1#define MINIMAL_STDERR_OUTPUT
2
3#include "llvm/Analysis/Passes.h"
4#include "llvm/ExecutionEngine/ExecutionEngine.h"
5#include "llvm/ExecutionEngine/MCJIT.h"
6#include "llvm/ExecutionEngine/ObjectCache.h"
7#include "llvm/ExecutionEngine/SectionMemoryManager.h"
8#include "llvm/IR/DataLayout.h"
9#include "llvm/IR/DerivedTypes.h"
10#include "llvm/IR/IRBuilder.h"
11#include "llvm/IR/LLVMContext.h"
12#include "llvm/IR/LegacyPassManager.h"
13#include "llvm/IR/Module.h"
14#include "llvm/IR/Verifier.h"
15#include "llvm/IRReader/IRReader.h"
16#include "llvm/Support/CommandLine.h"
17#include "llvm/Support/FileSystem.h"
18#include "llvm/Support/Path.h"
19#include "llvm/Support/SourceMgr.h"
20#include "llvm/Support/TargetSelect.h"
21#include "llvm/Support/raw_ostream.h"
22#include "llvm/Transforms/Scalar.h"
23#include <cctype>
24#include <cstdio>
25#include <map>
26#include <string>
27#include <vector>
28using namespace llvm;
29
30//===----------------------------------------------------------------------===//
31// Command-line options
32//===----------------------------------------------------------------------===//
33
34cl::opt<std::string>
35InputIR("input-IR",
36        cl::desc("Specify the name of an IR file to load for function definitions"),
37        cl::value_desc("input IR file name"));
38
39cl::opt<bool>
40UseObjectCache("use-object-cache",
41               cl::desc("Enable use of the MCJIT object caching"),
42               cl::init(false));
43
44//===----------------------------------------------------------------------===//
45// Lexer
46//===----------------------------------------------------------------------===//
47
48// The lexer returns tokens [0-255] if it is an unknown character, otherwise one
49// of these for known things.
50enum Token {
51  tok_eof = -1,
52
53  // commands
54  tok_def = -2, tok_extern = -3,
55
56  // primary
57  tok_identifier = -4, tok_number = -5,
58
59  // control
60  tok_if = -6, tok_then = -7, tok_else = -8,
61  tok_for = -9, tok_in = -10,
62
63  // operators
64  tok_binary = -11, tok_unary = -12,
65
66  // var definition
67  tok_var = -13
68};
69
70static std::string IdentifierStr;  // Filled in if tok_identifier
71static double NumVal;              // Filled in if tok_number
72
73/// gettok - Return the next token from standard input.
74static int gettok() {
75  static int LastChar = ' ';
76
77  // Skip any whitespace.
78  while (isspace(LastChar))
79    LastChar = getchar();
80
81  if (isalpha(LastChar)) { // identifier: [a-zA-Z][a-zA-Z0-9]*
82    IdentifierStr = LastChar;
83    while (isalnum((LastChar = getchar())))
84      IdentifierStr += LastChar;
85
86    if (IdentifierStr == "def") return tok_def;
87    if (IdentifierStr == "extern") return tok_extern;
88    if (IdentifierStr == "if") return tok_if;
89    if (IdentifierStr == "then") return tok_then;
90    if (IdentifierStr == "else") return tok_else;
91    if (IdentifierStr == "for") return tok_for;
92    if (IdentifierStr == "in") return tok_in;
93    if (IdentifierStr == "binary") return tok_binary;
94    if (IdentifierStr == "unary") return tok_unary;
95    if (IdentifierStr == "var") return tok_var;
96    return tok_identifier;
97  }
98
99  if (isdigit(LastChar) || LastChar == '.') {   // Number: [0-9.]+
100    std::string NumStr;
101    do {
102      NumStr += LastChar;
103      LastChar = getchar();
104    } while (isdigit(LastChar) || LastChar == '.');
105
106    NumVal = strtod(NumStr.c_str(), 0);
107    return tok_number;
108  }
109
110  if (LastChar == '#') {
111    // Comment until end of line.
112    do LastChar = getchar();
113    while (LastChar != EOF && LastChar != '\n' && LastChar != '\r');
114
115    if (LastChar != EOF)
116      return gettok();
117  }
118
119  // Check for end of file.  Don't eat the EOF.
120  if (LastChar == EOF)
121    return tok_eof;
122
123  // Otherwise, just return the character as its ascii value.
124  int ThisChar = LastChar;
125  LastChar = getchar();
126  return ThisChar;
127}
128
129//===----------------------------------------------------------------------===//
130// Abstract Syntax Tree (aka Parse Tree)
131//===----------------------------------------------------------------------===//
132
133/// ExprAST - Base class for all expression nodes.
134class ExprAST {
135public:
136  virtual ~ExprAST() {}
137  virtual Value *Codegen() = 0;
138};
139
140/// NumberExprAST - Expression class for numeric literals like "1.0".
141class NumberExprAST : public ExprAST {
142  double Val;
143public:
144  NumberExprAST(double val) : Val(val) {}
145  virtual Value *Codegen();
146};
147
148/// VariableExprAST - Expression class for referencing a variable, like "a".
149class VariableExprAST : public ExprAST {
150  std::string Name;
151public:
152  VariableExprAST(const std::string &name) : Name(name) {}
153  const std::string &getName() const { return Name; }
154  virtual Value *Codegen();
155};
156
157/// UnaryExprAST - Expression class for a unary operator.
158class UnaryExprAST : public ExprAST {
159  char Opcode;
160  ExprAST *Operand;
161public:
162  UnaryExprAST(char opcode, ExprAST *operand)
163    : Opcode(opcode), Operand(operand) {}
164  virtual Value *Codegen();
165};
166
167/// BinaryExprAST - Expression class for a binary operator.
168class BinaryExprAST : public ExprAST {
169  char Op;
170  ExprAST *LHS, *RHS;
171public:
172  BinaryExprAST(char op, ExprAST *lhs, ExprAST *rhs)
173    : Op(op), LHS(lhs), RHS(rhs) {}
174  virtual Value *Codegen();
175};
176
177/// CallExprAST - Expression class for function calls.
178class CallExprAST : public ExprAST {
179  std::string Callee;
180  std::vector<ExprAST*> Args;
181public:
182  CallExprAST(const std::string &callee, std::vector<ExprAST*> &args)
183    : Callee(callee), Args(args) {}
184  virtual Value *Codegen();
185};
186
187/// IfExprAST - Expression class for if/then/else.
188class IfExprAST : public ExprAST {
189  ExprAST *Cond, *Then, *Else;
190public:
191  IfExprAST(ExprAST *cond, ExprAST *then, ExprAST *_else)
192  : Cond(cond), Then(then), Else(_else) {}
193  virtual Value *Codegen();
194};
195
196/// ForExprAST - Expression class for for/in.
197class ForExprAST : public ExprAST {
198  std::string VarName;
199  ExprAST *Start, *End, *Step, *Body;
200public:
201  ForExprAST(const std::string &varname, ExprAST *start, ExprAST *end,
202             ExprAST *step, ExprAST *body)
203    : VarName(varname), Start(start), End(end), Step(step), Body(body) {}
204  virtual Value *Codegen();
205};
206
207/// VarExprAST - Expression class for var/in
208class VarExprAST : public ExprAST {
209  std::vector<std::pair<std::string, ExprAST*> > VarNames;
210  ExprAST *Body;
211public:
212  VarExprAST(const std::vector<std::pair<std::string, ExprAST*> > &varnames,
213             ExprAST *body)
214  : VarNames(varnames), Body(body) {}
215
216  virtual Value *Codegen();
217};
218
219/// PrototypeAST - This class represents the "prototype" for a function,
220/// which captures its argument names as well as if it is an operator.
221class PrototypeAST {
222  std::string Name;
223  std::vector<std::string> Args;
224  bool isOperator;
225  unsigned Precedence;  // Precedence if a binary op.
226public:
227  PrototypeAST(const std::string &name, const std::vector<std::string> &args,
228               bool isoperator = false, unsigned prec = 0)
229  : Name(name), Args(args), isOperator(isoperator), Precedence(prec) {}
230
231  bool isUnaryOp() const { return isOperator && Args.size() == 1; }
232  bool isBinaryOp() const { return isOperator && Args.size() == 2; }
233
234  char getOperatorName() const {
235    assert(isUnaryOp() || isBinaryOp());
236    return Name[Name.size()-1];
237  }
238
239  unsigned getBinaryPrecedence() const { return Precedence; }
240
241  Function *Codegen();
242
243  void CreateArgumentAllocas(Function *F);
244};
245
246/// FunctionAST - This class represents a function definition itself.
247class FunctionAST {
248  PrototypeAST *Proto;
249  ExprAST *Body;
250public:
251  FunctionAST(PrototypeAST *proto, ExprAST *body)
252    : Proto(proto), Body(body) {}
253
254  Function *Codegen();
255};
256
257//===----------------------------------------------------------------------===//
258// Parser
259//===----------------------------------------------------------------------===//
260
261/// CurTok/getNextToken - Provide a simple token buffer.  CurTok is the current
262/// token the parser is looking at.  getNextToken reads another token from the
263/// lexer and updates CurTok with its results.
264static int CurTok;
265static int getNextToken() {
266  return CurTok = gettok();
267}
268
269/// BinopPrecedence - This holds the precedence for each binary operator that is
270/// defined.
271static std::map<char, int> BinopPrecedence;
272
273/// GetTokPrecedence - Get the precedence of the pending binary operator token.
274static int GetTokPrecedence() {
275  if (!isascii(CurTok))
276    return -1;
277
278  // Make sure it's a declared binop.
279  int TokPrec = BinopPrecedence[CurTok];
280  if (TokPrec <= 0) return -1;
281  return TokPrec;
282}
283
284/// Error* - These are little helper functions for error handling.
285ExprAST *Error(const char *Str) { fprintf(stderr, "Error: %s\n", Str);return 0;}
286PrototypeAST *ErrorP(const char *Str) { Error(Str); return 0; }
287FunctionAST *ErrorF(const char *Str) { Error(Str); return 0; }
288
289static ExprAST *ParseExpression();
290
291/// identifierexpr
292///   ::= identifier
293///   ::= identifier '(' expression* ')'
294static ExprAST *ParseIdentifierExpr() {
295  std::string IdName = IdentifierStr;
296
297  getNextToken();  // eat identifier.
298
299  if (CurTok != '(') // Simple variable ref.
300    return new VariableExprAST(IdName);
301
302  // Call.
303  getNextToken();  // eat (
304  std::vector<ExprAST*> Args;
305  if (CurTok != ')') {
306    while (1) {
307      ExprAST *Arg = ParseExpression();
308      if (!Arg) return 0;
309      Args.push_back(Arg);
310
311      if (CurTok == ')') break;
312
313      if (CurTok != ',')
314        return Error("Expected ')' or ',' in argument list");
315      getNextToken();
316    }
317  }
318
319  // Eat the ')'.
320  getNextToken();
321
322  return new CallExprAST(IdName, Args);
323}
324
325/// numberexpr ::= number
326static ExprAST *ParseNumberExpr() {
327  ExprAST *Result = new NumberExprAST(NumVal);
328  getNextToken(); // consume the number
329  return Result;
330}
331
332/// parenexpr ::= '(' expression ')'
333static ExprAST *ParseParenExpr() {
334  getNextToken();  // eat (.
335  ExprAST *V = ParseExpression();
336  if (!V) return 0;
337
338  if (CurTok != ')')
339    return Error("expected ')'");
340  getNextToken();  // eat ).
341  return V;
342}
343
344/// ifexpr ::= 'if' expression 'then' expression 'else' expression
345static ExprAST *ParseIfExpr() {
346  getNextToken();  // eat the if.
347
348  // condition.
349  ExprAST *Cond = ParseExpression();
350  if (!Cond) return 0;
351
352  if (CurTok != tok_then)
353    return Error("expected then");
354  getNextToken();  // eat the then
355
356  ExprAST *Then = ParseExpression();
357  if (Then == 0) return 0;
358
359  if (CurTok != tok_else)
360    return Error("expected else");
361
362  getNextToken();
363
364  ExprAST *Else = ParseExpression();
365  if (!Else) return 0;
366
367  return new IfExprAST(Cond, Then, Else);
368}
369
370/// forexpr ::= 'for' identifier '=' expr ',' expr (',' expr)? 'in' expression
371static ExprAST *ParseForExpr() {
372  getNextToken();  // eat the for.
373
374  if (CurTok != tok_identifier)
375    return Error("expected identifier after for");
376
377  std::string IdName = IdentifierStr;
378  getNextToken();  // eat identifier.
379
380  if (CurTok != '=')
381    return Error("expected '=' after for");
382  getNextToken();  // eat '='.
383
384
385  ExprAST *Start = ParseExpression();
386  if (Start == 0) return 0;
387  if (CurTok != ',')
388    return Error("expected ',' after for start value");
389  getNextToken();
390
391  ExprAST *End = ParseExpression();
392  if (End == 0) return 0;
393
394  // The step value is optional.
395  ExprAST *Step = 0;
396  if (CurTok == ',') {
397    getNextToken();
398    Step = ParseExpression();
399    if (Step == 0) return 0;
400  }
401
402  if (CurTok != tok_in)
403    return Error("expected 'in' after for");
404  getNextToken();  // eat 'in'.
405
406  ExprAST *Body = ParseExpression();
407  if (Body == 0) return 0;
408
409  return new ForExprAST(IdName, Start, End, Step, Body);
410}
411
412/// varexpr ::= 'var' identifier ('=' expression)?
413//                    (',' identifier ('=' expression)?)* 'in' expression
414static ExprAST *ParseVarExpr() {
415  getNextToken();  // eat the var.
416
417  std::vector<std::pair<std::string, ExprAST*> > VarNames;
418
419  // At least one variable name is required.
420  if (CurTok != tok_identifier)
421    return Error("expected identifier after var");
422
423  while (1) {
424    std::string Name = IdentifierStr;
425    getNextToken();  // eat identifier.
426
427    // Read the optional initializer.
428    ExprAST *Init = 0;
429    if (CurTok == '=') {
430      getNextToken(); // eat the '='.
431
432      Init = ParseExpression();
433      if (Init == 0) return 0;
434    }
435
436    VarNames.push_back(std::make_pair(Name, Init));
437
438    // End of var list, exit loop.
439    if (CurTok != ',') break;
440    getNextToken(); // eat the ','.
441
442    if (CurTok != tok_identifier)
443      return Error("expected identifier list after var");
444  }
445
446  // At this point, we have to have 'in'.
447  if (CurTok != tok_in)
448    return Error("expected 'in' keyword after 'var'");
449  getNextToken();  // eat 'in'.
450
451  ExprAST *Body = ParseExpression();
452  if (Body == 0) return 0;
453
454  return new VarExprAST(VarNames, Body);
455}
456
457/// primary
458///   ::= identifierexpr
459///   ::= numberexpr
460///   ::= parenexpr
461///   ::= ifexpr
462///   ::= forexpr
463///   ::= varexpr
464static ExprAST *ParsePrimary() {
465  switch (CurTok) {
466  default: return Error("unknown token when expecting an expression");
467  case tok_identifier: return ParseIdentifierExpr();
468  case tok_number:     return ParseNumberExpr();
469  case '(':            return ParseParenExpr();
470  case tok_if:         return ParseIfExpr();
471  case tok_for:        return ParseForExpr();
472  case tok_var:        return ParseVarExpr();
473  }
474}
475
476/// unary
477///   ::= primary
478///   ::= '!' unary
479static ExprAST *ParseUnary() {
480  // If the current token is not an operator, it must be a primary expr.
481  if (!isascii(CurTok) || CurTok == '(' || CurTok == ',')
482    return ParsePrimary();
483
484  // If this is a unary operator, read it.
485  int Opc = CurTok;
486  getNextToken();
487  if (ExprAST *Operand = ParseUnary())
488    return new UnaryExprAST(Opc, Operand);
489  return 0;
490}
491
492/// binoprhs
493///   ::= ('+' unary)*
494static ExprAST *ParseBinOpRHS(int ExprPrec, ExprAST *LHS) {
495  // If this is a binop, find its precedence.
496  while (1) {
497    int TokPrec = GetTokPrecedence();
498
499    // If this is a binop that binds at least as tightly as the current binop,
500    // consume it, otherwise we are done.
501    if (TokPrec < ExprPrec)
502      return LHS;
503
504    // Okay, we know this is a binop.
505    int BinOp = CurTok;
506    getNextToken();  // eat binop
507
508    // Parse the unary expression after the binary operator.
509    ExprAST *RHS = ParseUnary();
510    if (!RHS) return 0;
511
512    // If BinOp binds less tightly with RHS than the operator after RHS, let
513    // the pending operator take RHS as its LHS.
514    int NextPrec = GetTokPrecedence();
515    if (TokPrec < NextPrec) {
516      RHS = ParseBinOpRHS(TokPrec+1, RHS);
517      if (RHS == 0) return 0;
518    }
519
520    // Merge LHS/RHS.
521    LHS = new BinaryExprAST(BinOp, LHS, RHS);
522  }
523}
524
525/// expression
526///   ::= unary binoprhs
527///
528static ExprAST *ParseExpression() {
529  ExprAST *LHS = ParseUnary();
530  if (!LHS) return 0;
531
532  return ParseBinOpRHS(0, LHS);
533}
534
535/// prototype
536///   ::= id '(' id* ')'
537///   ::= binary LETTER number? (id, id)
538///   ::= unary LETTER (id)
539static PrototypeAST *ParsePrototype() {
540  std::string FnName;
541
542  unsigned Kind = 0; // 0 = identifier, 1 = unary, 2 = binary.
543  unsigned BinaryPrecedence = 30;
544
545  switch (CurTok) {
546  default:
547    return ErrorP("Expected function name in prototype");
548  case tok_identifier:
549    FnName = IdentifierStr;
550    Kind = 0;
551    getNextToken();
552    break;
553  case tok_unary:
554    getNextToken();
555    if (!isascii(CurTok))
556      return ErrorP("Expected unary operator");
557    FnName = "unary";
558    FnName += (char)CurTok;
559    Kind = 1;
560    getNextToken();
561    break;
562  case tok_binary:
563    getNextToken();
564    if (!isascii(CurTok))
565      return ErrorP("Expected binary operator");
566    FnName = "binary";
567    FnName += (char)CurTok;
568    Kind = 2;
569    getNextToken();
570
571    // Read the precedence if present.
572    if (CurTok == tok_number) {
573      if (NumVal < 1 || NumVal > 100)
574        return ErrorP("Invalid precedecnce: must be 1..100");
575      BinaryPrecedence = (unsigned)NumVal;
576      getNextToken();
577    }
578    break;
579  }
580
581  if (CurTok != '(')
582    return ErrorP("Expected '(' in prototype");
583
584  std::vector<std::string> ArgNames;
585  while (getNextToken() == tok_identifier)
586    ArgNames.push_back(IdentifierStr);
587  if (CurTok != ')')
588    return ErrorP("Expected ')' in prototype");
589
590  // success.
591  getNextToken();  // eat ')'.
592
593  // Verify right number of names for operator.
594  if (Kind && ArgNames.size() != Kind)
595    return ErrorP("Invalid number of operands for operator");
596
597  return new PrototypeAST(FnName, ArgNames, Kind != 0, BinaryPrecedence);
598}
599
600/// definition ::= 'def' prototype expression
601static FunctionAST *ParseDefinition() {
602  getNextToken();  // eat def.
603  PrototypeAST *Proto = ParsePrototype();
604  if (Proto == 0) return 0;
605
606  if (ExprAST *E = ParseExpression())
607    return new FunctionAST(Proto, E);
608  return 0;
609}
610
611/// toplevelexpr ::= expression
612static FunctionAST *ParseTopLevelExpr() {
613  if (ExprAST *E = ParseExpression()) {
614    // Make an anonymous proto.
615    PrototypeAST *Proto = new PrototypeAST("", std::vector<std::string>());
616    return new FunctionAST(Proto, E);
617  }
618  return 0;
619}
620
621/// external ::= 'extern' prototype
622static PrototypeAST *ParseExtern() {
623  getNextToken();  // eat extern.
624  return ParsePrototype();
625}
626
627//===----------------------------------------------------------------------===//
628// Quick and dirty hack
629//===----------------------------------------------------------------------===//
630
631// FIXME: Obviously we can do better than this
632std::string GenerateUniqueName(const char *root)
633{
634  static int i = 0;
635  char s[16];
636  sprintf(s, "%s%d", root, i++);
637  std::string S = s;
638  return S;
639}
640
641std::string MakeLegalFunctionName(std::string Name)
642{
643  std::string NewName;
644  if (!Name.length())
645      return GenerateUniqueName("anon_func_");
646
647  // Start with what we have
648  NewName = Name;
649
650  // Look for a numberic first character
651  if (NewName.find_first_of("0123456789") == 0) {
652    NewName.insert(0, 1, 'n');
653  }
654
655  // Replace illegal characters with their ASCII equivalent
656  std::string legal_elements = "_abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
657  size_t pos;
658  while ((pos = NewName.find_first_not_of(legal_elements)) != std::string::npos) {
659    char old_c = NewName.at(pos);
660    char new_str[16];
661    sprintf(new_str, "%d", (int)old_c);
662    NewName = NewName.replace(pos, 1, new_str);
663  }
664
665  return NewName;
666}
667
668//===----------------------------------------------------------------------===//
669// MCJIT object cache class
670//===----------------------------------------------------------------------===//
671
672class MCJITObjectCache : public ObjectCache {
673public:
674  MCJITObjectCache() {
675    // Set IR cache directory
676    sys::fs::current_path(CacheDir);
677    sys::path::append(CacheDir, "toy_object_cache");
678  }
679
680  virtual ~MCJITObjectCache() {
681  }
682
683  virtual void notifyObjectCompiled(const Module *M, const MemoryBuffer *Obj) {
684    // Get the ModuleID
685    const std::string ModuleID = M->getModuleIdentifier();
686
687    // If we've flagged this as an IR file, cache it
688    if (0 == ModuleID.compare(0, 3, "IR:")) {
689      std::string IRFileName = ModuleID.substr(3);
690      SmallString<128>IRCacheFile = CacheDir;
691      sys::path::append(IRCacheFile, IRFileName);
692      if (!sys::fs::exists(CacheDir.str()) && sys::fs::create_directory(CacheDir.str())) {
693        fprintf(stderr, "Unable to create cache directory\n");
694        return;
695      }
696      std::string ErrStr;
697      raw_fd_ostream IRObjectFile(IRCacheFile.c_str(), ErrStr, raw_fd_ostream::F_Binary);
698      IRObjectFile << Obj->getBuffer();
699    }
700  }
701
702  // MCJIT will call this function before compiling any module
703  // MCJIT takes ownership of both the MemoryBuffer object and the memory
704  // to which it refers.
705  virtual MemoryBuffer* getObject(const Module* M) {
706    // Get the ModuleID
707    const std::string ModuleID = M->getModuleIdentifier();
708
709    // If we've flagged this as an IR file, cache it
710    if (0 == ModuleID.compare(0, 3, "IR:")) {
711      std::string IRFileName = ModuleID.substr(3);
712      SmallString<128> IRCacheFile = CacheDir;
713      sys::path::append(IRCacheFile, IRFileName);
714      if (!sys::fs::exists(IRCacheFile.str())) {
715        // This file isn't in our cache
716        return NULL;
717      }
718      std::unique_ptr<MemoryBuffer> IRObjectBuffer;
719      MemoryBuffer::getFile(IRCacheFile.c_str(), IRObjectBuffer, -1, false);
720      // MCJIT will want to write into this buffer, and we don't want that
721      // because the file has probably just been mmapped.  Instead we make
722      // a copy.  The filed-based buffer will be released when it goes
723      // out of scope.
724      return MemoryBuffer::getMemBufferCopy(IRObjectBuffer->getBuffer());
725    }
726
727    return NULL;
728  }
729
730private:
731  SmallString<128> CacheDir;
732};
733
734//===----------------------------------------------------------------------===//
735// MCJIT helper class
736//===----------------------------------------------------------------------===//
737
738class MCJITHelper
739{
740public:
741  MCJITHelper(LLVMContext& C) : Context(C), OpenModule(NULL) {}
742  ~MCJITHelper();
743
744  Function *getFunction(const std::string FnName);
745  Module *getModuleForNewFunction();
746  void *getPointerToFunction(Function* F);
747  void *getPointerToNamedFunction(const std::string &Name);
748  ExecutionEngine *compileModule(Module *M);
749  void closeCurrentModule();
750  void addModule(Module *M);
751  void dump();
752
753private:
754  typedef std::vector<Module*> ModuleVector;
755
756  LLVMContext  &Context;
757  Module       *OpenModule;
758  ModuleVector  Modules;
759  std::map<Module *, ExecutionEngine *> EngineMap;
760  MCJITObjectCache OurObjectCache;
761};
762
763class HelpingMemoryManager : public SectionMemoryManager
764{
765  HelpingMemoryManager(const HelpingMemoryManager&) = delete;
766  void operator=(const HelpingMemoryManager&) = delete;
767
768public:
769  HelpingMemoryManager(MCJITHelper *Helper) : MasterHelper(Helper) {}
770  virtual ~HelpingMemoryManager() {}
771
772  /// This method returns the address of the specified function.
773  /// Our implementation will attempt to find functions in other
774  /// modules associated with the MCJITHelper to cross link functions
775  /// from one generated module to another.
776  ///
777  /// If \p AbortOnFailure is false and no function with the given name is
778  /// found, this function returns a null pointer. Otherwise, it prints a
779  /// message to stderr and aborts.
780  virtual void *getPointerToNamedFunction(const std::string &Name,
781                                          bool AbortOnFailure = true);
782private:
783  MCJITHelper *MasterHelper;
784};
785
786void *HelpingMemoryManager::getPointerToNamedFunction(const std::string &Name,
787                                        bool AbortOnFailure)
788{
789  // Try the standard symbol resolution first, but ask it not to abort.
790  void *pfn = SectionMemoryManager::getPointerToNamedFunction(Name, false);
791  if (pfn)
792    return pfn;
793
794  pfn = MasterHelper->getPointerToNamedFunction(Name);
795  if (!pfn && AbortOnFailure)
796    report_fatal_error("Program used external function '" + Name +
797                        "' which could not be resolved!");
798  return pfn;
799}
800
801MCJITHelper::~MCJITHelper()
802{
803  // Walk the vector of modules.
804  ModuleVector::iterator it, end;
805  for (it = Modules.begin(), end = Modules.end();
806       it != end; ++it) {
807    // See if we have an execution engine for this module.
808    std::map<Module*, ExecutionEngine*>::iterator mapIt = EngineMap.find(*it);
809    // If we have an EE, the EE owns the module so just delete the EE.
810    if (mapIt != EngineMap.end()) {
811      delete mapIt->second;
812    } else {
813      // Otherwise, we still own the module.  Delete it now.
814      delete *it;
815    }
816  }
817}
818
819Function *MCJITHelper::getFunction(const std::string FnName) {
820  ModuleVector::iterator begin = Modules.begin();
821  ModuleVector::iterator end = Modules.end();
822  ModuleVector::iterator it;
823  for (it = begin; it != end; ++it) {
824    Function *F = (*it)->getFunction(FnName);
825    if (F) {
826      if (*it == OpenModule)
827          return F;
828
829      assert(OpenModule != NULL);
830
831      // This function is in a module that has already been JITed.
832      // We need to generate a new prototype for external linkage.
833      Function *PF = OpenModule->getFunction(FnName);
834      if (PF && !PF->empty()) {
835        ErrorF("redefinition of function across modules");
836        return 0;
837      }
838
839      // If we don't have a prototype yet, create one.
840      if (!PF)
841        PF = Function::Create(F->getFunctionType(),
842                                      Function::ExternalLinkage,
843                                      FnName,
844                                      OpenModule);
845      return PF;
846    }
847  }
848  return NULL;
849}
850
851Module *MCJITHelper::getModuleForNewFunction() {
852  // If we have a Module that hasn't been JITed, use that.
853  if (OpenModule)
854    return OpenModule;
855
856  // Otherwise create a new Module.
857  std::string ModName = GenerateUniqueName("mcjit_module_");
858  Module *M = new Module(ModName, Context);
859  Modules.push_back(M);
860  OpenModule = M;
861  return M;
862}
863
864void *MCJITHelper::getPointerToFunction(Function* F) {
865  // Look for this function in an existing module
866  ModuleVector::iterator begin = Modules.begin();
867  ModuleVector::iterator end = Modules.end();
868  ModuleVector::iterator it;
869  std::string FnName = F->getName();
870  for (it = begin; it != end; ++it) {
871    Function *MF = (*it)->getFunction(FnName);
872    if (MF == F) {
873      std::map<Module*, ExecutionEngine*>::iterator eeIt = EngineMap.find(*it);
874      if (eeIt != EngineMap.end()) {
875        void *P = eeIt->second->getPointerToFunction(F);
876        if (P)
877          return P;
878      } else {
879        ExecutionEngine *EE = compileModule(*it);
880        void *P = EE->getPointerToFunction(F);
881        if (P)
882          return P;
883      }
884    }
885  }
886  return NULL;
887}
888
889void MCJITHelper::closeCurrentModule() {
890  OpenModule = NULL;
891}
892
893ExecutionEngine *MCJITHelper::compileModule(Module *M) {
894  if (M == OpenModule)
895    closeCurrentModule();
896
897  std::string ErrStr;
898  ExecutionEngine *NewEngine = EngineBuilder(M)
899                                            .setErrorStr(&ErrStr)
900                                            .setMCJITMemoryManager(new HelpingMemoryManager(this))
901                                            .create();
902  if (!NewEngine) {
903    fprintf(stderr, "Could not create ExecutionEngine: %s\n", ErrStr.c_str());
904    exit(1);
905  }
906
907  if (UseObjectCache)
908    NewEngine->setObjectCache(&OurObjectCache);
909
910  // Get the ModuleID so we can identify IR input files
911  const std::string ModuleID = M->getModuleIdentifier();
912
913  // If we've flagged this as an IR file, it doesn't need function passes run.
914  if (0 != ModuleID.compare(0, 3, "IR:")) {
915    // Create a function pass manager for this engine
916    FunctionPassManager *FPM = new FunctionPassManager(M);
917
918    // Set up the optimizer pipeline.  Start with registering info about how the
919    // target lays out data structures.
920    FPM->add(new DataLayout(*NewEngine->getDataLayout()));
921    // Provide basic AliasAnalysis support for GVN.
922    FPM->add(createBasicAliasAnalysisPass());
923    // Promote allocas to registers.
924    FPM->add(createPromoteMemoryToRegisterPass());
925    // Do simple "peephole" optimizations and bit-twiddling optzns.
926    FPM->add(createInstructionCombiningPass());
927    // Reassociate expressions.
928    FPM->add(createReassociatePass());
929    // Eliminate Common SubExpressions.
930    FPM->add(createGVNPass());
931    // Simplify the control flow graph (deleting unreachable blocks, etc).
932    FPM->add(createCFGSimplificationPass());
933    FPM->doInitialization();
934
935    // For each function in the module
936    Module::iterator it;
937    Module::iterator end = M->end();
938    for (it = M->begin(); it != end; ++it) {
939      // Run the FPM on this function
940      FPM->run(*it);
941    }
942
943    // We don't need this anymore
944    delete FPM;
945  }
946
947  // Store this engine
948  EngineMap[M] = NewEngine;
949  NewEngine->finalizeObject();
950
951  return NewEngine;
952}
953
954void *MCJITHelper::getPointerToNamedFunction(const std::string &Name)
955{
956  // Look for the functions in our modules, compiling only as necessary
957  ModuleVector::iterator begin = Modules.begin();
958  ModuleVector::iterator end = Modules.end();
959  ModuleVector::iterator it;
960  for (it = begin; it != end; ++it) {
961    Function *F = (*it)->getFunction(Name);
962    if (F && !F->empty()) {
963      std::map<Module*, ExecutionEngine*>::iterator eeIt = EngineMap.find(*it);
964      if (eeIt != EngineMap.end()) {
965        void *P = eeIt->second->getPointerToFunction(F);
966        if (P)
967          return P;
968      } else {
969        ExecutionEngine *EE = compileModule(*it);
970        void *P = EE->getPointerToFunction(F);
971        if (P)
972          return P;
973      }
974    }
975  }
976  return NULL;
977}
978
979void MCJITHelper::addModule(Module* M) {
980  Modules.push_back(M);
981}
982
983void MCJITHelper::dump()
984{
985  ModuleVector::iterator begin = Modules.begin();
986  ModuleVector::iterator end = Modules.end();
987  ModuleVector::iterator it;
988  for (it = begin; it != end; ++it)
989    (*it)->dump();
990}
991
992//===----------------------------------------------------------------------===//
993// Code Generation
994//===----------------------------------------------------------------------===//
995
996static MCJITHelper *TheHelper;
997static LLVMContext TheContext;
998static IRBuilder<> Builder(TheContext);
999static std::map<std::string, AllocaInst*> NamedValues;
1000
1001Value *ErrorV(const char *Str) { Error(Str); return 0; }
1002
1003/// CreateEntryBlockAlloca - Create an alloca instruction in the entry block of
1004/// the function.  This is used for mutable variables etc.
1005static AllocaInst *CreateEntryBlockAlloca(Function *TheFunction,
1006                                          const std::string &VarName) {
1007  IRBuilder<> TmpB(&TheFunction->getEntryBlock(),
1008                 TheFunction->getEntryBlock().begin());
1009  return TmpB.CreateAlloca(Type::getDoubleTy(TheContext), 0, VarName.c_str());
1010}
1011
1012Value *NumberExprAST::Codegen() {
1013  return ConstantFP::get(TheContext, APFloat(Val));
1014}
1015
1016Value *VariableExprAST::Codegen() {
1017  // Look this variable up in the function.
1018  Value *V = NamedValues[Name];
1019  char ErrStr[256];
1020  sprintf(ErrStr, "Unknown variable name %s", Name.c_str());
1021  if (V == 0) return ErrorV(ErrStr);
1022
1023  // Load the value.
1024  return Builder.CreateLoad(V, Name.c_str());
1025}
1026
1027Value *UnaryExprAST::Codegen() {
1028  Value *OperandV = Operand->Codegen();
1029  if (OperandV == 0) return 0;
1030
1031  Function *F = TheHelper->getFunction(MakeLegalFunctionName(std::string("unary")+Opcode));
1032  if (F == 0)
1033    return ErrorV("Unknown unary operator");
1034
1035  return Builder.CreateCall(F, OperandV, "unop");
1036}
1037
1038Value *BinaryExprAST::Codegen() {
1039  // Special case '=' because we don't want to emit the LHS as an expression.
1040  if (Op == '=') {
1041    // Assignment requires the LHS to be an identifier.
1042    VariableExprAST *LHSE = static_cast<VariableExprAST*>(LHS);
1043    if (!LHSE)
1044      return ErrorV("destination of '=' must be a variable");
1045    // Codegen the RHS.
1046    Value *Val = RHS->Codegen();
1047    if (Val == 0) return 0;
1048
1049    // Look up the name.
1050    Value *Variable = NamedValues[LHSE->getName()];
1051    if (Variable == 0) return ErrorV("Unknown variable name");
1052
1053    Builder.CreateStore(Val, Variable);
1054    return Val;
1055  }
1056
1057  Value *L = LHS->Codegen();
1058  Value *R = RHS->Codegen();
1059  if (L == 0 || R == 0) return 0;
1060
1061  switch (Op) {
1062  case '+': return Builder.CreateFAdd(L, R, "addtmp");
1063  case '-': return Builder.CreateFSub(L, R, "subtmp");
1064  case '*': return Builder.CreateFMul(L, R, "multmp");
1065  case '/': return Builder.CreateFDiv(L, R, "divtmp");
1066  case '<':
1067    L = Builder.CreateFCmpULT(L, R, "cmptmp");
1068    // Convert bool 0/1 to double 0.0 or 1.0
1069    return Builder.CreateUIToFP(L, Type::getDoubleTy(TheContext), "booltmp");
1070  default: break;
1071  }
1072
1073  // If it wasn't a builtin binary operator, it must be a user defined one. Emit
1074  // a call to it.
1075  Function *F = TheHelper->getFunction(MakeLegalFunctionName(std::string("binary")+Op));
1076  assert(F && "binary operator not found!");
1077
1078  Value *Ops[] = { L, R };
1079  return Builder.CreateCall(F, Ops, "binop");
1080}
1081
1082Value *CallExprAST::Codegen() {
1083  // Look up the name in the global module table.
1084  Function *CalleeF = TheHelper->getFunction(Callee);
1085  if (CalleeF == 0)
1086    return ErrorV("Unknown function referenced");
1087
1088  // If argument mismatch error.
1089  if (CalleeF->arg_size() != Args.size())
1090    return ErrorV("Incorrect # arguments passed");
1091
1092  std::vector<Value*> ArgsV;
1093  for (unsigned i = 0, e = Args.size(); i != e; ++i) {
1094    ArgsV.push_back(Args[i]->Codegen());
1095    if (ArgsV.back() == 0) return 0;
1096  }
1097
1098  return Builder.CreateCall(CalleeF, ArgsV, "calltmp");
1099}
1100
1101Value *IfExprAST::Codegen() {
1102  Value *CondV = Cond->Codegen();
1103  if (CondV == 0) return 0;
1104
1105  // Convert condition to a bool by comparing equal to 0.0.
1106  CondV = Builder.CreateFCmpONE(
1107      CondV, ConstantFP::get(TheContext, APFloat(0.0)), "ifcond");
1108
1109  Function *TheFunction = Builder.GetInsertBlock()->getParent();
1110
1111  // Create blocks for the then and else cases.  Insert the 'then' block at the
1112  // end of the function.
1113  BasicBlock *ThenBB = BasicBlock::Create(TheContext, "then", TheFunction);
1114  BasicBlock *ElseBB = BasicBlock::Create(TheContext, "else");
1115  BasicBlock *MergeBB = BasicBlock::Create(TheContext, "ifcont");
1116
1117  Builder.CreateCondBr(CondV, ThenBB, ElseBB);
1118
1119  // Emit then value.
1120  Builder.SetInsertPoint(ThenBB);
1121
1122  Value *ThenV = Then->Codegen();
1123  if (ThenV == 0) return 0;
1124
1125  Builder.CreateBr(MergeBB);
1126  // Codegen of 'Then' can change the current block, update ThenBB for the PHI.
1127  ThenBB = Builder.GetInsertBlock();
1128
1129  // Emit else block.
1130  TheFunction->insert(TheFunction->end(), ElseBB);
1131  Builder.SetInsertPoint(ElseBB);
1132
1133  Value *ElseV = Else->Codegen();
1134  if (ElseV == 0) return 0;
1135
1136  Builder.CreateBr(MergeBB);
1137  // Codegen of 'Else' can change the current block, update ElseBB for the PHI.
1138  ElseBB = Builder.GetInsertBlock();
1139
1140  // Emit merge block.
1141  TheFunction->insert(TheFunction->end(), MergeBB);
1142  Builder.SetInsertPoint(MergeBB);
1143  PHINode *PN = Builder.CreatePHI(Type::getDoubleTy(TheContext), 2, "iftmp");
1144
1145  PN->addIncoming(ThenV, ThenBB);
1146  PN->addIncoming(ElseV, ElseBB);
1147  return PN;
1148}
1149
1150Value *ForExprAST::Codegen() {
1151  // Output this as:
1152  //   var = alloca double
1153  //   ...
1154  //   start = startexpr
1155  //   store start -> var
1156  //   goto loop
1157  // loop:
1158  //   ...
1159  //   bodyexpr
1160  //   ...
1161  // loopend:
1162  //   step = stepexpr
1163  //   endcond = endexpr
1164  //
1165  //   curvar = load var
1166  //   nextvar = curvar + step
1167  //   store nextvar -> var
1168  //   br endcond, loop, endloop
1169  // outloop:
1170
1171  Function *TheFunction = Builder.GetInsertBlock()->getParent();
1172
1173  // Create an alloca for the variable in the entry block.
1174  AllocaInst *Alloca = CreateEntryBlockAlloca(TheFunction, VarName);
1175
1176  // Emit the start code first, without 'variable' in scope.
1177  Value *StartVal = Start->Codegen();
1178  if (StartVal == 0) return 0;
1179
1180  // Store the value into the alloca.
1181  Builder.CreateStore(StartVal, Alloca);
1182
1183  // Make the new basic block for the loop header, inserting after current
1184  // block.
1185  BasicBlock *LoopBB = BasicBlock::Create(TheContext, "loop", TheFunction);
1186
1187  // Insert an explicit fall through from the current block to the LoopBB.
1188  Builder.CreateBr(LoopBB);
1189
1190  // Start insertion in LoopBB.
1191  Builder.SetInsertPoint(LoopBB);
1192
1193  // Within the loop, the variable is defined equal to the PHI node.  If it
1194  // shadows an existing variable, we have to restore it, so save it now.
1195  AllocaInst *OldVal = NamedValues[VarName];
1196  NamedValues[VarName] = Alloca;
1197
1198  // Emit the body of the loop.  This, like any other expr, can change the
1199  // current BB.  Note that we ignore the value computed by the body, but don't
1200  // allow an error.
1201  if (Body->Codegen() == 0)
1202    return 0;
1203
1204  // Emit the step value.
1205  Value *StepVal;
1206  if (Step) {
1207    StepVal = Step->Codegen();
1208    if (StepVal == 0) return 0;
1209  } else {
1210    // If not specified, use 1.0.
1211    StepVal = ConstantFP::get(TheContext, APFloat(1.0));
1212  }
1213
1214  // Compute the end condition.
1215  Value *EndCond = End->Codegen();
1216  if (EndCond == 0) return EndCond;
1217
1218  // Reload, increment, and restore the alloca.  This handles the case where
1219  // the body of the loop mutates the variable.
1220  Value *CurVar = Builder.CreateLoad(Alloca, VarName.c_str());
1221  Value *NextVar = Builder.CreateFAdd(CurVar, StepVal, "nextvar");
1222  Builder.CreateStore(NextVar, Alloca);
1223
1224  // Convert condition to a bool by comparing equal to 0.0.
1225  EndCond = Builder.CreateFCmpONE(
1226      EndCond, ConstantFP::get(TheContext, APFloat(0.0)), "loopcond");
1227
1228  // Create the "after loop" block and insert it.
1229  BasicBlock *AfterBB =
1230      BasicBlock::Create(TheContext, "afterloop", TheFunction);
1231
1232  // Insert the conditional branch into the end of LoopEndBB.
1233  Builder.CreateCondBr(EndCond, LoopBB, AfterBB);
1234
1235  // Any new code will be inserted in AfterBB.
1236  Builder.SetInsertPoint(AfterBB);
1237
1238  // Restore the unshadowed variable.
1239  if (OldVal)
1240    NamedValues[VarName] = OldVal;
1241  else
1242    NamedValues.erase(VarName);
1243
1244
1245  // for expr always returns 0.0.
1246  return Constant::getNullValue(Type::getDoubleTy(TheContext));
1247}
1248
1249Value *VarExprAST::Codegen() {
1250  std::vector<AllocaInst *> OldBindings;
1251
1252  Function *TheFunction = Builder.GetInsertBlock()->getParent();
1253
1254  // Register all variables and emit their initializer.
1255  for (unsigned i = 0, e = VarNames.size(); i != e; ++i) {
1256    const std::string &VarName = VarNames[i].first;
1257    ExprAST *Init = VarNames[i].second;
1258
1259    // Emit the initializer before adding the variable to scope, this prevents
1260    // the initializer from referencing the variable itself, and permits stuff
1261    // like this:
1262    //  var a = 1 in
1263    //    var a = a in ...   # refers to outer 'a'.
1264    Value *InitVal;
1265    if (Init) {
1266      InitVal = Init->Codegen();
1267      if (InitVal == 0) return 0;
1268    } else { // If not specified, use 0.0.
1269      InitVal = ConstantFP::get(TheContext, APFloat(0.0));
1270    }
1271
1272    AllocaInst *Alloca = CreateEntryBlockAlloca(TheFunction, VarName);
1273    Builder.CreateStore(InitVal, Alloca);
1274
1275    // Remember the old variable binding so that we can restore the binding when
1276    // we unrecurse.
1277    OldBindings.push_back(NamedValues[VarName]);
1278
1279    // Remember this binding.
1280    NamedValues[VarName] = Alloca;
1281  }
1282
1283  // Codegen the body, now that all vars are in scope.
1284  Value *BodyVal = Body->Codegen();
1285  if (BodyVal == 0) return 0;
1286
1287  // Pop all our variables from scope.
1288  for (unsigned i = 0, e = VarNames.size(); i != e; ++i)
1289    NamedValues[VarNames[i].first] = OldBindings[i];
1290
1291  // Return the body computation.
1292  return BodyVal;
1293}
1294
1295Function *PrototypeAST::Codegen() {
1296  // Make the function type:  double(double,double) etc.
1297  std::vector<Type *> Doubles(Args.size(), Type::getDoubleTy(TheContext));
1298  FunctionType *FT =
1299      FunctionType::get(Type::getDoubleTy(TheContext), Doubles, false);
1300
1301  std::string FnName = MakeLegalFunctionName(Name);
1302
1303  Module* M = TheHelper->getModuleForNewFunction();
1304
1305  Function *F = Function::Create(FT, Function::ExternalLinkage, FnName, M);
1306
1307  // If F conflicted, there was already something named 'FnName'.  If it has a
1308  // body, don't allow redefinition or reextern.
1309  if (F->getName() != FnName) {
1310    // Delete the one we just made and get the existing one.
1311    F->eraseFromParent();
1312    F = M->getFunction(Name);
1313
1314    // If F already has a body, reject this.
1315    if (!F->empty()) {
1316      ErrorF("redefinition of function");
1317      return 0;
1318    }
1319
1320    // If F took a different number of args, reject.
1321    if (F->arg_size() != Args.size()) {
1322      ErrorF("redefinition of function with different # args");
1323      return 0;
1324    }
1325  }
1326
1327  // Set names for all arguments.
1328  unsigned Idx = 0;
1329  for (Function::arg_iterator AI = F->arg_begin(); Idx != Args.size();
1330       ++AI, ++Idx)
1331    AI->setName(Args[Idx]);
1332
1333  return F;
1334}
1335
1336/// CreateArgumentAllocas - Create an alloca for each argument and register the
1337/// argument in the symbol table so that references to it will succeed.
1338void PrototypeAST::CreateArgumentAllocas(Function *F) {
1339  Function::arg_iterator AI = F->arg_begin();
1340  for (unsigned Idx = 0, e = Args.size(); Idx != e; ++Idx, ++AI) {
1341    // Create an alloca for this variable.
1342    AllocaInst *Alloca = CreateEntryBlockAlloca(F, Args[Idx]);
1343
1344    // Store the initial value into the alloca.
1345    Builder.CreateStore(AI, Alloca);
1346
1347    // Add arguments to variable symbol table.
1348    NamedValues[Args[Idx]] = Alloca;
1349  }
1350}
1351
1352Function *FunctionAST::Codegen() {
1353  NamedValues.clear();
1354
1355  Function *TheFunction = Proto->Codegen();
1356  if (TheFunction == 0)
1357    return 0;
1358
1359  // If this is an operator, install it.
1360  if (Proto->isBinaryOp())
1361    BinopPrecedence[Proto->getOperatorName()] = Proto->getBinaryPrecedence();
1362
1363  // Create a new basic block to start insertion into.
1364  BasicBlock *BB = BasicBlock::Create(TheContext, "entry", TheFunction);
1365  Builder.SetInsertPoint(BB);
1366
1367  // Add all arguments to the symbol table and create their allocas.
1368  Proto->CreateArgumentAllocas(TheFunction);
1369
1370  if (Value *RetVal = Body->Codegen()) {
1371    // Finish off the function.
1372    Builder.CreateRet(RetVal);
1373
1374    // Validate the generated code, checking for consistency.
1375    verifyFunction(*TheFunction);
1376
1377    return TheFunction;
1378  }
1379
1380  // Error reading body, remove function.
1381  TheFunction->eraseFromParent();
1382
1383  if (Proto->isBinaryOp())
1384    BinopPrecedence.erase(Proto->getOperatorName());
1385  return 0;
1386}
1387
1388//===----------------------------------------------------------------------===//
1389// Top-Level parsing and JIT Driver
1390//===----------------------------------------------------------------------===//
1391
1392static void HandleDefinition() {
1393  if (FunctionAST *F = ParseDefinition()) {
1394    TheHelper->closeCurrentModule();
1395    if (Function *LF = F->Codegen()) {
1396#ifndef MINIMAL_STDERR_OUTPUT
1397      fprintf(stderr, "Read function definition:");
1398      LF->print(errs());
1399      fprintf(stderr, "\n");
1400#endif
1401    }
1402  } else {
1403    // Skip token for error recovery.
1404    getNextToken();
1405  }
1406}
1407
1408static void HandleExtern() {
1409  if (PrototypeAST *P = ParseExtern()) {
1410    if (Function *F = P->Codegen()) {
1411#ifndef MINIMAL_STDERR_OUTPUT
1412      fprintf(stderr, "Read extern: ");
1413      F->print(errs());
1414      fprintf(stderr, "\n");
1415#endif
1416    }
1417  } else {
1418    // Skip token for error recovery.
1419    getNextToken();
1420  }
1421}
1422
1423static void HandleTopLevelExpression() {
1424  // Evaluate a top-level expression into an anonymous function.
1425  if (FunctionAST *F = ParseTopLevelExpr()) {
1426    if (Function *LF = F->Codegen()) {
1427      // JIT the function, returning a function pointer.
1428      void *FPtr = TheHelper->getPointerToFunction(LF);
1429
1430      // Cast it to the right type (takes no arguments, returns a double) so we
1431      // can call it as a native function.
1432      double (*FP)() = (double (*)())(intptr_t)FPtr;
1433#ifdef MINIMAL_STDERR_OUTPUT
1434      FP();
1435#else
1436      fprintf(stderr, "Evaluated to %f\n", FP());
1437#endif
1438    }
1439  } else {
1440    // Skip token for error recovery.
1441    getNextToken();
1442  }
1443}
1444
1445/// top ::= definition | external | expression | ';'
1446static void MainLoop() {
1447  while (1) {
1448#ifndef MINIMAL_STDERR_OUTPUT
1449    fprintf(stderr, "ready> ");
1450#endif
1451    switch (CurTok) {
1452    case tok_eof:    return;
1453    case ';':        getNextToken(); break;  // ignore top-level semicolons.
1454    case tok_def:    HandleDefinition(); break;
1455    case tok_extern: HandleExtern(); break;
1456    default:         HandleTopLevelExpression(); break;
1457    }
1458  }
1459}
1460
1461//===----------------------------------------------------------------------===//
1462// "Library" functions that can be "extern'd" from user code.
1463//===----------------------------------------------------------------------===//
1464
1465/// putchard - putchar that takes a double and returns 0.
1466extern "C"
1467double putchard(double X) {
1468  putchar((char)X);
1469  return 0;
1470}
1471
1472/// printd - printf that takes a double prints it as "%f\n", returning 0.
1473extern "C"
1474double printd(double X) {
1475  printf("%f", X);
1476  return 0;
1477}
1478
1479extern "C"
1480double printlf() {
1481  printf("\n");
1482  return 0;
1483}
1484
1485//===----------------------------------------------------------------------===//
1486// Command line input file handler
1487//===----------------------------------------------------------------------===//
1488
1489Module* parseInputIR(std::string InputFile) {
1490  SMDiagnostic Err;
1491  Module *M = ParseIRFile(InputFile, Err, TheContext);
1492  if (!M) {
1493    Err.print("IR parsing failed: ", errs());
1494    return NULL;
1495  }
1496
1497  char ModID[256];
1498  sprintf(ModID, "IR:%s", InputFile.c_str());
1499  M->setModuleIdentifier(ModID);
1500
1501  TheHelper->addModule(M);
1502  return M;
1503}
1504
1505//===----------------------------------------------------------------------===//
1506// Main driver code.
1507//===----------------------------------------------------------------------===//
1508
1509int main(int argc, char **argv) {
1510  InitializeNativeTarget();
1511  InitializeNativeTargetAsmPrinter();
1512  InitializeNativeTargetAsmParser();
1513  LLVMContext &Context = TheContext;
1514
1515  cl::ParseCommandLineOptions(argc, argv,
1516                              "Kaleidoscope example program\n");
1517
1518  // Install standard binary operators.
1519  // 1 is lowest precedence.
1520  BinopPrecedence['='] = 2;
1521  BinopPrecedence['<'] = 10;
1522  BinopPrecedence['+'] = 20;
1523  BinopPrecedence['-'] = 20;
1524  BinopPrecedence['/'] = 40;
1525  BinopPrecedence['*'] = 40;  // highest.
1526
1527  // Prime the first token.
1528#ifndef MINIMAL_STDERR_OUTPUT
1529  fprintf(stderr, "ready> ");
1530#endif
1531  getNextToken();
1532
1533  // Make the helper, which holds all the code.
1534  TheHelper = new MCJITHelper(Context);
1535
1536  if (!InputIR.empty()) {
1537    parseInputIR(InputIR);
1538  }
1539
1540  // Run the main "interpreter loop" now.
1541  MainLoop();
1542
1543#ifndef MINIMAL_STDERR_OUTPUT
1544  // Print out all of the generated code.
1545  TheHelper->print(errs());
1546#endif
1547
1548  return 0;
1549}
1550