examples/Kaleidoscope/Chapter6/toy.cpp

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