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.
getFPReg(const CSKYSubtarget & STI)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.
getBPReg(const CSKYSubtarget & STI)34 static Register getBPReg(const CSKYSubtarget &STI) { return CSKY::R7; }
35
hasFP(const MachineFunction & MF) const36 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
hasBP(const MachineFunction & MF) const45 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.
determineFrameLayout(MachineFunction & MF) const52 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
emitPrologue(MachineFunction & MF,MachineBasicBlock & MBB) const78 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
emitEpilogue(MachineFunction & MF,MachineBasicBlock & MBB) const223 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
EstimateFunctionSizeInBytes(const MachineFunction & MF,const CSKYInstrInfo & TII)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
estimateRSStackSizeLimit(MachineFunction & MF,const CSKYSubtarget & STI)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
determineCalleeSaves(MachineFunction & MF,BitVector & SavedRegs,RegScavenger * RS) const357 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.
hasReservedCallFrame(const MachineFunction & MF) const459 bool CSKYFrameLowering::hasReservedCallFrame(const MachineFunction &MF) const {
460 return !MF.getFrameInfo().hasVarSizedObjects();
461 }
462
spillCalleeSavedRegisters(MachineBasicBlock & MBB,MachineBasicBlock::iterator MI,ArrayRef<CalleeSavedInfo> CSI,const TargetRegisterInfo * TRI) const463 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
restoreCalleeSavedRegisters(MachineBasicBlock & MBB,MachineBasicBlock::iterator MI,MutableArrayRef<CalleeSavedInfo> CSI,const TargetRegisterInfo * TRI) const486 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.
eliminateCallFramePseudoInstr(MachineFunction & MF,MachineBasicBlock & MBB,MachineBasicBlock::iterator MI) const510 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
adjustReg(MachineBasicBlock & MBB,MachineBasicBlock::iterator MBBI,const DebugLoc & DL,Register DestReg,Register SrcReg,int64_t Val,MachineInstr::MIFlag Flag) const538 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
getFrameIndexReference(const MachineFunction & MF,int FI,Register & FrameReg) const582 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