toy.cpp revision 31c6c5d58a6d2254063e8a18fd32b851a06e2ddf 
1#include "llvm/DerivedTypes.h"
2#include "llvm/ExecutionEngine/ExecutionEngine.h"
3#include "llvm/ExecutionEngine/Interpreter.h"
4#include "llvm/ExecutionEngine/JIT.h"
5#include "llvm/LLVMContext.h"
6#include "llvm/Module.h"
7#include "llvm/ModuleProvider.h"
8#include "llvm/PassManager.h"
9#include "llvm/Analysis/Verifier.h"
10#include "llvm/Target/TargetData.h"
11#include "llvm/Target/TargetSelect.h"
12#include "llvm/Transforms/Scalar.h"
13#include "llvm/Support/IRBuilder.h"
14#include <cstdio>
15#include <string>
16#include <map>
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
36static std::string IdentifierStr;  // Filled in if tok_identifier
37static double NumVal;              // Filled in if tok_number
38
39/// gettok - Return the next token from standard input.
40static int gettok() {
41  static int LastChar = ' ';
42
43  // Skip any whitespace.
44  while (isspace(LastChar))
45    LastChar = getchar();
46
47  if (isalpha(LastChar)) { // identifier: [a-zA-Z][a-zA-Z0-9]*
48    IdentifierStr = LastChar;
49    while (isalnum((LastChar = getchar())))
50      IdentifierStr += LastChar;
51
52    if (IdentifierStr == "def") return tok_def;
53    if (IdentifierStr == "extern") return tok_extern;
54    return tok_identifier;
55  }
56
57  if (isdigit(LastChar) || LastChar == '.') {   // Number: [0-9.]+
58    std::string NumStr;
59    do {
60      NumStr += LastChar;
61      LastChar = getchar();
62    } while (isdigit(LastChar) || LastChar == '.');
63
64    NumVal = strtod(NumStr.c_str(), 0);
65    return tok_number;
66  }
67
68  if (LastChar == '#') {
69    // Comment until end of line.
70    do LastChar = getchar();
71    while (LastChar != EOF && LastChar != '\n' && LastChar != '\r');
72
73    if (LastChar != EOF)
74      return gettok();
75  }
76
77  // Check for end of file.  Don't eat the EOF.
78  if (LastChar == EOF)
79    return tok_eof;
80
81  // Otherwise, just return the character as its ascii value.
82  int ThisChar = LastChar;
83  LastChar = getchar();
84  return ThisChar;
85}
86
87//===----------------------------------------------------------------------===//
88// Abstract Syntax Tree (aka Parse Tree)
89//===----------------------------------------------------------------------===//
90
91/// ExprAST - Base class for all expression nodes.
92class ExprAST {
93public:
94  virtual ~ExprAST() {}
95  virtual Value *Codegen() = 0;
96};
97
98/// NumberExprAST - Expression class for numeric literals like "1.0".
99class NumberExprAST : public ExprAST {
100  double Val;
101public:
102  NumberExprAST(double val) : Val(val) {}
103  virtual Value *Codegen();
104};
105
106/// VariableExprAST - Expression class for referencing a variable, like "a".
107class VariableExprAST : public ExprAST {
108  std::string Name;
109public:
110  VariableExprAST(const std::string &name) : Name(name) {}
111  virtual Value *Codegen();
112};
113
114/// BinaryExprAST - Expression class for a binary operator.
115class BinaryExprAST : public ExprAST {
116  char Op;
117  ExprAST *LHS, *RHS;
118public:
119  BinaryExprAST(char op, ExprAST *lhs, ExprAST *rhs)
120    : Op(op), LHS(lhs), RHS(rhs) {}
121  virtual Value *Codegen();
122};
123
124/// CallExprAST - Expression class for function calls.
125class CallExprAST : public ExprAST {
126  std::string Callee;
127  std::vector<ExprAST*> Args;
128public:
129  CallExprAST(const std::string &callee, std::vector<ExprAST*> &args)
130    : Callee(callee), Args(args) {}
131  virtual Value *Codegen();
132};
133
134/// PrototypeAST - This class represents the "prototype" for a function,
135/// which captures its name, and its argument names (thus implicitly the number
136/// of arguments the function takes).
137class PrototypeAST {
138  std::string Name;
139  std::vector<std::string> Args;
140public:
141  PrototypeAST(const std::string &name, const std::vector<std::string> &args)
142    : Name(name), Args(args) {}
143
144  Function *Codegen();
145};
146
147/// FunctionAST - This class represents a function definition itself.
148class FunctionAST {
149  PrototypeAST *Proto;
150  ExprAST *Body;
151public:
152  FunctionAST(PrototypeAST *proto, ExprAST *body)
153    : Proto(proto), Body(body) {}
154
155  Function *Codegen();
156};
157
158//===----------------------------------------------------------------------===//
159// Parser
160//===----------------------------------------------------------------------===//
161
162/// CurTok/getNextToken - Provide a simple token buffer.  CurTok is the current
163/// token the parser is looking at.  getNextToken reads another token from the
164/// lexer and updates CurTok with its results.
165static int CurTok;
166static int getNextToken() {
167  return CurTok = gettok();
168}
169
170/// BinopPrecedence - This holds the precedence for each binary operator that is
171/// defined.
172static std::map<char, int> BinopPrecedence;
173
174/// GetTokPrecedence - Get the precedence of the pending binary operator token.
175static int GetTokPrecedence() {
176  if (!isascii(CurTok))
177    return -1;
178
179  // Make sure it's a declared binop.
180  int TokPrec = BinopPrecedence[CurTok];
181  if (TokPrec <= 0) return -1;
182  return TokPrec;
183}
184
185/// Error* - These are little helper functions for error handling.
186ExprAST *Error(const char *Str) { fprintf(stderr, "Error: %s\n", Str);return 0;}
187PrototypeAST *ErrorP(const char *Str) { Error(Str); return 0; }
188FunctionAST *ErrorF(const char *Str) { Error(Str); return 0; }
189
190static ExprAST *ParseExpression();
191
192/// identifierexpr
193///   ::= identifier
194///   ::= identifier '(' expression* ')'
195static ExprAST *ParseIdentifierExpr() {
196  std::string IdName = IdentifierStr;
197
198  getNextToken();  // eat identifier.
199
200  if (CurTok != '(') // Simple variable ref.
201    return new VariableExprAST(IdName);
202
203  // Call.
204  getNextToken();  // eat (
205  std::vector<ExprAST*> Args;
206  if (CurTok != ')') {
207    while (1) {
208      ExprAST *Arg = ParseExpression();
209      if (!Arg) return 0;
210      Args.push_back(Arg);
211
212      if (CurTok == ')') break;
213
214      if (CurTok != ',')
215        return Error("Expected ')' or ',' in argument list");
216      getNextToken();
217    }
218  }
219
220  // Eat the ')'.
221  getNextToken();
222
223  return new CallExprAST(IdName, Args);
224}
225
226/// numberexpr ::= number
227static ExprAST *ParseNumberExpr() {
228  ExprAST *Result = new NumberExprAST(NumVal);
229  getNextToken(); // consume the number
230  return Result;
231}
232
233/// parenexpr ::= '(' expression ')'
234static ExprAST *ParseParenExpr() {
235  getNextToken();  // eat (.
236  ExprAST *V = ParseExpression();
237  if (!V) return 0;
238
239  if (CurTok != ')')
240    return Error("expected ')'");
241  getNextToken();  // eat ).
242  return V;
243}
244
245/// primary
246///   ::= identifierexpr
247///   ::= numberexpr
248///   ::= parenexpr
249static ExprAST *ParsePrimary() {
250  switch (CurTok) {
251  default: return Error("unknown token when expecting an expression");
252  case tok_identifier: return ParseIdentifierExpr();
253  case tok_number:     return ParseNumberExpr();
254  case '(':            return ParseParenExpr();
255  }
256}
257
258/// binoprhs
259///   ::= ('+' primary)*
260static ExprAST *ParseBinOpRHS(int ExprPrec, ExprAST *LHS) {
261  // If this is a binop, find its precedence.
262  while (1) {
263    int TokPrec = GetTokPrecedence();
264
265    // If this is a binop that binds at least as tightly as the current binop,
266    // consume it, otherwise we are done.
267    if (TokPrec < ExprPrec)
268      return LHS;
269
270    // Okay, we know this is a binop.
271    int BinOp = CurTok;
272    getNextToken();  // eat binop
273
274    // Parse the primary expression after the binary operator.
275    ExprAST *RHS = ParsePrimary();
276    if (!RHS) return 0;
277
278    // If BinOp binds less tightly with RHS than the operator after RHS, let
279    // the pending operator take RHS as its LHS.
280    int NextPrec = GetTokPrecedence();
281    if (TokPrec < NextPrec) {
282      RHS = ParseBinOpRHS(TokPrec+1, RHS);
283      if (RHS == 0) return 0;
284    }
285
286    // Merge LHS/RHS.
287    LHS = new BinaryExprAST(BinOp, LHS, RHS);
288  }
289}
290
291/// expression
292///   ::= primary binoprhs
293///
294static ExprAST *ParseExpression() {
295  ExprAST *LHS = ParsePrimary();
296  if (!LHS) return 0;
297
298  return ParseBinOpRHS(0, LHS);
299}
300
301/// prototype
302///   ::= id '(' id* ')'
303static PrototypeAST *ParsePrototype() {
304  if (CurTok != tok_identifier)
305    return ErrorP("Expected function name in prototype");
306
307  std::string FnName = IdentifierStr;
308  getNextToken();
309
310  if (CurTok != '(')
311    return ErrorP("Expected '(' in prototype");
312
313  std::vector<std::string> ArgNames;
314  while (getNextToken() == tok_identifier)
315    ArgNames.push_back(IdentifierStr);
316  if (CurTok != ')')
317    return ErrorP("Expected ')' in prototype");
318
319  // success.
320  getNextToken();  // eat ')'.
321
322  return new PrototypeAST(FnName, ArgNames);
323}
324
325/// definition ::= 'def' prototype expression
326static FunctionAST *ParseDefinition() {
327  getNextToken();  // eat def.
328  PrototypeAST *Proto = ParsePrototype();
329  if (Proto == 0) return 0;
330
331  if (ExprAST *E = ParseExpression())
332    return new FunctionAST(Proto, E);
333  return 0;
334}
335
336/// toplevelexpr ::= expression
337static FunctionAST *ParseTopLevelExpr() {
338  if (ExprAST *E = ParseExpression()) {
339    // Make an anonymous proto.
340    PrototypeAST *Proto = new PrototypeAST("", std::vector<std::string>());
341    return new FunctionAST(Proto, E);
342  }
343  return 0;
344}
345
346/// external ::= 'extern' prototype
347static PrototypeAST *ParseExtern() {
348  getNextToken();  // eat extern.
349  return ParsePrototype();
350}
351
352//===----------------------------------------------------------------------===//
353// Code Generation
354//===----------------------------------------------------------------------===//
355
356static Module *TheModule;
357static IRBuilder<> Builder(getGlobalContext());
358static std::map<std::string, Value*> NamedValues;
359static FunctionPassManager *TheFPM;
360
361Value *ErrorV(const char *Str) { Error(Str); return 0; }
362
363Value *NumberExprAST::Codegen() {
364  return ConstantFP::get(getGlobalContext(), APFloat(Val));
365}
366
367Value *VariableExprAST::Codegen() {
368  // Look this variable up in the function.
369  Value *V = NamedValues[Name];
370  return V ? V : ErrorV("Unknown variable name");
371}
372
373Value *BinaryExprAST::Codegen() {
374  Value *L = LHS->Codegen();
375  Value *R = RHS->Codegen();
376  if (L == 0 || R == 0) return 0;
377
378  switch (Op) {
379  case '+': return Builder.CreateAdd(L, R, "addtmp");
380  case '-': return Builder.CreateSub(L, R, "subtmp");
381  case '*': return Builder.CreateMul(L, R, "multmp");
382  case '<':
383    L = Builder.CreateFCmpULT(L, R, "cmptmp");
384    // Convert bool 0/1 to double 0.0 or 1.0
385    return Builder.CreateUIToFP(L, Type::getDoubleTy(getGlobalContext()),
386                                "booltmp");
387  default: return ErrorV("invalid binary operator");
388  }
389}
390
391Value *CallExprAST::Codegen() {
392  // Look up the name in the global module table.
393  Function *CalleeF = TheModule->getFunction(Callee);
394  if (CalleeF == 0)
395    return ErrorV("Unknown function referenced");
396
397  // If argument mismatch error.
398  if (CalleeF->arg_size() != Args.size())
399    return ErrorV("Incorrect # arguments passed");
400
401  std::vector<Value*> ArgsV;
402  for (unsigned i = 0, e = Args.size(); i != e; ++i) {
403    ArgsV.push_back(Args[i]->Codegen());
404    if (ArgsV.back() == 0) return 0;
405  }
406
407  return Builder.CreateCall(CalleeF, ArgsV.begin(), ArgsV.end(), "calltmp");
408}
409
410Function *PrototypeAST::Codegen() {
411  // Make the function type:  double(double,double) etc.
412	std::vector<const Type*> Doubles(Args.size(),
413                                   Type::getDoubleTy(getGlobalContext()));
414  FunctionType *FT = FunctionType::get(Type::getDoubleTy(getGlobalContext()),
415                                       Doubles, false);
416
417  Function *F = Function::Create(FT, Function::ExternalLinkage, Name, TheModule);
418
419  // If F conflicted, there was already something named 'Name'.  If it has a
420  // body, don't allow redefinition or reextern.
421  if (F->getName() != Name) {
422    // Delete the one we just made and get the existing one.
423    F->eraseFromParent();
424    F = TheModule->getFunction(Name);
425
426    // If F already has a body, reject this.
427    if (!F->empty()) {
428      ErrorF("redefinition of function");
429      return 0;
430    }
431
432    // If F took a different number of args, reject.
433    if (F->arg_size() != Args.size()) {
434      ErrorF("redefinition of function with different # args");
435      return 0;
436    }
437  }
438
439  // Set names for all arguments.
440  unsigned Idx = 0;
441  for (Function::arg_iterator AI = F->arg_begin(); Idx != Args.size();
442       ++AI, ++Idx) {
443    AI->setName(Args[Idx]);
444
445    // Add arguments to variable symbol table.
446    NamedValues[Args[Idx]] = AI;
447  }
448
449  return F;
450}
451
452Function *FunctionAST::Codegen() {
453  NamedValues.clear();
454
455  Function *TheFunction = Proto->Codegen();
456  if (TheFunction == 0)
457    return 0;
458
459  // Create a new basic block to start insertion into.
460  BasicBlock *BB = BasicBlock::Create(getGlobalContext(), "entry", TheFunction);
461  Builder.SetInsertPoint(BB);
462
463  if (Value *RetVal = Body->Codegen()) {
464    // Finish off the function.
465    Builder.CreateRet(RetVal);
466
467    // Validate the generated code, checking for consistency.
468    verifyFunction(*TheFunction);
469
470    // Optimize the function.
471    TheFPM->run(*TheFunction);
472
473    return TheFunction;
474  }
475
476  // Error reading body, remove function.
477  TheFunction->eraseFromParent();
478  return 0;
479}
480
481//===----------------------------------------------------------------------===//
482// Top-Level parsing and JIT Driver
483//===----------------------------------------------------------------------===//
484
485static ExecutionEngine *TheExecutionEngine;
486
487static void HandleDefinition() {
488  if (FunctionAST *F = ParseDefinition()) {
489    if (Function *LF = F->Codegen()) {
490      fprintf(stderr, "Read function definition:");
491      LF->dump();
492    }
493  } else {
494    // Skip token for error recovery.
495    getNextToken();
496  }
497}
498
499static void HandleExtern() {
500  if (PrototypeAST *P = ParseExtern()) {
501    if (Function *F = P->Codegen()) {
502      fprintf(stderr, "Read extern: ");
503      F->dump();
504    }
505  } else {
506    // Skip token for error recovery.
507    getNextToken();
508  }
509}
510
511static void HandleTopLevelExpression() {
512  // Evaluate a top-level expression into an anonymous function.
513  if (FunctionAST *F = ParseTopLevelExpr()) {
514    if (Function *LF = F->Codegen()) {
515      // JIT the function, returning a function pointer.
516      void *FPtr = TheExecutionEngine->getPointerToFunction(LF);
517
518      // Cast it to the right type (takes no arguments, returns a double) so we
519      // can call it as a native function.
520      double (*FP)() = (double (*)())(intptr_t)FPtr;
521      fprintf(stderr, "Evaluated to %f\n", FP());
522    }
523  } else {
524    // Skip token for error recovery.
525    getNextToken();
526  }
527}
528
529/// top ::= definition | external | expression | ';'
530static void MainLoop() {
531  while (1) {
532    fprintf(stderr, "ready> ");
533    switch (CurTok) {
534    case tok_eof:    return;
535    case ';':        getNextToken(); break;  // ignore top-level semicolons.
536    case tok_def:    HandleDefinition(); break;
537    case tok_extern: HandleExtern(); break;
538    default:         HandleTopLevelExpression(); break;
539    }
540  }
541}
542
543//===----------------------------------------------------------------------===//
544// "Library" functions that can be "extern'd" from user code.
545//===----------------------------------------------------------------------===//
546
547/// putchard - putchar that takes a double and returns 0.
548extern "C"
549double putchard(double X) {
550  putchar((char)X);
551  return 0;
552}
553
554//===----------------------------------------------------------------------===//
555// Main driver code.
556//===----------------------------------------------------------------------===//
557
558int main() {
559  InitializeNativeTarget();
560  LLVMContext &Context = getGlobalContext();
561
562  // Install standard binary operators.
563  // 1 is lowest precedence.
564  BinopPrecedence['<'] = 10;
565  BinopPrecedence['+'] = 20;
566  BinopPrecedence['-'] = 20;
567  BinopPrecedence['*'] = 40;  // highest.
568
569  // Prime the first token.
570  fprintf(stderr, "ready> ");
571  getNextToken();
572
573  // Make the module, which holds all the code.
574  TheModule = new Module("my cool jit", Context);
575
576  ExistingModuleProvider *OurModuleProvider =
577      new ExistingModuleProvider(TheModule);
578
579  // Create the JIT.  This takes ownership of the module and module provider.
580  TheExecutionEngine = EngineBuilder(OurModuleProvider).create();
581
582  FunctionPassManager OurFPM(OurModuleProvider);
583
584  // Set up the optimizer pipeline.  Start with registering info about how the
585  // target lays out data structures.
586  OurFPM.add(new TargetData(*TheExecutionEngine->getTargetData()));
587  // Do simple "peephole" optimizations and bit-twiddling optzns.
588  OurFPM.add(createInstructionCombiningPass());
589  // Reassociate expressions.
590  OurFPM.add(createReassociatePass());
591  // Eliminate Common SubExpressions.
592  OurFPM.add(createGVNPass());
593  // Simplify the control flow graph (deleting unreachable blocks, etc).
594  OurFPM.add(createCFGSimplificationPass());
595
596  OurFPM.doInitialization();
597
598  // Set the global so the code gen can use this.
599  TheFPM = &OurFPM;
600
601  // Run the main "interpreter loop" now.
602  MainLoop();
603
604  TheFPM = 0;
605
606  // Print out all of the generated code.
607  TheModule->dump();
608
609  return 0;
610}
611