xref: /freebsd/contrib/llvm-project/llvm/lib/Target/CSKY/CSKYFrameLowering.cpp (revision 5ca8e32633c4ffbbcd6762e5888b6a4ba0708c6c)
1 //===-- CSKYFrameLowering.cpp - CSKY Frame Information ------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file contains the CSKY implementation of TargetFrameLowering class.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "CSKYFrameLowering.h"
14 #include "CSKYMachineFunctionInfo.h"
15 #include "CSKYSubtarget.h"
16 #include "llvm/CodeGen/MachineConstantPool.h"
17 #include "llvm/CodeGen/MachineFrameInfo.h"
18 #include "llvm/CodeGen/MachineFunction.h"
19 #include "llvm/CodeGen/MachineInstrBuilder.h"
20 #include "llvm/CodeGen/MachineRegisterInfo.h"
21 #include "llvm/CodeGen/RegisterScavenging.h"
22 #include "llvm/IR/DiagnosticInfo.h"
23 #include "llvm/MC/MCDwarf.h"
24 
25 using namespace llvm;
26 
27 #define DEBUG_TYPE "csky-frame-lowering"
28 
29 // Returns the register used to hold the frame pointer.
30 static Register getFPReg(const CSKYSubtarget &STI) { return CSKY::R8; }
31 
32 // To avoid the BP value clobbered by a function call, we need to choose a
33 // callee saved register to save the value.
34 static Register getBPReg(const CSKYSubtarget &STI) { return CSKY::R7; }
35 
36 bool CSKYFrameLowering::hasFP(const MachineFunction &MF) const {
37   const TargetRegisterInfo *RegInfo = MF.getSubtarget().getRegisterInfo();
38 
39   const MachineFrameInfo &MFI = MF.getFrameInfo();
40   return MF.getTarget().Options.DisableFramePointerElim(MF) ||
41          RegInfo->hasStackRealignment(MF) || MFI.hasVarSizedObjects() ||
42          MFI.isFrameAddressTaken();
43 }
44 
45 bool CSKYFrameLowering::hasBP(const MachineFunction &MF) const {
46   const MachineFrameInfo &MFI = MF.getFrameInfo();
47 
48   return MFI.hasVarSizedObjects();
49 }
50 
51 // Determines the size of the frame and maximum call frame size.
52 void CSKYFrameLowering::determineFrameLayout(MachineFunction &MF) const {
53   MachineFrameInfo &MFI = MF.getFrameInfo();
54   const CSKYRegisterInfo *RI = STI.getRegisterInfo();
55 
56   // Get the number of bytes to allocate from the FrameInfo.
57   uint64_t FrameSize = MFI.getStackSize();
58 
59   // Get the alignment.
60   Align StackAlign = getStackAlign();
61   if (RI->hasStackRealignment(MF)) {
62     Align MaxStackAlign = std::max(StackAlign, MFI.getMaxAlign());
63     FrameSize += (MaxStackAlign.value() - StackAlign.value());
64     StackAlign = MaxStackAlign;
65   }
66 
67   // Set Max Call Frame Size
68   uint64_t MaxCallSize = alignTo(MFI.getMaxCallFrameSize(), StackAlign);
69   MFI.setMaxCallFrameSize(MaxCallSize);
70 
71   // Make sure the frame is aligned.
72   FrameSize = alignTo(FrameSize, StackAlign);
73 
74   // Update frame info.
75   MFI.setStackSize(FrameSize);
76 }
77 
78 void CSKYFrameLowering::emitPrologue(MachineFunction &MF,
79                                      MachineBasicBlock &MBB) const {
80   CSKYMachineFunctionInfo *CFI = MF.getInfo<CSKYMachineFunctionInfo>();
81   MachineFrameInfo &MFI = MF.getFrameInfo();
82   const CSKYRegisterInfo *RI = STI.getRegisterInfo();
83   const CSKYInstrInfo *TII = STI.getInstrInfo();
84   MachineBasicBlock::iterator MBBI = MBB.begin();
85   const TargetRegisterInfo *TRI = MF.getSubtarget().getRegisterInfo();
86   const MachineRegisterInfo &MRI = MF.getRegInfo();
87 
88   Register FPReg = getFPReg(STI);
89   Register SPReg = CSKY::R14;
90   Register BPReg = getBPReg(STI);
91 
92   // Debug location must be unknown since the first debug location is used
93   // to determine the end of the prologue.
94   DebugLoc DL;
95 
96   if (MF.getFunction().hasFnAttribute("interrupt"))
97     BuildMI(MBB, MBBI, DL, TII->get(CSKY::NIE));
98 
99   // Determine the correct frame layout
100   determineFrameLayout(MF);
101 
102   // FIXME (note copied from Lanai): This appears to be overallocating.  Needs
103   // investigation. Get the number of bytes to allocate from the FrameInfo.
104   uint64_t StackSize = MFI.getStackSize();
105 
106   // Early exit if there is no need to allocate on the stack
107   if (StackSize == 0 && !MFI.adjustsStack())
108     return;
109 
110   const auto &CSI = MFI.getCalleeSavedInfo();
111 
112   unsigned spillAreaSize = CFI->getCalleeSaveAreaSize();
113 
114   uint64_t ActualSize = spillAreaSize + CFI->getVarArgsSaveSize();
115 
116   // First part stack allocation.
117   adjustReg(MBB, MBBI, DL, SPReg, SPReg, -(static_cast<int64_t>(ActualSize)),
118             MachineInstr::NoFlags);
119 
120   // Emit ".cfi_def_cfa_offset FirstSPAdjustAmount"
121   unsigned CFIIndex =
122       MF.addFrameInst(MCCFIInstruction::cfiDefCfaOffset(nullptr, ActualSize));
123   BuildMI(MBB, MBBI, DL, TII->get(TargetOpcode::CFI_INSTRUCTION))
124       .addCFIIndex(CFIIndex);
125 
126   // The frame pointer is callee-saved, and code has been generated for us to
127   // save it to the stack. We need to skip over the storing of callee-saved
128   // registers as the frame pointer must be modified after it has been saved
129   // to the stack, not before.
130   // FIXME: assumes exactly one instruction is used to save each callee-saved
131   // register.
132   std::advance(MBBI, CSI.size());
133 
134   // Iterate over list of callee-saved registers and emit .cfi_offset
135   // directives.
136   for (const auto &Entry : CSI) {
137     int64_t Offset = MFI.getObjectOffset(Entry.getFrameIdx());
138     Register Reg = Entry.getReg();
139 
140     unsigned Num = TRI->getRegSizeInBits(Reg, MRI) / 32;
141     for (unsigned i = 0; i < Num; i++) {
142       unsigned CFIIndex = MF.addFrameInst(MCCFIInstruction::createOffset(
143           nullptr, RI->getDwarfRegNum(Reg, true) + i, Offset + i * 4));
144       BuildMI(MBB, MBBI, DL, TII->get(TargetOpcode::CFI_INSTRUCTION))
145           .addCFIIndex(CFIIndex);
146     }
147   }
148 
149   // Generate new FP.
150   if (hasFP(MF)) {
151     BuildMI(MBB, MBBI, DL, TII->get(TargetOpcode::COPY), FPReg)
152         .addReg(SPReg)
153         .setMIFlag(MachineInstr::FrameSetup);
154 
155     // Emit ".cfi_def_cfa_register $fp"
156     unsigned CFIIndex = MF.addFrameInst(MCCFIInstruction::createDefCfaRegister(
157         nullptr, RI->getDwarfRegNum(FPReg, true)));
158     BuildMI(MBB, MBBI, DL, TII->get(TargetOpcode::CFI_INSTRUCTION))
159         .addCFIIndex(CFIIndex);
160 
161     // Second part stack allocation.
162     adjustReg(MBB, MBBI, DL, SPReg, SPReg,
163               -(static_cast<int64_t>(StackSize - ActualSize)),
164               MachineInstr::NoFlags);
165 
166     // Realign Stack
167     const CSKYRegisterInfo *RI = STI.getRegisterInfo();
168     if (RI->hasStackRealignment(MF)) {
169       Align MaxAlignment = MFI.getMaxAlign();
170 
171       const CSKYInstrInfo *TII = STI.getInstrInfo();
172       if (STI.hasE2() && isUInt<12>(~(-(int)MaxAlignment.value()))) {
173         BuildMI(MBB, MBBI, DL, TII->get(CSKY::ANDNI32), SPReg)
174             .addReg(SPReg)
175             .addImm(~(-(int)MaxAlignment.value()));
176       } else {
177         unsigned ShiftAmount = Log2(MaxAlignment);
178 
179         if (STI.hasE2()) {
180           Register VR =
181               MF.getRegInfo().createVirtualRegister(&CSKY::GPRRegClass);
182           BuildMI(MBB, MBBI, DL, TII->get(CSKY::LSRI32), VR)
183               .addReg(SPReg)
184               .addImm(ShiftAmount);
185           BuildMI(MBB, MBBI, DL, TII->get(CSKY::LSLI32), SPReg)
186               .addReg(VR)
187               .addImm(ShiftAmount);
188         } else {
189           Register VR =
190               MF.getRegInfo().createVirtualRegister(&CSKY::mGPRRegClass);
191           BuildMI(MBB, MBBI, DL, TII->get(CSKY::MOV16), VR).addReg(SPReg);
192           BuildMI(MBB, MBBI, DL, TII->get(CSKY::LSRI16), VR)
193               .addReg(VR)
194               .addImm(ShiftAmount);
195           BuildMI(MBB, MBBI, DL, TII->get(CSKY::LSLI16), VR)
196               .addReg(VR)
197               .addImm(ShiftAmount);
198           BuildMI(MBB, MBBI, DL, TII->get(CSKY::MOV16), SPReg).addReg(VR);
199         }
200       }
201     }
202 
203     // FP will be used to restore the frame in the epilogue, so we need
204     // another base register BP to record SP after re-alignment. SP will
205     // track the current stack after allocating variable sized objects.
206     if (hasBP(MF)) {
207       // move BP, SP
208       BuildMI(MBB, MBBI, DL, TII->get(TargetOpcode::COPY), BPReg).addReg(SPReg);
209     }
210 
211   } else {
212     adjustReg(MBB, MBBI, DL, SPReg, SPReg,
213               -(static_cast<int64_t>(StackSize - ActualSize)),
214               MachineInstr::NoFlags);
215     // Emit ".cfi_def_cfa_offset StackSize"
216     unsigned CFIIndex = MF.addFrameInst(
217         MCCFIInstruction::cfiDefCfaOffset(nullptr, MFI.getStackSize()));
218     BuildMI(MBB, MBBI, DL, TII->get(TargetOpcode::CFI_INSTRUCTION))
219         .addCFIIndex(CFIIndex);
220   }
221 }
222 
223 void CSKYFrameLowering::emitEpilogue(MachineFunction &MF,
224                                      MachineBasicBlock &MBB) const {
225   CSKYMachineFunctionInfo *CFI = MF.getInfo<CSKYMachineFunctionInfo>();
226 
227   MachineFrameInfo &MFI = MF.getFrameInfo();
228   Register FPReg = getFPReg(STI);
229   Register SPReg = CSKY::R14;
230 
231   // Get the insert location for the epilogue. If there were no terminators in
232   // the block, get the last instruction.
233   MachineBasicBlock::iterator MBBI = MBB.end();
234   DebugLoc DL;
235   if (!MBB.empty()) {
236     MBBI = MBB.getFirstTerminator();
237     if (MBBI == MBB.end())
238       MBBI = MBB.getLastNonDebugInstr();
239     DL = MBBI->getDebugLoc();
240 
241     // If this is not a terminator, the actual insert location should be after
242     // the last instruction.
243     if (!MBBI->isTerminator())
244       MBBI = std::next(MBBI);
245   }
246 
247   const auto &CSI = MFI.getCalleeSavedInfo();
248   uint64_t StackSize = MFI.getStackSize();
249 
250   uint64_t ActualSize =
251       CFI->getCalleeSaveAreaSize() + CFI->getVarArgsSaveSize();
252 
253   // Skip to before the restores of callee-saved registers
254   // FIXME: assumes exactly one instruction is used to restore each
255   // callee-saved register.
256   auto LastFrameDestroy = MBBI;
257   if (!CSI.empty())
258     LastFrameDestroy = std::prev(MBBI, CSI.size());
259 
260   if (hasFP(MF)) {
261     const CSKYInstrInfo *TII = STI.getInstrInfo();
262     BuildMI(MBB, LastFrameDestroy, DL, TII->get(TargetOpcode::COPY), SPReg)
263         .addReg(FPReg)
264         .setMIFlag(MachineInstr::NoFlags);
265   } else {
266     adjustReg(MBB, LastFrameDestroy, DL, SPReg, SPReg, (StackSize - ActualSize),
267               MachineInstr::FrameDestroy);
268   }
269 
270   adjustReg(MBB, MBBI, DL, SPReg, SPReg, ActualSize,
271             MachineInstr::FrameDestroy);
272 }
273 
274 static unsigned EstimateFunctionSizeInBytes(const MachineFunction &MF,
275                                             const CSKYInstrInfo &TII) {
276   unsigned FnSize = 0;
277   for (auto &MBB : MF) {
278     for (auto &MI : MBB)
279       FnSize += TII.getInstSizeInBytes(MI);
280   }
281   FnSize += MF.getConstantPool()->getConstants().size() * 4;
282   return FnSize;
283 }
284 
285 static unsigned estimateRSStackSizeLimit(MachineFunction &MF,
286                                          const CSKYSubtarget &STI) {
287   unsigned Limit = (1 << 12) - 1;
288 
289   for (auto &MBB : MF) {
290     for (auto &MI : MBB) {
291       if (MI.isDebugInstr())
292         continue;
293 
294       for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
295         if (!MI.getOperand(i).isFI())
296           continue;
297 
298         if (MI.getOpcode() == CSKY::SPILL_CARRY ||
299             MI.getOpcode() == CSKY::RESTORE_CARRY ||
300             MI.getOpcode() == CSKY::STORE_PAIR ||
301             MI.getOpcode() == CSKY::LOAD_PAIR) {
302           Limit = std::min(Limit, ((1U << 12) - 1) * 4);
303           break;
304         }
305 
306         if (MI.getOpcode() == CSKY::ADDI32) {
307           Limit = std::min(Limit, (1U << 12));
308           break;
309         }
310 
311         if (MI.getOpcode() == CSKY::ADDI16XZ) {
312           Limit = std::min(Limit, (1U << 3));
313           break;
314         }
315 
316         // ADDI16 will not require an extra register,
317         // it can reuse the destination.
318         if (MI.getOpcode() == CSKY::ADDI16)
319           break;
320 
321         // Otherwise check the addressing mode.
322         switch (MI.getDesc().TSFlags & CSKYII::AddrModeMask) {
323         default:
324           LLVM_DEBUG(MI.dump());
325           llvm_unreachable(
326               "Unhandled addressing mode in stack size limit calculation");
327         case CSKYII::AddrMode32B:
328           Limit = std::min(Limit, (1U << 12) - 1);
329           break;
330         case CSKYII::AddrMode32H:
331           Limit = std::min(Limit, ((1U << 12) - 1) * 2);
332           break;
333         case CSKYII::AddrMode32WD:
334           Limit = std::min(Limit, ((1U << 12) - 1) * 4);
335           break;
336         case CSKYII::AddrMode16B:
337           Limit = std::min(Limit, (1U << 5) - 1);
338           break;
339         case CSKYII::AddrMode16H:
340           Limit = std::min(Limit, ((1U << 5) - 1) * 2);
341           break;
342         case CSKYII::AddrMode16W:
343           Limit = std::min(Limit, ((1U << 5) - 1) * 4);
344           break;
345         case CSKYII::AddrMode32SDF:
346           Limit = std::min(Limit, ((1U << 8) - 1) * 4);
347           break;
348         }
349         break; // At most one FI per instruction
350       }
351     }
352   }
353 
354   return Limit;
355 }
356 
357 void CSKYFrameLowering::determineCalleeSaves(MachineFunction &MF,
358                                              BitVector &SavedRegs,
359                                              RegScavenger *RS) const {
360   TargetFrameLowering::determineCalleeSaves(MF, SavedRegs, RS);
361 
362   CSKYMachineFunctionInfo *CFI = MF.getInfo<CSKYMachineFunctionInfo>();
363   const TargetRegisterInfo *TRI = MF.getSubtarget().getRegisterInfo();
364   const CSKYInstrInfo *TII = STI.getInstrInfo();
365   const MachineRegisterInfo &MRI = MF.getRegInfo();
366   MachineFrameInfo &MFI = MF.getFrameInfo();
367 
368   if (hasFP(MF))
369     SavedRegs.set(CSKY::R8);
370 
371   // Mark BP as used if function has dedicated base pointer.
372   if (hasBP(MF))
373     SavedRegs.set(CSKY::R7);
374 
375   // If interrupt is enabled and there are calls in the handler,
376   // unconditionally save all Caller-saved registers and
377   // all FP registers, regardless whether they are used.
378   if (MF.getFunction().hasFnAttribute("interrupt") && MFI.hasCalls()) {
379 
380     static const MCPhysReg CSRegs[] = {CSKY::R0,  CSKY::R1,  CSKY::R2, CSKY::R3,
381                                        CSKY::R12, CSKY::R13, 0};
382 
383     for (unsigned i = 0; CSRegs[i]; ++i)
384       SavedRegs.set(CSRegs[i]);
385 
386     if (STI.hasHighRegisters()) {
387 
388       static const MCPhysReg CSHRegs[] = {CSKY::R18, CSKY::R19, CSKY::R20,
389                                           CSKY::R21, CSKY::R22, CSKY::R23,
390                                           CSKY::R24, CSKY::R25, 0};
391 
392       for (unsigned i = 0; CSHRegs[i]; ++i)
393         SavedRegs.set(CSHRegs[i]);
394     }
395 
396     static const MCPhysReg CSF32Regs[] = {
397         CSKY::F8_32,  CSKY::F9_32,  CSKY::F10_32,
398         CSKY::F11_32, CSKY::F12_32, CSKY::F13_32,
399         CSKY::F14_32, CSKY::F15_32, 0};
400     static const MCPhysReg CSF64Regs[] = {
401         CSKY::F8_64,  CSKY::F9_64,  CSKY::F10_64,
402         CSKY::F11_64, CSKY::F12_64, CSKY::F13_64,
403         CSKY::F14_64, CSKY::F15_64, 0};
404 
405     const MCPhysReg *FRegs = NULL;
406     if (STI.hasFPUv2DoubleFloat() || STI.hasFPUv3DoubleFloat())
407       FRegs = CSF64Regs;
408     else if (STI.hasFPUv2SingleFloat() || STI.hasFPUv3SingleFloat())
409       FRegs = CSF32Regs;
410 
411     if (FRegs != NULL) {
412       const MCPhysReg *Regs = MF.getRegInfo().getCalleeSavedRegs();
413 
414       for (unsigned i = 0; Regs[i]; ++i)
415         if (CSKY::FPR32RegClass.contains(Regs[i]) ||
416             CSKY::FPR64RegClass.contains(Regs[i])) {
417           unsigned x = 0;
418           for (; FRegs[x]; ++x)
419             if (FRegs[x] == Regs[i])
420               break;
421           if (FRegs[x] == 0)
422             SavedRegs.set(Regs[i]);
423         }
424     }
425   }
426 
427   unsigned CSStackSize = 0;
428   for (unsigned Reg : SavedRegs.set_bits()) {
429     auto RegSize = TRI->getRegSizeInBits(Reg, MRI) / 8;
430     CSStackSize += RegSize;
431   }
432 
433   CFI->setCalleeSaveAreaSize(CSStackSize);
434 
435   uint64_t Limit = estimateRSStackSizeLimit(MF, STI);
436 
437   bool BigFrame = (MFI.estimateStackSize(MF) + CSStackSize >= Limit);
438 
439   if (BigFrame || CFI->isCRSpilled() || !STI.hasE2()) {
440     const TargetRegisterClass *RC = &CSKY::GPRRegClass;
441     unsigned size = TRI->getSpillSize(*RC);
442     Align align = TRI->getSpillAlign(*RC);
443 
444     RS->addScavengingFrameIndex(MFI.CreateStackObject(size, align, false));
445   }
446 
447   unsigned FnSize = EstimateFunctionSizeInBytes(MF, *TII);
448   // Force R15 to be spilled if the function size is > 65534. This enables
449   // use of BSR to implement far jump.
450   if (FnSize >= ((1 << (16 - 1)) * 2))
451     SavedRegs.set(CSKY::R15);
452 
453   CFI->setLRIsSpilled(SavedRegs.test(CSKY::R15));
454 }
455 
456 // Not preserve stack space within prologue for outgoing variables when the
457 // function contains variable size objects and let eliminateCallFramePseudoInstr
458 // preserve stack space for it.
459 bool CSKYFrameLowering::hasReservedCallFrame(const MachineFunction &MF) const {
460   return !MF.getFrameInfo().hasVarSizedObjects();
461 }
462 
463 bool CSKYFrameLowering::spillCalleeSavedRegisters(
464     MachineBasicBlock &MBB, MachineBasicBlock::iterator MI,
465     ArrayRef<CalleeSavedInfo> CSI, const TargetRegisterInfo *TRI) const {
466   if (CSI.empty())
467     return true;
468 
469   MachineFunction *MF = MBB.getParent();
470   const TargetInstrInfo &TII = *MF->getSubtarget().getInstrInfo();
471   DebugLoc DL;
472   if (MI != MBB.end() && !MI->isDebugInstr())
473     DL = MI->getDebugLoc();
474 
475   for (auto &CS : CSI) {
476     // Insert the spill to the stack frame.
477     Register Reg = CS.getReg();
478     const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
479     TII.storeRegToStackSlot(MBB, MI, Reg, true, CS.getFrameIdx(), RC, TRI,
480                             Register());
481   }
482 
483   return true;
484 }
485 
486 bool CSKYFrameLowering::restoreCalleeSavedRegisters(
487     MachineBasicBlock &MBB, MachineBasicBlock::iterator MI,
488     MutableArrayRef<CalleeSavedInfo> CSI, const TargetRegisterInfo *TRI) const {
489   if (CSI.empty())
490     return true;
491 
492   MachineFunction *MF = MBB.getParent();
493   const TargetInstrInfo &TII = *MF->getSubtarget().getInstrInfo();
494   DebugLoc DL;
495   if (MI != MBB.end() && !MI->isDebugInstr())
496     DL = MI->getDebugLoc();
497 
498   for (auto &CS : reverse(CSI)) {
499     Register Reg = CS.getReg();
500     const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
501     TII.loadRegFromStackSlot(MBB, MI, Reg, CS.getFrameIdx(), RC, TRI,
502                              Register());
503     assert(MI != MBB.begin() && "loadRegFromStackSlot didn't insert any code!");
504   }
505 
506   return true;
507 }
508 
509 // Eliminate ADJCALLSTACKDOWN, ADJCALLSTACKUP pseudo instructions.
510 MachineBasicBlock::iterator CSKYFrameLowering::eliminateCallFramePseudoInstr(
511     MachineFunction &MF, MachineBasicBlock &MBB,
512     MachineBasicBlock::iterator MI) const {
513   Register SPReg = CSKY::R14;
514   DebugLoc DL = MI->getDebugLoc();
515 
516   if (!hasReservedCallFrame(MF)) {
517     // If space has not been reserved for a call frame, ADJCALLSTACKDOWN and
518     // ADJCALLSTACKUP must be converted to instructions manipulating the stack
519     // pointer. This is necessary when there is a variable length stack
520     // allocation (e.g. alloca), which means it's not possible to allocate
521     // space for outgoing arguments from within the function prologue.
522     int64_t Amount = MI->getOperand(0).getImm();
523 
524     if (Amount != 0) {
525       // Ensure the stack remains aligned after adjustment.
526       Amount = alignSPAdjust(Amount);
527 
528       if (MI->getOpcode() == CSKY::ADJCALLSTACKDOWN)
529         Amount = -Amount;
530 
531       adjustReg(MBB, MI, DL, SPReg, SPReg, Amount, MachineInstr::NoFlags);
532     }
533   }
534 
535   return MBB.erase(MI);
536 }
537 
538 void CSKYFrameLowering::adjustReg(MachineBasicBlock &MBB,
539                                   MachineBasicBlock::iterator MBBI,
540                                   const DebugLoc &DL, Register DestReg,
541                                   Register SrcReg, int64_t Val,
542                                   MachineInstr::MIFlag Flag) const {
543   const CSKYInstrInfo *TII = STI.getInstrInfo();
544 
545   if (DestReg == SrcReg && Val == 0)
546     return;
547 
548   // TODO: Add 16-bit instruction support with immediate num
549   if (STI.hasE2() && isUInt<12>(std::abs(Val) - 1)) {
550     BuildMI(MBB, MBBI, DL, TII->get(Val < 0 ? CSKY::SUBI32 : CSKY::ADDI32),
551             DestReg)
552         .addReg(SrcReg)
553         .addImm(std::abs(Val))
554         .setMIFlag(Flag);
555   } else if (!STI.hasE2() && isShiftedUInt<7, 2>(std::abs(Val))) {
556     BuildMI(MBB, MBBI, DL,
557             TII->get(Val < 0 ? CSKY::SUBI16SPSP : CSKY::ADDI16SPSP), CSKY::R14)
558         .addReg(CSKY::R14, RegState::Kill)
559         .addImm(std::abs(Val))
560         .setMIFlag(Flag);
561   } else {
562 
563     unsigned Op = 0;
564 
565     if (STI.hasE2()) {
566       Op = Val < 0 ? CSKY::SUBU32 : CSKY::ADDU32;
567     } else {
568       assert(SrcReg == DestReg);
569       Op = Val < 0 ? CSKY::SUBU16XZ : CSKY::ADDU16XZ;
570     }
571 
572     Register ScratchReg = TII->movImm(MBB, MBBI, DL, std::abs(Val), Flag);
573 
574     BuildMI(MBB, MBBI, DL, TII->get(Op), DestReg)
575         .addReg(SrcReg)
576         .addReg(ScratchReg, RegState::Kill)
577         .setMIFlag(Flag);
578   }
579 }
580 
581 StackOffset
582 CSKYFrameLowering::getFrameIndexReference(const MachineFunction &MF, int FI,
583                                           Register &FrameReg) const {
584   const CSKYMachineFunctionInfo *CFI = MF.getInfo<CSKYMachineFunctionInfo>();
585   const MachineFrameInfo &MFI = MF.getFrameInfo();
586   const TargetRegisterInfo *RI = MF.getSubtarget().getRegisterInfo();
587   const auto &CSI = MFI.getCalleeSavedInfo();
588 
589   int MinCSFI = 0;
590   int MaxCSFI = -1;
591 
592   int Offset = MFI.getObjectOffset(FI) + MFI.getOffsetAdjustment();
593 
594   if (CSI.size()) {
595     MinCSFI = CSI[0].getFrameIdx();
596     MaxCSFI = CSI[CSI.size() - 1].getFrameIdx();
597   }
598 
599   if (FI >= MinCSFI && FI <= MaxCSFI) {
600     FrameReg = CSKY::R14;
601     Offset += CFI->getVarArgsSaveSize() + CFI->getCalleeSaveAreaSize();
602   } else if (RI->hasStackRealignment(MF)) {
603     assert(hasFP(MF));
604     if (!MFI.isFixedObjectIndex(FI)) {
605       FrameReg = hasBP(MF) ? getBPReg(STI) : CSKY::R14;
606       Offset += MFI.getStackSize();
607     } else {
608       FrameReg = getFPReg(STI);
609       Offset += CFI->getVarArgsSaveSize() + CFI->getCalleeSaveAreaSize();
610     }
611   } else {
612     if (MFI.isFixedObjectIndex(FI) && hasFP(MF)) {
613       FrameReg = getFPReg(STI);
614       Offset += CFI->getVarArgsSaveSize() + CFI->getCalleeSaveAreaSize();
615     } else {
616       FrameReg = hasBP(MF) ? getBPReg(STI) : CSKY::R14;
617       Offset += MFI.getStackSize();
618     }
619   }
620 
621   return StackOffset::getFixed(Offset);
622 }
623