toy.cpp revision 36b56886974eae4f9c5ebc96befd3e7bfe5de338 
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
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//===----------------------------------------------------------------------===//
90namespace {
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} // end anonymous namespace
158
159//===----------------------------------------------------------------------===//
160// Parser
161//===----------------------------------------------------------------------===//
162
163/// CurTok/getNextToken - Provide a simple token buffer.  CurTok is the current
164/// token the parser is looking at.  getNextToken reads another token from the
165/// lexer and updates CurTok with its results.
166static int CurTok;
167static int getNextToken() {
168  return CurTok = gettok();
169}
170
171/// BinopPrecedence - This holds the precedence for each binary operator that is
172/// defined.
173static std::map<char, int> BinopPrecedence;
174
175/// GetTokPrecedence - Get the precedence of the pending binary operator token.
176static int GetTokPrecedence() {
177  if (!isascii(CurTok))
178    return -1;
179
180  // Make sure it's a declared binop.
181  int TokPrec = BinopPrecedence[CurTok];
182  if (TokPrec <= 0) return -1;
183  return TokPrec;
184}
185
186/// Error* - These are little helper functions for error handling.
187ExprAST *Error(const char *Str) { fprintf(stderr, "Error: %s\n", Str);return 0;}
188PrototypeAST *ErrorP(const char *Str) { Error(Str); return 0; }
189FunctionAST *ErrorF(const char *Str) { Error(Str); return 0; }
190
191static ExprAST *ParseExpression();
192
193/// identifierexpr
194///   ::= identifier
195///   ::= identifier '(' expression* ')'
196static ExprAST *ParseIdentifierExpr() {
197  std::string IdName = IdentifierStr;
198
199  getNextToken();  // eat identifier.
200
201  if (CurTok != '(') // Simple variable ref.
202    return new VariableExprAST(IdName);
203
204  // Call.
205  getNextToken();  // eat (
206  std::vector<ExprAST*> Args;
207  if (CurTok != ')') {
208    while (1) {
209      ExprAST *Arg = ParseExpression();
210      if (!Arg) return 0;
211      Args.push_back(Arg);
212
213      if (CurTok == ')') break;
214
215      if (CurTok != ',')
216        return Error("Expected ')' or ',' in argument list");
217      getNextToken();
218    }
219  }
220
221  // Eat the ')'.
222  getNextToken();
223
224  return new CallExprAST(IdName, Args);
225}
226
227/// numberexpr ::= number
228static ExprAST *ParseNumberExpr() {
229  ExprAST *Result = new NumberExprAST(NumVal);
230  getNextToken(); // consume the number
231  return Result;
232}
233
234/// parenexpr ::= '(' expression ')'
235static ExprAST *ParseParenExpr() {
236  getNextToken();  // eat (.
237  ExprAST *V = ParseExpression();
238  if (!V) return 0;
239
240  if (CurTok != ')')
241    return Error("expected ')'");
242  getNextToken();  // eat ).
243  return V;
244}
245
246/// primary
247///   ::= identifierexpr
248///   ::= numberexpr
249///   ::= parenexpr
250static ExprAST *ParsePrimary() {
251  switch (CurTok) {
252  default: return Error("unknown token when expecting an expression");
253  case tok_identifier: return ParseIdentifierExpr();
254  case tok_number:     return ParseNumberExpr();
255  case '(':            return ParseParenExpr();
256  }
257}
258
259/// binoprhs
260///   ::= ('+' primary)*
261static ExprAST *ParseBinOpRHS(int ExprPrec, ExprAST *LHS) {
262  // If this is a binop, find its precedence.
263  while (1) {
264    int TokPrec = GetTokPrecedence();
265
266    // If this is a binop that binds at least as tightly as the current binop,
267    // consume it, otherwise we are done.
268    if (TokPrec < ExprPrec)
269      return LHS;
270
271    // Okay, we know this is a binop.
272    int BinOp = CurTok;
273    getNextToken();  // eat binop
274
275    // Parse the primary expression after the binary operator.
276    ExprAST *RHS = ParsePrimary();
277    if (!RHS) return 0;
278
279    // If BinOp binds less tightly with RHS than the operator after RHS, let
280    // the pending operator take RHS as its LHS.
281    int NextPrec = GetTokPrecedence();
282    if (TokPrec < NextPrec) {
283      RHS = ParseBinOpRHS(TokPrec+1, RHS);
284      if (RHS == 0) return 0;
285    }
286
287    // Merge LHS/RHS.
288    LHS = new BinaryExprAST(BinOp, LHS, RHS);
289  }
290}
291
292/// expression
293///   ::= primary binoprhs
294///
295static ExprAST *ParseExpression() {
296  ExprAST *LHS = ParsePrimary();
297  if (!LHS) return 0;
298
299  return ParseBinOpRHS(0, LHS);
300}
301
302/// prototype
303///   ::= id '(' id* ')'
304static PrototypeAST *ParsePrototype() {
305  if (CurTok != tok_identifier)
306    return ErrorP("Expected function name in prototype");
307
308  std::string FnName = IdentifierStr;
309  getNextToken();
310
311  if (CurTok != '(')
312    return ErrorP("Expected '(' in prototype");
313
314  std::vector<std::string> ArgNames;
315  while (getNextToken() == tok_identifier)
316    ArgNames.push_back(IdentifierStr);
317  if (CurTok != ')')
318    return ErrorP("Expected ')' in prototype");
319
320  // success.
321  getNextToken();  // eat ')'.
322
323  return new PrototypeAST(FnName, ArgNames);
324}
325
326/// definition ::= 'def' prototype expression
327static FunctionAST *ParseDefinition() {
328  getNextToken();  // eat def.
329  PrototypeAST *Proto = ParsePrototype();
330  if (Proto == 0) return 0;
331
332  if (ExprAST *E = ParseExpression())
333    return new FunctionAST(Proto, E);
334  return 0;
335}
336
337/// toplevelexpr ::= expression
338static FunctionAST *ParseTopLevelExpr() {
339  if (ExprAST *E = ParseExpression()) {
340    // Make an anonymous proto.
341    PrototypeAST *Proto = new PrototypeAST("", std::vector<std::string>());
342    return new FunctionAST(Proto, E);
343  }
344  return 0;
345}
346
347/// external ::= 'extern' prototype
348static PrototypeAST *ParseExtern() {
349  getNextToken();  // eat extern.
350  return ParsePrototype();
351}
352
353//===----------------------------------------------------------------------===//
354// Code Generation
355//===----------------------------------------------------------------------===//
356
357static Module *TheModule;
358static IRBuilder<> Builder(getGlobalContext());
359static std::map<std::string, Value*> NamedValues;
360static FunctionPassManager *TheFPM;
361
362Value *ErrorV(const char *Str) { Error(Str); return 0; }
363
364Value *NumberExprAST::Codegen() {
365  return ConstantFP::get(getGlobalContext(), APFloat(Val));
366}
367
368Value *VariableExprAST::Codegen() {
369  // Look this variable up in the function.
370  Value *V = NamedValues[Name];
371  return V ? V : ErrorV("Unknown variable name");
372}
373
374Value *BinaryExprAST::Codegen() {
375  Value *L = LHS->Codegen();
376  Value *R = RHS->Codegen();
377  if (L == 0 || R == 0) return 0;
378
379  switch (Op) {
380  case '+': return Builder.CreateFAdd(L, R, "addtmp");
381  case '-': return Builder.CreateFSub(L, R, "subtmp");
382  case '*': return Builder.CreateFMul(L, R, "multmp");
383  case '<':
384    L = Builder.CreateFCmpULT(L, R, "cmptmp");
385    // Convert bool 0/1 to double 0.0 or 1.0
386    return Builder.CreateUIToFP(L, Type::getDoubleTy(getGlobalContext()),
387                                "booltmp");
388  default: return ErrorV("invalid binary operator");
389  }
390}
391
392Value *CallExprAST::Codegen() {
393  // Look up the name in the global module table.
394  Function *CalleeF = TheModule->getFunction(Callee);
395  if (CalleeF == 0)
396    return ErrorV("Unknown function referenced");
397
398  // If argument mismatch error.
399  if (CalleeF->arg_size() != Args.size())
400    return ErrorV("Incorrect # arguments passed");
401
402  std::vector<Value*> ArgsV;
403  for (unsigned i = 0, e = Args.size(); i != e; ++i) {
404    ArgsV.push_back(Args[i]->Codegen());
405    if (ArgsV.back() == 0) return 0;
406  }
407
408  return Builder.CreateCall(CalleeF, ArgsV, "calltmp");
409}
410
411Function *PrototypeAST::Codegen() {
412  // Make the function type:  double(double,double) etc.
413  std::vector<Type*> Doubles(Args.size(),
414                             Type::getDoubleTy(getGlobalContext()));
415  FunctionType *FT = FunctionType::get(Type::getDoubleTy(getGlobalContext()),
416                                       Doubles, false);
417
418  Function *F = Function::Create(FT, Function::ExternalLinkage, Name, TheModule);
419
420  // If F conflicted, there was already something named 'Name'.  If it has a
421  // body, don't allow redefinition or reextern.
422  if (F->getName() != Name) {
423    // Delete the one we just made and get the existing one.
424    F->eraseFromParent();
425    F = TheModule->getFunction(Name);
426
427    // If F already has a body, reject this.
428    if (!F->empty()) {
429      ErrorF("redefinition of function");
430      return 0;
431    }
432
433    // If F took a different number of args, reject.
434    if (F->arg_size() != Args.size()) {
435      ErrorF("redefinition of function with different # args");
436      return 0;
437    }
438  }
439
440  // Set names for all arguments.
441  unsigned Idx = 0;
442  for (Function::arg_iterator AI = F->arg_begin(); Idx != Args.size();
443       ++AI, ++Idx) {
444    AI->setName(Args[Idx]);
445
446    // Add arguments to variable symbol table.
447    NamedValues[Args[Idx]] = AI;
448  }
449
450  return F;
451}
452
453Function *FunctionAST::Codegen() {
454  NamedValues.clear();
455
456  Function *TheFunction = Proto->Codegen();
457  if (TheFunction == 0)
458    return 0;
459
460  // Create a new basic block to start insertion into.
461  BasicBlock *BB = BasicBlock::Create(getGlobalContext(), "entry", TheFunction);
462  Builder.SetInsertPoint(BB);
463
464  if (Value *RetVal = Body->Codegen()) {
465    // Finish off the function.
466    Builder.CreateRet(RetVal);
467
468    // Validate the generated code, checking for consistency.
469    verifyFunction(*TheFunction);
470
471    // Optimize the function.
472    TheFPM->run(*TheFunction);
473
474    return TheFunction;
475  }
476
477  // Error reading body, remove function.
478  TheFunction->eraseFromParent();
479  return 0;
480}
481
482//===----------------------------------------------------------------------===//
483// Top-Level parsing and JIT Driver
484//===----------------------------------------------------------------------===//
485
486static ExecutionEngine *TheExecutionEngine;
487
488static void HandleDefinition() {
489  if (FunctionAST *F = ParseDefinition()) {
490    if (Function *LF = F->Codegen()) {
491      fprintf(stderr, "Read function definition:");
492      LF->dump();
493    }
494  } else {
495    // Skip token for error recovery.
496    getNextToken();
497  }
498}
499
500static void HandleExtern() {
501  if (PrototypeAST *P = ParseExtern()) {
502    if (Function *F = P->Codegen()) {
503      fprintf(stderr, "Read extern: ");
504      F->dump();
505    }
506  } else {
507    // Skip token for error recovery.
508    getNextToken();
509  }
510}
511
512static void HandleTopLevelExpression() {
513  // Evaluate a top-level expression into an anonymous function.
514  if (FunctionAST *F = ParseTopLevelExpr()) {
515    if (Function *LF = F->Codegen()) {
516      // JIT the function, returning a function pointer.
517      void *FPtr = TheExecutionEngine->getPointerToFunction(LF);
518
519      // Cast it to the right type (takes no arguments, returns a double) so we
520      // can call it as a native function.
521      double (*FP)() = (double (*)())(intptr_t)FPtr;
522      fprintf(stderr, "Evaluated to %f\n", FP());
523    }
524  } else {
525    // Skip token for error recovery.
526    getNextToken();
527  }
528}
529
530/// top ::= definition | external | expression | ';'
531static void MainLoop() {
532  while (1) {
533    fprintf(stderr, "ready> ");
534    switch (CurTok) {
535    case tok_eof:    return;
536    case ';':        getNextToken(); break;  // ignore top-level semicolons.
537    case tok_def:    HandleDefinition(); break;
538    case tok_extern: HandleExtern(); break;
539    default:         HandleTopLevelExpression(); break;
540    }
541  }
542}
543
544//===----------------------------------------------------------------------===//
545// "Library" functions that can be "extern'd" from user code.
546//===----------------------------------------------------------------------===//
547
548/// putchard - putchar that takes a double and returns 0.
549extern "C"
550double putchard(double X) {
551  putchar((char)X);
552  return 0;
553}
554
555//===----------------------------------------------------------------------===//
556// Main driver code.
557//===----------------------------------------------------------------------===//
558
559int main() {
560  InitializeNativeTarget();
561  LLVMContext &Context = getGlobalContext();
562
563  // Install standard binary operators.
564  // 1 is lowest precedence.
565  BinopPrecedence['<'] = 10;
566  BinopPrecedence['+'] = 20;
567  BinopPrecedence['-'] = 20;
568  BinopPrecedence['*'] = 40;  // highest.
569
570  // Prime the first token.
571  fprintf(stderr, "ready> ");
572  getNextToken();
573
574  // Make the module, which holds all the code.
575  TheModule = new Module("my cool jit", Context);
576
577  // Create the JIT.  This takes ownership of the module.
578  std::string ErrStr;
579  TheExecutionEngine = EngineBuilder(TheModule).setErrorStr(&ErrStr).create();
580  if (!TheExecutionEngine) {
581    fprintf(stderr, "Could not create ExecutionEngine: %s\n", ErrStr.c_str());
582    exit(1);
583  }
584
585  FunctionPassManager OurFPM(TheModule);
586
587  // Set up the optimizer pipeline.  Start with registering info about how the
588  // target lays out data structures.
589  TheModule->setDataLayout(TheExecutionEngine->getDataLayout());
590  OurFPM.add(new DataLayoutPass(TheModule));
591  // Provide basic AliasAnalysis support for GVN.
592  OurFPM.add(createBasicAliasAnalysisPass());
593  // Do simple "peephole" optimizations and bit-twiddling optzns.
594  OurFPM.add(createInstructionCombiningPass());
595  // Reassociate expressions.
596  OurFPM.add(createReassociatePass());
597  // Eliminate Common SubExpressions.
598  OurFPM.add(createGVNPass());
599  // Simplify the control flow graph (deleting unreachable blocks, etc).
600  OurFPM.add(createCFGSimplificationPass());
601
602  OurFPM.doInitialization();
603
604  // Set the global so the code gen can use this.
605  TheFPM = &OurFPM;
606
607  // Run the main "interpreter loop" now.
608  MainLoop();
609
610  TheFPM = 0;
611
612  // Print out all of the generated code.
613  TheModule->dump();
614
615  return 0;
616}
617