examples/Kaleidoscope/Chapter5/toy.cpp

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