1#include "llvm/ADT/STLExtras.h"
2#include "llvm/Analysis/Passes.h"
3#include "llvm/ExecutionEngine/ExecutionEngine.h"
4#include "llvm/ExecutionEngine/MCJIT.h"
5#include "llvm/ExecutionEngine/SectionMemoryManager.h"
6#include "llvm/IR/DataLayout.h"
7#include "llvm/IR/DerivedTypes.h"
8#include "llvm/IR/IRBuilder.h"
9#include "llvm/IR/LLVMContext.h"
10#include "llvm/IR/LegacyPassManager.h"
11#include "llvm/IR/Module.h"
12#include "llvm/IR/Verifier.h"
13#include "llvm/Support/TargetSelect.h"
14#include "llvm/Transforms/Scalar.h"
15#include <cctype>
16#include <cstdio>
17#include <map>
18#include <string>
19#include <vector>
20using namespace llvm;
21
22//===----------------------------------------------------------------------===//
23// Lexer
24//===----------------------------------------------------------------------===//
25
26// The lexer returns tokens [0-255] if it is an unknown character, otherwise one
27// of these for known things.
28enum Token {
29  tok_eof = -1,
30
31  // commands
32  tok_def = -2,
33  tok_extern = -3,
34
35  // primary
36  tok_identifier = -4,
37  tok_number = -5,
38
39  // control
40  tok_if = -6,
41  tok_then = -7,
42  tok_else = -8,
43  tok_for = -9,
44  tok_in = -10
45};
46
47static std::string IdentifierStr; // Filled in if tok_identifier
48static double NumVal;             // Filled in if tok_number
49
50/// gettok - Return the next token from standard input.
51static int gettok() {
52  static int LastChar = ' ';
53
54  // Skip any whitespace.
55  while (isspace(LastChar))
56    LastChar = getchar();
57
58  if (isalpha(LastChar)) { // identifier: [a-zA-Z][a-zA-Z0-9]*
59    IdentifierStr = LastChar;
60    while (isalnum((LastChar = getchar())))
61      IdentifierStr += LastChar;
62
63    if (IdentifierStr == "def")
64      return tok_def;
65    if (IdentifierStr == "extern")
66      return tok_extern;
67    if (IdentifierStr == "if")
68      return tok_if;
69    if (IdentifierStr == "then")
70      return tok_then;
71    if (IdentifierStr == "else")
72      return tok_else;
73    if (IdentifierStr == "for")
74      return tok_for;
75    if (IdentifierStr == "in")
76      return tok_in;
77    return tok_identifier;
78  }
79
80  if (isdigit(LastChar) || LastChar == '.') { // Number: [0-9.]+
81    std::string NumStr;
82    do {
83      NumStr += LastChar;
84      LastChar = getchar();
85    } while (isdigit(LastChar) || LastChar == '.');
86
87    NumVal = strtod(NumStr.c_str(), 0);
88    return tok_number;
89  }
90
91  if (LastChar == '#') {
92    // Comment until end of line.
93    do
94      LastChar = getchar();
95    while (LastChar != EOF && LastChar != '\n' && LastChar != '\r');
96
97    if (LastChar != EOF)
98      return gettok();
99  }
100
101  // Check for end of file.  Don't eat the EOF.
102  if (LastChar == EOF)
103    return tok_eof;
104
105  // Otherwise, just return the character as its ascii value.
106  int ThisChar = LastChar;
107  LastChar = getchar();
108  return ThisChar;
109}
110
111//===----------------------------------------------------------------------===//
112// Abstract Syntax Tree (aka Parse Tree)
113//===----------------------------------------------------------------------===//
114namespace {
115/// ExprAST - Base class for all expression nodes.
116class ExprAST {
117public:
118  virtual ~ExprAST() {}
119  virtual Value *Codegen() = 0;
120};
121
122/// NumberExprAST - Expression class for numeric literals like "1.0".
123class NumberExprAST : public ExprAST {
124  double Val;
125
126public:
127  NumberExprAST(double val) : Val(val) {}
128  Value *Codegen() override;
129};
130
131/// VariableExprAST - Expression class for referencing a variable, like "a".
132class VariableExprAST : public ExprAST {
133  std::string Name;
134
135public:
136  VariableExprAST(const std::string &name) : Name(name) {}
137  Value *Codegen() override;
138};
139
140/// BinaryExprAST - Expression class for a binary operator.
141class BinaryExprAST : public ExprAST {
142  char Op;
143  ExprAST *LHS, *RHS;
144
145public:
146  BinaryExprAST(char op, ExprAST *lhs, ExprAST *rhs)
147      : Op(op), LHS(lhs), RHS(rhs) {}
148  Value *Codegen() override;
149};
150
151/// CallExprAST - Expression class for function calls.
152class CallExprAST : public ExprAST {
153  std::string Callee;
154  std::vector<ExprAST *> Args;
155
156public:
157  CallExprAST(const std::string &callee, std::vector<ExprAST *> &args)
158      : Callee(callee), Args(args) {}
159  Value *Codegen() override;
160};
161
162/// IfExprAST - Expression class for if/then/else.
163class IfExprAST : public ExprAST {
164  ExprAST *Cond, *Then, *Else;
165
166public:
167  IfExprAST(ExprAST *cond, ExprAST *then, ExprAST *_else)
168      : Cond(cond), Then(then), Else(_else) {}
169  Value *Codegen() override;
170};
171
172/// ForExprAST - Expression class for for/in.
173class ForExprAST : public ExprAST {
174  std::string VarName;
175  ExprAST *Start, *End, *Step, *Body;
176
177public:
178  ForExprAST(const std::string &varname, ExprAST *start, ExprAST *end,
179             ExprAST *step, ExprAST *body)
180      : VarName(varname), Start(start), End(end), Step(step), Body(body) {}
181  Value *Codegen() override;
182};
183
184/// PrototypeAST - This class represents the "prototype" for a function,
185/// which captures its name, and its argument names (thus implicitly the number
186/// of arguments the function takes).
187class PrototypeAST {
188  std::string Name;
189  std::vector<std::string> Args;
190
191public:
192  PrototypeAST(const std::string &name, const std::vector<std::string> &args)
193      : Name(name), Args(args) {}
194
195  Function *Codegen();
196};
197
198/// FunctionAST - This class represents a function definition itself.
199class FunctionAST {
200  PrototypeAST *Proto;
201  ExprAST *Body;
202
203public:
204  FunctionAST(PrototypeAST *proto, ExprAST *body) : Proto(proto), Body(body) {}
205
206  Function *Codegen();
207};
208} // end anonymous namespace
209
210//===----------------------------------------------------------------------===//
211// Parser
212//===----------------------------------------------------------------------===//
213
214/// CurTok/getNextToken - Provide a simple token buffer.  CurTok is the current
215/// token the parser is looking at.  getNextToken reads another token from the
216/// lexer and updates CurTok with its results.
217static int CurTok;
218static int getNextToken() { return CurTok = gettok(); }
219
220/// BinopPrecedence - This holds the precedence for each binary operator that is
221/// defined.
222static std::map<char, int> BinopPrecedence;
223
224/// GetTokPrecedence - Get the precedence of the pending binary operator token.
225static int GetTokPrecedence() {
226  if (!isascii(CurTok))
227    return -1;
228
229  // Make sure it's a declared binop.
230  int TokPrec = BinopPrecedence[CurTok];
231  if (TokPrec <= 0)
232    return -1;
233  return TokPrec;
234}
235
236/// Error* - These are little helper functions for error handling.
237ExprAST *Error(const char *Str) {
238  fprintf(stderr, "Error: %s\n", Str);
239  return 0;
240}
241PrototypeAST *ErrorP(const char *Str) {
242  Error(Str);
243  return 0;
244}
245FunctionAST *ErrorF(const char *Str) {
246  Error(Str);
247  return 0;
248}
249
250static ExprAST *ParseExpression();
251
252/// identifierexpr
253///   ::= identifier
254///   ::= identifier '(' expression* ')'
255static ExprAST *ParseIdentifierExpr() {
256  std::string IdName = IdentifierStr;
257
258  getNextToken(); // eat identifier.
259
260  if (CurTok != '(') // Simple variable ref.
261    return new VariableExprAST(IdName);
262
263  // Call.
264  getNextToken(); // eat (
265  std::vector<ExprAST *> Args;
266  if (CurTok != ')') {
267    while (1) {
268      ExprAST *Arg = ParseExpression();
269      if (!Arg)
270        return 0;
271      Args.push_back(Arg);
272
273      if (CurTok == ')')
274        break;
275
276      if (CurTok != ',')
277        return Error("Expected ')' or ',' in argument list");
278      getNextToken();
279    }
280  }
281
282  // Eat the ')'.
283  getNextToken();
284
285  return new CallExprAST(IdName, Args);
286}
287
288/// numberexpr ::= number
289static ExprAST *ParseNumberExpr() {
290  ExprAST *Result = new NumberExprAST(NumVal);
291  getNextToken(); // consume the number
292  return Result;
293}
294
295/// parenexpr ::= '(' expression ')'
296static ExprAST *ParseParenExpr() {
297  getNextToken(); // eat (.
298  ExprAST *V = ParseExpression();
299  if (!V)
300    return 0;
301
302  if (CurTok != ')')
303    return Error("expected ')'");
304  getNextToken(); // eat ).
305  return V;
306}
307
308/// ifexpr ::= 'if' expression 'then' expression 'else' expression
309static ExprAST *ParseIfExpr() {
310  getNextToken(); // eat the if.
311
312  // condition.
313  ExprAST *Cond = ParseExpression();
314  if (!Cond)
315    return 0;
316
317  if (CurTok != tok_then)
318    return Error("expected then");
319  getNextToken(); // eat the then
320
321  ExprAST *Then = ParseExpression();
322  if (Then == 0)
323    return 0;
324
325  if (CurTok != tok_else)
326    return Error("expected else");
327
328  getNextToken();
329
330  ExprAST *Else = ParseExpression();
331  if (!Else)
332    return 0;
333
334  return new IfExprAST(Cond, Then, Else);
335}
336
337/// forexpr ::= 'for' identifier '=' expr ',' expr (',' expr)? 'in' expression
338static ExprAST *ParseForExpr() {
339  getNextToken(); // eat the for.
340
341  if (CurTok != tok_identifier)
342    return Error("expected identifier after for");
343
344  std::string IdName = IdentifierStr;
345  getNextToken(); // eat identifier.
346
347  if (CurTok != '=')
348    return Error("expected '=' after for");
349  getNextToken(); // eat '='.
350
351  ExprAST *Start = ParseExpression();
352  if (Start == 0)
353    return 0;
354  if (CurTok != ',')
355    return Error("expected ',' after for start value");
356  getNextToken();
357
358  ExprAST *End = ParseExpression();
359  if (End == 0)
360    return 0;
361
362  // The step value is optional.
363  ExprAST *Step = 0;
364  if (CurTok == ',') {
365    getNextToken();
366    Step = ParseExpression();
367    if (Step == 0)
368      return 0;
369  }
370
371  if (CurTok != tok_in)
372    return Error("expected 'in' after for");
373  getNextToken(); // eat 'in'.
374
375  ExprAST *Body = ParseExpression();
376  if (Body == 0)
377    return 0;
378
379  return new ForExprAST(IdName, Start, End, Step, Body);
380}
381
382/// primary
383///   ::= identifierexpr
384///   ::= numberexpr
385///   ::= parenexpr
386///   ::= ifexpr
387///   ::= forexpr
388static ExprAST *ParsePrimary() {
389  switch (CurTok) {
390  default:
391    return Error("unknown token when expecting an expression");
392  case tok_identifier:
393    return ParseIdentifierExpr();
394  case tok_number:
395    return ParseNumberExpr();
396  case '(':
397    return ParseParenExpr();
398  case tok_if:
399    return ParseIfExpr();
400  case tok_for:
401    return ParseForExpr();
402  }
403}
404
405/// binoprhs
406///   ::= ('+' primary)*
407static ExprAST *ParseBinOpRHS(int ExprPrec, ExprAST *LHS) {
408  // If this is a binop, find its precedence.
409  while (1) {
410    int TokPrec = GetTokPrecedence();
411
412    // If this is a binop that binds at least as tightly as the current binop,
413    // consume it, otherwise we are done.
414    if (TokPrec < ExprPrec)
415      return LHS;
416
417    // Okay, we know this is a binop.
418    int BinOp = CurTok;
419    getNextToken(); // eat binop
420
421    // Parse the primary expression after the binary operator.
422    ExprAST *RHS = ParsePrimary();
423    if (!RHS)
424      return 0;
425
426    // If BinOp binds less tightly with RHS than the operator after RHS, let
427    // the pending operator take RHS as its LHS.
428    int NextPrec = GetTokPrecedence();
429    if (TokPrec < NextPrec) {
430      RHS = ParseBinOpRHS(TokPrec + 1, RHS);
431      if (RHS == 0)
432        return 0;
433    }
434
435    // Merge LHS/RHS.
436    LHS = new BinaryExprAST(BinOp, LHS, RHS);
437  }
438}
439
440/// expression
441///   ::= primary binoprhs
442///
443static ExprAST *ParseExpression() {
444  ExprAST *LHS = ParsePrimary();
445  if (!LHS)
446    return 0;
447
448  return ParseBinOpRHS(0, LHS);
449}
450
451/// prototype
452///   ::= id '(' id* ')'
453static PrototypeAST *ParsePrototype() {
454  if (CurTok != tok_identifier)
455    return ErrorP("Expected function name in prototype");
456
457  std::string FnName = IdentifierStr;
458  getNextToken();
459
460  if (CurTok != '(')
461    return ErrorP("Expected '(' in prototype");
462
463  std::vector<std::string> ArgNames;
464  while (getNextToken() == tok_identifier)
465    ArgNames.push_back(IdentifierStr);
466  if (CurTok != ')')
467    return ErrorP("Expected ')' in prototype");
468
469  // success.
470  getNextToken(); // eat ')'.
471
472  return new PrototypeAST(FnName, ArgNames);
473}
474
475/// definition ::= 'def' prototype expression
476static FunctionAST *ParseDefinition() {
477  getNextToken(); // eat def.
478  PrototypeAST *Proto = ParsePrototype();
479  if (Proto == 0)
480    return 0;
481
482  if (ExprAST *E = ParseExpression())
483    return new FunctionAST(Proto, E);
484  return 0;
485}
486
487/// toplevelexpr ::= expression
488static FunctionAST *ParseTopLevelExpr() {
489  if (ExprAST *E = ParseExpression()) {
490    // Make an anonymous proto.
491    PrototypeAST *Proto = new PrototypeAST("", std::vector<std::string>());
492    return new FunctionAST(Proto, E);
493  }
494  return 0;
495}
496
497/// external ::= 'extern' prototype
498static PrototypeAST *ParseExtern() {
499  getNextToken(); // eat extern.
500  return ParsePrototype();
501}
502
503//===----------------------------------------------------------------------===//
504// Code Generation
505//===----------------------------------------------------------------------===//
506
507static Module *TheModule;
508static IRBuilder<> Builder(getGlobalContext());
509static std::map<std::string, Value *> NamedValues;
510static legacy::FunctionPassManager *TheFPM;
511
512Value *ErrorV(const char *Str) {
513  Error(Str);
514  return 0;
515}
516
517Value *NumberExprAST::Codegen() {
518  return ConstantFP::get(getGlobalContext(), APFloat(Val));
519}
520
521Value *VariableExprAST::Codegen() {
522  // Look this variable up in the function.
523  Value *V = NamedValues[Name];
524  return V ? V : ErrorV("Unknown variable name");
525}
526
527Value *BinaryExprAST::Codegen() {
528  Value *L = LHS->Codegen();
529  Value *R = RHS->Codegen();
530  if (L == 0 || R == 0)
531    return 0;
532
533  switch (Op) {
534  case '+':
535    return Builder.CreateFAdd(L, R, "addtmp");
536  case '-':
537    return Builder.CreateFSub(L, R, "subtmp");
538  case '*':
539    return Builder.CreateFMul(L, R, "multmp");
540  case '<':
541    L = Builder.CreateFCmpULT(L, R, "cmptmp");
542    // Convert bool 0/1 to double 0.0 or 1.0
543    return Builder.CreateUIToFP(L, Type::getDoubleTy(getGlobalContext()),
544                                "booltmp");
545  default:
546    return ErrorV("invalid binary operator");
547  }
548}
549
550Value *CallExprAST::Codegen() {
551  // Look up the name in the global module table.
552  Function *CalleeF = TheModule->getFunction(Callee);
553  if (CalleeF == 0)
554    return ErrorV("Unknown function referenced");
555
556  // If argument mismatch error.
557  if (CalleeF->arg_size() != Args.size())
558    return ErrorV("Incorrect # arguments passed");
559
560  std::vector<Value *> ArgsV;
561  for (unsigned i = 0, e = Args.size(); i != e; ++i) {
562    ArgsV.push_back(Args[i]->Codegen());
563    if (ArgsV.back() == 0)
564      return 0;
565  }
566
567  return Builder.CreateCall(CalleeF, ArgsV, "calltmp");
568}
569
570Value *IfExprAST::Codegen() {
571  Value *CondV = Cond->Codegen();
572  if (CondV == 0)
573    return 0;
574
575  // Convert condition to a bool by comparing equal to 0.0.
576  CondV = Builder.CreateFCmpONE(
577      CondV, ConstantFP::get(getGlobalContext(), APFloat(0.0)), "ifcond");
578
579  Function *TheFunction = Builder.GetInsertBlock()->getParent();
580
581  // Create blocks for the then and else cases.  Insert the 'then' block at the
582  // end of the function.
583  BasicBlock *ThenBB =
584      BasicBlock::Create(getGlobalContext(), "then", TheFunction);
585  BasicBlock *ElseBB = BasicBlock::Create(getGlobalContext(), "else");
586  BasicBlock *MergeBB = BasicBlock::Create(getGlobalContext(), "ifcont");
587
588  Builder.CreateCondBr(CondV, ThenBB, ElseBB);
589
590  // Emit then value.
591  Builder.SetInsertPoint(ThenBB);
592
593  Value *ThenV = Then->Codegen();
594  if (ThenV == 0)
595    return 0;
596
597  Builder.CreateBr(MergeBB);
598  // Codegen of 'Then' can change the current block, update ThenBB for the PHI.
599  ThenBB = Builder.GetInsertBlock();
600
601  // Emit else block.
602  TheFunction->getBasicBlockList().push_back(ElseBB);
603  Builder.SetInsertPoint(ElseBB);
604
605  Value *ElseV = Else->Codegen();
606  if (ElseV == 0)
607    return 0;
608
609  Builder.CreateBr(MergeBB);
610  // Codegen of 'Else' can change the current block, update ElseBB for the PHI.
611  ElseBB = Builder.GetInsertBlock();
612
613  // Emit merge block.
614  TheFunction->getBasicBlockList().push_back(MergeBB);
615  Builder.SetInsertPoint(MergeBB);
616  PHINode *PN =
617      Builder.CreatePHI(Type::getDoubleTy(getGlobalContext()), 2, "iftmp");
618
619  PN->addIncoming(ThenV, ThenBB);
620  PN->addIncoming(ElseV, ElseBB);
621  return PN;
622}
623
624Value *ForExprAST::Codegen() {
625  // Output this as:
626  //   ...
627  //   start = startexpr
628  //   goto loop
629  // loop:
630  //   variable = phi [start, loopheader], [nextvariable, loopend]
631  //   ...
632  //   bodyexpr
633  //   ...
634  // loopend:
635  //   step = stepexpr
636  //   nextvariable = variable + step
637  //   endcond = endexpr
638  //   br endcond, loop, endloop
639  // outloop:
640
641  // Emit the start code first, without 'variable' in scope.
642  Value *StartVal = Start->Codegen();
643  if (StartVal == 0)
644    return 0;
645
646  // Make the new basic block for the loop header, inserting after current
647  // block.
648  Function *TheFunction = Builder.GetInsertBlock()->getParent();
649  BasicBlock *PreheaderBB = Builder.GetInsertBlock();
650  BasicBlock *LoopBB =
651      BasicBlock::Create(getGlobalContext(), "loop", TheFunction);
652
653  // Insert an explicit fall through from the current block to the LoopBB.
654  Builder.CreateBr(LoopBB);
655
656  // Start insertion in LoopBB.
657  Builder.SetInsertPoint(LoopBB);
658
659  // Start the PHI node with an entry for Start.
660  PHINode *Variable = Builder.CreatePHI(Type::getDoubleTy(getGlobalContext()),
661                                        2, VarName.c_str());
662  Variable->addIncoming(StartVal, PreheaderBB);
663
664  // Within the loop, the variable is defined equal to the PHI node.  If it
665  // shadows an existing variable, we have to restore it, so save it now.
666  Value *OldVal = NamedValues[VarName];
667  NamedValues[VarName] = Variable;
668
669  // Emit the body of the loop.  This, like any other expr, can change the
670  // current BB.  Note that we ignore the value computed by the body, but don't
671  // allow an error.
672  if (Body->Codegen() == 0)
673    return 0;
674
675  // Emit the step value.
676  Value *StepVal;
677  if (Step) {
678    StepVal = Step->Codegen();
679    if (StepVal == 0)
680      return 0;
681  } else {
682    // If not specified, use 1.0.
683    StepVal = ConstantFP::get(getGlobalContext(), APFloat(1.0));
684  }
685
686  Value *NextVar = Builder.CreateFAdd(Variable, StepVal, "nextvar");
687
688  // Compute the end condition.
689  Value *EndCond = End->Codegen();
690  if (EndCond == 0)
691    return EndCond;
692
693  // Convert condition to a bool by comparing equal to 0.0.
694  EndCond = Builder.CreateFCmpONE(
695      EndCond, ConstantFP::get(getGlobalContext(), APFloat(0.0)), "loopcond");
696
697  // Create the "after loop" block and insert it.
698  BasicBlock *LoopEndBB = Builder.GetInsertBlock();
699  BasicBlock *AfterBB =
700      BasicBlock::Create(getGlobalContext(), "afterloop", TheFunction);
701
702  // Insert the conditional branch into the end of LoopEndBB.
703  Builder.CreateCondBr(EndCond, LoopBB, AfterBB);
704
705  // Any new code will be inserted in AfterBB.
706  Builder.SetInsertPoint(AfterBB);
707
708  // Add a new entry to the PHI node for the backedge.
709  Variable->addIncoming(NextVar, LoopEndBB);
710
711  // Restore the unshadowed variable.
712  if (OldVal)
713    NamedValues[VarName] = OldVal;
714  else
715    NamedValues.erase(VarName);
716
717  // for expr always returns 0.0.
718  return Constant::getNullValue(Type::getDoubleTy(getGlobalContext()));
719}
720
721Function *PrototypeAST::Codegen() {
722  // Make the function type:  double(double,double) etc.
723  std::vector<Type *> Doubles(Args.size(),
724                              Type::getDoubleTy(getGlobalContext()));
725  FunctionType *FT =
726      FunctionType::get(Type::getDoubleTy(getGlobalContext()), Doubles, false);
727
728  Function *F =
729      Function::Create(FT, Function::ExternalLinkage, Name, TheModule);
730
731  // If F conflicted, there was already something named 'Name'.  If it has a
732  // body, don't allow redefinition or reextern.
733  if (F->getName() != Name) {
734    // Delete the one we just made and get the existing one.
735    F->eraseFromParent();
736    F = TheModule->getFunction(Name);
737
738    // If F already has a body, reject this.
739    if (!F->empty()) {
740      ErrorF("redefinition of function");
741      return 0;
742    }
743
744    // If F took a different number of args, reject.
745    if (F->arg_size() != Args.size()) {
746      ErrorF("redefinition of function with different # args");
747      return 0;
748    }
749  }
750
751  // Set names for all arguments.
752  unsigned Idx = 0;
753  for (Function::arg_iterator AI = F->arg_begin(); Idx != Args.size();
754       ++AI, ++Idx) {
755    AI->setName(Args[Idx]);
756
757    // Add arguments to variable symbol table.
758    NamedValues[Args[Idx]] = AI;
759  }
760
761  return F;
762}
763
764Function *FunctionAST::Codegen() {
765  NamedValues.clear();
766
767  Function *TheFunction = Proto->Codegen();
768  if (TheFunction == 0)
769    return 0;
770
771  // Create a new basic block to start insertion into.
772  BasicBlock *BB = BasicBlock::Create(getGlobalContext(), "entry", TheFunction);
773  Builder.SetInsertPoint(BB);
774
775  if (Value *RetVal = Body->Codegen()) {
776    // Finish off the function.
777    Builder.CreateRet(RetVal);
778
779    // Validate the generated code, checking for consistency.
780    verifyFunction(*TheFunction);
781
782    // Optimize the function.
783    TheFPM->run(*TheFunction);
784
785    return TheFunction;
786  }
787
788  // Error reading body, remove function.
789  TheFunction->eraseFromParent();
790  return 0;
791}
792
793//===----------------------------------------------------------------------===//
794// Top-Level parsing and JIT Driver
795//===----------------------------------------------------------------------===//
796
797static ExecutionEngine *TheExecutionEngine;
798
799static void HandleDefinition() {
800  if (FunctionAST *F = ParseDefinition()) {
801    if (Function *LF = F->Codegen()) {
802      fprintf(stderr, "Read function definition:");
803      LF->dump();
804    }
805  } else {
806    // Skip token for error recovery.
807    getNextToken();
808  }
809}
810
811static void HandleExtern() {
812  if (PrototypeAST *P = ParseExtern()) {
813    if (Function *F = P->Codegen()) {
814      fprintf(stderr, "Read extern: ");
815      F->dump();
816    }
817  } else {
818    // Skip token for error recovery.
819    getNextToken();
820  }
821}
822
823static void HandleTopLevelExpression() {
824  // Evaluate a top-level expression into an anonymous function.
825  if (FunctionAST *F = ParseTopLevelExpr()) {
826    if (Function *LF = F->Codegen()) {
827      TheExecutionEngine->finalizeObject();
828      // JIT the function, returning a function pointer.
829      void *FPtr = TheExecutionEngine->getPointerToFunction(LF);
830
831      // Cast it to the right type (takes no arguments, returns a double) so we
832      // can call it as a native function.
833      double (*FP)() = (double (*)())(intptr_t)FPtr;
834      fprintf(stderr, "Evaluated to %f\n", FP());
835    }
836  } else {
837    // Skip token for error recovery.
838    getNextToken();
839  }
840}
841
842/// top ::= definition | external | expression | ';'
843static void MainLoop() {
844  while (1) {
845    fprintf(stderr, "ready> ");
846    switch (CurTok) {
847    case tok_eof:
848      return;
849    case ';':
850      getNextToken();
851      break; // ignore top-level semicolons.
852    case tok_def:
853      HandleDefinition();
854      break;
855    case tok_extern:
856      HandleExtern();
857      break;
858    default:
859      HandleTopLevelExpression();
860      break;
861    }
862  }
863}
864
865//===----------------------------------------------------------------------===//
866// "Library" functions that can be "extern'd" from user code.
867//===----------------------------------------------------------------------===//
868
869/// putchard - putchar that takes a double and returns 0.
870extern "C" double putchard(double X) {
871  putchar((char)X);
872  return 0;
873}
874
875//===----------------------------------------------------------------------===//
876// Main driver code.
877//===----------------------------------------------------------------------===//
878
879int main() {
880  InitializeNativeTarget();
881  InitializeNativeTargetAsmPrinter();
882  InitializeNativeTargetAsmParser();
883  LLVMContext &Context = getGlobalContext();
884
885  // Install standard binary operators.
886  // 1 is lowest precedence.
887  BinopPrecedence['<'] = 10;
888  BinopPrecedence['+'] = 20;
889  BinopPrecedence['-'] = 20;
890  BinopPrecedence['*'] = 40; // highest.
891
892  // Prime the first token.
893  fprintf(stderr, "ready> ");
894  getNextToken();
895
896  // Make the module, which holds all the code.
897  std::unique_ptr<Module> Owner = make_unique<Module>("my cool jit", Context);
898  TheModule = Owner.get();
899
900  // Create the JIT.  This takes ownership of the module.
901  std::string ErrStr;
902  TheExecutionEngine =
903      EngineBuilder(std::move(Owner))
904          .setErrorStr(&ErrStr)
905          .setMCJITMemoryManager(llvm::make_unique<SectionMemoryManager>())
906          .create();
907  if (!TheExecutionEngine) {
908    fprintf(stderr, "Could not create ExecutionEngine: %s\n", ErrStr.c_str());
909    exit(1);
910  }
911
912  legacy::FunctionPassManager OurFPM(TheModule);
913
914  // Set up the optimizer pipeline.  Start with registering info about how the
915  // target lays out data structures.
916  TheModule->setDataLayout(*TheExecutionEngine->getDataLayout());
917  // Provide basic AliasAnalysis support for GVN.
918  OurFPM.add(createBasicAliasAnalysisPass());
919  // Do simple "peephole" optimizations and bit-twiddling optzns.
920  OurFPM.add(createInstructionCombiningPass());
921  // Reassociate expressions.
922  OurFPM.add(createReassociatePass());
923  // Eliminate Common SubExpressions.
924  OurFPM.add(createGVNPass());
925  // Simplify the control flow graph (deleting unreachable blocks, etc).
926  OurFPM.add(createCFGSimplificationPass());
927
928  OurFPM.doInitialization();
929
930  // Set the global so the code gen can use this.
931  TheFPM = &OurFPM;
932
933  // Run the main "interpreter loop" now.
934  MainLoop();
935
936  TheFPM = 0;
937
938  // Print out all of the generated code.
939  TheModule->dump();
940
941  return 0;
942}
943