1 //===- MIRParser.cpp - MIR serialization format parser implementation -----===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file implements the class that parses the optional LLVM IR and machine
11 // functions that are stored in MIR files.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "llvm/CodeGen/MIRParser/MIRParser.h"
16 #include "MIParser.h"
17 #include "llvm/ADT/DenseMap.h"
18 #include "llvm/ADT/StringRef.h"
19 #include "llvm/ADT/StringMap.h"
20 #include "llvm/ADT/STLExtras.h"
21 #include "llvm/AsmParser/Parser.h"
22 #include "llvm/AsmParser/SlotMapping.h"
23 #include "llvm/CodeGen/MachineConstantPool.h"
24 #include "llvm/CodeGen/MachineFunction.h"
25 #include "llvm/CodeGen/MachineFrameInfo.h"
26 #include "llvm/CodeGen/MachineRegisterInfo.h"
27 #include "llvm/CodeGen/MIRYamlMapping.h"
28 #include "llvm/IR/BasicBlock.h"
29 #include "llvm/IR/DiagnosticInfo.h"
30 #include "llvm/IR/Instructions.h"
31 #include "llvm/IR/LLVMContext.h"
32 #include "llvm/IR/Module.h"
33 #include "llvm/IR/ValueSymbolTable.h"
34 #include "llvm/Support/LineIterator.h"
35 #include "llvm/Support/SMLoc.h"
36 #include "llvm/Support/SourceMgr.h"
37 #include "llvm/Support/MemoryBuffer.h"
38 #include "llvm/Support/YAMLTraits.h"
39 #include <memory>
40 
41 using namespace llvm;
42 
43 namespace llvm {
44 
45 /// This class implements the parsing of LLVM IR that's embedded inside a MIR
46 /// file.
47 class MIRParserImpl {
48   SourceMgr SM;
49   StringRef Filename;
50   LLVMContext &Context;
51   StringMap<std::unique_ptr<yaml::MachineFunction>> Functions;
52   SlotMapping IRSlots;
53   /// Maps from register class names to register classes.
54   StringMap<const TargetRegisterClass *> Names2RegClasses;
55 
56 public:
57   MIRParserImpl(std::unique_ptr<MemoryBuffer> Contents, StringRef Filename,
58                 LLVMContext &Context);
59 
60   void reportDiagnostic(const SMDiagnostic &Diag);
61 
62   /// Report an error with the given message at unknown location.
63   ///
64   /// Always returns true.
65   bool error(const Twine &Message);
66 
67   /// Report an error with the given message at the given location.
68   ///
69   /// Always returns true.
70   bool error(SMLoc Loc, const Twine &Message);
71 
72   /// Report a given error with the location translated from the location in an
73   /// embedded string literal to a location in the MIR file.
74   ///
75   /// Always returns true.
76   bool error(const SMDiagnostic &Error, SMRange SourceRange);
77 
78   /// Try to parse the optional LLVM module and the machine functions in the MIR
79   /// file.
80   ///
81   /// Return null if an error occurred.
82   std::unique_ptr<Module> parse();
83 
84   /// Parse the machine function in the current YAML document.
85   ///
86   /// \param NoLLVMIR - set to true when the MIR file doesn't have LLVM IR.
87   /// A dummy IR function is created and inserted into the given module when
88   /// this parameter is true.
89   ///
90   /// Return true if an error occurred.
91   bool parseMachineFunction(yaml::Input &In, Module &M, bool NoLLVMIR);
92 
93   /// Initialize the machine function to the state that's described in the MIR
94   /// file.
95   ///
96   /// Return true if error occurred.
97   bool initializeMachineFunction(MachineFunction &MF);
98 
99   /// Initialize the machine basic block using it's YAML representation.
100   ///
101   /// Return true if an error occurred.
102   bool initializeMachineBasicBlock(MachineFunction &MF, MachineBasicBlock &MBB,
103                                    const yaml::MachineBasicBlock &YamlMBB,
104                                    const PerFunctionMIParsingState &PFS);
105 
106   bool
107   initializeRegisterInfo(const MachineFunction &MF,
108                          MachineRegisterInfo &RegInfo,
109                          const yaml::MachineFunction &YamlMF,
110                          DenseMap<unsigned, unsigned> &VirtualRegisterSlots);
111 
112   bool initializeFrameInfo(const Function &F, MachineFrameInfo &MFI,
113                            const yaml::MachineFunction &YamlMF,
114                            DenseMap<unsigned, int> &StackObjectSlots,
115                            DenseMap<unsigned, int> &FixedStackObjectSlots);
116 
117   bool initializeConstantPool(MachineConstantPool &ConstantPool,
118                               const yaml::MachineFunction &YamlMF,
119                               const MachineFunction &MF,
120                               DenseMap<unsigned, unsigned> &ConstantPoolSlots);
121 
122   bool initializeJumpTableInfo(MachineFunction &MF,
123                                const yaml::MachineJumpTable &YamlJTI,
124                                PerFunctionMIParsingState &PFS);
125 
126 private:
127   /// Return a MIR diagnostic converted from an MI string diagnostic.
128   SMDiagnostic diagFromMIStringDiag(const SMDiagnostic &Error,
129                                     SMRange SourceRange);
130 
131   /// Return a MIR diagnostic converted from an LLVM assembly diagnostic.
132   SMDiagnostic diagFromLLVMAssemblyDiag(const SMDiagnostic &Error,
133                                         SMRange SourceRange);
134 
135   /// Create an empty function with the given name.
136   void createDummyFunction(StringRef Name, Module &M);
137 
138   void initNames2RegClasses(const MachineFunction &MF);
139 
140   /// Check if the given identifier is a name of a register class.
141   ///
142   /// Return null if the name isn't a register class.
143   const TargetRegisterClass *getRegClass(const MachineFunction &MF,
144                                          StringRef Name);
145 };
146 
147 } // end namespace llvm
148 
149 MIRParserImpl::MIRParserImpl(std::unique_ptr<MemoryBuffer> Contents,
150                              StringRef Filename, LLVMContext &Context)
151     : SM(), Filename(Filename), Context(Context) {
152   SM.AddNewSourceBuffer(std::move(Contents), SMLoc());
153 }
154 
155 bool MIRParserImpl::error(const Twine &Message) {
156   Context.diagnose(DiagnosticInfoMIRParser(
157       DS_Error, SMDiagnostic(Filename, SourceMgr::DK_Error, Message.str())));
158   return true;
159 }
160 
161 bool MIRParserImpl::error(SMLoc Loc, const Twine &Message) {
162   Context.diagnose(DiagnosticInfoMIRParser(
163       DS_Error, SM.GetMessage(Loc, SourceMgr::DK_Error, Message)));
164   return true;
165 }
166 
167 bool MIRParserImpl::error(const SMDiagnostic &Error, SMRange SourceRange) {
168   assert(Error.getKind() == SourceMgr::DK_Error && "Expected an error");
169   reportDiagnostic(diagFromMIStringDiag(Error, SourceRange));
170   return true;
171 }
172 
173 void MIRParserImpl::reportDiagnostic(const SMDiagnostic &Diag) {
174   DiagnosticSeverity Kind;
175   switch (Diag.getKind()) {
176   case SourceMgr::DK_Error:
177     Kind = DS_Error;
178     break;
179   case SourceMgr::DK_Warning:
180     Kind = DS_Warning;
181     break;
182   case SourceMgr::DK_Note:
183     Kind = DS_Note;
184     break;
185   }
186   Context.diagnose(DiagnosticInfoMIRParser(Kind, Diag));
187 }
188 
189 static void handleYAMLDiag(const SMDiagnostic &Diag, void *Context) {
190   reinterpret_cast<MIRParserImpl *>(Context)->reportDiagnostic(Diag);
191 }
192 
193 std::unique_ptr<Module> MIRParserImpl::parse() {
194   yaml::Input In(SM.getMemoryBuffer(SM.getMainFileID())->getBuffer(),
195                  /*Ctxt=*/nullptr, handleYAMLDiag, this);
196   In.setContext(&In);
197 
198   if (!In.setCurrentDocument()) {
199     if (In.error())
200       return nullptr;
201     // Create an empty module when the MIR file is empty.
202     return llvm::make_unique<Module>(Filename, Context);
203   }
204 
205   std::unique_ptr<Module> M;
206   bool NoLLVMIR = false;
207   // Parse the block scalar manually so that we can return unique pointer
208   // without having to go trough YAML traits.
209   if (const auto *BSN =
210           dyn_cast_or_null<yaml::BlockScalarNode>(In.getCurrentNode())) {
211     SMDiagnostic Error;
212     M = parseAssembly(MemoryBufferRef(BSN->getValue(), Filename), Error,
213                       Context, &IRSlots);
214     if (!M) {
215       reportDiagnostic(diagFromLLVMAssemblyDiag(Error, BSN->getSourceRange()));
216       return M;
217     }
218     In.nextDocument();
219     if (!In.setCurrentDocument())
220       return M;
221   } else {
222     // Create an new, empty module.
223     M = llvm::make_unique<Module>(Filename, Context);
224     NoLLVMIR = true;
225   }
226 
227   // Parse the machine functions.
228   do {
229     if (parseMachineFunction(In, *M, NoLLVMIR))
230       return nullptr;
231     In.nextDocument();
232   } while (In.setCurrentDocument());
233 
234   return M;
235 }
236 
237 bool MIRParserImpl::parseMachineFunction(yaml::Input &In, Module &M,
238                                          bool NoLLVMIR) {
239   auto MF = llvm::make_unique<yaml::MachineFunction>();
240   yaml::yamlize(In, *MF, false);
241   if (In.error())
242     return true;
243   auto FunctionName = MF->Name;
244   if (Functions.find(FunctionName) != Functions.end())
245     return error(Twine("redefinition of machine function '") + FunctionName +
246                  "'");
247   Functions.insert(std::make_pair(FunctionName, std::move(MF)));
248   if (NoLLVMIR)
249     createDummyFunction(FunctionName, M);
250   else if (!M.getFunction(FunctionName))
251     return error(Twine("function '") + FunctionName +
252                  "' isn't defined in the provided LLVM IR");
253   return false;
254 }
255 
256 void MIRParserImpl::createDummyFunction(StringRef Name, Module &M) {
257   auto &Context = M.getContext();
258   Function *F = cast<Function>(M.getOrInsertFunction(
259       Name, FunctionType::get(Type::getVoidTy(Context), false)));
260   BasicBlock *BB = BasicBlock::Create(Context, "entry", F);
261   new UnreachableInst(Context, BB);
262 }
263 
264 bool MIRParserImpl::initializeMachineFunction(MachineFunction &MF) {
265   auto It = Functions.find(MF.getName());
266   if (It == Functions.end())
267     return error(Twine("no machine function information for function '") +
268                  MF.getName() + "' in the MIR file");
269   // TODO: Recreate the machine function.
270   const yaml::MachineFunction &YamlMF = *It->getValue();
271   if (YamlMF.Alignment)
272     MF.setAlignment(YamlMF.Alignment);
273   MF.setExposesReturnsTwice(YamlMF.ExposesReturnsTwice);
274   MF.setHasInlineAsm(YamlMF.HasInlineAsm);
275   PerFunctionMIParsingState PFS;
276   if (initializeRegisterInfo(MF, MF.getRegInfo(), YamlMF,
277                              PFS.VirtualRegisterSlots))
278     return true;
279   if (initializeFrameInfo(*MF.getFunction(), *MF.getFrameInfo(), YamlMF,
280                           PFS.StackObjectSlots, PFS.FixedStackObjectSlots))
281     return true;
282   if (!YamlMF.Constants.empty()) {
283     auto *ConstantPool = MF.getConstantPool();
284     assert(ConstantPool && "Constant pool must be created");
285     if (initializeConstantPool(*ConstantPool, YamlMF, MF,
286                                PFS.ConstantPoolSlots))
287       return true;
288   }
289 
290   const auto &F = *MF.getFunction();
291   for (const auto &YamlMBB : YamlMF.BasicBlocks) {
292     const BasicBlock *BB = nullptr;
293     const yaml::StringValue &Name = YamlMBB.Name;
294     if (!Name.Value.empty()) {
295       BB = dyn_cast_or_null<BasicBlock>(
296           F.getValueSymbolTable().lookup(Name.Value));
297       if (!BB)
298         return error(Name.SourceRange.Start,
299                      Twine("basic block '") + Name.Value +
300                          "' is not defined in the function '" + MF.getName() +
301                          "'");
302     }
303     auto *MBB = MF.CreateMachineBasicBlock(BB);
304     MF.insert(MF.end(), MBB);
305     bool WasInserted =
306         PFS.MBBSlots.insert(std::make_pair(YamlMBB.ID, MBB)).second;
307     if (!WasInserted)
308       return error(Twine("redefinition of machine basic block with id #") +
309                    Twine(YamlMBB.ID));
310   }
311 
312   if (YamlMF.BasicBlocks.empty())
313     return error(Twine("machine function '") + Twine(MF.getName()) +
314                  "' requires at least one machine basic block in its body");
315   // Initialize the jump table after creating all the MBBs so that the MBB
316   // references can be resolved.
317   if (!YamlMF.JumpTableInfo.Entries.empty() &&
318       initializeJumpTableInfo(MF, YamlMF.JumpTableInfo, PFS))
319     return true;
320   // Initialize the machine basic blocks after creating them all so that the
321   // machine instructions parser can resolve the MBB references.
322   unsigned I = 0;
323   for (const auto &YamlMBB : YamlMF.BasicBlocks) {
324     if (initializeMachineBasicBlock(MF, *MF.getBlockNumbered(I++), YamlMBB,
325                                     PFS))
326       return true;
327   }
328   return false;
329 }
330 
331 bool MIRParserImpl::initializeMachineBasicBlock(
332     MachineFunction &MF, MachineBasicBlock &MBB,
333     const yaml::MachineBasicBlock &YamlMBB,
334     const PerFunctionMIParsingState &PFS) {
335   MBB.setAlignment(YamlMBB.Alignment);
336   if (YamlMBB.AddressTaken)
337     MBB.setHasAddressTaken();
338   MBB.setIsLandingPad(YamlMBB.IsLandingPad);
339   SMDiagnostic Error;
340   // Parse the successors.
341   for (const auto &MBBSource : YamlMBB.Successors) {
342     MachineBasicBlock *SuccMBB = nullptr;
343     if (parseMBBReference(SuccMBB, SM, MF, MBBSource.Value, PFS, IRSlots,
344                           Error))
345       return error(Error, MBBSource.SourceRange);
346     // TODO: Report an error when adding the same successor more than once.
347     MBB.addSuccessor(SuccMBB);
348   }
349   // Parse the liveins.
350   for (const auto &LiveInSource : YamlMBB.LiveIns) {
351     unsigned Reg = 0;
352     if (parseNamedRegisterReference(Reg, SM, MF, LiveInSource.Value, PFS,
353                                     IRSlots, Error))
354       return error(Error, LiveInSource.SourceRange);
355     MBB.addLiveIn(Reg);
356   }
357   // Parse the instructions.
358   for (const auto &MISource : YamlMBB.Instructions) {
359     MachineInstr *MI = nullptr;
360     if (parseMachineInstr(MI, SM, MF, MISource.Value, PFS, IRSlots, Error))
361       return error(Error, MISource.SourceRange);
362     MBB.insert(MBB.end(), MI);
363   }
364   return false;
365 }
366 
367 bool MIRParserImpl::initializeRegisterInfo(
368     const MachineFunction &MF, MachineRegisterInfo &RegInfo,
369     const yaml::MachineFunction &YamlMF,
370     DenseMap<unsigned, unsigned> &VirtualRegisterSlots) {
371   assert(RegInfo.isSSA());
372   if (!YamlMF.IsSSA)
373     RegInfo.leaveSSA();
374   assert(RegInfo.tracksLiveness());
375   if (!YamlMF.TracksRegLiveness)
376     RegInfo.invalidateLiveness();
377   RegInfo.enableSubRegLiveness(YamlMF.TracksSubRegLiveness);
378 
379   // Parse the virtual register information.
380   for (const auto &VReg : YamlMF.VirtualRegisters) {
381     const auto *RC = getRegClass(MF, VReg.Class.Value);
382     if (!RC)
383       return error(VReg.Class.SourceRange.Start,
384                    Twine("use of undefined register class '") +
385                        VReg.Class.Value + "'");
386     unsigned Reg = RegInfo.createVirtualRegister(RC);
387     // TODO: Report an error when the same virtual register with the same ID is
388     // redefined.
389     VirtualRegisterSlots.insert(std::make_pair(VReg.ID, Reg));
390   }
391   return false;
392 }
393 
394 bool MIRParserImpl::initializeFrameInfo(
395     const Function &F, MachineFrameInfo &MFI,
396     const yaml::MachineFunction &YamlMF,
397     DenseMap<unsigned, int> &StackObjectSlots,
398     DenseMap<unsigned, int> &FixedStackObjectSlots) {
399   const yaml::MachineFrameInfo &YamlMFI = YamlMF.FrameInfo;
400   MFI.setFrameAddressIsTaken(YamlMFI.IsFrameAddressTaken);
401   MFI.setReturnAddressIsTaken(YamlMFI.IsReturnAddressTaken);
402   MFI.setHasStackMap(YamlMFI.HasStackMap);
403   MFI.setHasPatchPoint(YamlMFI.HasPatchPoint);
404   MFI.setStackSize(YamlMFI.StackSize);
405   MFI.setOffsetAdjustment(YamlMFI.OffsetAdjustment);
406   if (YamlMFI.MaxAlignment)
407     MFI.ensureMaxAlignment(YamlMFI.MaxAlignment);
408   MFI.setAdjustsStack(YamlMFI.AdjustsStack);
409   MFI.setHasCalls(YamlMFI.HasCalls);
410   MFI.setMaxCallFrameSize(YamlMFI.MaxCallFrameSize);
411   MFI.setHasOpaqueSPAdjustment(YamlMFI.HasOpaqueSPAdjustment);
412   MFI.setHasVAStart(YamlMFI.HasVAStart);
413   MFI.setHasMustTailInVarArgFunc(YamlMFI.HasMustTailInVarArgFunc);
414 
415   // Initialize the fixed frame objects.
416   for (const auto &Object : YamlMF.FixedStackObjects) {
417     int ObjectIdx;
418     if (Object.Type != yaml::FixedMachineStackObject::SpillSlot)
419       ObjectIdx = MFI.CreateFixedObject(Object.Size, Object.Offset,
420                                         Object.IsImmutable, Object.IsAliased);
421     else
422       ObjectIdx = MFI.CreateFixedSpillStackObject(Object.Size, Object.Offset);
423     MFI.setObjectAlignment(ObjectIdx, Object.Alignment);
424     // TODO: Report an error when objects are redefined.
425     FixedStackObjectSlots.insert(std::make_pair(Object.ID, ObjectIdx));
426   }
427 
428   // Initialize the ordinary frame objects.
429   for (const auto &Object : YamlMF.StackObjects) {
430     int ObjectIdx;
431     const AllocaInst *Alloca = nullptr;
432     const yaml::StringValue &Name = Object.Name;
433     if (!Name.Value.empty()) {
434       Alloca = dyn_cast_or_null<AllocaInst>(
435           F.getValueSymbolTable().lookup(Name.Value));
436       if (!Alloca)
437         return error(Name.SourceRange.Start,
438                      "alloca instruction named '" + Name.Value +
439                          "' isn't defined in the function '" + F.getName() +
440                          "'");
441     }
442     if (Object.Type == yaml::MachineStackObject::VariableSized)
443       ObjectIdx = MFI.CreateVariableSizedObject(Object.Alignment, Alloca);
444     else
445       ObjectIdx = MFI.CreateStackObject(
446           Object.Size, Object.Alignment,
447           Object.Type == yaml::MachineStackObject::SpillSlot, Alloca);
448     MFI.setObjectOffset(ObjectIdx, Object.Offset);
449     // TODO: Report an error when objects are redefined.
450     StackObjectSlots.insert(std::make_pair(Object.ID, ObjectIdx));
451   }
452   return false;
453 }
454 
455 bool MIRParserImpl::initializeConstantPool(
456     MachineConstantPool &ConstantPool, const yaml::MachineFunction &YamlMF,
457     const MachineFunction &MF,
458     DenseMap<unsigned, unsigned> &ConstantPoolSlots) {
459   const auto &M = *MF.getFunction()->getParent();
460   SMDiagnostic Error;
461   for (const auto &YamlConstant : YamlMF.Constants) {
462     const Constant *Value = dyn_cast_or_null<Constant>(
463         parseConstantValue(YamlConstant.Value.Value, Error, M));
464     if (!Value)
465       return error(Error, YamlConstant.Value.SourceRange);
466     unsigned Alignment =
467         YamlConstant.Alignment
468             ? YamlConstant.Alignment
469             : M.getDataLayout().getPrefTypeAlignment(Value->getType());
470     // TODO: Report an error when the same constant pool value ID is redefined.
471     ConstantPoolSlots.insert(std::make_pair(
472         YamlConstant.ID, ConstantPool.getConstantPoolIndex(Value, Alignment)));
473   }
474   return false;
475 }
476 
477 bool MIRParserImpl::initializeJumpTableInfo(
478     MachineFunction &MF, const yaml::MachineJumpTable &YamlJTI,
479     PerFunctionMIParsingState &PFS) {
480   MachineJumpTableInfo *JTI = MF.getOrCreateJumpTableInfo(YamlJTI.Kind);
481   SMDiagnostic Error;
482   for (const auto &Entry : YamlJTI.Entries) {
483     std::vector<MachineBasicBlock *> Blocks;
484     for (const auto &MBBSource : Entry.Blocks) {
485       MachineBasicBlock *MBB = nullptr;
486       if (parseMBBReference(MBB, SM, MF, MBBSource.Value, PFS, IRSlots, Error))
487         return error(Error, MBBSource.SourceRange);
488       Blocks.push_back(MBB);
489     }
490     unsigned Index = JTI->createJumpTableIndex(Blocks);
491     // TODO: Report an error when the same jump table slot ID is redefined.
492     PFS.JumpTableSlots.insert(std::make_pair(Entry.ID, Index));
493   }
494   return false;
495 }
496 
497 SMDiagnostic MIRParserImpl::diagFromMIStringDiag(const SMDiagnostic &Error,
498                                                  SMRange SourceRange) {
499   assert(SourceRange.isValid() && "Invalid source range");
500   SMLoc Loc = SourceRange.Start;
501   bool HasQuote = Loc.getPointer() < SourceRange.End.getPointer() &&
502                   *Loc.getPointer() == '\'';
503   // Translate the location of the error from the location in the MI string to
504   // the corresponding location in the MIR file.
505   Loc = Loc.getFromPointer(Loc.getPointer() + Error.getColumnNo() +
506                            (HasQuote ? 1 : 0));
507 
508   // TODO: Translate any source ranges as well.
509   return SM.GetMessage(Loc, Error.getKind(), Error.getMessage(), None,
510                        Error.getFixIts());
511 }
512 
513 SMDiagnostic MIRParserImpl::diagFromLLVMAssemblyDiag(const SMDiagnostic &Error,
514                                                      SMRange SourceRange) {
515   assert(SourceRange.isValid());
516 
517   // Translate the location of the error from the location in the llvm IR string
518   // to the corresponding location in the MIR file.
519   auto LineAndColumn = SM.getLineAndColumn(SourceRange.Start);
520   unsigned Line = LineAndColumn.first + Error.getLineNo() - 1;
521   unsigned Column = Error.getColumnNo();
522   StringRef LineStr = Error.getLineContents();
523   SMLoc Loc = Error.getLoc();
524 
525   // Get the full line and adjust the column number by taking the indentation of
526   // LLVM IR into account.
527   for (line_iterator L(*SM.getMemoryBuffer(SM.getMainFileID()), false), E;
528        L != E; ++L) {
529     if (L.line_number() == Line) {
530       LineStr = *L;
531       Loc = SMLoc::getFromPointer(LineStr.data());
532       auto Indent = LineStr.find(Error.getLineContents());
533       if (Indent != StringRef::npos)
534         Column += Indent;
535       break;
536     }
537   }
538 
539   return SMDiagnostic(SM, Loc, Filename, Line, Column, Error.getKind(),
540                       Error.getMessage(), LineStr, Error.getRanges(),
541                       Error.getFixIts());
542 }
543 
544 void MIRParserImpl::initNames2RegClasses(const MachineFunction &MF) {
545   if (!Names2RegClasses.empty())
546     return;
547   const TargetRegisterInfo *TRI = MF.getSubtarget().getRegisterInfo();
548   for (unsigned I = 0, E = TRI->getNumRegClasses(); I < E; ++I) {
549     const auto *RC = TRI->getRegClass(I);
550     Names2RegClasses.insert(
551         std::make_pair(StringRef(TRI->getRegClassName(RC)).lower(), RC));
552   }
553 }
554 
555 const TargetRegisterClass *MIRParserImpl::getRegClass(const MachineFunction &MF,
556                                                       StringRef Name) {
557   initNames2RegClasses(MF);
558   auto RegClassInfo = Names2RegClasses.find(Name);
559   if (RegClassInfo == Names2RegClasses.end())
560     return nullptr;
561   return RegClassInfo->getValue();
562 }
563 
564 MIRParser::MIRParser(std::unique_ptr<MIRParserImpl> Impl)
565     : Impl(std::move(Impl)) {}
566 
567 MIRParser::~MIRParser() {}
568 
569 std::unique_ptr<Module> MIRParser::parseLLVMModule() { return Impl->parse(); }
570 
571 bool MIRParser::initializeMachineFunction(MachineFunction &MF) {
572   return Impl->initializeMachineFunction(MF);
573 }
574 
575 std::unique_ptr<MIRParser> llvm::createMIRParserFromFile(StringRef Filename,
576                                                          SMDiagnostic &Error,
577                                                          LLVMContext &Context) {
578   auto FileOrErr = MemoryBuffer::getFile(Filename);
579   if (std::error_code EC = FileOrErr.getError()) {
580     Error = SMDiagnostic(Filename, SourceMgr::DK_Error,
581                          "Could not open input file: " + EC.message());
582     return nullptr;
583   }
584   return createMIRParser(std::move(FileOrErr.get()), Context);
585 }
586 
587 std::unique_ptr<MIRParser>
588 llvm::createMIRParser(std::unique_ptr<MemoryBuffer> Contents,
589                       LLVMContext &Context) {
590   auto Filename = Contents->getBufferIdentifier();
591   return llvm::make_unique<MIRParser>(
592       llvm::make_unique<MIRParserImpl>(std::move(Contents), Filename, Context));
593 }
594