1#include "llvm/IR/Verifier.h"
2#include "llvm/IR/DerivedTypes.h"
3#include "llvm/IR/IRBuilder.h"
4#include "llvm/IR/LLVMContext.h"
5#include "llvm/IR/Module.h"
6#include <cctype>
7#include <cstdio>
8#include <map>
9#include <string>
10#include <vector>
11using namespace llvm;
12
13//===----------------------------------------------------------------------===//
14// Lexer
15//===----------------------------------------------------------------------===//
16
17// The lexer returns tokens [0-255] if it is an unknown character, otherwise one
18// of these for known things.
19enum Token {
20  tok_eof = -1,
21
22  // commands
23  tok_def = -2, tok_extern = -3,
24
25  // primary
26  tok_identifier = -4, tok_number = -5
27};
28
29static std::string IdentifierStr;  // Filled in if tok_identifier
30static double NumVal;              // Filled in if tok_number
31
32/// gettok - Return the next token from standard input.
33static int gettok() {
34  static int LastChar = ' ';
35
36  // Skip any whitespace.
37  while (isspace(LastChar))
38    LastChar = getchar();
39
40  if (isalpha(LastChar)) { // identifier: [a-zA-Z][a-zA-Z0-9]*
41    IdentifierStr = LastChar;
42    while (isalnum((LastChar = getchar())))
43      IdentifierStr += LastChar;
44
45    if (IdentifierStr == "def") return tok_def;
46    if (IdentifierStr == "extern") return tok_extern;
47    return tok_identifier;
48  }
49
50  if (isdigit(LastChar) || LastChar == '.') {   // Number: [0-9.]+
51    std::string NumStr;
52    do {
53      NumStr += LastChar;
54      LastChar = getchar();
55    } while (isdigit(LastChar) || LastChar == '.');
56
57    NumVal = strtod(NumStr.c_str(), 0);
58    return tok_number;
59  }
60
61  if (LastChar == '#') {
62    // Comment until end of line.
63    do LastChar = getchar();
64    while (LastChar != EOF && LastChar != '\n' && LastChar != '\r');
65
66    if (LastChar != EOF)
67      return gettok();
68  }
69
70  // Check for end of file.  Don't eat the EOF.
71  if (LastChar == EOF)
72    return tok_eof;
73
74  // Otherwise, just return the character as its ascii value.
75  int ThisChar = LastChar;
76  LastChar = getchar();
77  return ThisChar;
78}
79
80//===----------------------------------------------------------------------===//
81// Abstract Syntax Tree (aka Parse Tree)
82//===----------------------------------------------------------------------===//
83namespace {
84/// ExprAST - Base class for all expression nodes.
85class ExprAST {
86public:
87  virtual ~ExprAST() {}
88  virtual Value *Codegen() = 0;
89};
90
91/// NumberExprAST - Expression class for numeric literals like "1.0".
92class NumberExprAST : public ExprAST {
93  double Val;
94public:
95  NumberExprAST(double val) : Val(val) {}
96  virtual Value *Codegen();
97};
98
99/// VariableExprAST - Expression class for referencing a variable, like "a".
100class VariableExprAST : public ExprAST {
101  std::string Name;
102public:
103  VariableExprAST(const std::string &name) : Name(name) {}
104  virtual Value *Codegen();
105};
106
107/// BinaryExprAST - Expression class for a binary operator.
108class BinaryExprAST : public ExprAST {
109  char Op;
110  ExprAST *LHS, *RHS;
111public:
112  BinaryExprAST(char op, ExprAST *lhs, ExprAST *rhs)
113    : Op(op), LHS(lhs), RHS(rhs) {}
114  virtual Value *Codegen();
115};
116
117/// CallExprAST - Expression class for function calls.
118class CallExprAST : public ExprAST {
119  std::string Callee;
120  std::vector<ExprAST*> Args;
121public:
122  CallExprAST(const std::string &callee, std::vector<ExprAST*> &args)
123    : Callee(callee), Args(args) {}
124  virtual Value *Codegen();
125};
126
127/// PrototypeAST - This class represents the "prototype" for a function,
128/// which captures its name, and its argument names (thus implicitly the number
129/// of arguments the function takes).
130class PrototypeAST {
131  std::string Name;
132  std::vector<std::string> Args;
133public:
134  PrototypeAST(const std::string &name, const std::vector<std::string> &args)
135    : Name(name), Args(args) {}
136
137  Function *Codegen();
138};
139
140/// FunctionAST - This class represents a function definition itself.
141class FunctionAST {
142  PrototypeAST *Proto;
143  ExprAST *Body;
144public:
145  FunctionAST(PrototypeAST *proto, ExprAST *body)
146    : Proto(proto), Body(body) {}
147
148  Function *Codegen();
149};
150} // end anonymous namespace
151
152//===----------------------------------------------------------------------===//
153// Parser
154//===----------------------------------------------------------------------===//
155
156/// CurTok/getNextToken - Provide a simple token buffer.  CurTok is the current
157/// token the parser is looking at.  getNextToken reads another token from the
158/// lexer and updates CurTok with its results.
159static int CurTok;
160static int getNextToken() {
161  return CurTok = gettok();
162}
163
164/// BinopPrecedence - This holds the precedence for each binary operator that is
165/// defined.
166static std::map<char, int> BinopPrecedence;
167
168/// GetTokPrecedence - Get the precedence of the pending binary operator token.
169static int GetTokPrecedence() {
170  if (!isascii(CurTok))
171    return -1;
172
173  // Make sure it's a declared binop.
174  int TokPrec = BinopPrecedence[CurTok];
175  if (TokPrec <= 0) return -1;
176  return TokPrec;
177}
178
179/// Error* - These are little helper functions for error handling.
180ExprAST *Error(const char *Str) { fprintf(stderr, "Error: %s\n", Str);return 0;}
181PrototypeAST *ErrorP(const char *Str) { Error(Str); return 0; }
182FunctionAST *ErrorF(const char *Str) { Error(Str); return 0; }
183
184static ExprAST *ParseExpression();
185
186/// identifierexpr
187///   ::= identifier
188///   ::= identifier '(' expression* ')'
189static ExprAST *ParseIdentifierExpr() {
190  std::string IdName = IdentifierStr;
191
192  getNextToken();  // eat identifier.
193
194  if (CurTok != '(') // Simple variable ref.
195    return new VariableExprAST(IdName);
196
197  // Call.
198  getNextToken();  // eat (
199  std::vector<ExprAST*> Args;
200  if (CurTok != ')') {
201    while (1) {
202      ExprAST *Arg = ParseExpression();
203      if (!Arg) return 0;
204      Args.push_back(Arg);
205
206      if (CurTok == ')') break;
207
208      if (CurTok != ',')
209        return Error("Expected ')' or ',' in argument list");
210      getNextToken();
211    }
212  }
213
214  // Eat the ')'.
215  getNextToken();
216
217  return new CallExprAST(IdName, Args);
218}
219
220/// numberexpr ::= number
221static ExprAST *ParseNumberExpr() {
222  ExprAST *Result = new NumberExprAST(NumVal);
223  getNextToken(); // consume the number
224  return Result;
225}
226
227/// parenexpr ::= '(' expression ')'
228static ExprAST *ParseParenExpr() {
229  getNextToken();  // eat (.
230  ExprAST *V = ParseExpression();
231  if (!V) return 0;
232
233  if (CurTok != ')')
234    return Error("expected ')'");
235  getNextToken();  // eat ).
236  return V;
237}
238
239/// primary
240///   ::= identifierexpr
241///   ::= numberexpr
242///   ::= parenexpr
243static ExprAST *ParsePrimary() {
244  switch (CurTok) {
245  default: return Error("unknown token when expecting an expression");
246  case tok_identifier: return ParseIdentifierExpr();
247  case tok_number:     return ParseNumberExpr();
248  case '(':            return ParseParenExpr();
249  }
250}
251
252/// binoprhs
253///   ::= ('+' primary)*
254static ExprAST *ParseBinOpRHS(int ExprPrec, ExprAST *LHS) {
255  // If this is a binop, find its precedence.
256  while (1) {
257    int TokPrec = GetTokPrecedence();
258
259    // If this is a binop that binds at least as tightly as the current binop,
260    // consume it, otherwise we are done.
261    if (TokPrec < ExprPrec)
262      return LHS;
263
264    // Okay, we know this is a binop.
265    int BinOp = CurTok;
266    getNextToken();  // eat binop
267
268    // Parse the primary expression after the binary operator.
269    ExprAST *RHS = ParsePrimary();
270    if (!RHS) return 0;
271
272    // If BinOp binds less tightly with RHS than the operator after RHS, let
273    // the pending operator take RHS as its LHS.
274    int NextPrec = GetTokPrecedence();
275    if (TokPrec < NextPrec) {
276      RHS = ParseBinOpRHS(TokPrec+1, RHS);
277      if (RHS == 0) return 0;
278    }
279
280    // Merge LHS/RHS.
281    LHS = new BinaryExprAST(BinOp, LHS, RHS);
282  }
283}
284
285/// expression
286///   ::= primary binoprhs
287///
288static ExprAST *ParseExpression() {
289  ExprAST *LHS = ParsePrimary();
290  if (!LHS) return 0;
291
292  return ParseBinOpRHS(0, LHS);
293}
294
295/// prototype
296///   ::= id '(' id* ')'
297static PrototypeAST *ParsePrototype() {
298  if (CurTok != tok_identifier)
299    return ErrorP("Expected function name in prototype");
300
301  std::string FnName = IdentifierStr;
302  getNextToken();
303
304  if (CurTok != '(')
305    return ErrorP("Expected '(' in prototype");
306
307  std::vector<std::string> ArgNames;
308  while (getNextToken() == tok_identifier)
309    ArgNames.push_back(IdentifierStr);
310  if (CurTok != ')')
311    return ErrorP("Expected ')' in prototype");
312
313  // success.
314  getNextToken();  // eat ')'.
315
316  return new PrototypeAST(FnName, ArgNames);
317}
318
319/// definition ::= 'def' prototype expression
320static FunctionAST *ParseDefinition() {
321  getNextToken();  // eat def.
322  PrototypeAST *Proto = ParsePrototype();
323  if (Proto == 0) return 0;
324
325  if (ExprAST *E = ParseExpression())
326    return new FunctionAST(Proto, E);
327  return 0;
328}
329
330/// toplevelexpr ::= expression
331static FunctionAST *ParseTopLevelExpr() {
332  if (ExprAST *E = ParseExpression()) {
333    // Make an anonymous proto.
334    PrototypeAST *Proto = new PrototypeAST("", std::vector<std::string>());
335    return new FunctionAST(Proto, E);
336  }
337  return 0;
338}
339
340/// external ::= 'extern' prototype
341static PrototypeAST *ParseExtern() {
342  getNextToken();  // eat extern.
343  return ParsePrototype();
344}
345
346//===----------------------------------------------------------------------===//
347// Code Generation
348//===----------------------------------------------------------------------===//
349
350static Module *TheModule;
351static IRBuilder<> Builder(getGlobalContext());
352static std::map<std::string, Value*> NamedValues;
353
354Value *ErrorV(const char *Str) { Error(Str); return 0; }
355
356Value *NumberExprAST::Codegen() {
357  return ConstantFP::get(getGlobalContext(), APFloat(Val));
358}
359
360Value *VariableExprAST::Codegen() {
361  // Look this variable up in the function.
362  Value *V = NamedValues[Name];
363  return V ? V : ErrorV("Unknown variable name");
364}
365
366Value *BinaryExprAST::Codegen() {
367  Value *L = LHS->Codegen();
368  Value *R = RHS->Codegen();
369  if (L == 0 || R == 0) return 0;
370
371  switch (Op) {
372  case '+': return Builder.CreateFAdd(L, R, "addtmp");
373  case '-': return Builder.CreateFSub(L, R, "subtmp");
374  case '*': return Builder.CreateFMul(L, R, "multmp");
375  case '<':
376    L = Builder.CreateFCmpULT(L, R, "cmptmp");
377    // Convert bool 0/1 to double 0.0 or 1.0
378    return Builder.CreateUIToFP(L, Type::getDoubleTy(getGlobalContext()),
379                                "booltmp");
380  default: return ErrorV("invalid binary operator");
381  }
382}
383
384Value *CallExprAST::Codegen() {
385  // Look up the name in the global module table.
386  Function *CalleeF = TheModule->getFunction(Callee);
387  if (CalleeF == 0)
388    return ErrorV("Unknown function referenced");
389
390  // If argument mismatch error.
391  if (CalleeF->arg_size() != Args.size())
392    return ErrorV("Incorrect # arguments passed");
393
394  std::vector<Value*> ArgsV;
395  for (unsigned i = 0, e = Args.size(); i != e; ++i) {
396    ArgsV.push_back(Args[i]->Codegen());
397    if (ArgsV.back() == 0) return 0;
398  }
399
400  return Builder.CreateCall(CalleeF, ArgsV, "calltmp");
401}
402
403Function *PrototypeAST::Codegen() {
404  // Make the function type:  double(double,double) etc.
405  std::vector<Type*> Doubles(Args.size(),
406                             Type::getDoubleTy(getGlobalContext()));
407  FunctionType *FT = FunctionType::get(Type::getDoubleTy(getGlobalContext()),
408                                       Doubles, false);
409
410  Function *F = Function::Create(FT, Function::ExternalLinkage, Name, TheModule);
411
412  // If F conflicted, there was already something named 'Name'.  If it has a
413  // body, don't allow redefinition or reextern.
414  if (F->getName() != Name) {
415    // Delete the one we just made and get the existing one.
416    F->eraseFromParent();
417    F = TheModule->getFunction(Name);
418
419    // If F already has a body, reject this.
420    if (!F->empty()) {
421      ErrorF("redefinition of function");
422      return 0;
423    }
424
425    // If F took a different number of args, reject.
426    if (F->arg_size() != Args.size()) {
427      ErrorF("redefinition of function with different # args");
428      return 0;
429    }
430  }
431
432  // Set names for all arguments.
433  unsigned Idx = 0;
434  for (Function::arg_iterator AI = F->arg_begin(); Idx != Args.size();
435       ++AI, ++Idx) {
436    AI->setName(Args[Idx]);
437
438    // Add arguments to variable symbol table.
439    NamedValues[Args[Idx]] = AI;
440  }
441
442  return F;
443}
444
445Function *FunctionAST::Codegen() {
446  NamedValues.clear();
447
448  Function *TheFunction = Proto->Codegen();
449  if (TheFunction == 0)
450    return 0;
451
452  // Create a new basic block to start insertion into.
453  BasicBlock *BB = BasicBlock::Create(getGlobalContext(), "entry", TheFunction);
454  Builder.SetInsertPoint(BB);
455
456  if (Value *RetVal = Body->Codegen()) {
457    // Finish off the function.
458    Builder.CreateRet(RetVal);
459
460    // Validate the generated code, checking for consistency.
461    verifyFunction(*TheFunction);
462
463    return TheFunction;
464  }
465
466  // Error reading body, remove function.
467  TheFunction->eraseFromParent();
468  return 0;
469}
470
471//===----------------------------------------------------------------------===//
472// Top-Level parsing and JIT Driver
473//===----------------------------------------------------------------------===//
474
475static void HandleDefinition() {
476  if (FunctionAST *F = ParseDefinition()) {
477    if (Function *LF = F->Codegen()) {
478      fprintf(stderr, "Read function definition:");
479      LF->dump();
480    }
481  } else {
482    // Skip token for error recovery.
483    getNextToken();
484  }
485}
486
487static void HandleExtern() {
488  if (PrototypeAST *P = ParseExtern()) {
489    if (Function *F = P->Codegen()) {
490      fprintf(stderr, "Read extern: ");
491      F->dump();
492    }
493  } else {
494    // Skip token for error recovery.
495    getNextToken();
496  }
497}
498
499static void HandleTopLevelExpression() {
500  // Evaluate a top-level expression into an anonymous function.
501  if (FunctionAST *F = ParseTopLevelExpr()) {
502    if (Function *LF = F->Codegen()) {
503      fprintf(stderr, "Read top-level expression:");
504      LF->dump();
505    }
506  } else {
507    // Skip token for error recovery.
508    getNextToken();
509  }
510}
511
512/// top ::= definition | external | expression | ';'
513static void MainLoop() {
514  while (1) {
515    fprintf(stderr, "ready> ");
516    switch (CurTok) {
517    case tok_eof:    return;
518    case ';':        getNextToken(); break;  // ignore top-level semicolons.
519    case tok_def:    HandleDefinition(); break;
520    case tok_extern: HandleExtern(); break;
521    default:         HandleTopLevelExpression(); break;
522    }
523  }
524}
525
526//===----------------------------------------------------------------------===//
527// "Library" functions that can be "extern'd" from user code.
528//===----------------------------------------------------------------------===//
529
530/// putchard - putchar that takes a double and returns 0.
531extern "C"
532double putchard(double X) {
533  putchar((char)X);
534  return 0;
535}
536
537//===----------------------------------------------------------------------===//
538// Main driver code.
539//===----------------------------------------------------------------------===//
540
541int main() {
542  LLVMContext &Context = getGlobalContext();
543
544  // Install standard binary operators.
545  // 1 is lowest precedence.
546  BinopPrecedence['<'] = 10;
547  BinopPrecedence['+'] = 20;
548  BinopPrecedence['-'] = 20;
549  BinopPrecedence['*'] = 40;  // highest.
550
551  // Prime the first token.
552  fprintf(stderr, "ready> ");
553  getNextToken();
554
555  // Make the module, which holds all the code.
556  TheModule = new Module("my cool jit", Context);
557
558  // Run the main "interpreter loop" now.
559  MainLoop();
560
561  // Print out all of the generated code.
562  TheModule->dump();
563
564  return 0;
565}
566