examples/Kaleidoscope/Chapter9/toy.cpp

   1 #include "llvm/ADT/STLExtras.h"
   2 #include "llvm/Analysis/BasicAliasAnalysis.h"
   3 #include "llvm/Analysis/Passes.h"
   4 #include "llvm/IR/DIBuilder.h"
   5 #include "llvm/IR/IRBuilder.h"
   6 #include "llvm/IR/LLVMContext.h"
   7 #include "llvm/IR/LegacyPassManager.h"
   8 #include "llvm/IR/Module.h"
   9 #include "llvm/IR/Verifier.h"
  10 #include "llvm/Support/TargetSelect.h"
  11 #include "llvm/Transforms/Scalar.h"
  12 #include <cctype>
  13 #include <cstdio>
  14 #include <map>
  15 #include <string>
  16 #include <vector>
  17 #include "../include/KaleidoscopeJIT.h"
  18
  19 using namespace llvm;
  20 using namespace llvm::orc;
  21
  22 //===----------------------------------------------------------------------===//
  23 // Lexer
  24 //===----------------------------------------------------------------------===//
  25
  26 // The lexer returns tokens [0-255] if it is an unknown character, otherwise one
  27 // of these for known things.
  28 enum Token {
  29   tok_eof = -1,
  30
  31   // commands
  32   tok_def = -2,
  33   tok_extern = -3,
  34
  35   // primary
  36   tok_identifier = -4,
  37   tok_number = -5,
  38
  39   // control
  40   tok_if = -6,
  41   tok_then = -7,
  42   tok_else = -8,
  43   tok_for = -9,
  44   tok_in = -10,
  45
  46   // operators
  47   tok_binary = -11,
  48   tok_unary = -12,
  49
  50   // var definition
  51   tok_var = -13
  52 };
  53
  54 std::string getTokName(int Tok) {
  55   switch (Tok) {
  56   case tok_eof:
  57     return "eof";
  58   case tok_def:
  59     return "def";
  60   case tok_extern:
  61     return "extern";
  62   case tok_identifier:
  63     return "identifier";
  64   case tok_number:
  65     return "number";
  66   case tok_if:
  67     return "if";
  68   case tok_then:
  69     return "then";
  70   case tok_else:
  71     return "else";
  72   case tok_for:
  73     return "for";
  74   case tok_in:
  75     return "in";
  76   case tok_binary:
  77     return "binary";
  78   case tok_unary:
  79     return "unary";
  80   case tok_var:
  81     return "var";
  82   }
  83   return std::string(1, (char)Tok);
  84 }
  85
  86 namespace {
  87 class PrototypeAST;
  88 class ExprAST;
  89 }
  90 static LLVMContext TheContext;
  91 static IRBuilder<> Builder(TheContext);
  92 struct DebugInfo {
  93   DICompileUnit *TheCU;
  94   DIType *DblTy;
  95   std::vector<DIScope *> LexicalBlocks;
  96
  97   void emitLocation(ExprAST *AST);
  98   DIType *getDoubleTy();
  99 } KSDbgInfo;
 100
 101 struct SourceLocation {
 102   int Line;
 103   int Col;
 104 };
 105 static SourceLocation CurLoc;
 106 static SourceLocation LexLoc = {1, 0};
 107
 108 static int advance() {
 109   int LastChar = getchar();
 110
 111   if (LastChar == '\n' || LastChar == '\r') {
 112     LexLoc.Line++;
 113     LexLoc.Col = 0;
 114   } else
 115     LexLoc.Col++;
 116   return LastChar;
 117 }
 118
 119 static std::string IdentifierStr; // Filled in if tok_identifier
 120 static double NumVal;             // Filled in if tok_number
 121
 122 /// gettok - Return the next token from standard input.
 123 static int gettok() {
 124   static int LastChar = ' ';
 125
 126   // Skip any whitespace.
 127   while (isspace(LastChar))
 128     LastChar = advance();
 129
 130   CurLoc = LexLoc;
 131
 132   if (isalpha(LastChar)) { // identifier: [a-zA-Z][a-zA-Z0-9]*
 133     IdentifierStr = LastChar;
 134     while (isalnum((LastChar = advance())))
 135       IdentifierStr += LastChar;
 136
 137     if (IdentifierStr == "def")
 138       return tok_def;
 139     if (IdentifierStr == "extern")
 140       return tok_extern;
 141     if (IdentifierStr == "if")
 142       return tok_if;
 143     if (IdentifierStr == "then")
 144       return tok_then;
 145     if (IdentifierStr == "else")
 146       return tok_else;
 147     if (IdentifierStr == "for")
 148       return tok_for;
 149     if (IdentifierStr == "in")
 150       return tok_in;
 151     if (IdentifierStr == "binary")
 152       return tok_binary;
 153     if (IdentifierStr == "unary")
 154       return tok_unary;
 155     if (IdentifierStr == "var")
 156       return tok_var;
 157     return tok_identifier;
 158   }
 159
 160   if (isdigit(LastChar) || LastChar == '.') { // Number: [0-9.]+
 161     std::string NumStr;
 162     do {
 163       NumStr += LastChar;
 164       LastChar = advance();
 165     } while (isdigit(LastChar) || LastChar == '.');
 166
 167     NumVal = strtod(NumStr.c_str(), nullptr);
 168     return tok_number;
 169   }
 170
 171   if (LastChar == '#') {
 172     // Comment until end of line.
 173     do
 174       LastChar = advance();
 175     while (LastChar != EOF && LastChar != '\n' && LastChar != '\r');
 176
 177     if (LastChar != EOF)
 178       return gettok();
 179   }
 180
 181   // Check for end of file.  Don't eat the EOF.
 182   if (LastChar == EOF)
 183     return tok_eof;
 184
 185   // Otherwise, just return the character as its ascii value.
 186   int ThisChar = LastChar;
 187   LastChar = advance();
 188   return ThisChar;
 189 }
 190
 191 //===----------------------------------------------------------------------===//
 192 // Abstract Syntax Tree (aka Parse Tree)
 193 //===----------------------------------------------------------------------===//
 194 namespace {
 195
 196 raw_ostream &indent(raw_ostream &O, int size) {
 197   return O << std::string(size, ' ');
 198 }
 199
 200 /// ExprAST - Base class for all expression nodes.
 201 class ExprAST {
 202   SourceLocation Loc;
 203
 204 public:
 205   ExprAST(SourceLocation Loc = CurLoc) : Loc(Loc) {}
 206   virtual ~ExprAST() {}
 207   virtual Value *codegen() = 0;
 208   int getLine() const { return Loc.Line; }
 209   int getCol() const { return Loc.Col; }
 210   virtual raw_ostream &dump(raw_ostream &out, int ind) {
 211     return out << ':' << getLine() << ':' << getCol() << '\n';
 212   }
 213 };
 214
 215 /// NumberExprAST - Expression class for numeric literals like "1.0".
 216 class NumberExprAST : public ExprAST {
 217   double Val;
 218
 219 public:
 220   NumberExprAST(double Val) : Val(Val) {}
 221   raw_ostream &dump(raw_ostream &out, int ind) override {
 222     return ExprAST::dump(out << Val, ind);
 223   }
 224   Value *codegen() override;
 225 };
 226
 227 /// VariableExprAST - Expression class for referencing a variable, like "a".
 228 class VariableExprAST : public ExprAST {
 229   std::string Name;
 230
 231 public:
 232   VariableExprAST(SourceLocation Loc, const std::string &Name)
 233       : ExprAST(Loc), Name(Name) {}
 234   const std::string &getName() const { return Name; }
 235   Value *codegen() override;
 236   raw_ostream &dump(raw_ostream &out, int ind) override {
 237     return ExprAST::dump(out << Name, ind);
 238   }
 239 };
 240
 241 /// UnaryExprAST - Expression class for a unary operator.
 242 class UnaryExprAST : public ExprAST {
 243   char Opcode;
 244   std::unique_ptr<ExprAST> Operand;
 245
 246 public:
 247   UnaryExprAST(char Opcode, std::unique_ptr<ExprAST> Operand)
 248       : Opcode(Opcode), Operand(std::move(Operand)) {}
 249   Value *codegen() override;
 250   raw_ostream &dump(raw_ostream &out, int ind) override {
 251     ExprAST::dump(out << "unary" << Opcode, ind);
 252     Operand->dump(out, ind + 1);
 253     return out;
 254   }
 255 };
 256
 257 /// BinaryExprAST - Expression class for a binary operator.
 258 class BinaryExprAST : public ExprAST {
 259   char Op;
 260   std::unique_ptr<ExprAST> LHS, RHS;
 261
 262 public:
 263   BinaryExprAST(SourceLocation Loc, char Op, std::unique_ptr<ExprAST> LHS,
 264                 std::unique_ptr<ExprAST> RHS)
 265       : ExprAST(Loc), Op(Op), LHS(std::move(LHS)), RHS(std::move(RHS)) {}
 266   Value *codegen() override;
 267   raw_ostream &dump(raw_ostream &out, int ind) override {
 268     ExprAST::dump(out << "binary" << Op, ind);
 269     LHS->dump(indent(out, ind) << "LHS:", ind + 1);
 270     RHS->dump(indent(out, ind) << "RHS:", ind + 1);
 271     return out;
 272   }
 273 };
 274
 275 /// CallExprAST - Expression class for function calls.
 276 class CallExprAST : public ExprAST {
 277   std::string Callee;
 278   std::vector<std::unique_ptr<ExprAST>> Args;
 279
 280 public:
 281   CallExprAST(SourceLocation Loc, const std::string &Callee,
 282               std::vector<std::unique_ptr<ExprAST>> Args)
 283       : ExprAST(Loc), Callee(Callee), Args(std::move(Args)) {}
 284   Value *codegen() override;
 285   raw_ostream &dump(raw_ostream &out, int ind) override {
 286     ExprAST::dump(out << "call " << Callee, ind);
 287     for (const auto &Arg : Args)
 288       Arg->dump(indent(out, ind + 1), ind + 1);
 289     return out;
 290   }
 291 };
 292
 293 /// IfExprAST - Expression class for if/then/else.
 294 class IfExprAST : public ExprAST {
 295   std::unique_ptr<ExprAST> Cond, Then, Else;
 296
 297 public:
 298   IfExprAST(SourceLocation Loc, std::unique_ptr<ExprAST> Cond,
 299             std::unique_ptr<ExprAST> Then, std::unique_ptr<ExprAST> Else)
 300       : ExprAST(Loc), Cond(std::move(Cond)), Then(std::move(Then)),
 301         Else(std::move(Else)) {}
 302   Value *codegen() override;
 303   raw_ostream &dump(raw_ostream &out, int ind) override {
 304     ExprAST::dump(out << "if", ind);
 305     Cond->dump(indent(out, ind) << "Cond:", ind + 1);
 306     Then->dump(indent(out, ind) << "Then:", ind + 1);
 307     Else->dump(indent(out, ind) << "Else:", ind + 1);
 308     return out;
 309   }
 310 };
 311
 312 /// ForExprAST - Expression class for for/in.
 313 class ForExprAST : public ExprAST {
 314   std::string VarName;
 315   std::unique_ptr<ExprAST> Start, End, Step, Body;
 316
 317 public:
 318   ForExprAST(const std::string &VarName, std::unique_ptr<ExprAST> Start,
 319              std::unique_ptr<ExprAST> End, std::unique_ptr<ExprAST> Step,
 320              std::unique_ptr<ExprAST> Body)
 321       : VarName(VarName), Start(std::move(Start)), End(std::move(End)),
 322         Step(std::move(Step)), Body(std::move(Body)) {}
 323   Value *codegen() override;
 324   raw_ostream &dump(raw_ostream &out, int ind) override {
 325     ExprAST::dump(out << "for", ind);
 326     Start->dump(indent(out, ind) << "Cond:", ind + 1);
 327     End->dump(indent(out, ind) << "End:", ind + 1);
 328     Step->dump(indent(out, ind) << "Step:", ind + 1);
 329     Body->dump(indent(out, ind) << "Body:", ind + 1);
 330     return out;
 331   }
 332 };
 333
 334 /// VarExprAST - Expression class for var/in
 335 class VarExprAST : public ExprAST {
 336   std::vector<std::pair<std::string, std::unique_ptr<ExprAST>>> VarNames;
 337   std::unique_ptr<ExprAST> Body;
 338
 339 public:
 340   VarExprAST(
 341       std::vector<std::pair<std::string, std::unique_ptr<ExprAST>>> VarNames,
 342       std::unique_ptr<ExprAST> Body)
 343       : VarNames(std::move(VarNames)), Body(std::move(Body)) {}
 344   Value *codegen() override;
 345   raw_ostream &dump(raw_ostream &out, int ind) override {
 346     ExprAST::dump(out << "var", ind);
 347     for (const auto &NamedVar : VarNames)
 348       NamedVar.second->dump(indent(out, ind) << NamedVar.first << ':', ind + 1);
 349     Body->dump(indent(out, ind) << "Body:", ind + 1);
 350     return out;
 351   }
 352 };
 353
 354 /// PrototypeAST - This class represents the "prototype" for a function,
 355 /// which captures its name, and its argument names (thus implicitly the number
 356 /// of arguments the function takes), as well as if it is an operator.
 357 class PrototypeAST {
 358   std::string Name;
 359   std::vector<std::string> Args;
 360   bool IsOperator;
 361   unsigned Precedence; // Precedence if a binary op.
 362   int Line;
 363
 364 public:
 365   PrototypeAST(SourceLocation Loc, const std::string &Name,
 366                std::vector<std::string> Args, bool IsOperator = false,
 367                unsigned Prec = 0)
 368       : Name(Name), Args(std::move(Args)), IsOperator(IsOperator),
 369         Precedence(Prec), Line(Loc.Line) {}
 370   Function *codegen();
 371   const std::string &getName() const { return Name; }
 372
 373   bool isUnaryOp() const { return IsOperator && Args.size() == 1; }
 374   bool isBinaryOp() const { return IsOperator && Args.size() == 2; }
 375
 376   char getOperatorName() const {
 377     assert(isUnaryOp() || isBinaryOp());
 378     return Name[Name.size() - 1];
 379   }
 380
 381   unsigned getBinaryPrecedence() const { return Precedence; }
 382   int getLine() const { return Line; }
 383 };
 384
 385 /// FunctionAST - This class represents a function definition itself.
 386 class FunctionAST {
 387   std::unique_ptr<PrototypeAST> Proto;
 388   std::unique_ptr<ExprAST> Body;
 389
 390 public:
 391   FunctionAST(std::unique_ptr<PrototypeAST> Proto,
 392               std::unique_ptr<ExprAST> Body)
 393       : Proto(std::move(Proto)), Body(std::move(Body)) {}
 394   Function *codegen();
 395   raw_ostream &dump(raw_ostream &out, int ind) {
 396     indent(out, ind) << "FunctionAST\n";
 397     ++ind;
 398     indent(out, ind) << "Body:";
 399     return Body ? Body->dump(out, ind) : out << "null\n";
 400   }
 401 };
 402 } // end anonymous namespace
 403
 404 //===----------------------------------------------------------------------===//
 405 // Parser
 406 //===----------------------------------------------------------------------===//
 407
 408 /// CurTok/getNextToken - Provide a simple token buffer.  CurTok is the current
 409 /// token the parser is looking at.  getNextToken reads another token from the
 410 /// lexer and updates CurTok with its results.
 411 static int CurTok;
 412 static int getNextToken() { return CurTok = gettok(); }
 413
 414 /// BinopPrecedence - This holds the precedence for each binary operator that is
 415 /// defined.
 416 static std::map<char, int> BinopPrecedence;
 417
 418 /// GetTokPrecedence - Get the precedence of the pending binary operator token.
 419 static int GetTokPrecedence() {
 420   if (!isascii(CurTok))
 421     return -1;
 422
 423   // Make sure it's a declared binop.
 424   int TokPrec = BinopPrecedence[CurTok];
 425   if (TokPrec <= 0)
 426     return -1;
 427   return TokPrec;
 428 }
 429
 430 /// LogError* - These are little helper functions for error handling.
 431 std::unique_ptr<ExprAST> LogError(const char *Str) {
 432   fprintf(stderr, "Error: %s\n", Str);
 433   return nullptr;
 434 }
 435
 436 std::unique_ptr<PrototypeAST> LogErrorP(const char *Str) {
 437   LogError(Str);
 438   return nullptr;
 439 }
 440
 441 static std::unique_ptr<ExprAST> ParseExpression();
 442
 443 /// numberexpr ::= number
 444 static std::unique_ptr<ExprAST> ParseNumberExpr() {
 445   auto Result = llvm::make_unique<NumberExprAST>(NumVal);
 446   getNextToken(); // consume the number
 447   return std::move(Result);
 448 }
 449
 450 /// parenexpr ::= '(' expression ')'
 451 static std::unique_ptr<ExprAST> ParseParenExpr() {
 452   getNextToken(); // eat (.
 453   auto V = ParseExpression();
 454   if (!V)
 455     return nullptr;
 456
 457   if (CurTok != ')')
 458     return LogError("expected ')'");
 459   getNextToken(); // eat ).
 460   return V;
 461 }
 462
 463 /// identifierexpr
 464 ///   ::= identifier
 465 ///   ::= identifier '(' expression* ')'
 466 static std::unique_ptr<ExprAST> ParseIdentifierExpr() {
 467   std::string IdName = IdentifierStr;
 468
 469   SourceLocation LitLoc = CurLoc;
 470
 471   getNextToken(); // eat identifier.
 472
 473   if (CurTok != '(') // Simple variable ref.
 474     return llvm::make_unique<VariableExprAST>(LitLoc, IdName);
 475
 476   // Call.
 477   getNextToken(); // eat (
 478   std::vector<std::unique_ptr<ExprAST>> Args;
 479   if (CurTok != ')') {
 480     while (1) {
 481       if (auto Arg = ParseExpression())
 482         Args.push_back(std::move(Arg));
 483       else
 484         return nullptr;
 485
 486       if (CurTok == ')')
 487         break;
 488
 489       if (CurTok != ',')
 490         return LogError("Expected ')' or ',' in argument list");
 491       getNextToken();
 492     }
 493   }
 494
 495   // Eat the ')'.
 496   getNextToken();
 497
 498   return llvm::make_unique<CallExprAST>(LitLoc, IdName, std::move(Args));
 499 }
 500
 501 /// ifexpr ::= 'if' expression 'then' expression 'else' expression
 502 static std::unique_ptr<ExprAST> ParseIfExpr() {
 503   SourceLocation IfLoc = CurLoc;
 504
 505   getNextToken(); // eat the if.
 506
 507   // condition.
 508   auto Cond = ParseExpression();
 509   if (!Cond)
 510     return nullptr;
 511
 512   if (CurTok != tok_then)
 513     return LogError("expected then");
 514   getNextToken(); // eat the then
 515
 516   auto Then = ParseExpression();
 517   if (!Then)
 518     return nullptr;
 519
 520   if (CurTok != tok_else)
 521     return LogError("expected else");
 522
 523   getNextToken();
 524
 525   auto Else = ParseExpression();
 526   if (!Else)
 527     return nullptr;
 528
 529   return llvm::make_unique<IfExprAST>(IfLoc, std::move(Cond), std::move(Then),
 530                                       std::move(Else));
 531 }
 532
 533 /// forexpr ::= 'for' identifier '=' expr ',' expr (',' expr)? 'in' expression
 534 static std::unique_ptr<ExprAST> ParseForExpr() {
 535   getNextToken(); // eat the for.
 536
 537   if (CurTok != tok_identifier)
 538     return LogError("expected identifier after for");
 539
 540   std::string IdName = IdentifierStr;
 541   getNextToken(); // eat identifier.
 542
 543   if (CurTok != '=')
 544     return LogError("expected '=' after for");
 545   getNextToken(); // eat '='.
 546
 547   auto Start = ParseExpression();
 548   if (!Start)
 549     return nullptr;
 550   if (CurTok != ',')
 551     return LogError("expected ',' after for start value");
 552   getNextToken();
 553
 554   auto End = ParseExpression();
 555   if (!End)
 556     return nullptr;
 557
 558   // The step value is optional.
 559   std::unique_ptr<ExprAST> Step;
 560   if (CurTok == ',') {
 561     getNextToken();
 562     Step = ParseExpression();
 563     if (!Step)
 564       return nullptr;
 565   }
 566
 567   if (CurTok != tok_in)
 568     return LogError("expected 'in' after for");
 569   getNextToken(); // eat 'in'.
 570
 571   auto Body = ParseExpression();
 572   if (!Body)
 573     return nullptr;
 574
 575   return llvm::make_unique<ForExprAST>(IdName, std::move(Start), std::move(End),
 576                                        std::move(Step), std::move(Body));
 577 }
 578
 579 /// varexpr ::= 'var' identifier ('=' expression)?
 580 //                    (',' identifier ('=' expression)?)* 'in' expression
 581 static std::unique_ptr<ExprAST> ParseVarExpr() {
 582   getNextToken(); // eat the var.
 583
 584   std::vector<std::pair<std::string, std::unique_ptr<ExprAST>>> VarNames;
 585
 586   // At least one variable name is required.
 587   if (CurTok != tok_identifier)
 588     return LogError("expected identifier after var");
 589
 590   while (1) {
 591     std::string Name = IdentifierStr;
 592     getNextToken(); // eat identifier.
 593
 594     // Read the optional initializer.
 595     std::unique_ptr<ExprAST> Init = nullptr;
 596     if (CurTok == '=') {
 597       getNextToken(); // eat the '='.
 598
 599       Init = ParseExpression();
 600       if (!Init)
 601         return nullptr;
 602     }
 603
 604     VarNames.push_back(std::make_pair(Name, std::move(Init)));
 605
 606     // End of var list, exit loop.
 607     if (CurTok != ',')
 608       break;
 609     getNextToken(); // eat the ','.
 610
 611     if (CurTok != tok_identifier)
 612       return LogError("expected identifier list after var");
 613   }
 614
 615   // At this point, we have to have 'in'.
 616   if (CurTok != tok_in)
 617     return LogError("expected 'in' keyword after 'var'");
 618   getNextToken(); // eat 'in'.
 619
 620   auto Body = ParseExpression();
 621   if (!Body)
 622     return nullptr;
 623
 624   return llvm::make_unique<VarExprAST>(std::move(VarNames), std::move(Body));
 625 }
 626
 627 /// primary
 628 ///   ::= identifierexpr
 629 ///   ::= numberexpr
 630 ///   ::= parenexpr
 631 ///   ::= ifexpr
 632 ///   ::= forexpr
 633 ///   ::= varexpr
 634 static std::unique_ptr<ExprAST> ParsePrimary() {
 635   switch (CurTok) {
 636   default:
 637     return LogError("unknown token when expecting an expression");
 638   case tok_identifier:
 639     return ParseIdentifierExpr();
 640   case tok_number:
 641     return ParseNumberExpr();
 642   case '(':
 643     return ParseParenExpr();
 644   case tok_if:
 645     return ParseIfExpr();
 646   case tok_for:
 647     return ParseForExpr();
 648   case tok_var:
 649     return ParseVarExpr();
 650   }
 651 }
 652
 653 /// unary
 654 ///   ::= primary
 655 ///   ::= '!' unary
 656 static std::unique_ptr<ExprAST> ParseUnary() {
 657   // If the current token is not an operator, it must be a primary expr.
 658   if (!isascii(CurTok) || CurTok == '(' || CurTok == ',')
 659     return ParsePrimary();
 660
 661   // If this is a unary operator, read it.
 662   int Opc = CurTok;
 663   getNextToken();
 664   if (auto Operand = ParseUnary())
 665     return llvm::make_unique<UnaryExprAST>(Opc, std::move(Operand));
 666   return nullptr;
 667 }
 668
 669 /// binoprhs
 670 ///   ::= ('+' unary)*
 671 static std::unique_ptr<ExprAST> ParseBinOpRHS(int ExprPrec,
 672                                               std::unique_ptr<ExprAST> LHS) {
 673   // If this is a binop, find its precedence.
 674   while (1) {
 675     int TokPrec = GetTokPrecedence();
 676
 677     // If this is a binop that binds at least as tightly as the current binop,
 678     // consume it, otherwise we are done.
 679     if (TokPrec < ExprPrec)
 680       return LHS;
 681
 682     // Okay, we know this is a binop.
 683     int BinOp = CurTok;
 684     SourceLocation BinLoc = CurLoc;
 685     getNextToken(); // eat binop
 686
 687     // Parse the unary expression after the binary operator.
 688     auto RHS = ParseUnary();
 689     if (!RHS)
 690       return nullptr;
 691
 692     // If BinOp binds less tightly with RHS than the operator after RHS, let
 693     // the pending operator take RHS as its LHS.
 694     int NextPrec = GetTokPrecedence();
 695     if (TokPrec < NextPrec) {
 696       RHS = ParseBinOpRHS(TokPrec + 1, std::move(RHS));
 697       if (!RHS)
 698         return nullptr;
 699     }
 700
 701     // Merge LHS/RHS.
 702     LHS = llvm::make_unique<BinaryExprAST>(BinLoc, BinOp, std::move(LHS),
 703                                            std::move(RHS));
 704   }
 705 }
 706
 707 /// expression
 708 ///   ::= unary binoprhs
 709 ///
 710 static std::unique_ptr<ExprAST> ParseExpression() {
 711   auto LHS = ParseUnary();
 712   if (!LHS)
 713     return nullptr;
 714
 715   return ParseBinOpRHS(0, std::move(LHS));
 716 }
 717
 718 /// prototype
 719 ///   ::= id '(' id* ')'
 720 ///   ::= binary LETTER number? (id, id)
 721 ///   ::= unary LETTER (id)
 722 static std::unique_ptr<PrototypeAST> ParsePrototype() {
 723   std::string FnName;
 724
 725   SourceLocation FnLoc = CurLoc;
 726
 727   unsigned Kind = 0; // 0 = identifier, 1 = unary, 2 = binary.
 728   unsigned BinaryPrecedence = 30;
 729
 730   switch (CurTok) {
 731   default:
 732     return LogErrorP("Expected function name in prototype");
 733   case tok_identifier:
 734     FnName = IdentifierStr;
 735     Kind = 0;
 736     getNextToken();
 737     break;
 738   case tok_unary:
 739     getNextToken();
 740     if (!isascii(CurTok))
 741       return LogErrorP("Expected unary operator");
 742     FnName = "unary";
 743     FnName += (char)CurTok;
 744     Kind = 1;
 745     getNextToken();
 746     break;
 747   case tok_binary:
 748     getNextToken();
 749     if (!isascii(CurTok))
 750       return LogErrorP("Expected binary operator");
 751     FnName = "binary";
 752     FnName += (char)CurTok;
 753     Kind = 2;
 754     getNextToken();
 755
 756     // Read the precedence if present.
 757     if (CurTok == tok_number) {
 758       if (NumVal < 1 || NumVal > 100)
 759         return LogErrorP("Invalid precedence: must be 1..100");
 760       BinaryPrecedence = (unsigned)NumVal;
 761       getNextToken();
 762     }
 763     break;
 764   }
 765
 766   if (CurTok != '(')
 767     return LogErrorP("Expected '(' in prototype");
 768
 769   std::vector<std::string> ArgNames;
 770   while (getNextToken() == tok_identifier)
 771     ArgNames.push_back(IdentifierStr);
 772   if (CurTok != ')')
 773     return LogErrorP("Expected ')' in prototype");
 774
 775   // success.
 776   getNextToken(); // eat ')'.
 777
 778   // Verify right number of names for operator.
 779   if (Kind && ArgNames.size() != Kind)
 780     return LogErrorP("Invalid number of operands for operator");
 781
 782   return llvm::make_unique<PrototypeAST>(FnLoc, FnName, ArgNames, Kind != 0,
 783                                          BinaryPrecedence);
 784 }
 785
 786 /// definition ::= 'def' prototype expression
 787 static std::unique_ptr<FunctionAST> ParseDefinition() {
 788   getNextToken(); // eat def.
 789   auto Proto = ParsePrototype();
 790   if (!Proto)
 791     return nullptr;
 792
 793   if (auto E = ParseExpression())
 794     return llvm::make_unique<FunctionAST>(std::move(Proto), std::move(E));
 795   return nullptr;
 796 }
 797
 798 /// toplevelexpr ::= expression
 799 static std::unique_ptr<FunctionAST> ParseTopLevelExpr() {
 800   SourceLocation FnLoc = CurLoc;
 801   if (auto E = ParseExpression()) {
 802     // Make an anonymous proto.
 803     auto Proto = llvm::make_unique<PrototypeAST>(FnLoc, "__anon_expr",
 804                                                  std::vector<std::string>());
 805     return llvm::make_unique<FunctionAST>(std::move(Proto), std::move(E));
 806   }
 807   return nullptr;
 808 }
 809
 810 /// external ::= 'extern' prototype
 811 static std::unique_ptr<PrototypeAST> ParseExtern() {
 812   getNextToken(); // eat extern.
 813   return ParsePrototype();
 814 }
 815
 816 //===----------------------------------------------------------------------===//
 817 // Debug Info Support
 818 //===----------------------------------------------------------------------===//
 819
 820 static std::unique_ptr<DIBuilder> DBuilder;
 821
 822 DIType *DebugInfo::getDoubleTy() {
 823   if (DblTy)
 824     return DblTy;
 825
 826   DblTy = DBuilder->createBasicType("double", 64, dwarf::DW_ATE_float);
 827   return DblTy;
 828 }
 829
 830 void DebugInfo::emitLocation(ExprAST *AST) {
 831   if (!AST)
 832     return Builder.SetCurrentDebugLocation(DebugLoc());
 833   DIScope *Scope;
 834   if (LexicalBlocks.empty())
 835     Scope = TheCU;
 836   else
 837     Scope = LexicalBlocks.back();
 838   Builder.SetCurrentDebugLocation(
 839       DebugLoc::get(AST->getLine(), AST->getCol(), Scope));
 840 }
 841
 842 static DISubroutineType *CreateFunctionType(unsigned NumArgs, DIFile *Unit) {
 843   SmallVector<Metadata *, 8> EltTys;
 844   DIType *DblTy = KSDbgInfo.getDoubleTy();
 845
 846   // Add the result type.
 847   EltTys.push_back(DblTy);
 848
 849   for (unsigned i = 0, e = NumArgs; i != e; ++i)
 850     EltTys.push_back(DblTy);
 851
 852   return DBuilder->createSubroutineType(DBuilder->getOrCreateTypeArray(EltTys));
 853 }
 854
 855 //===----------------------------------------------------------------------===//
 856 // Code Generation
 857 //===----------------------------------------------------------------------===//
 858
 859 static std::unique_ptr<Module> TheModule;
 860 static std::map<std::string, AllocaInst *> NamedValues;
 861 static std::unique_ptr<KaleidoscopeJIT> TheJIT;
 862 static std::map<std::string, std::unique_ptr<PrototypeAST>> FunctionProtos;
 863
 864 Value *LogErrorV(const char *Str) {
 865   LogError(Str);
 866   return nullptr;
 867 }
 868
 869 Function *getFunction(std::string Name) {
 870   // First, see if the function has already been added to the current module.
 871   if (auto *F = TheModule->getFunction(Name))
 872     return F;
 873
 874   // If not, check whether we can codegen the declaration from some existing
 875   // prototype.
 876   auto FI = FunctionProtos.find(Name);
 877   if (FI != FunctionProtos.end())
 878     return FI->second->codegen();
 879
 880   // If no existing prototype exists, return null.
 881   return nullptr;
 882 }
 883
 884 /// CreateEntryBlockAlloca - Create an alloca instruction in the entry block of
 885 /// the function.  This is used for mutable variables etc.
 886 static AllocaInst *CreateEntryBlockAlloca(Function *TheFunction,
 887                                           const std::string &VarName) {
 888   IRBuilder<> TmpB(&TheFunction->getEntryBlock(),
 889                    TheFunction->getEntryBlock().begin());
 890   return TmpB.CreateAlloca(Type::getDoubleTy(TheContext), nullptr,
 891                            VarName.c_str());
 892 }
 893
 894 Value *NumberExprAST::codegen() {
 895   KSDbgInfo.emitLocation(this);
 896   return ConstantFP::get(TheContext, APFloat(Val));
 897 }
 898
 899 Value *VariableExprAST::codegen() {
 900   // Look this variable up in the function.
 901   Value *V = NamedValues[Name];
 902   if (!V)
 903     return LogErrorV("Unknown variable name");
 904
 905   KSDbgInfo.emitLocation(this);
 906   // Load the value.
 907   return Builder.CreateLoad(V, Name.c_str());
 908 }
 909
 910 Value *UnaryExprAST::codegen() {
 911   Value *OperandV = Operand->codegen();
 912   if (!OperandV)
 913     return nullptr;
 914
 915   Function *F = getFunction(std::string("unary") + Opcode);
 916   if (!F)
 917     return LogErrorV("Unknown unary operator");
 918
 919   KSDbgInfo.emitLocation(this);
 920   return Builder.CreateCall(F, OperandV, "unop");
 921 }
 922
 923 Value *BinaryExprAST::codegen() {
 924   KSDbgInfo.emitLocation(this);
 925
 926   // Special case '=' because we don't want to emit the LHS as an expression.
 927   if (Op == '=') {
 928     // Assignment requires the LHS to be an identifier.
 929     // This assume we're building without RTTI because LLVM builds that way by
 930     // default.  If you build LLVM with RTTI this can be changed to a
 931     // dynamic_cast for automatic error checking.
 932     VariableExprAST *LHSE = static_cast<VariableExprAST *>(LHS.get());
 933     if (!LHSE)
 934       return LogErrorV("destination of '=' must be a variable");
 935     // Codegen the RHS.
 936     Value *Val = RHS->codegen();
 937     if (!Val)
 938       return nullptr;
 939
 940     // Look up the name.
 941     Value *Variable = NamedValues[LHSE->getName()];
 942     if (!Variable)
 943       return LogErrorV("Unknown variable name");
 944
 945     Builder.CreateStore(Val, Variable);
 946     return Val;
 947   }
 948
 949   Value *L = LHS->codegen();
 950   Value *R = RHS->codegen();
 951   if (!L || !R)
 952     return nullptr;
 953
 954   switch (Op) {
 955   case '+':
 956     return Builder.CreateFAdd(L, R, "addtmp");
 957   case '-':
 958     return Builder.CreateFSub(L, R, "subtmp");
 959   case '*':
 960     return Builder.CreateFMul(L, R, "multmp");
 961   case '<':
 962     L = Builder.CreateFCmpULT(L, R, "cmptmp");
 963     // Convert bool 0/1 to double 0.0 or 1.0
 964     return Builder.CreateUIToFP(L, Type::getDoubleTy(TheContext), "booltmp");
 965   default:
 966     break;
 967   }
 968
 969   // If it wasn't a builtin binary operator, it must be a user defined one. Emit
 970   // a call to it.
 971   Function *F = getFunction(std::string("binary") + Op);
 972   assert(F && "binary operator not found!");
 973
 974   Value *Ops[] = {L, R};
 975   return Builder.CreateCall(F, Ops, "binop");
 976 }
 977
 978 Value *CallExprAST::codegen() {
 979   KSDbgInfo.emitLocation(this);
 980
 981   // Look up the name in the global module table.
 982   Function *CalleeF = getFunction(Callee);
 983   if (!CalleeF)
 984     return LogErrorV("Unknown function referenced");
 985
 986   // If argument mismatch error.
 987   if (CalleeF->arg_size() != Args.size())
 988     return LogErrorV("Incorrect # arguments passed");
 989
 990   std::vector<Value *> ArgsV;
 991   for (unsigned i = 0, e = Args.size(); i != e; ++i) {
 992     ArgsV.push_back(Args[i]->codegen());
 993     if (!ArgsV.back())
 994       return nullptr;
 995   }
 996
 997   return Builder.CreateCall(CalleeF, ArgsV, "calltmp");
 998 }
 999
1000 Value *IfExprAST::codegen() {
1001   KSDbgInfo.emitLocation(this);
1002
1003   Value *CondV = Cond->codegen();
1004   if (!CondV)
1005     return nullptr;
1006
1007   // Convert condition to a bool by comparing non-equal to 0.0.
1008   CondV = Builder.CreateFCmpONE(
1009       CondV, ConstantFP::get(TheContext, APFloat(0.0)), "ifcond");
1010
1011   Function *TheFunction = Builder.GetInsertBlock()->getParent();
1012
1013   // Create blocks for the then and else cases.  Insert the 'then' block at the
1014   // end of the function.
1015   BasicBlock *ThenBB = BasicBlock::Create(TheContext, "then", TheFunction);
1016   BasicBlock *ElseBB = BasicBlock::Create(TheContext, "else");
1017   BasicBlock *MergeBB = BasicBlock::Create(TheContext, "ifcont");
1018
1019   Builder.CreateCondBr(CondV, ThenBB, ElseBB);
1020
1021   // Emit then value.
1022   Builder.SetInsertPoint(ThenBB);
1023
1024   Value *ThenV = Then->codegen();
1025   if (!ThenV)
1026     return nullptr;
1027
1028   Builder.CreateBr(MergeBB);
1029   // Codegen of 'Then' can change the current block, update ThenBB for the PHI.
1030   ThenBB = Builder.GetInsertBlock();
1031
1032   // Emit else block.
1033   TheFunction->getBasicBlockList().push_back(ElseBB);
1034   Builder.SetInsertPoint(ElseBB);
1035
1036   Value *ElseV = Else->codegen();
1037   if (!ElseV)
1038     return nullptr;
1039
1040   Builder.CreateBr(MergeBB);
1041   // Codegen of 'Else' can change the current block, update ElseBB for the PHI.
1042   ElseBB = Builder.GetInsertBlock();
1043
1044   // Emit merge block.
1045   TheFunction->getBasicBlockList().push_back(MergeBB);
1046   Builder.SetInsertPoint(MergeBB);
1047   PHINode *PN = Builder.CreatePHI(Type::getDoubleTy(TheContext), 2, "iftmp");
1048
1049   PN->addIncoming(ThenV, ThenBB);
1050   PN->addIncoming(ElseV, ElseBB);
1051   return PN;
1052 }
1053
1054 // Output for-loop as:
1055 //   var = alloca double
1056 //   ...
1057 //   start = startexpr
1058 //   store start -> var
1059 //   goto loop
1060 // loop:
1061 //   ...
1062 //   bodyexpr
1063 //   ...
1064 // loopend:
1065 //   step = stepexpr
1066 //   endcond = endexpr
1067 //
1068 //   curvar = load var
1069 //   nextvar = curvar + step
1070 //   store nextvar -> var
1071 //   br endcond, loop, endloop
1072 // outloop:
1073 Value *ForExprAST::codegen() {
1074   Function *TheFunction = Builder.GetInsertBlock()->getParent();
1075
1076   // Create an alloca for the variable in the entry block.
1077   AllocaInst *Alloca = CreateEntryBlockAlloca(TheFunction, VarName);
1078
1079   KSDbgInfo.emitLocation(this);
1080
1081   // Emit the start code first, without 'variable' in scope.
1082   Value *StartVal = Start->codegen();
1083   if (!StartVal)
1084     return nullptr;
1085
1086   // Store the value into the alloca.
1087   Builder.CreateStore(StartVal, Alloca);
1088
1089   // Make the new basic block for the loop header, inserting after current
1090   // block.
1091   BasicBlock *LoopBB = BasicBlock::Create(TheContext, "loop", TheFunction);
1092
1093   // Insert an explicit fall through from the current block to the LoopBB.
1094   Builder.CreateBr(LoopBB);
1095
1096   // Start insertion in LoopBB.
1097   Builder.SetInsertPoint(LoopBB);
1098
1099   // Within the loop, the variable is defined equal to the PHI node.  If it
1100   // shadows an existing variable, we have to restore it, so save it now.
1101   AllocaInst *OldVal = NamedValues[VarName];
1102   NamedValues[VarName] = Alloca;
1103
1104   // Emit the body of the loop.  This, like any other expr, can change the
1105   // current BB.  Note that we ignore the value computed by the body, but don't
1106   // allow an error.
1107   if (!Body->codegen())
1108     return nullptr;
1109
1110   // Emit the step value.
1111   Value *StepVal = nullptr;
1112   if (Step) {
1113     StepVal = Step->codegen();
1114     if (!StepVal)
1115       return nullptr;
1116   } else {
1117     // If not specified, use 1.0.
1118     StepVal = ConstantFP::get(TheContext, APFloat(1.0));
1119   }
1120
1121   // Compute the end condition.
1122   Value *EndCond = End->codegen();
1123   if (!EndCond)
1124     return nullptr;
1125
1126   // Reload, increment, and restore the alloca.  This handles the case where
1127   // the body of the loop mutates the variable.
1128   Value *CurVar = Builder.CreateLoad(Alloca, VarName.c_str());
1129   Value *NextVar = Builder.CreateFAdd(CurVar, StepVal, "nextvar");
1130   Builder.CreateStore(NextVar, Alloca);
1131
1132   // Convert condition to a bool by comparing non-equal to 0.0.
1133   EndCond = Builder.CreateFCmpONE(
1134       EndCond, ConstantFP::get(TheContext, APFloat(0.0)), "loopcond");
1135
1136   // Create the "after loop" block and insert it.
1137   BasicBlock *AfterBB =
1138       BasicBlock::Create(TheContext, "afterloop", TheFunction);
1139
1140   // Insert the conditional branch into the end of LoopEndBB.
1141   Builder.CreateCondBr(EndCond, LoopBB, AfterBB);
1142
1143   // Any new code will be inserted in AfterBB.
1144   Builder.SetInsertPoint(AfterBB);
1145
1146   // Restore the unshadowed variable.
1147   if (OldVal)
1148     NamedValues[VarName] = OldVal;
1149   else
1150     NamedValues.erase(VarName);
1151
1152   // for expr always returns 0.0.
1153   return Constant::getNullValue(Type::getDoubleTy(TheContext));
1154 }
1155
1156 Value *VarExprAST::codegen() {
1157   std::vector<AllocaInst *> OldBindings;
1158
1159   Function *TheFunction = Builder.GetInsertBlock()->getParent();
1160
1161   // Register all variables and emit their initializer.
1162   for (unsigned i = 0, e = VarNames.size(); i != e; ++i) {
1163     const std::string &VarName = VarNames[i].first;
1164     ExprAST *Init = VarNames[i].second.get();
1165
1166     // Emit the initializer before adding the variable to scope, this prevents
1167     // the initializer from referencing the variable itself, and permits stuff
1168     // like this:
1169     //  var a = 1 in
1170     //    var a = a in ...   # refers to outer 'a'.
1171     Value *InitVal;
1172     if (Init) {
1173       InitVal = Init->codegen();
1174       if (!InitVal)
1175         return nullptr;
1176     } else { // If not specified, use 0.0.
1177       InitVal = ConstantFP::get(TheContext, APFloat(0.0));
1178     }
1179
1180     AllocaInst *Alloca = CreateEntryBlockAlloca(TheFunction, VarName);
1181     Builder.CreateStore(InitVal, Alloca);
1182
1183     // Remember the old variable binding so that we can restore the binding when
1184     // we unrecurse.
1185     OldBindings.push_back(NamedValues[VarName]);
1186
1187     // Remember this binding.
1188     NamedValues[VarName] = Alloca;
1189   }
1190
1191   KSDbgInfo.emitLocation(this);
1192
1193   // Codegen the body, now that all vars are in scope.
1194   Value *BodyVal = Body->codegen();
1195   if (!BodyVal)
1196     return nullptr;
1197
1198   // Pop all our variables from scope.
1199   for (unsigned i = 0, e = VarNames.size(); i != e; ++i)
1200     NamedValues[VarNames[i].first] = OldBindings[i];
1201
1202   // Return the body computation.
1203   return BodyVal;
1204 }
1205
1206 Function *PrototypeAST::codegen() {
1207   // Make the function type:  double(double,double) etc.
1208   std::vector<Type *> Doubles(Args.size(), Type::getDoubleTy(TheContext));
1209   FunctionType *FT =
1210       FunctionType::get(Type::getDoubleTy(TheContext), Doubles, false);
1211
1212   Function *F =
1213       Function::Create(FT, Function::ExternalLinkage, Name, TheModule.get());
1214
1215   // Set names for all arguments.
1216   unsigned Idx = 0;
1217   for (auto &Arg : F->args())
1218     Arg.setName(Args[Idx++]);
1219
1220   return F;
1221 }
1222
1223 Function *FunctionAST::codegen() {
1224   // Transfer ownership of the prototype to the FunctionProtos map, but keep a
1225   // reference to it for use below.
1226   auto &P = *Proto;
1227   FunctionProtos[Proto->getName()] = std::move(Proto);
1228   Function *TheFunction = getFunction(P.getName());
1229   if (!TheFunction)
1230     return nullptr;
1231
1232   // If this is an operator, install it.
1233   if (P.isBinaryOp())
1234     BinopPrecedence[P.getOperatorName()] = P.getBinaryPrecedence();
1235
1236   // Create a new basic block to start insertion into.
1237   BasicBlock *BB = BasicBlock::Create(TheContext, "entry", TheFunction);
1238   Builder.SetInsertPoint(BB);
1239
1240   // Create a subprogram DIE for this function.
1241   DIFile *Unit = DBuilder->createFile(KSDbgInfo.TheCU->getFilename(),
1242                                       KSDbgInfo.TheCU->getDirectory());
1243   DIScope *FContext = Unit;
1244   unsigned LineNo = P.getLine();
1245   unsigned ScopeLine = LineNo;
1246   DISubprogram *SP = DBuilder->createFunction(
1247       FContext, P.getName(), StringRef(), Unit, LineNo,
1248       CreateFunctionType(TheFunction->arg_size(), Unit),
1249       false /* internal linkage */, true /* definition */, ScopeLine,
1250       DINode::FlagPrototyped, false);
1251   TheFunction->setSubprogram(SP);
1252
1253   // Push the current scope.
1254   KSDbgInfo.LexicalBlocks.push_back(SP);
1255
1256   // Unset the location for the prologue emission (leading instructions with no
1257   // location in a function are considered part of the prologue and the debugger
1258   // will run past them when breaking on a function)
1259   KSDbgInfo.emitLocation(nullptr);
1260
1261   // Record the function arguments in the NamedValues map.
1262   NamedValues.clear();
1263   unsigned ArgIdx = 0;
1264   for (auto &Arg : TheFunction->args()) {
1265     // Create an alloca for this variable.
1266     AllocaInst *Alloca = CreateEntryBlockAlloca(TheFunction, Arg.getName());
1267
1268     // Create a debug descriptor for the variable.
1269     DILocalVariable *D = DBuilder->createParameterVariable(
1270         SP, Arg.getName(), ++ArgIdx, Unit, LineNo, KSDbgInfo.getDoubleTy(),
1271         true);
1272
1273     DBuilder->insertDeclare(Alloca, D, DBuilder->createExpression(),
1274                             DebugLoc::get(LineNo, 0, SP),
1275                             Builder.GetInsertBlock());
1276
1277     // Store the initial value into the alloca.
1278     Builder.CreateStore(&Arg, Alloca);
1279
1280     // Add arguments to variable symbol table.
1281     NamedValues[Arg.getName()] = Alloca;
1282   }
1283
1284   KSDbgInfo.emitLocation(Body.get());
1285
1286   if (Value *RetVal = Body->codegen()) {
1287     // Finish off the function.
1288     Builder.CreateRet(RetVal);
1289
1290     // Pop off the lexical block for the function.
1291     KSDbgInfo.LexicalBlocks.pop_back();
1292
1293     // Validate the generated code, checking for consistency.
1294     verifyFunction(*TheFunction);
1295
1296     return TheFunction;
1297   }
1298
1299   // Error reading body, remove function.
1300   TheFunction->eraseFromParent();
1301
1302   if (P.isBinaryOp())
1303     BinopPrecedence.erase(Proto->getOperatorName());
1304
1305   // Pop off the lexical block for the function since we added it
1306   // unconditionally.
1307   KSDbgInfo.LexicalBlocks.pop_back();
1308
1309   return nullptr;
1310 }
1311
1312 //===----------------------------------------------------------------------===//
1313 // Top-Level parsing and JIT Driver
1314 //===----------------------------------------------------------------------===//
1315
1316 static void InitializeModule() {
1317   // Open a new module.
1318   TheModule = llvm::make_unique<Module>("my cool jit", TheContext);
1319   TheModule->setDataLayout(TheJIT->getTargetMachine().createDataLayout());
1320 }
1321
1322 static void HandleDefinition() {
1323   if (auto FnAST = ParseDefinition()) {
1324     if (!FnAST->codegen())
1325       fprintf(stderr, "Error reading function definition:");
1326   } else {
1327     // Skip token for error recovery.
1328     getNextToken();
1329   }
1330 }
1331
1332 static void HandleExtern() {
1333   if (auto ProtoAST = ParseExtern()) {
1334     if (!ProtoAST->codegen())
1335       fprintf(stderr, "Error reading extern");
1336     else
1337       FunctionProtos[ProtoAST->getName()] = std::move(ProtoAST);
1338   } else {
1339     // Skip token for error recovery.
1340     getNextToken();
1341   }
1342 }
1343
1344 static void HandleTopLevelExpression() {
1345   // Evaluate a top-level expression into an anonymous function.
1346   if (auto FnAST = ParseTopLevelExpr()) {
1347     if (!FnAST->codegen()) {
1348       fprintf(stderr, "Error generating code for top level expr");
1349     }
1350   } else {
1351     // Skip token for error recovery.
1352     getNextToken();
1353   }
1354 }
1355
1356 /// top ::= definition | external | expression | ';'
1357 static void MainLoop() {
1358   while (1) {
1359     switch (CurTok) {
1360     case tok_eof:
1361       return;
1362     case ';': // ignore top-level semicolons.
1363       getNextToken();
1364       break;
1365     case tok_def:
1366       HandleDefinition();
1367       break;
1368     case tok_extern:
1369       HandleExtern();
1370       break;
1371     default:
1372       HandleTopLevelExpression();
1373       break;
1374     }
1375   }
1376 }
1377
1378 //===----------------------------------------------------------------------===//
1379 // "Library" functions that can be "extern'd" from user code.
1380 //===----------------------------------------------------------------------===//
1381
1382 #ifdef _WIN32
1383 #define DLLEXPORT __declspec(dllexport)
1384 #else
1385 #define DLLEXPORT
1386 #endif
1387
1388 /// putchard - putchar that takes a double and returns 0.
1389 extern "C" DLLEXPORT double putchard(double X) {
1390   fputc((char)X, stderr);
1391   return 0;
1392 }
1393
1394 /// printd - printf that takes a double prints it as "%f\n", returning 0.
1395 extern "C" DLLEXPORT double printd(double X) {
1396   fprintf(stderr, "%f\n", X);
1397   return 0;
1398 }
1399
1400 //===----------------------------------------------------------------------===//
1401 // Main driver code.
1402 //===----------------------------------------------------------------------===//
1403
1404 int main() {
1405   InitializeNativeTarget();
1406   InitializeNativeTargetAsmPrinter();
1407   InitializeNativeTargetAsmParser();
1408
1409   // Install standard binary operators.
1410   // 1 is lowest precedence.
1411   BinopPrecedence['='] = 2;
1412   BinopPrecedence['<'] = 10;
1413   BinopPrecedence['+'] = 20;
1414   BinopPrecedence['-'] = 20;
1415   BinopPrecedence['*'] = 40; // highest.
1416
1417   // Prime the first token.
1418   getNextToken();
1419
1420   TheJIT = llvm::make_unique<KaleidoscopeJIT>();
1421
1422   InitializeModule();
1423
1424   // Add the current debug info version into the module.
1425   TheModule->addModuleFlag(Module::Warning, "Debug Info Version",
1426                            DEBUG_METADATA_VERSION);
1427
1428   // Darwin only supports dwarf2.
1429   if (Triple(sys::getProcessTriple()).isOSDarwin())
1430     TheModule->addModuleFlag(llvm::Module::Warning, "Dwarf Version", 2);
1431
1432   // Construct the DIBuilder, we do this here because we need the module.
1433   DBuilder = llvm::make_unique<DIBuilder>(*TheModule);
1434
1435   // Create the compile unit for the module.
1436   // Currently down as "fib.ks" as a filename since we're redirecting stdin
1437   // but we'd like actual source locations.
1438   KSDbgInfo.TheCU = DBuilder->createCompileUnit(
1439       dwarf::DW_LANG_C, DBuilder->createFile("fib.ks", "."),
1440       "Kaleidoscope Compiler", 0, "", 0);
1441
1442   // Run the main "interpreter loop" now.
1443   MainLoop();
1444
1445   // Finalize the debug info.
1446   DBuilder->finalize();
1447
1448   // Print out all of the generated code.
1449   TheModule->print(errs(), nullptr);
1450
1451   return 0;
1452 }