, we may need 2 scratch registers.
// When using FP, for large or small frames, we may need 1 scratch register.
if (XFI->isLargeFrame(MF) || hasFP(MF))
RS->addScavengingFrameIndex(MFI->CreateStackObject(RC->getSize(),
RC->getAlignment(),
false));
if (XFI->isLargeFrame(MF) && !hasFP(MF))
RS->addScavengingFrameIndex(MFI->CreateStackObject(RC->getSize(),
RC->getAlignment(),
false));
}
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