1 //===-- XCoreFrameLowering.cpp - Frame info for XCore Target --------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file contains XCore frame information that doesn't fit anywhere else
13 //===----------------------------------------------------------------------===//
15 #include "XCoreFrameLowering.h"
17 #include "XCoreInstrInfo.h"
18 #include "XCoreMachineFunctionInfo.h"
19 #include "XCoreSubtarget.h"
20 #include "llvm/CodeGen/MachineFrameInfo.h"
21 #include "llvm/CodeGen/MachineFunction.h"
22 #include "llvm/CodeGen/MachineInstrBuilder.h"
23 #include "llvm/CodeGen/MachineModuleInfo.h"
24 #include "llvm/CodeGen/MachineRegisterInfo.h"
25 #include "llvm/CodeGen/RegisterScavenging.h"
26 #include "llvm/IR/DataLayout.h"
27 #include "llvm/IR/Function.h"
28 #include "llvm/Support/ErrorHandling.h"
29 #include "llvm/Target/TargetLowering.h"
30 #include "llvm/Target/TargetOptions.h"
31 #include <algorithm> // std::sort
35 static const unsigned FramePtr = XCore::R10;
36 static const int MaxImmU16 = (1<<16) - 1;
38 // helper functions. FIXME: Eliminate.
39 static inline bool isImmU6(unsigned val) {
40 return val < (1 << 6);
43 static inline bool isImmU16(unsigned val) {
44 return val < (1 << 16);
47 // Helper structure with compare function for handling stack slots.
49 struct StackSlotInfo {
53 StackSlotInfo(int f, int o, int r) : FI(f), Offset(o), Reg(r){};
55 } // end anonymous namespace
57 static bool CompareSSIOffset(const StackSlotInfo& a, const StackSlotInfo& b) {
58 return a.Offset < b.Offset;
62 static void EmitDefCfaRegister(MachineBasicBlock &MBB,
63 MachineBasicBlock::iterator MBBI, DebugLoc dl,
64 const TargetInstrInfo &TII,
65 MachineModuleInfo *MMI, unsigned DRegNum) {
66 unsigned CFIIndex = MMI->addFrameInst(
67 MCCFIInstruction::createDefCfaRegister(nullptr, DRegNum));
68 BuildMI(MBB, MBBI, dl, TII.get(TargetOpcode::CFI_INSTRUCTION))
69 .addCFIIndex(CFIIndex);
72 static void EmitDefCfaOffset(MachineBasicBlock &MBB,
73 MachineBasicBlock::iterator MBBI, DebugLoc dl,
74 const TargetInstrInfo &TII,
75 MachineModuleInfo *MMI, int Offset) {
77 MMI->addFrameInst(MCCFIInstruction::createDefCfaOffset(nullptr, -Offset));
78 BuildMI(MBB, MBBI, dl, TII.get(TargetOpcode::CFI_INSTRUCTION))
79 .addCFIIndex(CFIIndex);
82 static void EmitCfiOffset(MachineBasicBlock &MBB,
83 MachineBasicBlock::iterator MBBI, DebugLoc dl,
84 const TargetInstrInfo &TII, MachineModuleInfo *MMI,
85 unsigned DRegNum, int Offset) {
86 unsigned CFIIndex = MMI->addFrameInst(
87 MCCFIInstruction::createOffset(nullptr, DRegNum, Offset));
88 BuildMI(MBB, MBBI, dl, TII.get(TargetOpcode::CFI_INSTRUCTION))
89 .addCFIIndex(CFIIndex);
92 /// The SP register is moved in steps of 'MaxImmU16' towards the bottom of the
93 /// frame. During these steps, it may be necessary to spill registers.
94 /// IfNeededExtSP emits the necessary EXTSP instructions to move the SP only
95 /// as far as to make 'OffsetFromBottom' reachable using an STWSP_lru6.
96 /// \param OffsetFromTop the spill offset from the top of the frame.
97 /// \param [in,out] Adjusted the current SP offset from the top of the frame.
98 static void IfNeededExtSP(MachineBasicBlock &MBB,
99 MachineBasicBlock::iterator MBBI, DebugLoc dl,
100 const TargetInstrInfo &TII, MachineModuleInfo *MMI,
101 int OffsetFromTop, int &Adjusted, int FrameSize,
102 bool emitFrameMoves) {
103 while (OffsetFromTop > Adjusted) {
104 assert(Adjusted < FrameSize && "OffsetFromTop is beyond FrameSize");
105 int remaining = FrameSize - Adjusted;
106 int OpImm = (remaining > MaxImmU16) ? MaxImmU16 : remaining;
107 int Opcode = isImmU6(OpImm) ? XCore::EXTSP_u6 : XCore::EXTSP_lu6;
108 BuildMI(MBB, MBBI, dl, TII.get(Opcode)).addImm(OpImm);
111 EmitDefCfaOffset(MBB, MBBI, dl, TII, MMI, Adjusted*4);
115 /// The SP register is moved in steps of 'MaxImmU16' towards the top of the
116 /// frame. During these steps, it may be necessary to re-load registers.
117 /// IfNeededLDAWSP emits the necessary LDAWSP instructions to move the SP only
118 /// as far as to make 'OffsetFromTop' reachable using an LDAWSP_lru6.
119 /// \param OffsetFromTop the spill offset from the top of the frame.
120 /// \param [in,out] RemainingAdj the current SP offset from the top of the
122 static void IfNeededLDAWSP(MachineBasicBlock &MBB,
123 MachineBasicBlock::iterator MBBI, DebugLoc dl,
124 const TargetInstrInfo &TII, int OffsetFromTop,
126 while (OffsetFromTop < RemainingAdj - MaxImmU16) {
127 assert(RemainingAdj && "OffsetFromTop is beyond FrameSize");
128 int OpImm = (RemainingAdj > MaxImmU16) ? MaxImmU16 : RemainingAdj;
129 int Opcode = isImmU6(OpImm) ? XCore::LDAWSP_ru6 : XCore::LDAWSP_lru6;
130 BuildMI(MBB, MBBI, dl, TII.get(Opcode), XCore::SP).addImm(OpImm);
131 RemainingAdj -= OpImm;
135 /// Creates an ordered list of registers that are spilled
136 /// during the emitPrologue/emitEpilogue.
137 /// Registers are ordered according to their frame offset.
138 /// As offsets are negative, the largest offsets will be first.
139 static void GetSpillList(SmallVectorImpl<StackSlotInfo> &SpillList,
140 MachineFrameInfo *MFI, XCoreFunctionInfo *XFI,
141 bool fetchLR, bool fetchFP) {
143 int Offset = MFI->getObjectOffset(XFI->getLRSpillSlot());
144 SpillList.push_back(StackSlotInfo(XFI->getLRSpillSlot(),
149 int Offset = MFI->getObjectOffset(XFI->getFPSpillSlot());
150 SpillList.push_back(StackSlotInfo(XFI->getFPSpillSlot(),
154 std::sort(SpillList.begin(), SpillList.end(), CompareSSIOffset);
157 /// Creates an ordered list of EH info register 'spills'.
158 /// These slots are only used by the unwinder and calls to llvm.eh.return().
159 /// Registers are ordered according to their frame offset.
160 /// As offsets are negative, the largest offsets will be first.
161 static void GetEHSpillList(SmallVectorImpl<StackSlotInfo> &SpillList,
162 MachineFrameInfo *MFI, XCoreFunctionInfo *XFI,
163 const TargetLowering *TL) {
164 assert(XFI->hasEHSpillSlot() && "There are no EH register spill slots");
165 const int* EHSlot = XFI->getEHSpillSlot();
166 SpillList.push_back(StackSlotInfo(EHSlot[0],
167 MFI->getObjectOffset(EHSlot[0]),
168 TL->getExceptionPointerRegister()));
169 SpillList.push_back(StackSlotInfo(EHSlot[0],
170 MFI->getObjectOffset(EHSlot[1]),
171 TL->getExceptionSelectorRegister()));
172 std::sort(SpillList.begin(), SpillList.end(), CompareSSIOffset);
176 static MachineMemOperand *
177 getFrameIndexMMO(MachineBasicBlock &MBB, int FrameIndex, unsigned flags) {
178 MachineFunction *MF = MBB.getParent();
179 const MachineFrameInfo &MFI = *MF->getFrameInfo();
180 MachineMemOperand *MMO =
181 MF->getMachineMemOperand(MachinePointerInfo::getFixedStack(FrameIndex),
182 flags, MFI.getObjectSize(FrameIndex),
183 MFI.getObjectAlignment(FrameIndex));
188 /// Restore clobbered registers with their spill slot value.
189 /// The SP will be adjusted at the same time, thus the SpillList must be ordered
190 /// with the largest (negative) offsets first.
192 RestoreSpillList(MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBI,
193 DebugLoc dl, const TargetInstrInfo &TII, int &RemainingAdj,
194 SmallVectorImpl<StackSlotInfo> &SpillList) {
195 for (unsigned i = 0, e = SpillList.size(); i != e; ++i) {
196 assert(SpillList[i].Offset % 4 == 0 && "Misaligned stack offset");
197 assert(SpillList[i].Offset <= 0 && "Unexpected positive stack offset");
198 int OffsetFromTop = - SpillList[i].Offset/4;
199 IfNeededLDAWSP(MBB, MBBI, dl, TII, OffsetFromTop, RemainingAdj);
200 int Offset = RemainingAdj - OffsetFromTop;
201 int Opcode = isImmU6(Offset) ? XCore::LDWSP_ru6 : XCore::LDWSP_lru6;
202 BuildMI(MBB, MBBI, dl, TII.get(Opcode), SpillList[i].Reg)
204 .addMemOperand(getFrameIndexMMO(MBB, SpillList[i].FI,
205 MachineMemOperand::MOLoad));
209 //===----------------------------------------------------------------------===//
210 // XCoreFrameLowering:
211 //===----------------------------------------------------------------------===//
213 XCoreFrameLowering::XCoreFrameLowering(const XCoreSubtarget &sti)
214 : TargetFrameLowering(TargetFrameLowering::StackGrowsDown, 4, 0) {
218 bool XCoreFrameLowering::hasFP(const MachineFunction &MF) const {
219 return MF.getTarget().Options.DisableFramePointerElim(MF) ||
220 MF.getFrameInfo()->hasVarSizedObjects();
223 void XCoreFrameLowering::emitPrologue(MachineFunction &MF) const {
224 MachineBasicBlock &MBB = MF.front(); // Prolog goes in entry BB
225 MachineBasicBlock::iterator MBBI = MBB.begin();
226 MachineFrameInfo *MFI = MF.getFrameInfo();
227 MachineModuleInfo *MMI = &MF.getMMI();
228 const MCRegisterInfo *MRI = MMI->getContext().getRegisterInfo();
229 const XCoreInstrInfo &TII =
230 *static_cast<const XCoreInstrInfo *>(MF.getSubtarget().getInstrInfo());
231 XCoreFunctionInfo *XFI = MF.getInfo<XCoreFunctionInfo>();
232 // Debug location must be unknown since the first debug location is used
233 // to determine the end of the prologue.
236 if (MFI->getMaxAlignment() > getStackAlignment())
237 report_fatal_error("emitPrologue unsupported alignment: "
238 + Twine(MFI->getMaxAlignment()));
240 const AttributeSet &PAL = MF.getFunction()->getAttributes();
241 if (PAL.hasAttrSomewhere(Attribute::Nest))
242 BuildMI(MBB, MBBI, dl, TII.get(XCore::LDWSP_ru6), XCore::R11).addImm(0);
243 // FIX: Needs addMemOperand() but can't use getFixedStack() or getStack().
245 // Work out frame sizes.
246 // We will adjust the SP in stages towards the final FrameSize.
247 assert(MFI->getStackSize()%4 == 0 && "Misaligned frame size");
248 const int FrameSize = MFI->getStackSize() / 4;
251 bool saveLR = XFI->hasLRSpillSlot();
252 bool UseENTSP = saveLR && FrameSize
253 && (MFI->getObjectOffset(XFI->getLRSpillSlot()) == 0);
257 bool emitFrameMoves = XCoreRegisterInfo::needsFrameMoves(MF);
260 // Allocate space on the stack at the same time as saving LR.
261 Adjusted = (FrameSize > MaxImmU16) ? MaxImmU16 : FrameSize;
262 int Opcode = isImmU6(Adjusted) ? XCore::ENTSP_u6 : XCore::ENTSP_lu6;
263 MBB.addLiveIn(XCore::LR);
264 MachineInstrBuilder MIB = BuildMI(MBB, MBBI, dl, TII.get(Opcode));
265 MIB.addImm(Adjusted);
266 MIB->addRegisterKilled(XCore::LR, MF.getSubtarget().getRegisterInfo(),
268 if (emitFrameMoves) {
269 EmitDefCfaOffset(MBB, MBBI, dl, TII, MMI, Adjusted*4);
270 unsigned DRegNum = MRI->getDwarfRegNum(XCore::LR, true);
271 EmitCfiOffset(MBB, MBBI, dl, TII, MMI, DRegNum, 0);
275 // If necessary, save LR and FP to the stack, as we EXTSP.
276 SmallVector<StackSlotInfo,2> SpillList;
277 GetSpillList(SpillList, MFI, XFI, saveLR, FP);
278 // We want the nearest (negative) offsets first, so reverse list.
279 std::reverse(SpillList.begin(), SpillList.end());
280 for (unsigned i = 0, e = SpillList.size(); i != e; ++i) {
281 assert(SpillList[i].Offset % 4 == 0 && "Misaligned stack offset");
282 assert(SpillList[i].Offset <= 0 && "Unexpected positive stack offset");
283 int OffsetFromTop = - SpillList[i].Offset/4;
284 IfNeededExtSP(MBB, MBBI, dl, TII, MMI, OffsetFromTop, Adjusted, FrameSize,
286 int Offset = Adjusted - OffsetFromTop;
287 int Opcode = isImmU6(Offset) ? XCore::STWSP_ru6 : XCore::STWSP_lru6;
288 MBB.addLiveIn(SpillList[i].Reg);
289 BuildMI(MBB, MBBI, dl, TII.get(Opcode))
290 .addReg(SpillList[i].Reg, RegState::Kill)
292 .addMemOperand(getFrameIndexMMO(MBB, SpillList[i].FI,
293 MachineMemOperand::MOStore));
294 if (emitFrameMoves) {
295 unsigned DRegNum = MRI->getDwarfRegNum(SpillList[i].Reg, true);
296 EmitCfiOffset(MBB, MBBI, dl, TII, MMI, DRegNum, SpillList[i].Offset);
300 // Complete any remaining Stack adjustment.
301 IfNeededExtSP(MBB, MBBI, dl, TII, MMI, FrameSize, Adjusted, FrameSize,
303 assert(Adjusted==FrameSize && "IfNeededExtSP has not completed adjustment");
306 // Set the FP from the SP.
307 BuildMI(MBB, MBBI, dl, TII.get(XCore::LDAWSP_ru6), FramePtr).addImm(0);
309 EmitDefCfaRegister(MBB, MBBI, dl, TII, MMI,
310 MRI->getDwarfRegNum(FramePtr, true));
313 if (emitFrameMoves) {
314 // Frame moves for callee saved.
315 auto SpillLabels = XFI->getSpillLabels();
316 for (unsigned I = 0, E = SpillLabels.size(); I != E; ++I) {
317 MachineBasicBlock::iterator Pos = SpillLabels[I].first;
319 CalleeSavedInfo &CSI = SpillLabels[I].second;
320 int Offset = MFI->getObjectOffset(CSI.getFrameIdx());
321 unsigned DRegNum = MRI->getDwarfRegNum(CSI.getReg(), true);
322 EmitCfiOffset(MBB, Pos, dl, TII, MMI, DRegNum, Offset);
324 if (XFI->hasEHSpillSlot()) {
325 // The unwinder requires stack slot & CFI offsets for the exception info.
326 // We do not save/spill these registers.
327 SmallVector<StackSlotInfo,2> SpillList;
328 GetEHSpillList(SpillList, MFI, XFI,
329 MF.getSubtarget().getTargetLowering());
330 assert(SpillList.size()==2 && "Unexpected SpillList size");
331 EmitCfiOffset(MBB, MBBI, dl, TII, MMI,
332 MRI->getDwarfRegNum(SpillList[0].Reg, true),
333 SpillList[0].Offset);
334 EmitCfiOffset(MBB, MBBI, dl, TII, MMI,
335 MRI->getDwarfRegNum(SpillList[1].Reg, true),
336 SpillList[1].Offset);
341 void XCoreFrameLowering::emitEpilogue(MachineFunction &MF,
342 MachineBasicBlock &MBB) const {
343 MachineFrameInfo *MFI = MF.getFrameInfo();
344 MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr();
345 const XCoreInstrInfo &TII =
346 *static_cast<const XCoreInstrInfo *>(MF.getSubtarget().getInstrInfo());
347 XCoreFunctionInfo *XFI = MF.getInfo<XCoreFunctionInfo>();
348 DebugLoc dl = MBBI->getDebugLoc();
349 unsigned RetOpcode = MBBI->getOpcode();
351 // Work out frame sizes.
352 // We will adjust the SP in stages towards the final FrameSize.
353 int RemainingAdj = MFI->getStackSize();
354 assert(RemainingAdj%4 == 0 && "Misaligned frame size");
357 if (RetOpcode == XCore::EH_RETURN) {
358 // 'Restore' the exception info the unwinder has placed into the stack
360 SmallVector<StackSlotInfo,2> SpillList;
361 GetEHSpillList(SpillList, MFI, XFI, MF.getSubtarget().getTargetLowering());
362 RestoreSpillList(MBB, MBBI, dl, TII, RemainingAdj, SpillList);
364 // Return to the landing pad.
365 unsigned EhStackReg = MBBI->getOperand(0).getReg();
366 unsigned EhHandlerReg = MBBI->getOperand(1).getReg();
367 BuildMI(MBB, MBBI, dl, TII.get(XCore::SETSP_1r)).addReg(EhStackReg);
368 BuildMI(MBB, MBBI, dl, TII.get(XCore::BAU_1r)).addReg(EhHandlerReg);
369 MBB.erase(MBBI); // Erase the previous return instruction.
373 bool restoreLR = XFI->hasLRSpillSlot();
374 bool UseRETSP = restoreLR && RemainingAdj
375 && (MFI->getObjectOffset(XFI->getLRSpillSlot()) == 0);
380 if (FP) // Restore the stack pointer.
381 BuildMI(MBB, MBBI, dl, TII.get(XCore::SETSP_1r)).addReg(FramePtr);
383 // If necessary, restore LR and FP from the stack, as we EXTSP.
384 SmallVector<StackSlotInfo,2> SpillList;
385 GetSpillList(SpillList, MFI, XFI, restoreLR, FP);
386 RestoreSpillList(MBB, MBBI, dl, TII, RemainingAdj, SpillList);
389 // Complete all but one of the remaining Stack adjustments.
390 IfNeededLDAWSP(MBB, MBBI, dl, TII, 0, RemainingAdj);
392 // Fold prologue into return instruction
393 assert(RetOpcode == XCore::RETSP_u6
394 || RetOpcode == XCore::RETSP_lu6);
395 int Opcode = isImmU6(RemainingAdj) ? XCore::RETSP_u6 : XCore::RETSP_lu6;
396 MachineInstrBuilder MIB = BuildMI(MBB, MBBI, dl, TII.get(Opcode))
397 .addImm(RemainingAdj);
398 for (unsigned i = 3, e = MBBI->getNumOperands(); i < e; ++i)
399 MIB->addOperand(MBBI->getOperand(i)); // copy any variadic operands
400 MBB.erase(MBBI); // Erase the previous return instruction.
402 int Opcode = isImmU6(RemainingAdj) ? XCore::LDAWSP_ru6 :
404 BuildMI(MBB, MBBI, dl, TII.get(Opcode), XCore::SP).addImm(RemainingAdj);
405 // Don't erase the return instruction.
407 } // else Don't erase the return instruction.
410 bool XCoreFrameLowering::
411 spillCalleeSavedRegisters(MachineBasicBlock &MBB,
412 MachineBasicBlock::iterator MI,
413 const std::vector<CalleeSavedInfo> &CSI,
414 const TargetRegisterInfo *TRI) const {
418 MachineFunction *MF = MBB.getParent();
419 const TargetInstrInfo &TII = *MF->getSubtarget().getInstrInfo();
420 XCoreFunctionInfo *XFI = MF->getInfo<XCoreFunctionInfo>();
421 bool emitFrameMoves = XCoreRegisterInfo::needsFrameMoves(*MF);
424 if (MI != MBB.end() && !MI->isDebugValue())
425 DL = MI->getDebugLoc();
427 for (std::vector<CalleeSavedInfo>::const_iterator it = CSI.begin();
428 it != CSI.end(); ++it) {
429 unsigned Reg = it->getReg();
430 assert(Reg != XCore::LR && !(Reg == XCore::R10 && hasFP(*MF)) &&
431 "LR & FP are always handled in emitPrologue");
433 // Add the callee-saved register as live-in. It's killed at the spill.
435 const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
436 TII.storeRegToStackSlot(MBB, MI, Reg, true, it->getFrameIdx(), RC, TRI);
437 if (emitFrameMoves) {
440 XFI->getSpillLabels().push_back(std::make_pair(Store, *it));
446 bool XCoreFrameLowering::
447 restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
448 MachineBasicBlock::iterator MI,
449 const std::vector<CalleeSavedInfo> &CSI,
450 const TargetRegisterInfo *TRI) const{
451 MachineFunction *MF = MBB.getParent();
452 const TargetInstrInfo &TII = *MF->getSubtarget().getInstrInfo();
453 bool AtStart = MI == MBB.begin();
454 MachineBasicBlock::iterator BeforeI = MI;
457 for (std::vector<CalleeSavedInfo>::const_iterator it = CSI.begin();
458 it != CSI.end(); ++it) {
459 unsigned Reg = it->getReg();
460 assert(Reg != XCore::LR && !(Reg == XCore::R10 && hasFP(*MF)) &&
461 "LR & FP are always handled in emitEpilogue");
463 const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
464 TII.loadRegFromStackSlot(MBB, MI, Reg, it->getFrameIdx(), RC, TRI);
465 assert(MI != MBB.begin() &&
466 "loadRegFromStackSlot didn't insert any code!");
467 // Insert in reverse order. loadRegFromStackSlot can insert multiple
479 // This function eliminates ADJCALLSTACKDOWN,
480 // ADJCALLSTACKUP pseudo instructions
481 void XCoreFrameLowering::
482 eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
483 MachineBasicBlock::iterator I) const {
484 const XCoreInstrInfo &TII =
485 *static_cast<const XCoreInstrInfo *>(MF.getSubtarget().getInstrInfo());
486 if (!hasReservedCallFrame(MF)) {
487 // Turn the adjcallstackdown instruction into 'extsp <amt>' and the
488 // adjcallstackup instruction into 'ldaw sp, sp[<amt>]'
489 MachineInstr *Old = I;
490 uint64_t Amount = Old->getOperand(0).getImm();
492 // We need to keep the stack aligned properly. To do this, we round the
493 // amount of space needed for the outgoing arguments up to the next
494 // alignment boundary.
495 unsigned Align = getStackAlignment();
496 Amount = (Amount+Align-1)/Align*Align;
498 assert(Amount%4 == 0);
501 bool isU6 = isImmU6(Amount);
502 if (!isU6 && !isImmU16(Amount)) {
503 // FIX could emit multiple instructions in this case.
505 errs() << "eliminateCallFramePseudoInstr size too big: "
508 llvm_unreachable(nullptr);
512 if (Old->getOpcode() == XCore::ADJCALLSTACKDOWN) {
513 int Opcode = isU6 ? XCore::EXTSP_u6 : XCore::EXTSP_lu6;
514 New=BuildMI(MF, Old->getDebugLoc(), TII.get(Opcode))
517 assert(Old->getOpcode() == XCore::ADJCALLSTACKUP);
518 int Opcode = isU6 ? XCore::LDAWSP_ru6 : XCore::LDAWSP_lru6;
519 New=BuildMI(MF, Old->getDebugLoc(), TII.get(Opcode), XCore::SP)
523 // Replace the pseudo instruction with a new instruction...
531 void XCoreFrameLowering::
532 processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
533 RegScavenger *RS) const {
534 XCoreFunctionInfo *XFI = MF.getInfo<XCoreFunctionInfo>();
536 bool LRUsed = MF.getRegInfo().isPhysRegUsed(XCore::LR);
538 if (!LRUsed && !MF.getFunction()->isVarArg() &&
539 MF.getFrameInfo()->estimateStackSize(MF))
540 // If we need to extend the stack it is more efficient to use entsp / retsp.
541 // We force the LR to be saved so these instructions are used.
544 if (MF.getMMI().callsUnwindInit() || MF.getMMI().callsEHReturn()) {
545 // The unwinder expects to find spill slots for the exception info regs R0
546 // & R1. These are used during llvm.eh.return() to 'restore' the exception
547 // info. N.B. we do not spill or restore R0, R1 during normal operation.
548 XFI->createEHSpillSlot(MF);
549 // As we will have a stack, we force the LR to be saved.
554 // We will handle the LR in the prologue/epilogue
555 // and allocate space on the stack ourselves.
556 MF.getRegInfo().setPhysRegUnused(XCore::LR);
557 XFI->createLRSpillSlot(MF);
561 // A callee save register is used to hold the FP.
562 // This needs saving / restoring in the epilogue / prologue.
563 XFI->createFPSpillSlot(MF);
566 void XCoreFrameLowering::
567 processFunctionBeforeFrameFinalized(MachineFunction &MF,
568 RegScavenger *RS) const {
569 assert(RS && "requiresRegisterScavenging failed");
570 MachineFrameInfo *MFI = MF.getFrameInfo();
571 const TargetRegisterClass *RC = &XCore::GRRegsRegClass;
572 XCoreFunctionInfo *XFI = MF.getInfo<XCoreFunctionInfo>();
573 // Reserve slots close to SP or frame pointer for Scavenging spills.
574 // When using SP for small frames, we don't need any scratch registers.
575 // When using SP for large frames, we may need 2 scratch registers.
576 // When using FP, for large or small frames, we may need 1 scratch register.
577 if (XFI->isLargeFrame(MF) || hasFP(MF))
578 RS->addScavengingFrameIndex(MFI->CreateStackObject(RC->getSize(),
581 if (XFI->isLargeFrame(MF) && !hasFP(MF))
582 RS->addScavengingFrameIndex(MFI->CreateStackObject(RC->getSize(),