1 //===- MipsAsmPrinter.cpp - Mips LLVM Assembly Printer --------------------===//
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 a printer that converts from our internal representation
10 // of machine-dependent LLVM code to GAS-format MIPS assembly language.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "MipsAsmPrinter.h"
15 #include "InstPrinter/MipsInstPrinter.h"
16 #include "MCTargetDesc/MipsABIInfo.h"
17 #include "MCTargetDesc/MipsBaseInfo.h"
18 #include "MCTargetDesc/MipsMCNaCl.h"
19 #include "MCTargetDesc/MipsMCTargetDesc.h"
20 #include "Mips.h"
21 #include "MipsMCInstLower.h"
22 #include "MipsMachineFunction.h"
23 #include "MipsSubtarget.h"
24 #include "MipsTargetMachine.h"
25 #include "MipsTargetStreamer.h"
26 #include "llvm/ADT/SmallString.h"
27 #include "llvm/ADT/StringRef.h"
28 #include "llvm/ADT/Triple.h"
29 #include "llvm/ADT/Twine.h"
30 #include "llvm/BinaryFormat/ELF.h"
31 #include "llvm/CodeGen/MachineBasicBlock.h"
32 #include "llvm/CodeGen/MachineConstantPool.h"
33 #include "llvm/CodeGen/MachineFrameInfo.h"
34 #include "llvm/CodeGen/MachineFunction.h"
35 #include "llvm/CodeGen/MachineInstr.h"
36 #include "llvm/CodeGen/MachineJumpTableInfo.h"
37 #include "llvm/CodeGen/MachineOperand.h"
38 #include "llvm/CodeGen/TargetRegisterInfo.h"
39 #include "llvm/CodeGen/TargetSubtargetInfo.h"
40 #include "llvm/IR/Attributes.h"
41 #include "llvm/IR/BasicBlock.h"
42 #include "llvm/IR/DataLayout.h"
43 #include "llvm/IR/Function.h"
44 #include "llvm/IR/InlineAsm.h"
45 #include "llvm/IR/Instructions.h"
46 #include "llvm/MC/MCContext.h"
47 #include "llvm/MC/MCExpr.h"
48 #include "llvm/MC/MCInst.h"
49 #include "llvm/MC/MCInstBuilder.h"
50 #include "llvm/MC/MCObjectFileInfo.h"
51 #include "llvm/MC/MCSectionELF.h"
52 #include "llvm/MC/MCSymbol.h"
53 #include "llvm/MC/MCSymbolELF.h"
54 #include "llvm/Support/Casting.h"
55 #include "llvm/Support/ErrorHandling.h"
56 #include "llvm/Support/TargetRegistry.h"
57 #include "llvm/Support/raw_ostream.h"
58 #include "llvm/Target/TargetMachine.h"
59 #include <cassert>
60 #include <cstdint>
61 #include <map>
62 #include <memory>
63 #include <string>
64 #include <vector>
65 
66 using namespace llvm;
67 
68 #define DEBUG_TYPE "mips-asm-printer"
69 
70 extern cl::opt<bool> EmitJalrReloc;
71 
72 MipsTargetStreamer &MipsAsmPrinter::getTargetStreamer() const {
73   return static_cast<MipsTargetStreamer &>(*OutStreamer->getTargetStreamer());
74 }
75 
76 bool MipsAsmPrinter::runOnMachineFunction(MachineFunction &MF) {
77   Subtarget = &MF.getSubtarget<MipsSubtarget>();
78 
79   MipsFI = MF.getInfo<MipsFunctionInfo>();
80   if (Subtarget->inMips16Mode())
81     for (std::map<
82              const char *,
83              const Mips16HardFloatInfo::FuncSignature *>::const_iterator
84              it = MipsFI->StubsNeeded.begin();
85          it != MipsFI->StubsNeeded.end(); ++it) {
86       const char *Symbol = it->first;
87       const Mips16HardFloatInfo::FuncSignature *Signature = it->second;
88       if (StubsNeeded.find(Symbol) == StubsNeeded.end())
89         StubsNeeded[Symbol] = Signature;
90     }
91   MCP = MF.getConstantPool();
92 
93   // In NaCl, all indirect jump targets must be aligned to bundle size.
94   if (Subtarget->isTargetNaCl())
95     NaClAlignIndirectJumpTargets(MF);
96 
97   AsmPrinter::runOnMachineFunction(MF);
98 
99   emitXRayTable();
100 
101   return true;
102 }
103 
104 bool MipsAsmPrinter::lowerOperand(const MachineOperand &MO, MCOperand &MCOp) {
105   MCOp = MCInstLowering.LowerOperand(MO);
106   return MCOp.isValid();
107 }
108 
109 #include "MipsGenMCPseudoLowering.inc"
110 
111 // Lower PseudoReturn/PseudoIndirectBranch/PseudoIndirectBranch64 to JR, JR_MM,
112 // JALR, or JALR64 as appropriate for the target.
113 void MipsAsmPrinter::emitPseudoIndirectBranch(MCStreamer &OutStreamer,
114                                               const MachineInstr *MI) {
115   bool HasLinkReg = false;
116   bool InMicroMipsMode = Subtarget->inMicroMipsMode();
117   MCInst TmpInst0;
118 
119   if (Subtarget->hasMips64r6()) {
120     // MIPS64r6 should use (JALR64 ZERO_64, $rs)
121     TmpInst0.setOpcode(Mips::JALR64);
122     HasLinkReg = true;
123   } else if (Subtarget->hasMips32r6()) {
124     // MIPS32r6 should use (JALR ZERO, $rs)
125     if (InMicroMipsMode)
126       TmpInst0.setOpcode(Mips::JRC16_MMR6);
127     else {
128       TmpInst0.setOpcode(Mips::JALR);
129       HasLinkReg = true;
130     }
131   } else if (Subtarget->inMicroMipsMode())
132     // microMIPS should use (JR_MM $rs)
133     TmpInst0.setOpcode(Mips::JR_MM);
134   else {
135     // Everything else should use (JR $rs)
136     TmpInst0.setOpcode(Mips::JR);
137   }
138 
139   MCOperand MCOp;
140 
141   if (HasLinkReg) {
142     unsigned ZeroReg = Subtarget->isGP64bit() ? Mips::ZERO_64 : Mips::ZERO;
143     TmpInst0.addOperand(MCOperand::createReg(ZeroReg));
144   }
145 
146   lowerOperand(MI->getOperand(0), MCOp);
147   TmpInst0.addOperand(MCOp);
148 
149   EmitToStreamer(OutStreamer, TmpInst0);
150 }
151 
152 // If there is an MO_JALR operand, insert:
153 //
154 // .reloc tmplabel, R_{MICRO}MIPS_JALR, symbol
155 // tmplabel:
156 //
157 // This is an optimization hint for the linker which may then replace
158 // an indirect call with a direct branch.
159 static void emitDirectiveRelocJalr(const MachineInstr &MI,
160                                    MCContext &OutContext,
161                                    TargetMachine &TM,
162                                    MCStreamer &OutStreamer,
163                                    const MipsSubtarget &Subtarget) {
164   for (unsigned int I = MI.getDesc().getNumOperands(), E = MI.getNumOperands();
165        I < E; ++I) {
166     MachineOperand MO = MI.getOperand(I);
167     if (MO.isMCSymbol() && (MO.getTargetFlags() & MipsII::MO_JALR)) {
168       MCSymbol *Callee = MO.getMCSymbol();
169       if (Callee && !Callee->getName().empty()) {
170         MCSymbol *OffsetLabel = OutContext.createTempSymbol();
171         const MCExpr *OffsetExpr =
172             MCSymbolRefExpr::create(OffsetLabel, OutContext);
173         const MCExpr *CaleeExpr =
174             MCSymbolRefExpr::create(Callee, OutContext);
175         OutStreamer.EmitRelocDirective
176             (*OffsetExpr,
177              Subtarget.inMicroMipsMode() ? "R_MICROMIPS_JALR" : "R_MIPS_JALR",
178              CaleeExpr, SMLoc(), *TM.getMCSubtargetInfo());
179         OutStreamer.EmitLabel(OffsetLabel);
180         return;
181       }
182     }
183   }
184 }
185 
186 void MipsAsmPrinter::EmitInstruction(const MachineInstr *MI) {
187   MipsTargetStreamer &TS = getTargetStreamer();
188   unsigned Opc = MI->getOpcode();
189   TS.forbidModuleDirective();
190 
191   if (MI->isDebugValue()) {
192     SmallString<128> Str;
193     raw_svector_ostream OS(Str);
194 
195     PrintDebugValueComment(MI, OS);
196     return;
197   }
198   if (MI->isDebugLabel())
199     return;
200 
201   // If we just ended a constant pool, mark it as such.
202   if (InConstantPool && Opc != Mips::CONSTPOOL_ENTRY) {
203     OutStreamer->EmitDataRegion(MCDR_DataRegionEnd);
204     InConstantPool = false;
205   }
206   if (Opc == Mips::CONSTPOOL_ENTRY) {
207     // CONSTPOOL_ENTRY - This instruction represents a floating
208     // constant pool in the function.  The first operand is the ID#
209     // for this instruction, the second is the index into the
210     // MachineConstantPool that this is, the third is the size in
211     // bytes of this constant pool entry.
212     // The required alignment is specified on the basic block holding this MI.
213     //
214     unsigned LabelId = (unsigned)MI->getOperand(0).getImm();
215     unsigned CPIdx = (unsigned)MI->getOperand(1).getIndex();
216 
217     // If this is the first entry of the pool, mark it.
218     if (!InConstantPool) {
219       OutStreamer->EmitDataRegion(MCDR_DataRegion);
220       InConstantPool = true;
221     }
222 
223     OutStreamer->EmitLabel(GetCPISymbol(LabelId));
224 
225     const MachineConstantPoolEntry &MCPE = MCP->getConstants()[CPIdx];
226     if (MCPE.isMachineConstantPoolEntry())
227       EmitMachineConstantPoolValue(MCPE.Val.MachineCPVal);
228     else
229       EmitGlobalConstant(MF->getDataLayout(), MCPE.Val.ConstVal);
230     return;
231   }
232 
233   switch (Opc) {
234   case Mips::PATCHABLE_FUNCTION_ENTER:
235     LowerPATCHABLE_FUNCTION_ENTER(*MI);
236     return;
237   case Mips::PATCHABLE_FUNCTION_EXIT:
238     LowerPATCHABLE_FUNCTION_EXIT(*MI);
239     return;
240   case Mips::PATCHABLE_TAIL_CALL:
241     LowerPATCHABLE_TAIL_CALL(*MI);
242     return;
243   }
244 
245   if (EmitJalrReloc &&
246       (MI->isReturn() || MI->isCall() || MI->isIndirectBranch())) {
247     emitDirectiveRelocJalr(*MI, OutContext, TM, *OutStreamer, *Subtarget);
248   }
249 
250   MachineBasicBlock::const_instr_iterator I = MI->getIterator();
251   MachineBasicBlock::const_instr_iterator E = MI->getParent()->instr_end();
252 
253   do {
254     // Do any auto-generated pseudo lowerings.
255     if (emitPseudoExpansionLowering(*OutStreamer, &*I))
256       continue;
257 
258     if (I->getOpcode() == Mips::PseudoReturn ||
259         I->getOpcode() == Mips::PseudoReturn64 ||
260         I->getOpcode() == Mips::PseudoIndirectBranch ||
261         I->getOpcode() == Mips::PseudoIndirectBranch64 ||
262         I->getOpcode() == Mips::TAILCALLREG ||
263         I->getOpcode() == Mips::TAILCALLREG64) {
264       emitPseudoIndirectBranch(*OutStreamer, &*I);
265       continue;
266     }
267 
268     // The inMips16Mode() test is not permanent.
269     // Some instructions are marked as pseudo right now which
270     // would make the test fail for the wrong reason but
271     // that will be fixed soon. We need this here because we are
272     // removing another test for this situation downstream in the
273     // callchain.
274     //
275     if (I->isPseudo() && !Subtarget->inMips16Mode()
276         && !isLongBranchPseudo(I->getOpcode()))
277       llvm_unreachable("Pseudo opcode found in EmitInstruction()");
278 
279     MCInst TmpInst0;
280     MCInstLowering.Lower(&*I, TmpInst0);
281     EmitToStreamer(*OutStreamer, TmpInst0);
282   } while ((++I != E) && I->isInsideBundle()); // Delay slot check
283 }
284 
285 //===----------------------------------------------------------------------===//
286 //
287 //  Mips Asm Directives
288 //
289 //  -- Frame directive "frame Stackpointer, Stacksize, RARegister"
290 //  Describe the stack frame.
291 //
292 //  -- Mask directives "(f)mask  bitmask, offset"
293 //  Tells the assembler which registers are saved and where.
294 //  bitmask - contain a little endian bitset indicating which registers are
295 //            saved on function prologue (e.g. with a 0x80000000 mask, the
296 //            assembler knows the register 31 (RA) is saved at prologue.
297 //  offset  - the position before stack pointer subtraction indicating where
298 //            the first saved register on prologue is located. (e.g. with a
299 //
300 //  Consider the following function prologue:
301 //
302 //    .frame  $fp,48,$ra
303 //    .mask   0xc0000000,-8
304 //       addiu $sp, $sp, -48
305 //       sw $ra, 40($sp)
306 //       sw $fp, 36($sp)
307 //
308 //    With a 0xc0000000 mask, the assembler knows the register 31 (RA) and
309 //    30 (FP) are saved at prologue. As the save order on prologue is from
310 //    left to right, RA is saved first. A -8 offset means that after the
311 //    stack pointer subtration, the first register in the mask (RA) will be
312 //    saved at address 48-8=40.
313 //
314 //===----------------------------------------------------------------------===//
315 
316 //===----------------------------------------------------------------------===//
317 // Mask directives
318 //===----------------------------------------------------------------------===//
319 
320 // Create a bitmask with all callee saved registers for CPU or Floating Point
321 // registers. For CPU registers consider RA, GP and FP for saving if necessary.
322 void MipsAsmPrinter::printSavedRegsBitmask() {
323   // CPU and FPU Saved Registers Bitmasks
324   unsigned CPUBitmask = 0, FPUBitmask = 0;
325   int CPUTopSavedRegOff, FPUTopSavedRegOff;
326 
327   // Set the CPU and FPU Bitmasks
328   const MachineFrameInfo &MFI = MF->getFrameInfo();
329   const TargetRegisterInfo *TRI = MF->getSubtarget().getRegisterInfo();
330   const std::vector<CalleeSavedInfo> &CSI = MFI.getCalleeSavedInfo();
331   // size of stack area to which FP callee-saved regs are saved.
332   unsigned CPURegSize = TRI->getRegSizeInBits(Mips::GPR32RegClass) / 8;
333   unsigned FGR32RegSize = TRI->getRegSizeInBits(Mips::FGR32RegClass) / 8;
334   unsigned AFGR64RegSize = TRI->getRegSizeInBits(Mips::AFGR64RegClass) / 8;
335   bool HasAFGR64Reg = false;
336   unsigned CSFPRegsSize = 0;
337 
338   for (const auto &I : CSI) {
339     unsigned Reg = I.getReg();
340     unsigned RegNum = TRI->getEncodingValue(Reg);
341 
342     // If it's a floating point register, set the FPU Bitmask.
343     // If it's a general purpose register, set the CPU Bitmask.
344     if (Mips::FGR32RegClass.contains(Reg)) {
345       FPUBitmask |= (1 << RegNum);
346       CSFPRegsSize += FGR32RegSize;
347     } else if (Mips::AFGR64RegClass.contains(Reg)) {
348       FPUBitmask |= (3 << RegNum);
349       CSFPRegsSize += AFGR64RegSize;
350       HasAFGR64Reg = true;
351     } else if (Mips::GPR32RegClass.contains(Reg))
352       CPUBitmask |= (1 << RegNum);
353   }
354 
355   // FP Regs are saved right below where the virtual frame pointer points to.
356   FPUTopSavedRegOff = FPUBitmask ?
357     (HasAFGR64Reg ? -AFGR64RegSize : -FGR32RegSize) : 0;
358 
359   // CPU Regs are saved below FP Regs.
360   CPUTopSavedRegOff = CPUBitmask ? -CSFPRegsSize - CPURegSize : 0;
361 
362   MipsTargetStreamer &TS = getTargetStreamer();
363   // Print CPUBitmask
364   TS.emitMask(CPUBitmask, CPUTopSavedRegOff);
365 
366   // Print FPUBitmask
367   TS.emitFMask(FPUBitmask, FPUTopSavedRegOff);
368 }
369 
370 //===----------------------------------------------------------------------===//
371 // Frame and Set directives
372 //===----------------------------------------------------------------------===//
373 
374 /// Frame Directive
375 void MipsAsmPrinter::emitFrameDirective() {
376   const TargetRegisterInfo &RI = *MF->getSubtarget().getRegisterInfo();
377 
378   unsigned stackReg  = RI.getFrameRegister(*MF);
379   unsigned returnReg = RI.getRARegister();
380   unsigned stackSize = MF->getFrameInfo().getStackSize();
381 
382   getTargetStreamer().emitFrame(stackReg, stackSize, returnReg);
383 }
384 
385 /// Emit Set directives.
386 const char *MipsAsmPrinter::getCurrentABIString() const {
387   switch (static_cast<MipsTargetMachine &>(TM).getABI().GetEnumValue()) {
388   case MipsABIInfo::ABI::O32:  return "abi32";
389   case MipsABIInfo::ABI::N32:  return "abiN32";
390   case MipsABIInfo::ABI::N64:  return "abi64";
391   default: llvm_unreachable("Unknown Mips ABI");
392   }
393 }
394 
395 void MipsAsmPrinter::EmitFunctionEntryLabel() {
396   MipsTargetStreamer &TS = getTargetStreamer();
397 
398   // NaCl sandboxing requires that indirect call instructions are masked.
399   // This means that function entry points should be bundle-aligned.
400   if (Subtarget->isTargetNaCl())
401     EmitAlignment(std::max(MF->getAlignment(), MIPS_NACL_BUNDLE_ALIGN));
402 
403   if (Subtarget->inMicroMipsMode()) {
404     TS.emitDirectiveSetMicroMips();
405     TS.setUsesMicroMips();
406     TS.updateABIInfo(*Subtarget);
407   } else
408     TS.emitDirectiveSetNoMicroMips();
409 
410   if (Subtarget->inMips16Mode())
411     TS.emitDirectiveSetMips16();
412   else
413     TS.emitDirectiveSetNoMips16();
414 
415   TS.emitDirectiveEnt(*CurrentFnSym);
416   OutStreamer->EmitLabel(CurrentFnSym);
417 }
418 
419 /// EmitFunctionBodyStart - Targets can override this to emit stuff before
420 /// the first basic block in the function.
421 void MipsAsmPrinter::EmitFunctionBodyStart() {
422   MipsTargetStreamer &TS = getTargetStreamer();
423 
424   MCInstLowering.Initialize(&MF->getContext());
425 
426   bool IsNakedFunction = MF->getFunction().hasFnAttribute(Attribute::Naked);
427   if (!IsNakedFunction)
428     emitFrameDirective();
429 
430   if (!IsNakedFunction)
431     printSavedRegsBitmask();
432 
433   if (!Subtarget->inMips16Mode()) {
434     TS.emitDirectiveSetNoReorder();
435     TS.emitDirectiveSetNoMacro();
436     TS.emitDirectiveSetNoAt();
437   }
438 }
439 
440 /// EmitFunctionBodyEnd - Targets can override this to emit stuff after
441 /// the last basic block in the function.
442 void MipsAsmPrinter::EmitFunctionBodyEnd() {
443   MipsTargetStreamer &TS = getTargetStreamer();
444 
445   // There are instruction for this macros, but they must
446   // always be at the function end, and we can't emit and
447   // break with BB logic.
448   if (!Subtarget->inMips16Mode()) {
449     TS.emitDirectiveSetAt();
450     TS.emitDirectiveSetMacro();
451     TS.emitDirectiveSetReorder();
452   }
453   TS.emitDirectiveEnd(CurrentFnSym->getName());
454   // Make sure to terminate any constant pools that were at the end
455   // of the function.
456   if (!InConstantPool)
457     return;
458   InConstantPool = false;
459   OutStreamer->EmitDataRegion(MCDR_DataRegionEnd);
460 }
461 
462 void MipsAsmPrinter::EmitBasicBlockEnd(const MachineBasicBlock &MBB) {
463   AsmPrinter::EmitBasicBlockEnd(MBB);
464   MipsTargetStreamer &TS = getTargetStreamer();
465   if (MBB.empty())
466     TS.emitDirectiveInsn();
467 }
468 
469 /// isBlockOnlyReachableByFallthough - Return true if the basic block has
470 /// exactly one predecessor and the control transfer mechanism between
471 /// the predecessor and this block is a fall-through.
472 bool MipsAsmPrinter::isBlockOnlyReachableByFallthrough(const MachineBasicBlock*
473                                                        MBB) const {
474   // The predecessor has to be immediately before this block.
475   const MachineBasicBlock *Pred = *MBB->pred_begin();
476 
477   // If the predecessor is a switch statement, assume a jump table
478   // implementation, so it is not a fall through.
479   if (const BasicBlock *bb = Pred->getBasicBlock())
480     if (isa<SwitchInst>(bb->getTerminator()))
481       return false;
482 
483   // If this is a landing pad, it isn't a fall through.  If it has no preds,
484   // then nothing falls through to it.
485   if (MBB->isEHPad() || MBB->pred_empty())
486     return false;
487 
488   // If there isn't exactly one predecessor, it can't be a fall through.
489   MachineBasicBlock::const_pred_iterator PI = MBB->pred_begin(), PI2 = PI;
490   ++PI2;
491 
492   if (PI2 != MBB->pred_end())
493     return false;
494 
495   // The predecessor has to be immediately before this block.
496   if (!Pred->isLayoutSuccessor(MBB))
497     return false;
498 
499   // If the block is completely empty, then it definitely does fall through.
500   if (Pred->empty())
501     return true;
502 
503   // Otherwise, check the last instruction.
504   // Check if the last terminator is an unconditional branch.
505   MachineBasicBlock::const_iterator I = Pred->end();
506   while (I != Pred->begin() && !(--I)->isTerminator()) ;
507 
508   return !I->isBarrier();
509 }
510 
511 // Print out an operand for an inline asm expression.
512 bool MipsAsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNum,
513                                      const char *ExtraCode, raw_ostream &O) {
514   // Does this asm operand have a single letter operand modifier?
515   if (ExtraCode && ExtraCode[0]) {
516     if (ExtraCode[1] != 0) return true; // Unknown modifier.
517 
518     const MachineOperand &MO = MI->getOperand(OpNum);
519     switch (ExtraCode[0]) {
520     default:
521       // See if this is a generic print operand
522       return AsmPrinter::PrintAsmOperand(MI, OpNum, ExtraCode, O);
523     case 'X': // hex const int
524       if ((MO.getType()) != MachineOperand::MO_Immediate)
525         return true;
526       O << "0x" << Twine::utohexstr(MO.getImm());
527       return false;
528     case 'x': // hex const int (low 16 bits)
529       if ((MO.getType()) != MachineOperand::MO_Immediate)
530         return true;
531       O << "0x" << Twine::utohexstr(MO.getImm() & 0xffff);
532       return false;
533     case 'd': // decimal const int
534       if ((MO.getType()) != MachineOperand::MO_Immediate)
535         return true;
536       O << MO.getImm();
537       return false;
538     case 'm': // decimal const int minus 1
539       if ((MO.getType()) != MachineOperand::MO_Immediate)
540         return true;
541       O << MO.getImm() - 1;
542       return false;
543     case 'y': // exact log2
544       if ((MO.getType()) != MachineOperand::MO_Immediate)
545         return true;
546       if (!isPowerOf2_64(MO.getImm()))
547         return true;
548       O << Log2_64(MO.getImm());
549       return false;
550     case 'z':
551       // $0 if zero, regular printing otherwise
552       if (MO.getType() == MachineOperand::MO_Immediate && MO.getImm() == 0) {
553         O << "$0";
554         return false;
555       }
556       // If not, call printOperand as normal.
557       break;
558     case 'D': // Second part of a double word register operand
559     case 'L': // Low order register of a double word register operand
560     case 'M': // High order register of a double word register operand
561     {
562       if (OpNum == 0)
563         return true;
564       const MachineOperand &FlagsOP = MI->getOperand(OpNum - 1);
565       if (!FlagsOP.isImm())
566         return true;
567       unsigned Flags = FlagsOP.getImm();
568       unsigned NumVals = InlineAsm::getNumOperandRegisters(Flags);
569       // Number of registers represented by this operand. We are looking
570       // for 2 for 32 bit mode and 1 for 64 bit mode.
571       if (NumVals != 2) {
572         if (Subtarget->isGP64bit() && NumVals == 1 && MO.isReg()) {
573           unsigned Reg = MO.getReg();
574           O << '$' << MipsInstPrinter::getRegisterName(Reg);
575           return false;
576         }
577         return true;
578       }
579 
580       unsigned RegOp = OpNum;
581       if (!Subtarget->isGP64bit()){
582         // Endianness reverses which register holds the high or low value
583         // between M and L.
584         switch(ExtraCode[0]) {
585         case 'M':
586           RegOp = (Subtarget->isLittle()) ? OpNum + 1 : OpNum;
587           break;
588         case 'L':
589           RegOp = (Subtarget->isLittle()) ? OpNum : OpNum + 1;
590           break;
591         case 'D': // Always the second part
592           RegOp = OpNum + 1;
593         }
594         if (RegOp >= MI->getNumOperands())
595           return true;
596         const MachineOperand &MO = MI->getOperand(RegOp);
597         if (!MO.isReg())
598           return true;
599         unsigned Reg = MO.getReg();
600         O << '$' << MipsInstPrinter::getRegisterName(Reg);
601         return false;
602       }
603       break;
604     }
605     case 'w':
606       // Print MSA registers for the 'f' constraint
607       // In LLVM, the 'w' modifier doesn't need to do anything.
608       // We can just call printOperand as normal.
609       break;
610     }
611   }
612 
613   printOperand(MI, OpNum, O);
614   return false;
615 }
616 
617 bool MipsAsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI,
618                                            unsigned OpNum,
619                                            const char *ExtraCode,
620                                            raw_ostream &O) {
621   assert(OpNum + 1 < MI->getNumOperands() && "Insufficient operands");
622   const MachineOperand &BaseMO = MI->getOperand(OpNum);
623   const MachineOperand &OffsetMO = MI->getOperand(OpNum + 1);
624   assert(BaseMO.isReg() && "Unexpected base pointer for inline asm memory operand.");
625   assert(OffsetMO.isImm() && "Unexpected offset for inline asm memory operand.");
626   int Offset = OffsetMO.getImm();
627 
628   // Currently we are expecting either no ExtraCode or 'D','M','L'.
629   if (ExtraCode) {
630     switch (ExtraCode[0]) {
631     case 'D':
632       Offset += 4;
633       break;
634     case 'M':
635       if (Subtarget->isLittle())
636         Offset += 4;
637       break;
638     case 'L':
639       if (!Subtarget->isLittle())
640         Offset += 4;
641       break;
642     default:
643       return true; // Unknown modifier.
644     }
645   }
646 
647   O << Offset << "($" << MipsInstPrinter::getRegisterName(BaseMO.getReg())
648     << ")";
649 
650   return false;
651 }
652 
653 void MipsAsmPrinter::printOperand(const MachineInstr *MI, int opNum,
654                                   raw_ostream &O) {
655   const MachineOperand &MO = MI->getOperand(opNum);
656   bool closeP = false;
657 
658   if (MO.getTargetFlags())
659     closeP = true;
660 
661   switch(MO.getTargetFlags()) {
662   case MipsII::MO_GPREL:    O << "%gp_rel("; break;
663   case MipsII::MO_GOT_CALL: O << "%call16("; break;
664   case MipsII::MO_GOT:      O << "%got(";    break;
665   case MipsII::MO_ABS_HI:   O << "%hi(";     break;
666   case MipsII::MO_ABS_LO:   O << "%lo(";     break;
667   case MipsII::MO_HIGHER:   O << "%higher("; break;
668   case MipsII::MO_HIGHEST:  O << "%highest(("; break;
669   case MipsII::MO_TLSGD:    O << "%tlsgd(";  break;
670   case MipsII::MO_GOTTPREL: O << "%gottprel("; break;
671   case MipsII::MO_TPREL_HI: O << "%tprel_hi("; break;
672   case MipsII::MO_TPREL_LO: O << "%tprel_lo("; break;
673   case MipsII::MO_GPOFF_HI: O << "%hi(%neg(%gp_rel("; break;
674   case MipsII::MO_GPOFF_LO: O << "%lo(%neg(%gp_rel("; break;
675   case MipsII::MO_GOT_DISP: O << "%got_disp("; break;
676   case MipsII::MO_GOT_PAGE: O << "%got_page("; break;
677   case MipsII::MO_GOT_OFST: O << "%got_ofst("; break;
678   }
679 
680   switch (MO.getType()) {
681     case MachineOperand::MO_Register:
682       O << '$'
683         << StringRef(MipsInstPrinter::getRegisterName(MO.getReg())).lower();
684       break;
685 
686     case MachineOperand::MO_Immediate:
687       O << MO.getImm();
688       break;
689 
690     case MachineOperand::MO_MachineBasicBlock:
691       MO.getMBB()->getSymbol()->print(O, MAI);
692       return;
693 
694     case MachineOperand::MO_GlobalAddress:
695       getSymbol(MO.getGlobal())->print(O, MAI);
696       break;
697 
698     case MachineOperand::MO_BlockAddress: {
699       MCSymbol *BA = GetBlockAddressSymbol(MO.getBlockAddress());
700       O << BA->getName();
701       break;
702     }
703 
704     case MachineOperand::MO_ConstantPoolIndex:
705       O << getDataLayout().getPrivateGlobalPrefix() << "CPI"
706         << getFunctionNumber() << "_" << MO.getIndex();
707       if (MO.getOffset())
708         O << "+" << MO.getOffset();
709       break;
710 
711     default:
712       llvm_unreachable("<unknown operand type>");
713   }
714 
715   if (closeP) O << ")";
716 }
717 
718 void MipsAsmPrinter::
719 printMemOperand(const MachineInstr *MI, int opNum, raw_ostream &O) {
720   // Load/Store memory operands -- imm($reg)
721   // If PIC target the target is loaded as the
722   // pattern lw $25,%call16($28)
723 
724   // opNum can be invalid if instruction has reglist as operand.
725   // MemOperand is always last operand of instruction (base + offset).
726   switch (MI->getOpcode()) {
727   default:
728     break;
729   case Mips::SWM32_MM:
730   case Mips::LWM32_MM:
731     opNum = MI->getNumOperands() - 2;
732     break;
733   }
734 
735   printOperand(MI, opNum+1, O);
736   O << "(";
737   printOperand(MI, opNum, O);
738   O << ")";
739 }
740 
741 void MipsAsmPrinter::
742 printMemOperandEA(const MachineInstr *MI, int opNum, raw_ostream &O) {
743   // when using stack locations for not load/store instructions
744   // print the same way as all normal 3 operand instructions.
745   printOperand(MI, opNum, O);
746   O << ", ";
747   printOperand(MI, opNum+1, O);
748 }
749 
750 void MipsAsmPrinter::
751 printFCCOperand(const MachineInstr *MI, int opNum, raw_ostream &O,
752                 const char *Modifier) {
753   const MachineOperand &MO = MI->getOperand(opNum);
754   O << Mips::MipsFCCToString((Mips::CondCode)MO.getImm());
755 }
756 
757 void MipsAsmPrinter::
758 printRegisterList(const MachineInstr *MI, int opNum, raw_ostream &O) {
759   for (int i = opNum, e = MI->getNumOperands(); i != e; ++i) {
760     if (i != opNum) O << ", ";
761     printOperand(MI, i, O);
762   }
763 }
764 
765 void MipsAsmPrinter::EmitStartOfAsmFile(Module &M) {
766   MipsTargetStreamer &TS = getTargetStreamer();
767 
768   // MipsTargetStreamer has an initialization order problem when emitting an
769   // object file directly (see MipsTargetELFStreamer for full details). Work
770   // around it by re-initializing the PIC state here.
771   TS.setPic(OutContext.getObjectFileInfo()->isPositionIndependent());
772 
773   // Compute MIPS architecture attributes based on the default subtarget
774   // that we'd have constructed. Module level directives aren't LTO
775   // clean anyhow.
776   // FIXME: For ifunc related functions we could iterate over and look
777   // for a feature string that doesn't match the default one.
778   const Triple &TT = TM.getTargetTriple();
779   StringRef CPU = MIPS_MC::selectMipsCPU(TT, TM.getTargetCPU());
780   StringRef FS = TM.getTargetFeatureString();
781   const MipsTargetMachine &MTM = static_cast<const MipsTargetMachine &>(TM);
782   const MipsSubtarget STI(TT, CPU, FS, MTM.isLittleEndian(), MTM, 0);
783 
784   bool IsABICalls = STI.isABICalls();
785   const MipsABIInfo &ABI = MTM.getABI();
786   if (IsABICalls) {
787     TS.emitDirectiveAbiCalls();
788     // FIXME: This condition should be a lot more complicated that it is here.
789     //        Ideally it should test for properties of the ABI and not the ABI
790     //        itself.
791     //        For the moment, I'm only correcting enough to make MIPS-IV work.
792     if (!isPositionIndependent() && STI.hasSym32())
793       TS.emitDirectiveOptionPic0();
794   }
795 
796   // Tell the assembler which ABI we are using
797   std::string SectionName = std::string(".mdebug.") + getCurrentABIString();
798   OutStreamer->SwitchSection(
799       OutContext.getELFSection(SectionName, ELF::SHT_PROGBITS, 0));
800 
801   // NaN: At the moment we only support:
802   // 1. .nan legacy (default)
803   // 2. .nan 2008
804   STI.isNaN2008() ? TS.emitDirectiveNaN2008()
805                   : TS.emitDirectiveNaNLegacy();
806 
807   // TODO: handle O64 ABI
808 
809   TS.updateABIInfo(STI);
810 
811   // We should always emit a '.module fp=...' but binutils 2.24 does not accept
812   // it. We therefore emit it when it contradicts the ABI defaults (-mfpxx or
813   // -mfp64) and omit it otherwise.
814   if ((ABI.IsO32() && (STI.isABI_FPXX() || STI.isFP64bit())) ||
815       STI.useSoftFloat())
816     TS.emitDirectiveModuleFP();
817 
818   // We should always emit a '.module [no]oddspreg' but binutils 2.24 does not
819   // accept it. We therefore emit it when it contradicts the default or an
820   // option has changed the default (i.e. FPXX) and omit it otherwise.
821   if (ABI.IsO32() && (!STI.useOddSPReg() || STI.isABI_FPXX()))
822     TS.emitDirectiveModuleOddSPReg();
823 }
824 
825 void MipsAsmPrinter::emitInlineAsmStart() const {
826   MipsTargetStreamer &TS = getTargetStreamer();
827 
828   // GCC's choice of assembler options for inline assembly code ('at', 'macro'
829   // and 'reorder') is different from LLVM's choice for generated code ('noat',
830   // 'nomacro' and 'noreorder').
831   // In order to maintain compatibility with inline assembly code which depends
832   // on GCC's assembler options being used, we have to switch to those options
833   // for the duration of the inline assembly block and then switch back.
834   TS.emitDirectiveSetPush();
835   TS.emitDirectiveSetAt();
836   TS.emitDirectiveSetMacro();
837   TS.emitDirectiveSetReorder();
838   OutStreamer->AddBlankLine();
839 }
840 
841 void MipsAsmPrinter::emitInlineAsmEnd(const MCSubtargetInfo &StartInfo,
842                                       const MCSubtargetInfo *EndInfo) const {
843   OutStreamer->AddBlankLine();
844   getTargetStreamer().emitDirectiveSetPop();
845 }
846 
847 void MipsAsmPrinter::EmitJal(const MCSubtargetInfo &STI, MCSymbol *Symbol) {
848   MCInst I;
849   I.setOpcode(Mips::JAL);
850   I.addOperand(
851       MCOperand::createExpr(MCSymbolRefExpr::create(Symbol, OutContext)));
852   OutStreamer->EmitInstruction(I, STI);
853 }
854 
855 void MipsAsmPrinter::EmitInstrReg(const MCSubtargetInfo &STI, unsigned Opcode,
856                                   unsigned Reg) {
857   MCInst I;
858   I.setOpcode(Opcode);
859   I.addOperand(MCOperand::createReg(Reg));
860   OutStreamer->EmitInstruction(I, STI);
861 }
862 
863 void MipsAsmPrinter::EmitInstrRegReg(const MCSubtargetInfo &STI,
864                                      unsigned Opcode, unsigned Reg1,
865                                      unsigned Reg2) {
866   MCInst I;
867   //
868   // Because of the current td files for Mips32, the operands for MTC1
869   // appear backwards from their normal assembly order. It's not a trivial
870   // change to fix this in the td file so we adjust for it here.
871   //
872   if (Opcode == Mips::MTC1) {
873     unsigned Temp = Reg1;
874     Reg1 = Reg2;
875     Reg2 = Temp;
876   }
877   I.setOpcode(Opcode);
878   I.addOperand(MCOperand::createReg(Reg1));
879   I.addOperand(MCOperand::createReg(Reg2));
880   OutStreamer->EmitInstruction(I, STI);
881 }
882 
883 void MipsAsmPrinter::EmitInstrRegRegReg(const MCSubtargetInfo &STI,
884                                         unsigned Opcode, unsigned Reg1,
885                                         unsigned Reg2, unsigned Reg3) {
886   MCInst I;
887   I.setOpcode(Opcode);
888   I.addOperand(MCOperand::createReg(Reg1));
889   I.addOperand(MCOperand::createReg(Reg2));
890   I.addOperand(MCOperand::createReg(Reg3));
891   OutStreamer->EmitInstruction(I, STI);
892 }
893 
894 void MipsAsmPrinter::EmitMovFPIntPair(const MCSubtargetInfo &STI,
895                                       unsigned MovOpc, unsigned Reg1,
896                                       unsigned Reg2, unsigned FPReg1,
897                                       unsigned FPReg2, bool LE) {
898   if (!LE) {
899     unsigned temp = Reg1;
900     Reg1 = Reg2;
901     Reg2 = temp;
902   }
903   EmitInstrRegReg(STI, MovOpc, Reg1, FPReg1);
904   EmitInstrRegReg(STI, MovOpc, Reg2, FPReg2);
905 }
906 
907 void MipsAsmPrinter::EmitSwapFPIntParams(const MCSubtargetInfo &STI,
908                                          Mips16HardFloatInfo::FPParamVariant PV,
909                                          bool LE, bool ToFP) {
910   using namespace Mips16HardFloatInfo;
911 
912   unsigned MovOpc = ToFP ? Mips::MTC1 : Mips::MFC1;
913   switch (PV) {
914   case FSig:
915     EmitInstrRegReg(STI, MovOpc, Mips::A0, Mips::F12);
916     break;
917   case FFSig:
918     EmitMovFPIntPair(STI, MovOpc, Mips::A0, Mips::A1, Mips::F12, Mips::F14, LE);
919     break;
920   case FDSig:
921     EmitInstrRegReg(STI, MovOpc, Mips::A0, Mips::F12);
922     EmitMovFPIntPair(STI, MovOpc, Mips::A2, Mips::A3, Mips::F14, Mips::F15, LE);
923     break;
924   case DSig:
925     EmitMovFPIntPair(STI, MovOpc, Mips::A0, Mips::A1, Mips::F12, Mips::F13, LE);
926     break;
927   case DDSig:
928     EmitMovFPIntPair(STI, MovOpc, Mips::A0, Mips::A1, Mips::F12, Mips::F13, LE);
929     EmitMovFPIntPair(STI, MovOpc, Mips::A2, Mips::A3, Mips::F14, Mips::F15, LE);
930     break;
931   case DFSig:
932     EmitMovFPIntPair(STI, MovOpc, Mips::A0, Mips::A1, Mips::F12, Mips::F13, LE);
933     EmitInstrRegReg(STI, MovOpc, Mips::A2, Mips::F14);
934     break;
935   case NoSig:
936     return;
937   }
938 }
939 
940 void MipsAsmPrinter::EmitSwapFPIntRetval(
941     const MCSubtargetInfo &STI, Mips16HardFloatInfo::FPReturnVariant RV,
942     bool LE) {
943   using namespace Mips16HardFloatInfo;
944 
945   unsigned MovOpc = Mips::MFC1;
946   switch (RV) {
947   case FRet:
948     EmitInstrRegReg(STI, MovOpc, Mips::V0, Mips::F0);
949     break;
950   case DRet:
951     EmitMovFPIntPair(STI, MovOpc, Mips::V0, Mips::V1, Mips::F0, Mips::F1, LE);
952     break;
953   case CFRet:
954     EmitMovFPIntPair(STI, MovOpc, Mips::V0, Mips::V1, Mips::F0, Mips::F1, LE);
955     break;
956   case CDRet:
957     EmitMovFPIntPair(STI, MovOpc, Mips::V0, Mips::V1, Mips::F0, Mips::F1, LE);
958     EmitMovFPIntPair(STI, MovOpc, Mips::A0, Mips::A1, Mips::F2, Mips::F3, LE);
959     break;
960   case NoFPRet:
961     break;
962   }
963 }
964 
965 void MipsAsmPrinter::EmitFPCallStub(
966     const char *Symbol, const Mips16HardFloatInfo::FuncSignature *Signature) {
967   using namespace Mips16HardFloatInfo;
968 
969   MCSymbol *MSymbol = OutContext.getOrCreateSymbol(StringRef(Symbol));
970   bool LE = getDataLayout().isLittleEndian();
971   // Construct a local MCSubtargetInfo here.
972   // This is because the MachineFunction won't exist (but have not yet been
973   // freed) and since we're at the global level we can use the default
974   // constructed subtarget.
975   std::unique_ptr<MCSubtargetInfo> STI(TM.getTarget().createMCSubtargetInfo(
976       TM.getTargetTriple().str(), TM.getTargetCPU(),
977       TM.getTargetFeatureString()));
978 
979   //
980   // .global xxxx
981   //
982   OutStreamer->EmitSymbolAttribute(MSymbol, MCSA_Global);
983   const char *RetType;
984   //
985   // make the comment field identifying the return and parameter
986   // types of the floating point stub
987   // # Stub function to call rettype xxxx (params)
988   //
989   switch (Signature->RetSig) {
990   case FRet:
991     RetType = "float";
992     break;
993   case DRet:
994     RetType = "double";
995     break;
996   case CFRet:
997     RetType = "complex";
998     break;
999   case CDRet:
1000     RetType = "double complex";
1001     break;
1002   case NoFPRet:
1003     RetType = "";
1004     break;
1005   }
1006   const char *Parms;
1007   switch (Signature->ParamSig) {
1008   case FSig:
1009     Parms = "float";
1010     break;
1011   case FFSig:
1012     Parms = "float, float";
1013     break;
1014   case FDSig:
1015     Parms = "float, double";
1016     break;
1017   case DSig:
1018     Parms = "double";
1019     break;
1020   case DDSig:
1021     Parms = "double, double";
1022     break;
1023   case DFSig:
1024     Parms = "double, float";
1025     break;
1026   case NoSig:
1027     Parms = "";
1028     break;
1029   }
1030   OutStreamer->AddComment("\t# Stub function to call " + Twine(RetType) + " " +
1031                           Twine(Symbol) + " (" + Twine(Parms) + ")");
1032   //
1033   // probably not necessary but we save and restore the current section state
1034   //
1035   OutStreamer->PushSection();
1036   //
1037   // .section mips16.call.fpxxxx,"ax",@progbits
1038   //
1039   MCSectionELF *M = OutContext.getELFSection(
1040       ".mips16.call.fp." + std::string(Symbol), ELF::SHT_PROGBITS,
1041       ELF::SHF_ALLOC | ELF::SHF_EXECINSTR);
1042   OutStreamer->SwitchSection(M, nullptr);
1043   //
1044   // .align 2
1045   //
1046   OutStreamer->EmitValueToAlignment(4);
1047   MipsTargetStreamer &TS = getTargetStreamer();
1048   //
1049   // .set nomips16
1050   // .set nomicromips
1051   //
1052   TS.emitDirectiveSetNoMips16();
1053   TS.emitDirectiveSetNoMicroMips();
1054   //
1055   // .ent __call_stub_fp_xxxx
1056   // .type  __call_stub_fp_xxxx,@function
1057   //  __call_stub_fp_xxxx:
1058   //
1059   std::string x = "__call_stub_fp_" + std::string(Symbol);
1060   MCSymbolELF *Stub =
1061       cast<MCSymbolELF>(OutContext.getOrCreateSymbol(StringRef(x)));
1062   TS.emitDirectiveEnt(*Stub);
1063   MCSymbol *MType =
1064       OutContext.getOrCreateSymbol("__call_stub_fp_" + Twine(Symbol));
1065   OutStreamer->EmitSymbolAttribute(MType, MCSA_ELF_TypeFunction);
1066   OutStreamer->EmitLabel(Stub);
1067 
1068   // Only handle non-pic for now.
1069   assert(!isPositionIndependent() &&
1070          "should not be here if we are compiling pic");
1071   TS.emitDirectiveSetReorder();
1072   //
1073   // We need to add a MipsMCExpr class to MCTargetDesc to fully implement
1074   // stubs without raw text but this current patch is for compiler generated
1075   // functions and they all return some value.
1076   // The calling sequence for non pic is different in that case and we need
1077   // to implement %lo and %hi in order to handle the case of no return value
1078   // See the corresponding method in Mips16HardFloat for details.
1079   //
1080   // mov the return address to S2.
1081   // we have no stack space to store it and we are about to make another call.
1082   // We need to make sure that the enclosing function knows to save S2
1083   // This should have already been handled.
1084   //
1085   // Mov $18, $31
1086 
1087   EmitInstrRegRegReg(*STI, Mips::OR, Mips::S2, Mips::RA, Mips::ZERO);
1088 
1089   EmitSwapFPIntParams(*STI, Signature->ParamSig, LE, true);
1090 
1091   // Jal xxxx
1092   //
1093   EmitJal(*STI, MSymbol);
1094 
1095   // fix return values
1096   EmitSwapFPIntRetval(*STI, Signature->RetSig, LE);
1097   //
1098   // do the return
1099   // if (Signature->RetSig == NoFPRet)
1100   //  llvm_unreachable("should not be any stubs here with no return value");
1101   // else
1102   EmitInstrReg(*STI, Mips::JR, Mips::S2);
1103 
1104   MCSymbol *Tmp = OutContext.createTempSymbol();
1105   OutStreamer->EmitLabel(Tmp);
1106   const MCSymbolRefExpr *E = MCSymbolRefExpr::create(Stub, OutContext);
1107   const MCSymbolRefExpr *T = MCSymbolRefExpr::create(Tmp, OutContext);
1108   const MCExpr *T_min_E = MCBinaryExpr::createSub(T, E, OutContext);
1109   OutStreamer->emitELFSize(Stub, T_min_E);
1110   TS.emitDirectiveEnd(x);
1111   OutStreamer->PopSection();
1112 }
1113 
1114 void MipsAsmPrinter::EmitEndOfAsmFile(Module &M) {
1115   // Emit needed stubs
1116   //
1117   for (std::map<
1118            const char *,
1119            const Mips16HardFloatInfo::FuncSignature *>::const_iterator
1120            it = StubsNeeded.begin();
1121        it != StubsNeeded.end(); ++it) {
1122     const char *Symbol = it->first;
1123     const Mips16HardFloatInfo::FuncSignature *Signature = it->second;
1124     EmitFPCallStub(Symbol, Signature);
1125   }
1126   // return to the text section
1127   OutStreamer->SwitchSection(OutContext.getObjectFileInfo()->getTextSection());
1128 }
1129 
1130 void MipsAsmPrinter::EmitSled(const MachineInstr &MI, SledKind Kind) {
1131   const uint8_t NoopsInSledCount = Subtarget->isGP64bit() ? 15 : 11;
1132   // For mips32 we want to emit the following pattern:
1133   //
1134   // .Lxray_sled_N:
1135   //   ALIGN
1136   //   B .tmpN
1137   //   11 NOP instructions (44 bytes)
1138   //   ADDIU T9, T9, 52
1139   // .tmpN
1140   //
1141   // We need the 44 bytes (11 instructions) because at runtime, we'd
1142   // be patching over the full 48 bytes (12 instructions) with the following
1143   // pattern:
1144   //
1145   //   ADDIU    SP, SP, -8
1146   //   NOP
1147   //   SW       RA, 4(SP)
1148   //   SW       T9, 0(SP)
1149   //   LUI      T9, %hi(__xray_FunctionEntry/Exit)
1150   //   ORI      T9, T9, %lo(__xray_FunctionEntry/Exit)
1151   //   LUI      T0, %hi(function_id)
1152   //   JALR     T9
1153   //   ORI      T0, T0, %lo(function_id)
1154   //   LW       T9, 0(SP)
1155   //   LW       RA, 4(SP)
1156   //   ADDIU    SP, SP, 8
1157   //
1158   // We add 52 bytes to t9 because we want to adjust the function pointer to
1159   // the actual start of function i.e. the address just after the noop sled.
1160   // We do this because gp displacement relocation is emitted at the start of
1161   // of the function i.e after the nop sled and to correctly calculate the
1162   // global offset table address, t9 must hold the address of the instruction
1163   // containing the gp displacement relocation.
1164   // FIXME: Is this correct for the static relocation model?
1165   //
1166   // For mips64 we want to emit the following pattern:
1167   //
1168   // .Lxray_sled_N:
1169   //   ALIGN
1170   //   B .tmpN
1171   //   15 NOP instructions (60 bytes)
1172   // .tmpN
1173   //
1174   // We need the 60 bytes (15 instructions) because at runtime, we'd
1175   // be patching over the full 64 bytes (16 instructions) with the following
1176   // pattern:
1177   //
1178   //   DADDIU   SP, SP, -16
1179   //   NOP
1180   //   SD       RA, 8(SP)
1181   //   SD       T9, 0(SP)
1182   //   LUI      T9, %highest(__xray_FunctionEntry/Exit)
1183   //   ORI      T9, T9, %higher(__xray_FunctionEntry/Exit)
1184   //   DSLL     T9, T9, 16
1185   //   ORI      T9, T9, %hi(__xray_FunctionEntry/Exit)
1186   //   DSLL     T9, T9, 16
1187   //   ORI      T9, T9, %lo(__xray_FunctionEntry/Exit)
1188   //   LUI      T0, %hi(function_id)
1189   //   JALR     T9
1190   //   ADDIU    T0, T0, %lo(function_id)
1191   //   LD       T9, 0(SP)
1192   //   LD       RA, 8(SP)
1193   //   DADDIU   SP, SP, 16
1194   //
1195   OutStreamer->EmitCodeAlignment(4);
1196   auto CurSled = OutContext.createTempSymbol("xray_sled_", true);
1197   OutStreamer->EmitLabel(CurSled);
1198   auto Target = OutContext.createTempSymbol();
1199 
1200   // Emit "B .tmpN" instruction, which jumps over the nop sled to the actual
1201   // start of function
1202   const MCExpr *TargetExpr = MCSymbolRefExpr::create(
1203       Target, MCSymbolRefExpr::VariantKind::VK_None, OutContext);
1204   EmitToStreamer(*OutStreamer, MCInstBuilder(Mips::BEQ)
1205                                    .addReg(Mips::ZERO)
1206                                    .addReg(Mips::ZERO)
1207                                    .addExpr(TargetExpr));
1208 
1209   for (int8_t I = 0; I < NoopsInSledCount; I++)
1210     EmitToStreamer(*OutStreamer, MCInstBuilder(Mips::SLL)
1211                                      .addReg(Mips::ZERO)
1212                                      .addReg(Mips::ZERO)
1213                                      .addImm(0));
1214 
1215   OutStreamer->EmitLabel(Target);
1216 
1217   if (!Subtarget->isGP64bit()) {
1218     EmitToStreamer(*OutStreamer,
1219                    MCInstBuilder(Mips::ADDiu)
1220                        .addReg(Mips::T9)
1221                        .addReg(Mips::T9)
1222                        .addImm(0x34));
1223   }
1224 
1225   recordSled(CurSled, MI, Kind);
1226 }
1227 
1228 void MipsAsmPrinter::LowerPATCHABLE_FUNCTION_ENTER(const MachineInstr &MI) {
1229   EmitSled(MI, SledKind::FUNCTION_ENTER);
1230 }
1231 
1232 void MipsAsmPrinter::LowerPATCHABLE_FUNCTION_EXIT(const MachineInstr &MI) {
1233   EmitSled(MI, SledKind::FUNCTION_EXIT);
1234 }
1235 
1236 void MipsAsmPrinter::LowerPATCHABLE_TAIL_CALL(const MachineInstr &MI) {
1237   EmitSled(MI, SledKind::TAIL_CALL);
1238 }
1239 
1240 void MipsAsmPrinter::PrintDebugValueComment(const MachineInstr *MI,
1241                                            raw_ostream &OS) {
1242   // TODO: implement
1243 }
1244 
1245 // Emit .dtprelword or .dtpreldword directive
1246 // and value for debug thread local expression.
1247 void MipsAsmPrinter::EmitDebugValue(const MCExpr *Value, unsigned Size) const {
1248   if (auto *MipsExpr = dyn_cast<MipsMCExpr>(Value)) {
1249     if (MipsExpr && MipsExpr->getKind() == MipsMCExpr::MEK_DTPREL) {
1250       switch (Size) {
1251       case 4:
1252         OutStreamer->EmitDTPRel32Value(MipsExpr->getSubExpr());
1253         break;
1254       case 8:
1255         OutStreamer->EmitDTPRel64Value(MipsExpr->getSubExpr());
1256         break;
1257       default:
1258         llvm_unreachable("Unexpected size of expression value.");
1259       }
1260       return;
1261     }
1262   }
1263   AsmPrinter::EmitDebugValue(Value, Size);
1264 }
1265 
1266 // Align all targets of indirect branches on bundle size.  Used only if target
1267 // is NaCl.
1268 void MipsAsmPrinter::NaClAlignIndirectJumpTargets(MachineFunction &MF) {
1269   // Align all blocks that are jumped to through jump table.
1270   if (MachineJumpTableInfo *JtInfo = MF.getJumpTableInfo()) {
1271     const std::vector<MachineJumpTableEntry> &JT = JtInfo->getJumpTables();
1272     for (unsigned I = 0; I < JT.size(); ++I) {
1273       const std::vector<MachineBasicBlock*> &MBBs = JT[I].MBBs;
1274 
1275       for (unsigned J = 0; J < MBBs.size(); ++J)
1276         MBBs[J]->setAlignment(MIPS_NACL_BUNDLE_ALIGN);
1277     }
1278   }
1279 
1280   // If basic block address is taken, block can be target of indirect branch.
1281   for (auto &MBB : MF) {
1282     if (MBB.hasAddressTaken())
1283       MBB.setAlignment(MIPS_NACL_BUNDLE_ALIGN);
1284   }
1285 }
1286 
1287 bool MipsAsmPrinter::isLongBranchPseudo(int Opcode) const {
1288   return (Opcode == Mips::LONG_BRANCH_LUi
1289           || Opcode == Mips::LONG_BRANCH_LUi2Op
1290           || Opcode == Mips::LONG_BRANCH_LUi2Op_64
1291           || Opcode == Mips::LONG_BRANCH_ADDiu
1292           || Opcode == Mips::LONG_BRANCH_ADDiu2Op
1293           || Opcode == Mips::LONG_BRANCH_DADDiu
1294           || Opcode == Mips::LONG_BRANCH_DADDiu2Op);
1295 }
1296 
1297 // Force static initialization.
1298 extern "C" void LLVMInitializeMipsAsmPrinter() {
1299   RegisterAsmPrinter<MipsAsmPrinter> X(getTheMipsTarget());
1300   RegisterAsmPrinter<MipsAsmPrinter> Y(getTheMipselTarget());
1301   RegisterAsmPrinter<MipsAsmPrinter> A(getTheMips64Target());
1302   RegisterAsmPrinter<MipsAsmPrinter> B(getTheMips64elTarget());
1303 }
1304