llvm/examples/Kaleidoscope/Chapter8/toy.cpp

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