examples/Kaleidoscope/Chapter7/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   // operators
  39   tok_binary = -11, tok_unary = -12,
  40
  41   // var definition
  42   tok_var = -13
  43 };
  44
  45 static std::string IdentifierStr;  // Filled in if tok_identifier
  46 static double NumVal;              // Filled in if tok_number
  47
  48 /// gettok - Return the next token from standard input.
  49 static int gettok() {
  50   static int LastChar = ' ';
  51
  52   // Skip any whitespace.
  53   while (isspace(LastChar))
  54     LastChar = getchar();
  55
  56   if (isalpha(LastChar)) { // identifier: [a-zA-Z][a-zA-Z0-9]*
  57     IdentifierStr = LastChar;
  58     while (isalnum((LastChar = getchar())))
  59       IdentifierStr += LastChar;
  60
  61     if (IdentifierStr == "def") return tok_def;
  62     if (IdentifierStr == "extern") return tok_extern;
  63     if (IdentifierStr == "if") return tok_if;
  64     if (IdentifierStr == "then") return tok_then;
  65     if (IdentifierStr == "else") return tok_else;
  66     if (IdentifierStr == "for") return tok_for;
  67     if (IdentifierStr == "in") return tok_in;
  68     if (IdentifierStr == "binary") return tok_binary;
  69     if (IdentifierStr == "unary") return tok_unary;
  70     if (IdentifierStr == "var") return tok_var;
  71     return tok_identifier;
  72   }
  73
  74   if (isdigit(LastChar) || LastChar == '.') {   // Number: [0-9.]+
  75     std::string NumStr;
  76     do {
  77       NumStr += LastChar;
  78       LastChar = getchar();
  79     } while (isdigit(LastChar) || LastChar == '.');
  80
  81     NumVal = strtod(NumStr.c_str(), 0);
  82     return tok_number;
  83   }
  84
  85   if (LastChar == '#') {
  86     // Comment until end of line.
  87     do LastChar = getchar();
  88     while (LastChar != EOF && LastChar != '\n' && LastChar != '\r');
  89
  90     if (LastChar != EOF)
  91       return gettok();
  92   }
  93
  94   // Check for end of file.  Don't eat the EOF.
  95   if (LastChar == EOF)
  96     return tok_eof;
  97
  98   // Otherwise, just return the character as its ascii value.
  99   int ThisChar = LastChar;
 100   LastChar = getchar();
 101   return ThisChar;
 102 }
 103
 104 //===----------------------------------------------------------------------===//
 105 // Abstract Syntax Tree (aka Parse Tree)
 106 //===----------------------------------------------------------------------===//
 107
 108 /// ExprAST - Base class for all expression nodes.
 109 class ExprAST {
 110 public:
 111   virtual ~ExprAST() {}
 112   virtual Value *Codegen() = 0;
 113 };
 114
 115 /// NumberExprAST - Expression class for numeric literals like "1.0".
 116 class NumberExprAST : public ExprAST {
 117   double Val;
 118 public:
 119   NumberExprAST(double val) : Val(val) {}
 120   virtual Value *Codegen();
 121 };
 122
 123 /// VariableExprAST - Expression class for referencing a variable, like "a".
 124 class VariableExprAST : public ExprAST {
 125   std::string Name;
 126 public:
 127   VariableExprAST(const std::string &name) : Name(name) {}
 128   const std::string &getName() const { return Name; }
 129   virtual Value *Codegen();
 130 };
 131
 132 /// UnaryExprAST - Expression class for a unary operator.
 133 class UnaryExprAST : public ExprAST {
 134   char Opcode;
 135   ExprAST *Operand;
 136 public:
 137   UnaryExprAST(char opcode, ExprAST *operand)
 138     : Opcode(opcode), Operand(operand) {}
 139   virtual Value *Codegen();
 140 };
 141
 142 /// BinaryExprAST - Expression class for a binary operator.
 143 class BinaryExprAST : public ExprAST {
 144   char Op;
 145   ExprAST *LHS, *RHS;
 146 public:
 147   BinaryExprAST(char op, ExprAST *lhs, ExprAST *rhs)
 148     : Op(op), LHS(lhs), RHS(rhs) {}
 149   virtual Value *Codegen();
 150 };
 151
 152 /// CallExprAST - Expression class for function calls.
 153 class CallExprAST : public ExprAST {
 154   std::string Callee;
 155   std::vector<ExprAST*> Args;
 156 public:
 157   CallExprAST(const std::string &callee, std::vector<ExprAST*> &args)
 158     : Callee(callee), Args(args) {}
 159   virtual Value *Codegen();
 160 };
 161
 162 /// IfExprAST - Expression class for if/then/else.
 163 class IfExprAST : public ExprAST {
 164   ExprAST *Cond, *Then, *Else;
 165 public:
 166   IfExprAST(ExprAST *cond, ExprAST *then, ExprAST *_else)
 167   : Cond(cond), Then(then), Else(_else) {}
 168   virtual Value *Codegen();
 169 };
 170
 171 /// ForExprAST - Expression class for for/in.
 172 class ForExprAST : public ExprAST {
 173   std::string VarName;
 174   ExprAST *Start, *End, *Step, *Body;
 175 public:
 176   ForExprAST(const std::string &varname, ExprAST *start, ExprAST *end,
 177              ExprAST *step, ExprAST *body)
 178     : VarName(varname), Start(start), End(end), Step(step), Body(body) {}
 179   virtual Value *Codegen();
 180 };
 181
 182 /// VarExprAST - Expression class for var/in
 183 class VarExprAST : public ExprAST {
 184   std::vector<std::pair<std::string, ExprAST*> > VarNames;
 185   ExprAST *Body;
 186 public:
 187   VarExprAST(const std::vector<std::pair<std::string, ExprAST*> > &varnames,
 188              ExprAST *body)
 189   : VarNames(varnames), Body(body) {}
 190
 191   virtual Value *Codegen();
 192 };
 193
 194 /// PrototypeAST - This class represents the "prototype" for a function,
 195 /// which captures its argument names as well as if it is an operator.
 196 class PrototypeAST {
 197   std::string Name;
 198   std::vector<std::string> Args;
 199   bool isOperator;
 200   unsigned Precedence;  // Precedence if a binary op.
 201 public:
 202   PrototypeAST(const std::string &name, const std::vector<std::string> &args,
 203                bool isoperator = false, unsigned prec = 0)
 204   : Name(name), Args(args), isOperator(isoperator), Precedence(prec) {}
 205
 206   bool isUnaryOp() const { return isOperator && Args.size() == 1; }
 207   bool isBinaryOp() const { return isOperator && Args.size() == 2; }
 208
 209   char getOperatorName() const {
 210     assert(isUnaryOp() || isBinaryOp());
 211     return Name[Name.size()-1];
 212   }
 213
 214   unsigned getBinaryPrecedence() const { return Precedence; }
 215
 216   Function *Codegen();
 217
 218   void CreateArgumentAllocas(Function *F);
 219 };
 220
 221 /// FunctionAST - This class represents a function definition itself.
 222 class FunctionAST {
 223   PrototypeAST *Proto;
 224   ExprAST *Body;
 225 public:
 226   FunctionAST(PrototypeAST *proto, ExprAST *body)
 227     : Proto(proto), Body(body) {}
 228
 229   Function *Codegen();
 230 };
 231
 232 //===----------------------------------------------------------------------===//
 233 // Parser
 234 //===----------------------------------------------------------------------===//
 235
 236 /// CurTok/getNextToken - Provide a simple token buffer.  CurTok is the current
 237 /// token the parser is looking at.  getNextToken reads another token from the
 238 /// lexer and updates CurTok with its results.
 239 static int CurTok;
 240 static int getNextToken() {
 241   return CurTok = gettok();
 242 }
 243
 244 /// BinopPrecedence - This holds the precedence for each binary operator that is
 245 /// defined.
 246 static std::map<char, int> BinopPrecedence;
 247
 248 /// GetTokPrecedence - Get the precedence of the pending binary operator token.
 249 static int GetTokPrecedence() {
 250   if (!isascii(CurTok))
 251     return -1;
 252
 253   // Make sure it's a declared binop.
 254   int TokPrec = BinopPrecedence[CurTok];
 255   if (TokPrec <= 0) return -1;
 256   return TokPrec;
 257 }
 258
 259 /// Error* - These are little helper functions for error handling.
 260 ExprAST *Error(const char *Str) { fprintf(stderr, "Error: %s\n", Str);return 0;}
 261 PrototypeAST *ErrorP(const char *Str) { Error(Str); return 0; }
 262 FunctionAST *ErrorF(const char *Str) { Error(Str); return 0; }
 263
 264 static ExprAST *ParseExpression();
 265
 266 /// identifierexpr
 267 ///   ::= identifier
 268 ///   ::= identifier '(' expression* ')'
 269 static ExprAST *ParseIdentifierExpr() {
 270   std::string IdName = IdentifierStr;
 271
 272   getNextToken();  // eat identifier.
 273
 274   if (CurTok != '(') // Simple variable ref.
 275     return new VariableExprAST(IdName);
 276
 277   // Call.
 278   getNextToken();  // eat (
 279   std::vector<ExprAST*> Args;
 280   if (CurTok != ')') {
 281     while (1) {
 282       ExprAST *Arg = ParseExpression();
 283       if (!Arg) return 0;
 284       Args.push_back(Arg);
 285
 286       if (CurTok == ')') break;
 287
 288       if (CurTok != ',')
 289         return Error("Expected ')' or ',' in argument list");
 290       getNextToken();
 291     }
 292   }
 293
 294   // Eat the ')'.
 295   getNextToken();
 296
 297   return new CallExprAST(IdName, Args);
 298 }
 299
 300 /// numberexpr ::= number
 301 static ExprAST *ParseNumberExpr() {
 302   ExprAST *Result = new NumberExprAST(NumVal);
 303   getNextToken(); // consume the number
 304   return Result;
 305 }
 306
 307 /// parenexpr ::= '(' expression ')'
 308 static ExprAST *ParseParenExpr() {
 309   getNextToken();  // eat (.
 310   ExprAST *V = ParseExpression();
 311   if (!V) return 0;
 312
 313   if (CurTok != ')')
 314     return Error("expected ')'");
 315   getNextToken();  // eat ).
 316   return V;
 317 }
 318
 319 /// ifexpr ::= 'if' expression 'then' expression 'else' expression
 320 static ExprAST *ParseIfExpr() {
 321   getNextToken();  // eat the if.
 322
 323   // condition.
 324   ExprAST *Cond = ParseExpression();
 325   if (!Cond) return 0;
 326
 327   if (CurTok != tok_then)
 328     return Error("expected then");
 329   getNextToken();  // eat the then
 330
 331   ExprAST *Then = ParseExpression();
 332   if (Then == 0) return 0;
 333
 334   if (CurTok != tok_else)
 335     return Error("expected else");
 336
 337   getNextToken();
 338
 339   ExprAST *Else = ParseExpression();
 340   if (!Else) return 0;
 341
 342   return new IfExprAST(Cond, Then, Else);
 343 }
 344
 345 /// forexpr ::= 'for' identifier '=' expr ',' expr (',' expr)? 'in' expression
 346 static ExprAST *ParseForExpr() {
 347   getNextToken();  // eat the for.
 348
 349   if (CurTok != tok_identifier)
 350     return Error("expected identifier after for");
 351
 352   std::string IdName = IdentifierStr;
 353   getNextToken();  // eat identifier.
 354
 355   if (CurTok != '=')
 356     return Error("expected '=' after for");
 357   getNextToken();  // eat '='.
 358
 359
 360   ExprAST *Start = ParseExpression();
 361   if (Start == 0) return 0;
 362   if (CurTok != ',')
 363     return Error("expected ',' after for start value");
 364   getNextToken();
 365
 366   ExprAST *End = ParseExpression();
 367   if (End == 0) return 0;
 368
 369   // The step value is optional.
 370   ExprAST *Step = 0;
 371   if (CurTok == ',') {
 372     getNextToken();
 373     Step = ParseExpression();
 374     if (Step == 0) return 0;
 375   }
 376
 377   if (CurTok != tok_in)
 378     return Error("expected 'in' after for");
 379   getNextToken();  // eat 'in'.
 380
 381   ExprAST *Body = ParseExpression();
 382   if (Body == 0) return 0;
 383
 384   return new ForExprAST(IdName, Start, End, Step, Body);
 385 }
 386
 387 /// varexpr ::= 'var' identifier ('=' expression)?
 388 //                    (',' identifier ('=' expression)?)* 'in' expression
 389 static ExprAST *ParseVarExpr() {
 390   getNextToken();  // eat the var.
 391
 392   std::vector<std::pair<std::string, ExprAST*> > VarNames;
 393
 394   // At least one variable name is required.
 395   if (CurTok != tok_identifier)
 396     return Error("expected identifier after var");
 397
 398   while (1) {
 399     std::string Name = IdentifierStr;
 400     getNextToken();  // eat identifier.
 401
 402     // Read the optional initializer.
 403     ExprAST *Init = 0;
 404     if (CurTok == '=') {
 405       getNextToken(); // eat the '='.
 406
 407       Init = ParseExpression();
 408       if (Init == 0) return 0;
 409     }
 410
 411     VarNames.push_back(std::make_pair(Name, Init));
 412
 413     // End of var list, exit loop.
 414     if (CurTok != ',') break;
 415     getNextToken(); // eat the ','.
 416
 417     if (CurTok != tok_identifier)
 418       return Error("expected identifier list after var");
 419   }
 420
 421   // At this point, we have to have 'in'.
 422   if (CurTok != tok_in)
 423     return Error("expected 'in' keyword after 'var'");
 424   getNextToken();  // eat 'in'.
 425
 426   ExprAST *Body = ParseExpression();
 427   if (Body == 0) return 0;
 428
 429   return new VarExprAST(VarNames, Body);
 430 }
 431
 432 /// primary
 433 ///   ::= identifierexpr
 434 ///   ::= numberexpr
 435 ///   ::= parenexpr
 436 ///   ::= ifexpr
 437 ///   ::= forexpr
 438 ///   ::= varexpr
 439 static ExprAST *ParsePrimary() {
 440   switch (CurTok) {
 441   default: return Error("unknown token when expecting an expression");
 442   case tok_identifier: return ParseIdentifierExpr();
 443   case tok_number:     return ParseNumberExpr();
 444   case '(':            return ParseParenExpr();
 445   case tok_if:         return ParseIfExpr();
 446   case tok_for:        return ParseForExpr();
 447   case tok_var:        return ParseVarExpr();
 448   }
 449 }
 450
 451 /// unary
 452 ///   ::= primary
 453 ///   ::= '!' unary
 454 static ExprAST *ParseUnary() {
 455   // If the current token is not an operator, it must be a primary expr.
 456   if (!isascii(CurTok) || CurTok == '(' || CurTok == ',')
 457     return ParsePrimary();
 458
 459   // If this is a unary operator, read it.
 460   int Opc = CurTok;
 461   getNextToken();
 462   if (ExprAST *Operand = ParseUnary())
 463     return new UnaryExprAST(Opc, Operand);
 464   return 0;
 465 }
 466
 467 /// binoprhs
 468 ///   ::= ('+' unary)*
 469 static ExprAST *ParseBinOpRHS(int ExprPrec, ExprAST *LHS) {
 470   // If this is a binop, find its precedence.
 471   while (1) {
 472     int TokPrec = GetTokPrecedence();
 473
 474     // If this is a binop that binds at least as tightly as the current binop,
 475     // consume it, otherwise we are done.
 476     if (TokPrec < ExprPrec)
 477       return LHS;
 478
 479     // Okay, we know this is a binop.
 480     int BinOp = CurTok;
 481     getNextToken();  // eat binop
 482
 483     // Parse the unary expression after the binary operator.
 484     ExprAST *RHS = ParseUnary();
 485     if (!RHS) return 0;
 486
 487     // If BinOp binds less tightly with RHS than the operator after RHS, let
 488     // the pending operator take RHS as its LHS.
 489     int NextPrec = GetTokPrecedence();
 490     if (TokPrec < NextPrec) {
 491       RHS = ParseBinOpRHS(TokPrec+1, RHS);
 492       if (RHS == 0) return 0;
 493     }
 494
 495     // Merge LHS/RHS.
 496     LHS = new BinaryExprAST(BinOp, LHS, RHS);
 497   }
 498 }
 499
 500 /// expression
 501 ///   ::= unary binoprhs
 502 ///
 503 static ExprAST *ParseExpression() {
 504   ExprAST *LHS = ParseUnary();
 505   if (!LHS) return 0;
 506
 507   return ParseBinOpRHS(0, LHS);
 508 }
 509
 510 /// prototype
 511 ///   ::= id '(' id* ')'
 512 ///   ::= binary LETTER number? (id, id)
 513 ///   ::= unary LETTER (id)
 514 static PrototypeAST *ParsePrototype() {
 515   std::string FnName;
 516
 517   unsigned Kind = 0; // 0 = identifier, 1 = unary, 2 = binary.
 518   unsigned BinaryPrecedence = 30;
 519
 520   switch (CurTok) {
 521   default:
 522     return ErrorP("Expected function name in prototype");
 523   case tok_identifier:
 524     FnName = IdentifierStr;
 525     Kind = 0;
 526     getNextToken();
 527     break;
 528   case tok_unary:
 529     getNextToken();
 530     if (!isascii(CurTok))
 531       return ErrorP("Expected unary operator");
 532     FnName = "unary";
 533     FnName += (char)CurTok;
 534     Kind = 1;
 535     getNextToken();
 536     break;
 537   case tok_binary:
 538     getNextToken();
 539     if (!isascii(CurTok))
 540       return ErrorP("Expected binary operator");
 541     FnName = "binary";
 542     FnName += (char)CurTok;
 543     Kind = 2;
 544     getNextToken();
 545
 546     // Read the precedence if present.
 547     if (CurTok == tok_number) {
 548       if (NumVal < 1 || NumVal > 100)
 549         return ErrorP("Invalid precedecnce: must be 1..100");
 550       BinaryPrecedence = (unsigned)NumVal;
 551       getNextToken();
 552     }
 553     break;
 554   }
 555
 556   if (CurTok != '(')
 557     return ErrorP("Expected '(' in prototype");
 558
 559   std::vector<std::string> ArgNames;
 560   while (getNextToken() == tok_identifier)
 561     ArgNames.push_back(IdentifierStr);
 562   if (CurTok != ')')
 563     return ErrorP("Expected ')' in prototype");
 564
 565   // success.
 566   getNextToken();  // eat ')'.
 567
 568   // Verify right number of names for operator.
 569   if (Kind && ArgNames.size() != Kind)
 570     return ErrorP("Invalid number of operands for operator");
 571
 572   return new PrototypeAST(FnName, ArgNames, Kind != 0, BinaryPrecedence);
 573 }
 574
 575 /// definition ::= 'def' prototype expression
 576 static FunctionAST *ParseDefinition() {
 577   getNextToken();  // eat def.
 578   PrototypeAST *Proto = ParsePrototype();
 579   if (Proto == 0) return 0;
 580
 581   if (ExprAST *E = ParseExpression())
 582     return new FunctionAST(Proto, E);
 583   return 0;
 584 }
 585
 586 /// toplevelexpr ::= expression
 587 static FunctionAST *ParseTopLevelExpr() {
 588   if (ExprAST *E = ParseExpression()) {
 589     // Make an anonymous proto.
 590     PrototypeAST *Proto = new PrototypeAST("", std::vector<std::string>());
 591     return new FunctionAST(Proto, E);
 592   }
 593   return 0;
 594 }
 595
 596 /// external ::= 'extern' prototype
 597 static PrototypeAST *ParseExtern() {
 598   getNextToken();  // eat extern.
 599   return ParsePrototype();
 600 }
 601
 602 //===----------------------------------------------------------------------===//
 603 // Code Generation
 604 //===----------------------------------------------------------------------===//
 605
 606 static Module *TheModule;
 607 static IRBuilder<> Builder(getGlobalContext());
 608 static std::map<std::string, AllocaInst*> NamedValues;
 609 static FunctionPassManager *TheFPM;
 610
 611 Value *ErrorV(const char *Str) { Error(Str); return 0; }
 612
 613 /// CreateEntryBlockAlloca - Create an alloca instruction in the entry block of
 614 /// the function.  This is used for mutable variables etc.
 615 static AllocaInst *CreateEntryBlockAlloca(Function *TheFunction,
 616                                           const std::string &VarName) {
 617   IRBuilder<> TmpB(&TheFunction->getEntryBlock(),
 618                  TheFunction->getEntryBlock().begin());
 619   return TmpB.CreateAlloca(Type::getDoubleTy(getGlobalContext()), 0,
 620                            VarName.c_str());
 621 }
 622
 623 Value *NumberExprAST::Codegen() {
 624   return ConstantFP::get(getGlobalContext(), APFloat(Val));
 625 }
 626
 627 Value *VariableExprAST::Codegen() {
 628   // Look this variable up in the function.
 629   Value *V = NamedValues[Name];
 630   if (V == 0) return ErrorV("Unknown variable name");
 631
 632   // Load the value.
 633   return Builder.CreateLoad(V, Name.c_str());
 634 }
 635
 636 Value *UnaryExprAST::Codegen() {
 637   Value *OperandV = Operand->Codegen();
 638   if (OperandV == 0) return 0;
 639
 640   Function *F = TheModule->getFunction(std::string("unary")+Opcode);
 641   if (F == 0)
 642     return ErrorV("Unknown unary operator");
 643
 644   return Builder.CreateCall(F, OperandV, "unop");
 645 }
 646
 647 Value *BinaryExprAST::Codegen() {
 648   // Special case '=' because we don't want to emit the LHS as an expression.
 649   if (Op == '=') {
 650     // Assignment requires the LHS to be an identifier.
 651     VariableExprAST *LHSE = dynamic_cast<VariableExprAST*>(LHS);
 652     if (!LHSE)
 653       return ErrorV("destination of '=' must be a variable");
 654     // Codegen the RHS.
 655     Value *Val = RHS->Codegen();
 656     if (Val == 0) return 0;
 657
 658     // Look up the name.
 659     Value *Variable = NamedValues[LHSE->getName()];
 660     if (Variable == 0) return ErrorV("Unknown variable name");
 661
 662     Builder.CreateStore(Val, Variable);
 663     return Val;
 664   }
 665
 666   Value *L = LHS->Codegen();
 667   Value *R = RHS->Codegen();
 668   if (L == 0 || R == 0) return 0;
 669
 670   switch (Op) {
 671   case '+': return Builder.CreateFAdd(L, R, "addtmp");
 672   case '-': return Builder.CreateFSub(L, R, "subtmp");
 673   case '*': return Builder.CreateFMul(L, R, "multmp");
 674   case '<':
 675     L = Builder.CreateFCmpULT(L, R, "cmptmp");
 676     // Convert bool 0/1 to double 0.0 or 1.0
 677     return Builder.CreateUIToFP(L, Type::getDoubleTy(getGlobalContext()),
 678                                 "booltmp");
 679   default: break;
 680   }
 681
 682   // If it wasn't a builtin binary operator, it must be a user defined one. Emit
 683   // a call to it.
 684   Function *F = TheModule->getFunction(std::string("binary")+Op);
 685   assert(F && "binary operator not found!");
 686
 687   Value *Ops[] = { L, R };
 688   return Builder.CreateCall(F, Ops, Ops+2, "binop");
 689 }
 690
 691 Value *CallExprAST::Codegen() {
 692   // Look up the name in the global module table.
 693   Function *CalleeF = TheModule->getFunction(Callee);
 694   if (CalleeF == 0)
 695     return ErrorV("Unknown function referenced");
 696
 697   // If argument mismatch error.
 698   if (CalleeF->arg_size() != Args.size())
 699     return ErrorV("Incorrect # arguments passed");
 700
 701   std::vector<Value*> ArgsV;
 702   for (unsigned i = 0, e = Args.size(); i != e; ++i) {
 703     ArgsV.push_back(Args[i]->Codegen());
 704     if (ArgsV.back() == 0) return 0;
 705   }
 706
 707   return Builder.CreateCall(CalleeF, ArgsV.begin(), ArgsV.end(), "calltmp");
 708 }
 709
 710 Value *IfExprAST::Codegen() {
 711   Value *CondV = Cond->Codegen();
 712   if (CondV == 0) return 0;
 713
 714   // Convert condition to a bool by comparing equal to 0.0.
 715   CondV = Builder.CreateFCmpONE(CondV,
 716                               ConstantFP::get(getGlobalContext(), APFloat(0.0)),
 717                                 "ifcond");
 718
 719   Function *TheFunction = Builder.GetInsertBlock()->getParent();
 720
 721   // Create blocks for the then and else cases.  Insert the 'then' block at the
 722   // end of the function.
 723   BasicBlock *ThenBB = BasicBlock::Create(getGlobalContext(), "then", TheFunction);
 724   BasicBlock *ElseBB = BasicBlock::Create(getGlobalContext(), "else");
 725   BasicBlock *MergeBB = BasicBlock::Create(getGlobalContext(), "ifcont");
 726
 727   Builder.CreateCondBr(CondV, ThenBB, ElseBB);
 728
 729   // Emit then value.
 730   Builder.SetInsertPoint(ThenBB);
 731
 732   Value *ThenV = Then->Codegen();
 733   if (ThenV == 0) return 0;
 734
 735   Builder.CreateBr(MergeBB);
 736   // Codegen of 'Then' can change the current block, update ThenBB for the PHI.
 737   ThenBB = Builder.GetInsertBlock();
 738
 739   // Emit else block.
 740   TheFunction->getBasicBlockList().push_back(ElseBB);
 741   Builder.SetInsertPoint(ElseBB);
 742
 743   Value *ElseV = Else->Codegen();
 744   if (ElseV == 0) return 0;
 745
 746   Builder.CreateBr(MergeBB);
 747   // Codegen of 'Else' can change the current block, update ElseBB for the PHI.
 748   ElseBB = Builder.GetInsertBlock();
 749
 750   // Emit merge block.
 751   TheFunction->getBasicBlockList().push_back(MergeBB);
 752   Builder.SetInsertPoint(MergeBB);
 753   PHINode *PN = Builder.CreatePHI(Type::getDoubleTy(getGlobalContext()), 2,
 754                                   "iftmp");
 755
 756   PN->addIncoming(ThenV, ThenBB);
 757   PN->addIncoming(ElseV, ElseBB);
 758   return PN;
 759 }
 760
 761 Value *ForExprAST::Codegen() {
 762   // Output this as:
 763   //   var = alloca double
 764   //   ...
 765   //   start = startexpr
 766   //   store start -> var
 767   //   goto loop
 768   // loop:
 769   //   ...
 770   //   bodyexpr
 771   //   ...
 772   // loopend:
 773   //   step = stepexpr
 774   //   endcond = endexpr
 775   //
 776   //   curvar = load var
 777   //   nextvar = curvar + step
 778   //   store nextvar -> var
 779   //   br endcond, loop, endloop
 780   // outloop:
 781
 782   Function *TheFunction = Builder.GetInsertBlock()->getParent();
 783
 784   // Create an alloca for the variable in the entry block.
 785   AllocaInst *Alloca = CreateEntryBlockAlloca(TheFunction, VarName);
 786
 787   // Emit the start code first, without 'variable' in scope.
 788   Value *StartVal = Start->Codegen();
 789   if (StartVal == 0) return 0;
 790
 791   // Store the value into the alloca.
 792   Builder.CreateStore(StartVal, Alloca);
 793
 794   // Make the new basic block for the loop header, inserting after current
 795   // block.
 796   BasicBlock *LoopBB = BasicBlock::Create(getGlobalContext(), "loop", TheFunction);
 797
 798   // Insert an explicit fall through from the current block to the LoopBB.
 799   Builder.CreateBr(LoopBB);
 800
 801   // Start insertion in LoopBB.
 802   Builder.SetInsertPoint(LoopBB);
 803
 804   // Within the loop, the variable is defined equal to the PHI node.  If it
 805   // shadows an existing variable, we have to restore it, so save it now.
 806   AllocaInst *OldVal = NamedValues[VarName];
 807   NamedValues[VarName] = Alloca;
 808
 809   // Emit the body of the loop.  This, like any other expr, can change the
 810   // current BB.  Note that we ignore the value computed by the body, but don't
 811   // allow an error.
 812   if (Body->Codegen() == 0)
 813     return 0;
 814
 815   // Emit the step value.
 816   Value *StepVal;
 817   if (Step) {
 818     StepVal = Step->Codegen();
 819     if (StepVal == 0) return 0;
 820   } else {
 821     // If not specified, use 1.0.
 822     StepVal = ConstantFP::get(getGlobalContext(), APFloat(1.0));
 823   }
 824
 825   // Compute the end condition.
 826   Value *EndCond = End->Codegen();
 827   if (EndCond == 0) return EndCond;
 828
 829   // Reload, increment, and restore the alloca.  This handles the case where
 830   // the body of the loop mutates the variable.
 831   Value *CurVar = Builder.CreateLoad(Alloca, VarName.c_str());
 832   Value *NextVar = Builder.CreateFAdd(CurVar, StepVal, "nextvar");
 833   Builder.CreateStore(NextVar, Alloca);
 834
 835   // Convert condition to a bool by comparing equal to 0.0.
 836   EndCond = Builder.CreateFCmpONE(EndCond,
 837                               ConstantFP::get(getGlobalContext(), APFloat(0.0)),
 838                                   "loopcond");
 839
 840   // Create the "after loop" block and insert it.
 841   BasicBlock *AfterBB = BasicBlock::Create(getGlobalContext(), "afterloop", TheFunction);
 842
 843   // Insert the conditional branch into the end of LoopEndBB.
 844   Builder.CreateCondBr(EndCond, LoopBB, AfterBB);
 845
 846   // Any new code will be inserted in AfterBB.
 847   Builder.SetInsertPoint(AfterBB);
 848
 849   // Restore the unshadowed variable.
 850   if (OldVal)
 851     NamedValues[VarName] = OldVal;
 852   else
 853     NamedValues.erase(VarName);
 854
 855
 856   // for expr always returns 0.0.
 857   return Constant::getNullValue(Type::getDoubleTy(getGlobalContext()));
 858 }
 859
 860 Value *VarExprAST::Codegen() {
 861   std::vector<AllocaInst *> OldBindings;
 862
 863   Function *TheFunction = Builder.GetInsertBlock()->getParent();
 864
 865   // Register all variables and emit their initializer.
 866   for (unsigned i = 0, e = VarNames.size(); i != e; ++i) {
 867     const std::string &VarName = VarNames[i].first;
 868     ExprAST *Init = VarNames[i].second;
 869
 870     // Emit the initializer before adding the variable to scope, this prevents
 871     // the initializer from referencing the variable itself, and permits stuff
 872     // like this:
 873     //  var a = 1 in
 874     //    var a = a in ...   # refers to outer 'a'.
 875     Value *InitVal;
 876     if (Init) {
 877       InitVal = Init->Codegen();
 878       if (InitVal == 0) return 0;
 879     } else { // If not specified, use 0.0.
 880       InitVal = ConstantFP::get(getGlobalContext(), APFloat(0.0));
 881     }
 882
 883     AllocaInst *Alloca = CreateEntryBlockAlloca(TheFunction, VarName);
 884     Builder.CreateStore(InitVal, Alloca);
 885
 886     // Remember the old variable binding so that we can restore the binding when
 887     // we unrecurse.
 888     OldBindings.push_back(NamedValues[VarName]);
 889
 890     // Remember this binding.
 891     NamedValues[VarName] = Alloca;
 892   }
 893
 894   // Codegen the body, now that all vars are in scope.
 895   Value *BodyVal = Body->Codegen();
 896   if (BodyVal == 0) return 0;
 897
 898   // Pop all our variables from scope.
 899   for (unsigned i = 0, e = VarNames.size(); i != e; ++i)
 900     NamedValues[VarNames[i].first] = OldBindings[i];
 901
 902   // Return the body computation.
 903   return BodyVal;
 904 }
 905
 906 Function *PrototypeAST::Codegen() {
 907   // Make the function type:  double(double,double) etc.
 908   std::vector<const Type*> Doubles(Args.size(),
 909                                    Type::getDoubleTy(getGlobalContext()));
 910   FunctionType *FT = FunctionType::get(Type::getDoubleTy(getGlobalContext()),
 911                                        Doubles, false);
 912
 913   Function *F = Function::Create(FT, Function::ExternalLinkage, Name, TheModule);
 914
 915   // If F conflicted, there was already something named 'Name'.  If it has a
 916   // body, don't allow redefinition or reextern.
 917   if (F->getName() != Name) {
 918     // Delete the one we just made and get the existing one.
 919     F->eraseFromParent();
 920     F = TheModule->getFunction(Name);
 921
 922     // If F already has a body, reject this.
 923     if (!F->empty()) {
 924       ErrorF("redefinition of function");
 925       return 0;
 926     }
 927
 928     // If F took a different number of args, reject.
 929     if (F->arg_size() != Args.size()) {
 930       ErrorF("redefinition of function with different # args");
 931       return 0;
 932     }
 933   }
 934
 935   // Set names for all arguments.
 936   unsigned Idx = 0;
 937   for (Function::arg_iterator AI = F->arg_begin(); Idx != Args.size();
 938        ++AI, ++Idx)
 939     AI->setName(Args[Idx]);
 940
 941   return F;
 942 }
 943
 944 /// CreateArgumentAllocas - Create an alloca for each argument and register the
 945 /// argument in the symbol table so that references to it will succeed.
 946 void PrototypeAST::CreateArgumentAllocas(Function *F) {
 947   Function::arg_iterator AI = F->arg_begin();
 948   for (unsigned Idx = 0, e = Args.size(); Idx != e; ++Idx, ++AI) {
 949     // Create an alloca for this variable.
 950     AllocaInst *Alloca = CreateEntryBlockAlloca(F, Args[Idx]);
 951
 952     // Store the initial value into the alloca.
 953     Builder.CreateStore(AI, Alloca);
 954
 955     // Add arguments to variable symbol table.
 956     NamedValues[Args[Idx]] = Alloca;
 957   }
 958 }
 959
 960 Function *FunctionAST::Codegen() {
 961   NamedValues.clear();
 962
 963   Function *TheFunction = Proto->Codegen();
 964   if (TheFunction == 0)
 965     return 0;
 966
 967   // If this is an operator, install it.
 968   if (Proto->isBinaryOp())
 969     BinopPrecedence[Proto->getOperatorName()] = Proto->getBinaryPrecedence();
 970
 971   // Create a new basic block to start insertion into.
 972   BasicBlock *BB = BasicBlock::Create(getGlobalContext(), "entry", TheFunction);
 973   Builder.SetInsertPoint(BB);
 974
 975   // Add all arguments to the symbol table and create their allocas.
 976   Proto->CreateArgumentAllocas(TheFunction);
 977
 978   if (Value *RetVal = Body->Codegen()) {
 979     // Finish off the function.
 980     Builder.CreateRet(RetVal);
 981
 982     // Validate the generated code, checking for consistency.
 983     verifyFunction(*TheFunction);
 984
 985     // Optimize the function.
 986     TheFPM->run(*TheFunction);
 987
 988     return TheFunction;
 989   }
 990
 991   // Error reading body, remove function.
 992   TheFunction->eraseFromParent();
 993
 994   if (Proto->isBinaryOp())
 995     BinopPrecedence.erase(Proto->getOperatorName());
 996   return 0;
 997 }
 998
 999 //===----------------------------------------------------------------------===//
1000 // Top-Level parsing and JIT Driver
1001 //===----------------------------------------------------------------------===//
1002
1003 static ExecutionEngine *TheExecutionEngine;
1004
1005 static void HandleDefinition() {
1006   if (FunctionAST *F = ParseDefinition()) {
1007     if (Function *LF = F->Codegen()) {
1008       fprintf(stderr, "Read function definition:");
1009       LF->dump();
1010     }
1011   } else {
1012     // Skip token for error recovery.
1013     getNextToken();
1014   }
1015 }
1016
1017 static void HandleExtern() {
1018   if (PrototypeAST *P = ParseExtern()) {
1019     if (Function *F = P->Codegen()) {
1020       fprintf(stderr, "Read extern: ");
1021       F->dump();
1022     }
1023   } else {
1024     // Skip token for error recovery.
1025     getNextToken();
1026   }
1027 }
1028
1029 static void HandleTopLevelExpression() {
1030   // Evaluate a top-level expression into an anonymous function.
1031   if (FunctionAST *F = ParseTopLevelExpr()) {
1032     if (Function *LF = F->Codegen()) {
1033       // JIT the function, returning a function pointer.
1034       void *FPtr = TheExecutionEngine->getPointerToFunction(LF);
1035
1036       // Cast it to the right type (takes no arguments, returns a double) so we
1037       // can call it as a native function.
1038       double (*FP)() = (double (*)())(intptr_t)FPtr;
1039       fprintf(stderr, "Evaluated to %f\n", FP());
1040     }
1041   } else {
1042     // Skip token for error recovery.
1043     getNextToken();
1044   }
1045 }
1046
1047 /// top ::= definition | external | expression | ';'
1048 static void MainLoop() {
1049   while (1) {
1050     fprintf(stderr, "ready> ");
1051     switch (CurTok) {
1052     case tok_eof:    return;
1053     case ';':        getNextToken(); break;  // ignore top-level semicolons.
1054     case tok_def:    HandleDefinition(); break;
1055     case tok_extern: HandleExtern(); break;
1056     default:         HandleTopLevelExpression(); break;
1057     }
1058   }
1059 }
1060
1061 //===----------------------------------------------------------------------===//
1062 // "Library" functions that can be "extern'd" from user code.
1063 //===----------------------------------------------------------------------===//
1064
1065 /// putchard - putchar that takes a double and returns 0.
1066 extern "C"
1067 double putchard(double X) {
1068   putchar((char)X);
1069   return 0;
1070 }
1071
1072 /// printd - printf that takes a double prints it as "%f\n", returning 0.
1073 extern "C"
1074 double printd(double X) {
1075   printf("%f\n", X);
1076   return 0;
1077 }
1078
1079 //===----------------------------------------------------------------------===//
1080 // Main driver code.
1081 //===----------------------------------------------------------------------===//
1082
1083 int main() {
1084   InitializeNativeTarget();
1085   LLVMContext &Context = getGlobalContext();
1086
1087   // Install standard binary operators.
1088   // 1 is lowest precedence.
1089   BinopPrecedence['='] = 2;
1090   BinopPrecedence['<'] = 10;
1091   BinopPrecedence['+'] = 20;
1092   BinopPrecedence['-'] = 20;
1093   BinopPrecedence['*'] = 40;  // highest.
1094
1095   // Prime the first token.
1096   fprintf(stderr, "ready> ");
1097   getNextToken();
1098
1099   // Make the module, which holds all the code.
1100   TheModule = new Module("my cool jit", Context);
1101
1102   // Create the JIT.  This takes ownership of the module.
1103   std::string ErrStr;
1104   TheExecutionEngine = EngineBuilder(TheModule).setErrorStr(&ErrStr).create();
1105   if (!TheExecutionEngine) {
1106     fprintf(stderr, "Could not create ExecutionEngine: %s\n", ErrStr.c_str());
1107     exit(1);
1108   }
1109
1110   FunctionPassManager OurFPM(TheModule);
1111
1112   // Set up the optimizer pipeline.  Start with registering info about how the
1113   // target lays out data structures.
1114   OurFPM.add(new TargetData(*TheExecutionEngine->getTargetData()));
1115   // Provide basic AliasAnalysis support for GVN.
1116   OurFPM.add(createBasicAliasAnalysisPass());
1117   // Promote allocas to registers.
1118   OurFPM.add(createPromoteMemoryToRegisterPass());
1119   // Do simple "peephole" optimizations and bit-twiddling optzns.
1120   OurFPM.add(createInstructionCombiningPass());
1121   // Reassociate expressions.
1122   OurFPM.add(createReassociatePass());
1123   // Eliminate Common SubExpressions.
1124   OurFPM.add(createGVNPass());
1125   // Simplify the control flow graph (deleting unreachable blocks, etc).
1126   OurFPM.add(createCFGSimplificationPass());
1127
1128   OurFPM.doInitialization();
1129
1130   // Set the global so the code gen can use this.
1131   TheFPM = &OurFPM;
1132
1133   // Run the main "interpreter loop" now.
1134   MainLoop();
1135
1136   TheFPM = 0;
1137
1138   // Print out all of the generated code.
1139   TheModule->dump();
1140
1141   return 0;
1142 }