src/llvm/examples/Kaleidoscope/Chapter6/toy.cpp

   1 #include "llvm/Analysis/Passes.h"
   2 #include "llvm/ExecutionEngine/ExecutionEngine.h"
   3 #include "llvm/ExecutionEngine/MCJIT.h"
   4 #include "llvm/ExecutionEngine/SectionMemoryManager.h"
   5 #include "llvm/IR/DataLayout.h"
   6 #include "llvm/IR/DerivedTypes.h"
   7 #include "llvm/IR/IRBuilder.h"
   8 #include "llvm/IR/LLVMContext.h"
   9 #include "llvm/IR/Module.h"
  10 #include "llvm/IR/Verifier.h"
  11 #include "llvm/PassManager.h"
  12 #include "llvm/Support/TargetSelect.h"
  13 #include "llvm/Transforms/Scalar.h"
  14 #include <cctype>
  15 #include <cstdio>
  16 #include <map>
  17 #include <string>
  18 #include <vector>
  19 using namespace llvm;
  20
  21 //===----------------------------------------------------------------------===//
  22 // Lexer
  23 //===----------------------------------------------------------------------===//
  24
  25 // The lexer returns tokens [0-255] if it is an unknown character, otherwise one
  26 // of these for known things.
  27 enum Token {
  28   tok_eof = -1,
  29
  30   // commands
  31   tok_def = -2,
  32   tok_extern = -3,
  33
  34   // primary
  35   tok_identifier = -4,
  36   tok_number = -5,
  37
  38   // control
  39   tok_if = -6,
  40   tok_then = -7,
  41   tok_else = -8,
  42   tok_for = -9,
  43   tok_in = -10,
  44
  45   // operators
  46   tok_binary = -11,
  47   tok_unary = -12
  48 };
  49
  50 static std::string IdentifierStr; // Filled in if tok_identifier
  51 static double NumVal;             // Filled in if tok_number
  52
  53 /// gettok - Return the next token from standard input.
  54 static int gettok() {
  55   static int LastChar = ' ';
  56
  57   // Skip any whitespace.
  58   while (isspace(LastChar))
  59     LastChar = getchar();
  60
  61   if (isalpha(LastChar)) { // identifier: [a-zA-Z][a-zA-Z0-9]*
  62     IdentifierStr = LastChar;
  63     while (isalnum((LastChar = getchar())))
  64       IdentifierStr += LastChar;
  65
  66     if (IdentifierStr == "def")
  67       return tok_def;
  68     if (IdentifierStr == "extern")
  69       return tok_extern;
  70     if (IdentifierStr == "if")
  71       return tok_if;
  72     if (IdentifierStr == "then")
  73       return tok_then;
  74     if (IdentifierStr == "else")
  75       return tok_else;
  76     if (IdentifierStr == "for")
  77       return tok_for;
  78     if (IdentifierStr == "in")
  79       return tok_in;
  80     if (IdentifierStr == "binary")
  81       return tok_binary;
  82     if (IdentifierStr == "unary")
  83       return tok_unary;
  84     return tok_identifier;
  85   }
  86
  87   if (isdigit(LastChar) || LastChar == '.') { // Number: [0-9.]+
  88     std::string NumStr;
  89     do {
  90       NumStr += LastChar;
  91       LastChar = getchar();
  92     } while (isdigit(LastChar) || LastChar == '.');
  93
  94     NumVal = strtod(NumStr.c_str(), 0);
  95     return tok_number;
  96   }
  97
  98   if (LastChar == '#') {
  99     // Comment until end of line.
 100     do
 101       LastChar = getchar();
 102     while (LastChar != EOF && LastChar != '\n' && LastChar != '\r');
 103
 104     if (LastChar != EOF)
 105       return gettok();
 106   }
 107
 108   // Check for end of file.  Don't eat the EOF.
 109   if (LastChar == EOF)
 110     return tok_eof;
 111
 112   // Otherwise, just return the character as its ascii value.
 113   int ThisChar = LastChar;
 114   LastChar = getchar();
 115   return ThisChar;
 116 }
 117
 118 //===----------------------------------------------------------------------===//
 119 // Abstract Syntax Tree (aka Parse Tree)
 120 //===----------------------------------------------------------------------===//
 121 namespace {
 122 /// ExprAST - Base class for all expression nodes.
 123 class ExprAST {
 124 public:
 125   virtual ~ExprAST() {}
 126   virtual Value *Codegen() = 0;
 127 };
 128
 129 /// NumberExprAST - Expression class for numeric literals like "1.0".
 130 class NumberExprAST : public ExprAST {
 131   double Val;
 132
 133 public:
 134   NumberExprAST(double val) : Val(val) {}
 135   virtual Value *Codegen();
 136 };
 137
 138 /// VariableExprAST - Expression class for referencing a variable, like "a".
 139 class VariableExprAST : public ExprAST {
 140   std::string Name;
 141
 142 public:
 143   VariableExprAST(const std::string &name) : Name(name) {}
 144   virtual Value *Codegen();
 145 };
 146
 147 /// UnaryExprAST - Expression class for a unary operator.
 148 class UnaryExprAST : public ExprAST {
 149   char Opcode;
 150   ExprAST *Operand;
 151
 152 public:
 153   UnaryExprAST(char opcode, ExprAST *operand)
 154       : Opcode(opcode), Operand(operand) {}
 155   virtual Value *Codegen();
 156 };
 157
 158 /// BinaryExprAST - Expression class for a binary operator.
 159 class BinaryExprAST : public ExprAST {
 160   char Op;
 161   ExprAST *LHS, *RHS;
 162
 163 public:
 164   BinaryExprAST(char op, ExprAST *lhs, ExprAST *rhs)
 165       : Op(op), LHS(lhs), RHS(rhs) {}
 166   virtual Value *Codegen();
 167 };
 168
 169 /// CallExprAST - Expression class for function calls.
 170 class CallExprAST : public ExprAST {
 171   std::string Callee;
 172   std::vector<ExprAST *> Args;
 173
 174 public:
 175   CallExprAST(const std::string &callee, std::vector<ExprAST *> &args)
 176       : Callee(callee), Args(args) {}
 177   virtual Value *Codegen();
 178 };
 179
 180 /// IfExprAST - Expression class for if/then/else.
 181 class IfExprAST : public ExprAST {
 182   ExprAST *Cond, *Then, *Else;
 183
 184 public:
 185   IfExprAST(ExprAST *cond, ExprAST *then, ExprAST *_else)
 186       : Cond(cond), Then(then), Else(_else) {}
 187   virtual Value *Codegen();
 188 };
 189
 190 /// ForExprAST - Expression class for for/in.
 191 class ForExprAST : public ExprAST {
 192   std::string VarName;
 193   ExprAST *Start, *End, *Step, *Body;
 194
 195 public:
 196   ForExprAST(const std::string &varname, ExprAST *start, ExprAST *end,
 197              ExprAST *step, ExprAST *body)
 198       : VarName(varname), Start(start), End(end), Step(step), Body(body) {}
 199   virtual Value *Codegen();
 200 };
 201
 202 /// PrototypeAST - This class represents the "prototype" for a function,
 203 /// which captures its name, and its argument names (thus implicitly the number
 204 /// of arguments the function takes), as well as if it is an operator.
 205 class PrototypeAST {
 206   std::string Name;
 207   std::vector<std::string> Args;
 208   bool isOperator;
 209   unsigned Precedence; // Precedence if a binary op.
 210 public:
 211   PrototypeAST(const std::string &name, const std::vector<std::string> &args,
 212                bool isoperator = false, unsigned prec = 0)
 213       : Name(name), Args(args), isOperator(isoperator), Precedence(prec) {}
 214
 215   bool isUnaryOp() const { return isOperator && Args.size() == 1; }
 216   bool isBinaryOp() const { return isOperator && Args.size() == 2; }
 217
 218   char getOperatorName() const {
 219     assert(isUnaryOp() || isBinaryOp());
 220     return Name[Name.size() - 1];
 221   }
 222
 223   unsigned getBinaryPrecedence() const { return Precedence; }
 224
 225   Function *Codegen();
 226 };
 227
 228 /// FunctionAST - This class represents a function definition itself.
 229 class FunctionAST {
 230   PrototypeAST *Proto;
 231   ExprAST *Body;
 232
 233 public:
 234   FunctionAST(PrototypeAST *proto, ExprAST *body) : Proto(proto), Body(body) {}
 235
 236   Function *Codegen();
 237 };
 238 } // end anonymous namespace
 239
 240 //===----------------------------------------------------------------------===//
 241 // Parser
 242 //===----------------------------------------------------------------------===//
 243
 244 /// CurTok/getNextToken - Provide a simple token buffer.  CurTok is the current
 245 /// token the parser is looking at.  getNextToken reads another token from the
 246 /// lexer and updates CurTok with its results.
 247 static int CurTok;
 248 static int getNextToken() { return CurTok = gettok(); }
 249
 250 /// BinopPrecedence - This holds the precedence for each binary operator that is
 251 /// defined.
 252 static std::map<char, int> BinopPrecedence;
 253
 254 /// GetTokPrecedence - Get the precedence of the pending binary operator token.
 255 static int GetTokPrecedence() {
 256   if (!isascii(CurTok))
 257     return -1;
 258
 259   // Make sure it's a declared binop.
 260   int TokPrec = BinopPrecedence[CurTok];
 261   if (TokPrec <= 0)
 262     return -1;
 263   return TokPrec;
 264 }
 265
 266 /// Error* - These are little helper functions for error handling.
 267 ExprAST *Error(const char *Str) {
 268   fprintf(stderr, "Error: %s\n", Str);
 269   return 0;
 270 }
 271 PrototypeAST *ErrorP(const char *Str) {
 272   Error(Str);
 273   return 0;
 274 }
 275 FunctionAST *ErrorF(const char *Str) {
 276   Error(Str);
 277   return 0;
 278 }
 279
 280 static ExprAST *ParseExpression();
 281
 282 /// identifierexpr
 283 ///   ::= identifier
 284 ///   ::= identifier '(' expression* ')'
 285 static ExprAST *ParseIdentifierExpr() {
 286   std::string IdName = IdentifierStr;
 287
 288   getNextToken(); // eat identifier.
 289
 290   if (CurTok != '(') // Simple variable ref.
 291     return new VariableExprAST(IdName);
 292
 293   // Call.
 294   getNextToken(); // eat (
 295   std::vector<ExprAST *> Args;
 296   if (CurTok != ')') {
 297     while (1) {
 298       ExprAST *Arg = ParseExpression();
 299       if (!Arg)
 300         return 0;
 301       Args.push_back(Arg);
 302
 303       if (CurTok == ')')
 304         break;
 305
 306       if (CurTok != ',')
 307         return Error("Expected ')' or ',' in argument list");
 308       getNextToken();
 309     }
 310   }
 311
 312   // Eat the ')'.
 313   getNextToken();
 314
 315   return new CallExprAST(IdName, Args);
 316 }
 317
 318 /// numberexpr ::= number
 319 static ExprAST *ParseNumberExpr() {
 320   ExprAST *Result = new NumberExprAST(NumVal);
 321   getNextToken(); // consume the number
 322   return Result;
 323 }
 324
 325 /// parenexpr ::= '(' expression ')'
 326 static ExprAST *ParseParenExpr() {
 327   getNextToken(); // eat (.
 328   ExprAST *V = ParseExpression();
 329   if (!V)
 330     return 0;
 331
 332   if (CurTok != ')')
 333     return Error("expected ')'");
 334   getNextToken(); // eat ).
 335   return V;
 336 }
 337
 338 /// ifexpr ::= 'if' expression 'then' expression 'else' expression
 339 static ExprAST *ParseIfExpr() {
 340   getNextToken(); // eat the if.
 341
 342   // condition.
 343   ExprAST *Cond = ParseExpression();
 344   if (!Cond)
 345     return 0;
 346
 347   if (CurTok != tok_then)
 348     return Error("expected then");
 349   getNextToken(); // eat the then
 350
 351   ExprAST *Then = ParseExpression();
 352   if (Then == 0)
 353     return 0;
 354
 355   if (CurTok != tok_else)
 356     return Error("expected else");
 357
 358   getNextToken();
 359
 360   ExprAST *Else = ParseExpression();
 361   if (!Else)
 362     return 0;
 363
 364   return new IfExprAST(Cond, Then, Else);
 365 }
 366
 367 /// forexpr ::= 'for' identifier '=' expr ',' expr (',' expr)? 'in' expression
 368 static ExprAST *ParseForExpr() {
 369   getNextToken(); // eat the for.
 370
 371   if (CurTok != tok_identifier)
 372     return Error("expected identifier after for");
 373
 374   std::string IdName = IdentifierStr;
 375   getNextToken(); // eat identifier.
 376
 377   if (CurTok != '=')
 378     return Error("expected '=' after for");
 379   getNextToken(); // eat '='.
 380
 381   ExprAST *Start = ParseExpression();
 382   if (Start == 0)
 383     return 0;
 384   if (CurTok != ',')
 385     return Error("expected ',' after for start value");
 386   getNextToken();
 387
 388   ExprAST *End = ParseExpression();
 389   if (End == 0)
 390     return 0;
 391
 392   // The step value is optional.
 393   ExprAST *Step = 0;
 394   if (CurTok == ',') {
 395     getNextToken();
 396     Step = ParseExpression();
 397     if (Step == 0)
 398       return 0;
 399   }
 400
 401   if (CurTok != tok_in)
 402     return Error("expected 'in' after for");
 403   getNextToken(); // eat 'in'.
 404
 405   ExprAST *Body = ParseExpression();
 406   if (Body == 0)
 407     return 0;
 408
 409   return new ForExprAST(IdName, Start, End, Step, Body);
 410 }
 411
 412 /// primary
 413 ///   ::= identifierexpr
 414 ///   ::= numberexpr
 415 ///   ::= parenexpr
 416 ///   ::= ifexpr
 417 ///   ::= forexpr
 418 static ExprAST *ParsePrimary() {
 419   switch (CurTok) {
 420   default:
 421     return Error("unknown token when expecting an expression");
 422   case tok_identifier:
 423     return ParseIdentifierExpr();
 424   case tok_number:
 425     return ParseNumberExpr();
 426   case '(':
 427     return ParseParenExpr();
 428   case tok_if:
 429     return ParseIfExpr();
 430   case tok_for:
 431     return ParseForExpr();
 432   }
 433 }
 434
 435 /// unary
 436 ///   ::= primary
 437 ///   ::= '!' unary
 438 static ExprAST *ParseUnary() {
 439   // If the current token is not an operator, it must be a primary expr.
 440   if (!isascii(CurTok) || CurTok == '(' || CurTok == ',')
 441     return ParsePrimary();
 442
 443   // If this is a unary operator, read it.
 444   int Opc = CurTok;
 445   getNextToken();
 446   if (ExprAST *Operand = ParseUnary())
 447     return new UnaryExprAST(Opc, Operand);
 448   return 0;
 449 }
 450
 451 /// binoprhs
 452 ///   ::= ('+' unary)*
 453 static ExprAST *ParseBinOpRHS(int ExprPrec, ExprAST *LHS) {
 454   // If this is a binop, find its precedence.
 455   while (1) {
 456     int TokPrec = GetTokPrecedence();
 457
 458     // If this is a binop that binds at least as tightly as the current binop,
 459     // consume it, otherwise we are done.
 460     if (TokPrec < ExprPrec)
 461       return LHS;
 462
 463     // Okay, we know this is a binop.
 464     int BinOp = CurTok;
 465     getNextToken(); // eat binop
 466
 467     // Parse the unary expression after the binary operator.
 468     ExprAST *RHS = ParseUnary();
 469     if (!RHS)
 470       return 0;
 471
 472     // If BinOp binds less tightly with RHS than the operator after RHS, let
 473     // the pending operator take RHS as its LHS.
 474     int NextPrec = GetTokPrecedence();
 475     if (TokPrec < NextPrec) {
 476       RHS = ParseBinOpRHS(TokPrec + 1, RHS);
 477       if (RHS == 0)
 478         return 0;
 479     }
 480
 481     // Merge LHS/RHS.
 482     LHS = new BinaryExprAST(BinOp, LHS, RHS);
 483   }
 484 }
 485
 486 /// expression
 487 ///   ::= unary binoprhs
 488 ///
 489 static ExprAST *ParseExpression() {
 490   ExprAST *LHS = ParseUnary();
 491   if (!LHS)
 492     return 0;
 493
 494   return ParseBinOpRHS(0, LHS);
 495 }
 496
 497 /// prototype
 498 ///   ::= id '(' id* ')'
 499 ///   ::= binary LETTER number? (id, id)
 500 ///   ::= unary LETTER (id)
 501 static PrototypeAST *ParsePrototype() {
 502   std::string FnName;
 503
 504   unsigned Kind = 0; // 0 = identifier, 1 = unary, 2 = binary.
 505   unsigned BinaryPrecedence = 30;
 506
 507   switch (CurTok) {
 508   default:
 509     return ErrorP("Expected function name in prototype");
 510   case tok_identifier:
 511     FnName = IdentifierStr;
 512     Kind = 0;
 513     getNextToken();
 514     break;
 515   case tok_unary:
 516     getNextToken();
 517     if (!isascii(CurTok))
 518       return ErrorP("Expected unary operator");
 519     FnName = "unary";
 520     FnName += (char)CurTok;
 521     Kind = 1;
 522     getNextToken();
 523     break;
 524   case tok_binary:
 525     getNextToken();
 526     if (!isascii(CurTok))
 527       return ErrorP("Expected binary operator");
 528     FnName = "binary";
 529     FnName += (char)CurTok;
 530     Kind = 2;
 531     getNextToken();
 532
 533     // Read the precedence if present.
 534     if (CurTok == tok_number) {
 535       if (NumVal < 1 || NumVal > 100)
 536         return ErrorP("Invalid precedecnce: must be 1..100");
 537       BinaryPrecedence = (unsigned)NumVal;
 538       getNextToken();
 539     }
 540     break;
 541   }
 542
 543   if (CurTok != '(')
 544     return ErrorP("Expected '(' in prototype");
 545
 546   std::vector<std::string> ArgNames;
 547   while (getNextToken() == tok_identifier)
 548     ArgNames.push_back(IdentifierStr);
 549   if (CurTok != ')')
 550     return ErrorP("Expected ')' in prototype");
 551
 552   // success.
 553   getNextToken(); // eat ')'.
 554
 555   // Verify right number of names for operator.
 556   if (Kind && ArgNames.size() != Kind)
 557     return ErrorP("Invalid number of operands for operator");
 558
 559   return new PrototypeAST(FnName, ArgNames, Kind != 0, BinaryPrecedence);
 560 }
 561
 562 /// definition ::= 'def' prototype expression
 563 static FunctionAST *ParseDefinition() {
 564   getNextToken(); // eat def.
 565   PrototypeAST *Proto = ParsePrototype();
 566   if (Proto == 0)
 567     return 0;
 568
 569   if (ExprAST *E = ParseExpression())
 570     return new FunctionAST(Proto, E);
 571   return 0;
 572 }
 573
 574 /// toplevelexpr ::= expression
 575 static FunctionAST *ParseTopLevelExpr() {
 576   if (ExprAST *E = ParseExpression()) {
 577     // Make an anonymous proto.
 578     PrototypeAST *Proto = new PrototypeAST("", std::vector<std::string>());
 579     return new FunctionAST(Proto, E);
 580   }
 581   return 0;
 582 }
 583
 584 /// external ::= 'extern' prototype
 585 static PrototypeAST *ParseExtern() {
 586   getNextToken(); // eat extern.
 587   return ParsePrototype();
 588 }
 589
 590 //===----------------------------------------------------------------------===//
 591 // Code Generation
 592 //===----------------------------------------------------------------------===//
 593
 594 static Module *TheModule;
 595 static IRBuilder<> Builder(getGlobalContext());
 596 static std::map<std::string, Value *> NamedValues;
 597 static FunctionPassManager *TheFPM;
 598
 599 Value *ErrorV(const char *Str) {
 600   Error(Str);
 601   return 0;
 602 }
 603
 604 Value *NumberExprAST::Codegen() {
 605   return ConstantFP::get(getGlobalContext(), APFloat(Val));
 606 }
 607
 608 Value *VariableExprAST::Codegen() {
 609   // Look this variable up in the function.
 610   Value *V = NamedValues[Name];
 611   return V ? V : ErrorV("Unknown variable name");
 612 }
 613
 614 Value *UnaryExprAST::Codegen() {
 615   Value *OperandV = Operand->Codegen();
 616   if (OperandV == 0)
 617     return 0;
 618
 619   Function *F = TheModule->getFunction(std::string("unary") + Opcode);
 620   if (F == 0)
 621     return ErrorV("Unknown unary operator");
 622
 623   return Builder.CreateCall(F, OperandV, "unop");
 624 }
 625
 626 Value *BinaryExprAST::Codegen() {
 627   Value *L = LHS->Codegen();
 628   Value *R = RHS->Codegen();
 629   if (L == 0 || R == 0)
 630     return 0;
 631
 632   switch (Op) {
 633   case '+':
 634     return Builder.CreateFAdd(L, R, "addtmp");
 635   case '-':
 636     return Builder.CreateFSub(L, R, "subtmp");
 637   case '*':
 638     return Builder.CreateFMul(L, R, "multmp");
 639   case '<':
 640     L = Builder.CreateFCmpULT(L, R, "cmptmp");
 641     // Convert bool 0/1 to double 0.0 or 1.0
 642     return Builder.CreateUIToFP(L, Type::getDoubleTy(getGlobalContext()),
 643                                 "booltmp");
 644   default:
 645     break;
 646   }
 647
 648   // If it wasn't a builtin binary operator, it must be a user defined one. Emit
 649   // a call to it.
 650   Function *F = TheModule->getFunction(std::string("binary") + Op);
 651   assert(F && "binary operator not found!");
 652
 653   Value *Ops[] = { L, R };
 654   return Builder.CreateCall(F, Ops, "binop");
 655 }
 656
 657 Value *CallExprAST::Codegen() {
 658   // Look up the name in the global module table.
 659   Function *CalleeF = TheModule->getFunction(Callee);
 660   if (CalleeF == 0)
 661     return ErrorV("Unknown function referenced");
 662
 663   // If argument mismatch error.
 664   if (CalleeF->arg_size() != Args.size())
 665     return ErrorV("Incorrect # arguments passed");
 666
 667   std::vector<Value *> ArgsV;
 668   for (unsigned i = 0, e = Args.size(); i != e; ++i) {
 669     ArgsV.push_back(Args[i]->Codegen());
 670     if (ArgsV.back() == 0)
 671       return 0;
 672   }
 673
 674   return Builder.CreateCall(CalleeF, ArgsV, "calltmp");
 675 }
 676
 677 Value *IfExprAST::Codegen() {
 678   Value *CondV = Cond->Codegen();
 679   if (CondV == 0)
 680     return 0;
 681
 682   // Convert condition to a bool by comparing equal to 0.0.
 683   CondV = Builder.CreateFCmpONE(
 684       CondV, ConstantFP::get(getGlobalContext(), APFloat(0.0)), "ifcond");
 685
 686   Function *TheFunction = Builder.GetInsertBlock()->getParent();
 687
 688   // Create blocks for the then and else cases.  Insert the 'then' block at the
 689   // end of the function.
 690   BasicBlock *ThenBB =
 691       BasicBlock::Create(getGlobalContext(), "then", TheFunction);
 692   BasicBlock *ElseBB = BasicBlock::Create(getGlobalContext(), "else");
 693   BasicBlock *MergeBB = BasicBlock::Create(getGlobalContext(), "ifcont");
 694
 695   Builder.CreateCondBr(CondV, ThenBB, ElseBB);
 696
 697   // Emit then value.
 698   Builder.SetInsertPoint(ThenBB);
 699
 700   Value *ThenV = Then->Codegen();
 701   if (ThenV == 0)
 702     return 0;
 703
 704   Builder.CreateBr(MergeBB);
 705   // Codegen of 'Then' can change the current block, update ThenBB for the PHI.
 706   ThenBB = Builder.GetInsertBlock();
 707
 708   // Emit else block.
 709   TheFunction->getBasicBlockList().push_back(ElseBB);
 710   Builder.SetInsertPoint(ElseBB);
 711
 712   Value *ElseV = Else->Codegen();
 713   if (ElseV == 0)
 714     return 0;
 715
 716   Builder.CreateBr(MergeBB);
 717   // Codegen of 'Else' can change the current block, update ElseBB for the PHI.
 718   ElseBB = Builder.GetInsertBlock();
 719
 720   // Emit merge block.
 721   TheFunction->getBasicBlockList().push_back(MergeBB);
 722   Builder.SetInsertPoint(MergeBB);
 723   PHINode *PN =
 724       Builder.CreatePHI(Type::getDoubleTy(getGlobalContext()), 2, "iftmp");
 725
 726   PN->addIncoming(ThenV, ThenBB);
 727   PN->addIncoming(ElseV, ElseBB);
 728   return PN;
 729 }
 730
 731 Value *ForExprAST::Codegen() {
 732   // Output this as:
 733   //   ...
 734   //   start = startexpr
 735   //   goto loop
 736   // loop:
 737   //   variable = phi [start, loopheader], [nextvariable, loopend]
 738   //   ...
 739   //   bodyexpr
 740   //   ...
 741   // loopend:
 742   //   step = stepexpr
 743   //   nextvariable = variable + step
 744   //   endcond = endexpr
 745   //   br endcond, loop, endloop
 746   // outloop:
 747
 748   // Emit the start code first, without 'variable' in scope.
 749   Value *StartVal = Start->Codegen();
 750   if (StartVal == 0)
 751     return 0;
 752
 753   // Make the new basic block for the loop header, inserting after current
 754   // block.
 755   Function *TheFunction = Builder.GetInsertBlock()->getParent();
 756   BasicBlock *PreheaderBB = Builder.GetInsertBlock();
 757   BasicBlock *LoopBB =
 758       BasicBlock::Create(getGlobalContext(), "loop", TheFunction);
 759
 760   // Insert an explicit fall through from the current block to the LoopBB.
 761   Builder.CreateBr(LoopBB);
 762
 763   // Start insertion in LoopBB.
 764   Builder.SetInsertPoint(LoopBB);
 765
 766   // Start the PHI node with an entry for Start.
 767   PHINode *Variable = Builder.CreatePHI(Type::getDoubleTy(getGlobalContext()),
 768                                         2, VarName.c_str());
 769   Variable->addIncoming(StartVal, PreheaderBB);
 770
 771   // Within the loop, the variable is defined equal to the PHI node.  If it
 772   // shadows an existing variable, we have to restore it, so save it now.
 773   Value *OldVal = NamedValues[VarName];
 774   NamedValues[VarName] = Variable;
 775
 776   // Emit the body of the loop.  This, like any other expr, can change the
 777   // current BB.  Note that we ignore the value computed by the body, but don't
 778   // allow an error.
 779   if (Body->Codegen() == 0)
 780     return 0;
 781
 782   // Emit the step value.
 783   Value *StepVal;
 784   if (Step) {
 785     StepVal = Step->Codegen();
 786     if (StepVal == 0)
 787       return 0;
 788   } else {
 789     // If not specified, use 1.0.
 790     StepVal = ConstantFP::get(getGlobalContext(), APFloat(1.0));
 791   }
 792
 793   Value *NextVar = Builder.CreateFAdd(Variable, StepVal, "nextvar");
 794
 795   // Compute the end condition.
 796   Value *EndCond = End->Codegen();
 797   if (EndCond == 0)
 798     return EndCond;
 799
 800   // Convert condition to a bool by comparing equal to 0.0.
 801   EndCond = Builder.CreateFCmpONE(
 802       EndCond, ConstantFP::get(getGlobalContext(), APFloat(0.0)), "loopcond");
 803
 804   // Create the "after loop" block and insert it.
 805   BasicBlock *LoopEndBB = Builder.GetInsertBlock();
 806   BasicBlock *AfterBB =
 807       BasicBlock::Create(getGlobalContext(), "afterloop", TheFunction);
 808
 809   // Insert the conditional branch into the end of LoopEndBB.
 810   Builder.CreateCondBr(EndCond, LoopBB, AfterBB);
 811
 812   // Any new code will be inserted in AfterBB.
 813   Builder.SetInsertPoint(AfterBB);
 814
 815   // Add a new entry to the PHI node for the backedge.
 816   Variable->addIncoming(NextVar, LoopEndBB);
 817
 818   // Restore the unshadowed variable.
 819   if (OldVal)
 820     NamedValues[VarName] = OldVal;
 821   else
 822     NamedValues.erase(VarName);
 823
 824   // for expr always returns 0.0.
 825   return Constant::getNullValue(Type::getDoubleTy(getGlobalContext()));
 826 }
 827
 828 Function *PrototypeAST::Codegen() {
 829   // Make the function type:  double(double,double) etc.
 830   std::vector<Type *> Doubles(Args.size(),
 831                               Type::getDoubleTy(getGlobalContext()));
 832   FunctionType *FT =
 833       FunctionType::get(Type::getDoubleTy(getGlobalContext()), Doubles, false);
 834
 835   Function *F =
 836       Function::Create(FT, Function::ExternalLinkage, Name, TheModule);
 837
 838   // If F conflicted, there was already something named 'Name'.  If it has a
 839   // body, don't allow redefinition or reextern.
 840   if (F->getName() != Name) {
 841     // Delete the one we just made and get the existing one.
 842     F->eraseFromParent();
 843     F = TheModule->getFunction(Name);
 844
 845     // If F already has a body, reject this.
 846     if (!F->empty()) {
 847       ErrorF("redefinition of function");
 848       return 0;
 849     }
 850
 851     // If F took a different number of args, reject.
 852     if (F->arg_size() != Args.size()) {
 853       ErrorF("redefinition of function with different # args");
 854       return 0;
 855     }
 856   }
 857
 858   // Set names for all arguments.
 859   unsigned Idx = 0;
 860   for (Function::arg_iterator AI = F->arg_begin(); Idx != Args.size();
 861        ++AI, ++Idx) {
 862     AI->setName(Args[Idx]);
 863
 864     // Add arguments to variable symbol table.
 865     NamedValues[Args[Idx]] = AI;
 866   }
 867
 868   return F;
 869 }
 870
 871 Function *FunctionAST::Codegen() {
 872   NamedValues.clear();
 873
 874   Function *TheFunction = Proto->Codegen();
 875   if (TheFunction == 0)
 876     return 0;
 877
 878   // If this is an operator, install it.
 879   if (Proto->isBinaryOp())
 880     BinopPrecedence[Proto->getOperatorName()] = Proto->getBinaryPrecedence();
 881
 882   // Create a new basic block to start insertion into.
 883   BasicBlock *BB = BasicBlock::Create(getGlobalContext(), "entry", TheFunction);
 884   Builder.SetInsertPoint(BB);
 885
 886   if (Value *RetVal = Body->Codegen()) {
 887     // Finish off the function.
 888     Builder.CreateRet(RetVal);
 889
 890     // Validate the generated code, checking for consistency.
 891     verifyFunction(*TheFunction);
 892
 893     // Optimize the function.
 894     TheFPM->run(*TheFunction);
 895
 896     return TheFunction;
 897   }
 898
 899   // Error reading body, remove function.
 900   TheFunction->eraseFromParent();
 901
 902   if (Proto->isBinaryOp())
 903     BinopPrecedence.erase(Proto->getOperatorName());
 904   return 0;
 905 }
 906
 907 //===----------------------------------------------------------------------===//
 908 // Top-Level parsing and JIT Driver
 909 //===----------------------------------------------------------------------===//
 910
 911 static ExecutionEngine *TheExecutionEngine;
 912
 913 static void HandleDefinition() {
 914   if (FunctionAST *F = ParseDefinition()) {
 915     if (Function *LF = F->Codegen()) {
 916       fprintf(stderr, "Read function definition:");
 917       LF->dump();
 918     }
 919   } else {
 920     // Skip token for error recovery.
 921     getNextToken();
 922   }
 923 }
 924
 925 static void HandleExtern() {
 926   if (PrototypeAST *P = ParseExtern()) {
 927     if (Function *F = P->Codegen()) {
 928       fprintf(stderr, "Read extern: ");
 929       F->dump();
 930     }
 931   } else {
 932     // Skip token for error recovery.
 933     getNextToken();
 934   }
 935 }
 936
 937 static void HandleTopLevelExpression() {
 938   // Evaluate a top-level expression into an anonymous function.
 939   if (FunctionAST *F = ParseTopLevelExpr()) {
 940     if (Function *LF = F->Codegen()) {
 941       TheExecutionEngine->finalizeObject();
 942       // JIT the function, returning a function pointer.
 943       void *FPtr = TheExecutionEngine->getPointerToFunction(LF);
 944
 945       // Cast it to the right type (takes no arguments, returns a double) so we
 946       // can call it as a native function.
 947       double (*FP)() = (double (*)())(intptr_t)FPtr;
 948       fprintf(stderr, "Evaluated to %f\n", FP());
 949     }
 950   } else {
 951     // Skip token for error recovery.
 952     getNextToken();
 953   }
 954 }
 955
 956 /// top ::= definition | external | expression | ';'
 957 static void MainLoop() {
 958   while (1) {
 959     fprintf(stderr, "ready> ");
 960     switch (CurTok) {
 961     case tok_eof:
 962       return;
 963     case ';':
 964       getNextToken();
 965       break; // ignore top-level semicolons.
 966     case tok_def:
 967       HandleDefinition();
 968       break;
 969     case tok_extern:
 970       HandleExtern();
 971       break;
 972     default:
 973       HandleTopLevelExpression();
 974       break;
 975     }
 976   }
 977 }
 978
 979 //===----------------------------------------------------------------------===//
 980 // "Library" functions that can be "extern'd" from user code.
 981 //===----------------------------------------------------------------------===//
 982
 983 /// putchard - putchar that takes a double and returns 0.
 984 extern "C" double putchard(double X) {
 985   putchar((char)X);
 986   return 0;
 987 }
 988
 989 /// printd - printf that takes a double prints it as "%f\n", returning 0.
 990 extern "C" double printd(double X) {
 991   printf("%f\n", X);
 992   return 0;
 993 }
 994
 995 //===----------------------------------------------------------------------===//
 996 // Main driver code.
 997 //===----------------------------------------------------------------------===//
 998
 999 int main() {
1000   InitializeNativeTarget();
1001   InitializeNativeTargetAsmPrinter();
1002   InitializeNativeTargetAsmParser();
1003   LLVMContext &Context = getGlobalContext();
1004
1005   // Install standard binary operators.
1006   // 1 is lowest precedence.
1007   BinopPrecedence['<'] = 10;
1008   BinopPrecedence['+'] = 20;
1009   BinopPrecedence['-'] = 20;
1010   BinopPrecedence['*'] = 40; // highest.
1011
1012   // Prime the first token.
1013   fprintf(stderr, "ready> ");
1014   getNextToken();
1015
1016   // Make the module, which holds all the code.
1017   std::unique_ptr<Module> Owner = make_unique<Module>("my cool jit", Context);
1018   TheModule = Owner.get();
1019
1020   // Create the JIT.  This takes ownership of the module.
1021   std::string ErrStr;
1022   TheExecutionEngine =
1023       EngineBuilder(std::move(Owner))
1024           .setErrorStr(&ErrStr)
1025           .setMCJITMemoryManager(llvm::make_unique<SectionMemoryManager>())
1026           .create();
1027   if (!TheExecutionEngine) {
1028     fprintf(stderr, "Could not create ExecutionEngine: %s\n", ErrStr.c_str());
1029     exit(1);
1030   }
1031
1032   FunctionPassManager OurFPM(TheModule);
1033
1034   // Set up the optimizer pipeline.  Start with registering info about how the
1035   // target lays out data structures.
1036   TheModule->setDataLayout(TheExecutionEngine->getDataLayout());
1037   OurFPM.add(new DataLayoutPass());
1038   // Provide basic AliasAnalysis support for GVN.
1039   OurFPM.add(createBasicAliasAnalysisPass());
1040   // Do simple "peephole" optimizations and bit-twiddling optzns.
1041   OurFPM.add(createInstructionCombiningPass());
1042   // Reassociate expressions.
1043   OurFPM.add(createReassociatePass());
1044   // Eliminate Common SubExpressions.
1045   OurFPM.add(createGVNPass());
1046   // Simplify the control flow graph (deleting unreachable blocks, etc).
1047   OurFPM.add(createCFGSimplificationPass());
1048
1049   OurFPM.doInitialization();
1050
1051   // Set the global so the code gen can use this.
1052   TheFPM = &OurFPM;
1053
1054   // Run the main "interpreter loop" now.
1055   MainLoop();
1056
1057   TheFPM = 0;
1058
1059   // Print out all of the generated code.
1060   TheModule->dump();
1061
1062   return 0;
1063 }