1#include "llvm/Analysis/Passes.h"
2#include "llvm/ExecutionEngine/ExecutionEngine.h"
3#include "llvm/ExecutionEngine/JIT.h"
4#include "llvm/IR/DataLayout.h"
5#include "llvm/IR/DerivedTypes.h"
6#include "llvm/IR/IRBuilder.h"
7#include "llvm/IR/LLVMContext.h"
8#include "llvm/IR/Module.h"
9#include "llvm/IR/Verifier.h"
10#include "llvm/PassManager.h"
11#include "llvm/Support/TargetSelect.h"
12#include "llvm/Transforms/Scalar.h"
13#include <cctype>
14#include <cstdio>
15#include <map>
16#include <string>
17#include <vector>
18using namespace llvm;
19
20//===----------------------------------------------------------------------===//
21// Lexer
22//===----------------------------------------------------------------------===//
23
24// The lexer returns tokens [0-255] if it is an unknown character, otherwise one
25// of these for known things.
26enum Token {
27  tok_eof = -1,
28
29  // commands
30  tok_def = -2, tok_extern = -3,
31
32  // primary
33  tok_identifier = -4, tok_number = -5,
34
35  // control
36  tok_if = -6, tok_then = -7, tok_else = -8,
37  tok_for = -9, tok_in = -10
38};
39
40static std::string IdentifierStr;  // Filled in if tok_identifier
41static double NumVal;              // Filled in if tok_number
42
43/// gettok - Return the next token from standard input.
44static int gettok() {
45  static int LastChar = ' ';
46
47  // Skip any whitespace.
48  while (isspace(LastChar))
49    LastChar = getchar();
50
51  if (isalpha(LastChar)) { // identifier: [a-zA-Z][a-zA-Z0-9]*
52    IdentifierStr = LastChar;
53    while (isalnum((LastChar = getchar())))
54      IdentifierStr += LastChar;
55
56    if (IdentifierStr == "def") return tok_def;
57    if (IdentifierStr == "extern") return tok_extern;
58    if (IdentifierStr == "if") return tok_if;
59    if (IdentifierStr == "then") return tok_then;
60    if (IdentifierStr == "else") return tok_else;
61    if (IdentifierStr == "for") return tok_for;
62    if (IdentifierStr == "in") return tok_in;
63    return tok_identifier;
64  }
65
66  if (isdigit(LastChar) || LastChar == '.') {   // Number: [0-9.]+
67    std::string NumStr;
68    do {
69      NumStr += LastChar;
70      LastChar = getchar();
71    } while (isdigit(LastChar) || LastChar == '.');
72
73    NumVal = strtod(NumStr.c_str(), 0);
74    return tok_number;
75  }
76
77  if (LastChar == '#') {
78    // Comment until end of line.
79    do LastChar = getchar();
80    while (LastChar != EOF && LastChar != '\n' && LastChar != '\r');
81
82    if (LastChar != EOF)
83      return gettok();
84  }
85
86  // Check for end of file.  Don't eat the EOF.
87  if (LastChar == EOF)
88    return tok_eof;
89
90  // Otherwise, just return the character as its ascii value.
91  int ThisChar = LastChar;
92  LastChar = getchar();
93  return ThisChar;
94}
95
96//===----------------------------------------------------------------------===//
97// Abstract Syntax Tree (aka Parse Tree)
98//===----------------------------------------------------------------------===//
99namespace {
100/// ExprAST - Base class for all expression nodes.
101class ExprAST {
102public:
103  virtual ~ExprAST() {}
104  virtual Value *Codegen() = 0;
105};
106
107/// NumberExprAST - Expression class for numeric literals like "1.0".
108class NumberExprAST : public ExprAST {
109  double Val;
110public:
111  NumberExprAST(double val) : Val(val) {}
112  virtual Value *Codegen();
113};
114
115/// VariableExprAST - Expression class for referencing a variable, like "a".
116class VariableExprAST : public ExprAST {
117  std::string Name;
118public:
119  VariableExprAST(const std::string &name) : Name(name) {}
120  virtual Value *Codegen();
121};
122
123/// BinaryExprAST - Expression class for a binary operator.
124class BinaryExprAST : public ExprAST {
125  char Op;
126  ExprAST *LHS, *RHS;
127public:
128  BinaryExprAST(char op, ExprAST *lhs, ExprAST *rhs)
129    : Op(op), LHS(lhs), RHS(rhs) {}
130  virtual Value *Codegen();
131};
132
133/// CallExprAST - Expression class for function calls.
134class CallExprAST : public ExprAST {
135  std::string Callee;
136  std::vector<ExprAST*> Args;
137public:
138  CallExprAST(const std::string &callee, std::vector<ExprAST*> &args)
139    : Callee(callee), Args(args) {}
140  virtual Value *Codegen();
141};
142
143/// IfExprAST - Expression class for if/then/else.
144class IfExprAST : public ExprAST {
145  ExprAST *Cond, *Then, *Else;
146public:
147  IfExprAST(ExprAST *cond, ExprAST *then, ExprAST *_else)
148  : Cond(cond), Then(then), Else(_else) {}
149  virtual Value *Codegen();
150};
151
152/// ForExprAST - Expression class for for/in.
153class ForExprAST : public ExprAST {
154  std::string VarName;
155  ExprAST *Start, *End, *Step, *Body;
156public:
157  ForExprAST(const std::string &varname, ExprAST *start, ExprAST *end,
158             ExprAST *step, ExprAST *body)
159    : VarName(varname), Start(start), End(end), Step(step), Body(body) {}
160  virtual Value *Codegen();
161};
162
163/// PrototypeAST - This class represents the "prototype" for a function,
164/// which captures its name, and its argument names (thus implicitly the number
165/// of arguments the function takes).
166class PrototypeAST {
167  std::string Name;
168  std::vector<std::string> Args;
169public:
170  PrototypeAST(const std::string &name, const std::vector<std::string> &args)
171    : Name(name), Args(args) {}
172
173  Function *Codegen();
174};
175
176/// FunctionAST - This class represents a function definition itself.
177class FunctionAST {
178  PrototypeAST *Proto;
179  ExprAST *Body;
180public:
181  FunctionAST(PrototypeAST *proto, ExprAST *body)
182    : Proto(proto), Body(body) {}
183
184  Function *Codegen();
185};
186} // end anonymous namespace
187
188//===----------------------------------------------------------------------===//
189// Parser
190//===----------------------------------------------------------------------===//
191
192/// CurTok/getNextToken - Provide a simple token buffer.  CurTok is the current
193/// token the parser is looking at.  getNextToken reads another token from the
194/// lexer and updates CurTok with its results.
195static int CurTok;
196static int getNextToken() {
197  return CurTok = gettok();
198}
199
200/// BinopPrecedence - This holds the precedence for each binary operator that is
201/// defined.
202static std::map<char, int> BinopPrecedence;
203
204/// GetTokPrecedence - Get the precedence of the pending binary operator token.
205static int GetTokPrecedence() {
206  if (!isascii(CurTok))
207    return -1;
208
209  // Make sure it's a declared binop.
210  int TokPrec = BinopPrecedence[CurTok];
211  if (TokPrec <= 0) return -1;
212  return TokPrec;
213}
214
215/// Error* - These are little helper functions for error handling.
216ExprAST *Error(const char *Str) { fprintf(stderr, "Error: %s\n", Str);return 0;}
217PrototypeAST *ErrorP(const char *Str) { Error(Str); return 0; }
218FunctionAST *ErrorF(const char *Str) { Error(Str); return 0; }
219
220static ExprAST *ParseExpression();
221
222/// identifierexpr
223///   ::= identifier
224///   ::= identifier '(' expression* ')'
225static ExprAST *ParseIdentifierExpr() {
226  std::string IdName = IdentifierStr;
227
228  getNextToken();  // eat identifier.
229
230  if (CurTok != '(') // Simple variable ref.
231    return new VariableExprAST(IdName);
232
233  // Call.
234  getNextToken();  // eat (
235  std::vector<ExprAST*> Args;
236  if (CurTok != ')') {
237    while (1) {
238      ExprAST *Arg = ParseExpression();
239      if (!Arg) return 0;
240      Args.push_back(Arg);
241
242      if (CurTok == ')') break;
243
244      if (CurTok != ',')
245        return Error("Expected ')' or ',' in argument list");
246      getNextToken();
247    }
248  }
249
250  // Eat the ')'.
251  getNextToken();
252
253  return new CallExprAST(IdName, Args);
254}
255
256/// numberexpr ::= number
257static ExprAST *ParseNumberExpr() {
258  ExprAST *Result = new NumberExprAST(NumVal);
259  getNextToken(); // consume the number
260  return Result;
261}
262
263/// parenexpr ::= '(' expression ')'
264static ExprAST *ParseParenExpr() {
265  getNextToken();  // eat (.
266  ExprAST *V = ParseExpression();
267  if (!V) return 0;
268
269  if (CurTok != ')')
270    return Error("expected ')'");
271  getNextToken();  // eat ).
272  return V;
273}
274
275/// ifexpr ::= 'if' expression 'then' expression 'else' expression
276static ExprAST *ParseIfExpr() {
277  getNextToken();  // eat the if.
278
279  // condition.
280  ExprAST *Cond = ParseExpression();
281  if (!Cond) return 0;
282
283  if (CurTok != tok_then)
284    return Error("expected then");
285  getNextToken();  // eat the then
286
287  ExprAST *Then = ParseExpression();
288  if (Then == 0) return 0;
289
290  if (CurTok != tok_else)
291    return Error("expected else");
292
293  getNextToken();
294
295  ExprAST *Else = ParseExpression();
296  if (!Else) return 0;
297
298  return new IfExprAST(Cond, Then, Else);
299}
300
301/// forexpr ::= 'for' identifier '=' expr ',' expr (',' expr)? 'in' expression
302static ExprAST *ParseForExpr() {
303  getNextToken();  // eat the for.
304
305  if (CurTok != tok_identifier)
306    return Error("expected identifier after for");
307
308  std::string IdName = IdentifierStr;
309  getNextToken();  // eat identifier.
310
311  if (CurTok != '=')
312    return Error("expected '=' after for");
313  getNextToken();  // eat '='.
314
315
316  ExprAST *Start = ParseExpression();
317  if (Start == 0) return 0;
318  if (CurTok != ',')
319    return Error("expected ',' after for start value");
320  getNextToken();
321
322  ExprAST *End = ParseExpression();
323  if (End == 0) return 0;
324
325  // The step value is optional.
326  ExprAST *Step = 0;
327  if (CurTok == ',') {
328    getNextToken();
329    Step = ParseExpression();
330    if (Step == 0) return 0;
331  }
332
333  if (CurTok != tok_in)
334    return Error("expected 'in' after for");
335  getNextToken();  // eat 'in'.
336
337  ExprAST *Body = ParseExpression();
338  if (Body == 0) return 0;
339
340  return new ForExprAST(IdName, Start, End, Step, Body);
341}
342
343/// primary
344///   ::= identifierexpr
345///   ::= numberexpr
346///   ::= parenexpr
347///   ::= ifexpr
348///   ::= forexpr
349static ExprAST *ParsePrimary() {
350  switch (CurTok) {
351  default: return Error("unknown token when expecting an expression");
352  case tok_identifier: return ParseIdentifierExpr();
353  case tok_number:     return ParseNumberExpr();
354  case '(':            return ParseParenExpr();
355  case tok_if:         return ParseIfExpr();
356  case tok_for:        return ParseForExpr();
357  }
358}
359
360/// binoprhs
361///   ::= ('+' primary)*
362static ExprAST *ParseBinOpRHS(int ExprPrec, ExprAST *LHS) {
363  // If this is a binop, find its precedence.
364  while (1) {
365    int TokPrec = GetTokPrecedence();
366
367    // If this is a binop that binds at least as tightly as the current binop,
368    // consume it, otherwise we are done.
369    if (TokPrec < ExprPrec)
370      return LHS;
371
372    // Okay, we know this is a binop.
373    int BinOp = CurTok;
374    getNextToken();  // eat binop
375
376    // Parse the primary expression after the binary operator.
377    ExprAST *RHS = ParsePrimary();
378    if (!RHS) return 0;
379
380    // If BinOp binds less tightly with RHS than the operator after RHS, let
381    // the pending operator take RHS as its LHS.
382    int NextPrec = GetTokPrecedence();
383    if (TokPrec < NextPrec) {
384      RHS = ParseBinOpRHS(TokPrec+1, RHS);
385      if (RHS == 0) return 0;
386    }
387
388    // Merge LHS/RHS.
389    LHS = new BinaryExprAST(BinOp, LHS, RHS);
390  }
391}
392
393/// expression
394///   ::= primary binoprhs
395///
396static ExprAST *ParseExpression() {
397  ExprAST *LHS = ParsePrimary();
398  if (!LHS) return 0;
399
400  return ParseBinOpRHS(0, LHS);
401}
402
403/// prototype
404///   ::= id '(' id* ')'
405static PrototypeAST *ParsePrototype() {
406  if (CurTok != tok_identifier)
407    return ErrorP("Expected function name in prototype");
408
409  std::string FnName = IdentifierStr;
410  getNextToken();
411
412  if (CurTok != '(')
413    return ErrorP("Expected '(' in prototype");
414
415  std::vector<std::string> ArgNames;
416  while (getNextToken() == tok_identifier)
417    ArgNames.push_back(IdentifierStr);
418  if (CurTok != ')')
419    return ErrorP("Expected ')' in prototype");
420
421  // success.
422  getNextToken();  // eat ')'.
423
424  return new PrototypeAST(FnName, ArgNames);
425}
426
427/// definition ::= 'def' prototype expression
428static FunctionAST *ParseDefinition() {
429  getNextToken();  // eat def.
430  PrototypeAST *Proto = ParsePrototype();
431  if (Proto == 0) return 0;
432
433  if (ExprAST *E = ParseExpression())
434    return new FunctionAST(Proto, E);
435  return 0;
436}
437
438/// toplevelexpr ::= expression
439static FunctionAST *ParseTopLevelExpr() {
440  if (ExprAST *E = ParseExpression()) {
441    // Make an anonymous proto.
442    PrototypeAST *Proto = new PrototypeAST("", std::vector<std::string>());
443    return new FunctionAST(Proto, E);
444  }
445  return 0;
446}
447
448/// external ::= 'extern' prototype
449static PrototypeAST *ParseExtern() {
450  getNextToken();  // eat extern.
451  return ParsePrototype();
452}
453
454//===----------------------------------------------------------------------===//
455// Code Generation
456//===----------------------------------------------------------------------===//
457
458static Module *TheModule;
459static IRBuilder<> Builder(getGlobalContext());
460static std::map<std::string, Value*> NamedValues;
461static FunctionPassManager *TheFPM;
462
463Value *ErrorV(const char *Str) { Error(Str); return 0; }
464
465Value *NumberExprAST::Codegen() {
466  return ConstantFP::get(getGlobalContext(), APFloat(Val));
467}
468
469Value *VariableExprAST::Codegen() {
470  // Look this variable up in the function.
471  Value *V = NamedValues[Name];
472  return V ? V : ErrorV("Unknown variable name");
473}
474
475Value *BinaryExprAST::Codegen() {
476  Value *L = LHS->Codegen();
477  Value *R = RHS->Codegen();
478  if (L == 0 || R == 0) return 0;
479
480  switch (Op) {
481  case '+': return Builder.CreateFAdd(L, R, "addtmp");
482  case '-': return Builder.CreateFSub(L, R, "subtmp");
483  case '*': return Builder.CreateFMul(L, R, "multmp");
484  case '<':
485    L = Builder.CreateFCmpULT(L, R, "cmptmp");
486    // Convert bool 0/1 to double 0.0 or 1.0
487    return Builder.CreateUIToFP(L, Type::getDoubleTy(getGlobalContext()),
488                                "booltmp");
489  default: return ErrorV("invalid binary operator");
490  }
491}
492
493Value *CallExprAST::Codegen() {
494  // Look up the name in the global module table.
495  Function *CalleeF = TheModule->getFunction(Callee);
496  if (CalleeF == 0)
497    return ErrorV("Unknown function referenced");
498
499  // If argument mismatch error.
500  if (CalleeF->arg_size() != Args.size())
501    return ErrorV("Incorrect # arguments passed");
502
503  std::vector<Value*> ArgsV;
504  for (unsigned i = 0, e = Args.size(); i != e; ++i) {
505    ArgsV.push_back(Args[i]->Codegen());
506    if (ArgsV.back() == 0) return 0;
507  }
508
509  return Builder.CreateCall(CalleeF, ArgsV, "calltmp");
510}
511
512Value *IfExprAST::Codegen() {
513  Value *CondV = Cond->Codegen();
514  if (CondV == 0) return 0;
515
516  // Convert condition to a bool by comparing equal to 0.0.
517  CondV = Builder.CreateFCmpONE(CondV,
518                              ConstantFP::get(getGlobalContext(), APFloat(0.0)),
519                                "ifcond");
520
521  Function *TheFunction = Builder.GetInsertBlock()->getParent();
522
523  // Create blocks for the then and else cases.  Insert the 'then' block at the
524  // end of the function.
525  BasicBlock *ThenBB = BasicBlock::Create(getGlobalContext(), "then", TheFunction);
526  BasicBlock *ElseBB = BasicBlock::Create(getGlobalContext(), "else");
527  BasicBlock *MergeBB = BasicBlock::Create(getGlobalContext(), "ifcont");
528
529  Builder.CreateCondBr(CondV, ThenBB, ElseBB);
530
531  // Emit then value.
532  Builder.SetInsertPoint(ThenBB);
533
534  Value *ThenV = Then->Codegen();
535  if (ThenV == 0) return 0;
536
537  Builder.CreateBr(MergeBB);
538  // Codegen of 'Then' can change the current block, update ThenBB for the PHI.
539  ThenBB = Builder.GetInsertBlock();
540
541  // Emit else block.
542  TheFunction->getBasicBlockList().push_back(ElseBB);
543  Builder.SetInsertPoint(ElseBB);
544
545  Value *ElseV = Else->Codegen();
546  if (ElseV == 0) return 0;
547
548  Builder.CreateBr(MergeBB);
549  // Codegen of 'Else' can change the current block, update ElseBB for the PHI.
550  ElseBB = Builder.GetInsertBlock();
551
552  // Emit merge block.
553  TheFunction->getBasicBlockList().push_back(MergeBB);
554  Builder.SetInsertPoint(MergeBB);
555  PHINode *PN = Builder.CreatePHI(Type::getDoubleTy(getGlobalContext()), 2,
556                                  "iftmp");
557
558  PN->addIncoming(ThenV, ThenBB);
559  PN->addIncoming(ElseV, ElseBB);
560  return PN;
561}
562
563Value *ForExprAST::Codegen() {
564  // Output this as:
565  //   ...
566  //   start = startexpr
567  //   goto loop
568  // loop:
569  //   variable = phi [start, loopheader], [nextvariable, loopend]
570  //   ...
571  //   bodyexpr
572  //   ...
573  // loopend:
574  //   step = stepexpr
575  //   nextvariable = variable + step
576  //   endcond = endexpr
577  //   br endcond, loop, endloop
578  // outloop:
579
580  // Emit the start code first, without 'variable' in scope.
581  Value *StartVal = Start->Codegen();
582  if (StartVal == 0) return 0;
583
584  // Make the new basic block for the loop header, inserting after current
585  // block.
586  Function *TheFunction = Builder.GetInsertBlock()->getParent();
587  BasicBlock *PreheaderBB = Builder.GetInsertBlock();
588  BasicBlock *LoopBB = BasicBlock::Create(getGlobalContext(), "loop", TheFunction);
589
590  // Insert an explicit fall through from the current block to the LoopBB.
591  Builder.CreateBr(LoopBB);
592
593  // Start insertion in LoopBB.
594  Builder.SetInsertPoint(LoopBB);
595
596  // Start the PHI node with an entry for Start.
597  PHINode *Variable = Builder.CreatePHI(Type::getDoubleTy(getGlobalContext()), 2, VarName.c_str());
598  Variable->addIncoming(StartVal, PreheaderBB);
599
600  // Within the loop, the variable is defined equal to the PHI node.  If it
601  // shadows an existing variable, we have to restore it, so save it now.
602  Value *OldVal = NamedValues[VarName];
603  NamedValues[VarName] = Variable;
604
605  // Emit the body of the loop.  This, like any other expr, can change the
606  // current BB.  Note that we ignore the value computed by the body, but don't
607  // allow an error.
608  if (Body->Codegen() == 0)
609    return 0;
610
611  // Emit the step value.
612  Value *StepVal;
613  if (Step) {
614    StepVal = Step->Codegen();
615    if (StepVal == 0) return 0;
616  } else {
617    // If not specified, use 1.0.
618    StepVal = ConstantFP::get(getGlobalContext(), APFloat(1.0));
619  }
620
621  Value *NextVar = Builder.CreateFAdd(Variable, StepVal, "nextvar");
622
623  // Compute the end condition.
624  Value *EndCond = End->Codegen();
625  if (EndCond == 0) return EndCond;
626
627  // Convert condition to a bool by comparing equal to 0.0.
628  EndCond = Builder.CreateFCmpONE(EndCond,
629                              ConstantFP::get(getGlobalContext(), APFloat(0.0)),
630                                  "loopcond");
631
632  // Create the "after loop" block and insert it.
633  BasicBlock *LoopEndBB = Builder.GetInsertBlock();
634  BasicBlock *AfterBB = BasicBlock::Create(getGlobalContext(), "afterloop", TheFunction);
635
636  // Insert the conditional branch into the end of LoopEndBB.
637  Builder.CreateCondBr(EndCond, LoopBB, AfterBB);
638
639  // Any new code will be inserted in AfterBB.
640  Builder.SetInsertPoint(AfterBB);
641
642  // Add a new entry to the PHI node for the backedge.
643  Variable->addIncoming(NextVar, LoopEndBB);
644
645  // Restore the unshadowed variable.
646  if (OldVal)
647    NamedValues[VarName] = OldVal;
648  else
649    NamedValues.erase(VarName);
650
651
652  // for expr always returns 0.0.
653  return Constant::getNullValue(Type::getDoubleTy(getGlobalContext()));
654}
655
656Function *PrototypeAST::Codegen() {
657  // Make the function type:  double(double,double) etc.
658  std::vector<Type*> Doubles(Args.size(),
659                             Type::getDoubleTy(getGlobalContext()));
660  FunctionType *FT = FunctionType::get(Type::getDoubleTy(getGlobalContext()),
661                                       Doubles, false);
662
663  Function *F = Function::Create(FT, Function::ExternalLinkage, Name, TheModule);
664
665  // If F conflicted, there was already something named 'Name'.  If it has a
666  // body, don't allow redefinition or reextern.
667  if (F->getName() != Name) {
668    // Delete the one we just made and get the existing one.
669    F->eraseFromParent();
670    F = TheModule->getFunction(Name);
671
672    // If F already has a body, reject this.
673    if (!F->empty()) {
674      ErrorF("redefinition of function");
675      return 0;
676    }
677
678    // If F took a different number of args, reject.
679    if (F->arg_size() != Args.size()) {
680      ErrorF("redefinition of function with different # args");
681      return 0;
682    }
683  }
684
685  // Set names for all arguments.
686  unsigned Idx = 0;
687  for (Function::arg_iterator AI = F->arg_begin(); Idx != Args.size();
688       ++AI, ++Idx) {
689    AI->setName(Args[Idx]);
690
691    // Add arguments to variable symbol table.
692    NamedValues[Args[Idx]] = AI;
693  }
694
695  return F;
696}
697
698Function *FunctionAST::Codegen() {
699  NamedValues.clear();
700
701  Function *TheFunction = Proto->Codegen();
702  if (TheFunction == 0)
703    return 0;
704
705  // Create a new basic block to start insertion into.
706  BasicBlock *BB = BasicBlock::Create(getGlobalContext(), "entry", TheFunction);
707  Builder.SetInsertPoint(BB);
708
709  if (Value *RetVal = Body->Codegen()) {
710    // Finish off the function.
711    Builder.CreateRet(RetVal);
712
713    // Validate the generated code, checking for consistency.
714    verifyFunction(*TheFunction);
715
716    // Optimize the function.
717    TheFPM->run(*TheFunction);
718
719    return TheFunction;
720  }
721
722  // Error reading body, remove function.
723  TheFunction->eraseFromParent();
724  return 0;
725}
726
727//===----------------------------------------------------------------------===//
728// Top-Level parsing and JIT Driver
729//===----------------------------------------------------------------------===//
730
731static ExecutionEngine *TheExecutionEngine;
732
733static void HandleDefinition() {
734  if (FunctionAST *F = ParseDefinition()) {
735    if (Function *LF = F->Codegen()) {
736      fprintf(stderr, "Read function definition:");
737      LF->dump();
738    }
739  } else {
740    // Skip token for error recovery.
741    getNextToken();
742  }
743}
744
745static void HandleExtern() {
746  if (PrototypeAST *P = ParseExtern()) {
747    if (Function *F = P->Codegen()) {
748      fprintf(stderr, "Read extern: ");
749      F->dump();
750    }
751  } else {
752    // Skip token for error recovery.
753    getNextToken();
754  }
755}
756
757static void HandleTopLevelExpression() {
758  // Evaluate a top-level expression into an anonymous function.
759  if (FunctionAST *F = ParseTopLevelExpr()) {
760    if (Function *LF = F->Codegen()) {
761      // JIT the function, returning a function pointer.
762      void *FPtr = TheExecutionEngine->getPointerToFunction(LF);
763
764      // Cast it to the right type (takes no arguments, returns a double) so we
765      // can call it as a native function.
766      double (*FP)() = (double (*)())(intptr_t)FPtr;
767      fprintf(stderr, "Evaluated to %f\n", FP());
768    }
769  } else {
770    // Skip token for error recovery.
771    getNextToken();
772  }
773}
774
775/// top ::= definition | external | expression | ';'
776static void MainLoop() {
777  while (1) {
778    fprintf(stderr, "ready> ");
779    switch (CurTok) {
780    case tok_eof:    return;
781    case ';':        getNextToken(); break;  // ignore top-level semicolons.
782    case tok_def:    HandleDefinition(); break;
783    case tok_extern: HandleExtern(); break;
784    default:         HandleTopLevelExpression(); break;
785    }
786  }
787}
788
789//===----------------------------------------------------------------------===//
790// "Library" functions that can be "extern'd" from user code.
791//===----------------------------------------------------------------------===//
792
793/// putchard - putchar that takes a double and returns 0.
794extern "C"
795double putchard(double X) {
796  putchar((char)X);
797  return 0;
798}
799
800//===----------------------------------------------------------------------===//
801// Main driver code.
802//===----------------------------------------------------------------------===//
803
804int main() {
805  InitializeNativeTarget();
806  LLVMContext &Context = getGlobalContext();
807
808  // Install standard binary operators.
809  // 1 is lowest precedence.
810  BinopPrecedence['<'] = 10;
811  BinopPrecedence['+'] = 20;
812  BinopPrecedence['-'] = 20;
813  BinopPrecedence['*'] = 40;  // highest.
814
815  // Prime the first token.
816  fprintf(stderr, "ready> ");
817  getNextToken();
818
819  // Make the module, which holds all the code.
820  TheModule = new Module("my cool jit", Context);
821
822  // Create the JIT.  This takes ownership of the module.
823  std::string ErrStr;
824  TheExecutionEngine = EngineBuilder(TheModule).setErrorStr(&ErrStr).create();
825  if (!TheExecutionEngine) {
826    fprintf(stderr, "Could not create ExecutionEngine: %s\n", ErrStr.c_str());
827    exit(1);
828  }
829
830  FunctionPassManager OurFPM(TheModule);
831
832  // Set up the optimizer pipeline.  Start with registering info about how the
833  // target lays out data structures.
834  TheModule->setDataLayout(TheExecutionEngine->getDataLayout());
835  OurFPM.add(new DataLayoutPass(TheModule));
836  // Provide basic AliasAnalysis support for GVN.
837  OurFPM.add(createBasicAliasAnalysisPass());
838  // Do simple "peephole" optimizations and bit-twiddling optzns.
839  OurFPM.add(createInstructionCombiningPass());
840  // Reassociate expressions.
841  OurFPM.add(createReassociatePass());
842  // Eliminate Common SubExpressions.
843  OurFPM.add(createGVNPass());
844  // Simplify the control flow graph (deleting unreachable blocks, etc).
845  OurFPM.add(createCFGSimplificationPass());
846
847  OurFPM.doInitialization();
848
849  // Set the global so the code gen can use this.
850  TheFPM = &OurFPM;
851
852  // Run the main "interpreter loop" now.
853  MainLoop();
854
855  TheFPM = 0;
856
857  // Print out all of the generated code.
858  TheModule->dump();
859
860  return 0;
861}
862