1#include "llvm/DerivedTypes.h"
2#include "llvm/ExecutionEngine/ExecutionEngine.h"
3#include "llvm/ExecutionEngine/JIT.h"
4#include "llvm/IRBuilder.h"
5#include "llvm/LLVMContext.h"
6#include "llvm/Module.h"
7#include "llvm/PassManager.h"
8#include "llvm/Analysis/Verifier.h"
9#include "llvm/Analysis/Passes.h"
10#include "llvm/Target/TargetData.h"
11#include "llvm/Transforms/Scalar.h"
12#include "llvm/Support/TargetSelect.h"
13#include <cstdio>
14#include <string>
15#include <map>
16#include <vector>
17using 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.
25enum 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
42static std::string IdentifierStr;  // Filled in if tok_identifier
43static double NumVal;              // Filled in if tok_number
44
45/// gettok - Return the next token from standard input.
46static 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.
105class ExprAST {
106public:
107  virtual ~ExprAST() {}
108  virtual Value *Codegen() = 0;
109};
110
111/// NumberExprAST - Expression class for numeric literals like "1.0".
112class NumberExprAST : public ExprAST {
113  double Val;
114public:
115  NumberExprAST(double val) : Val(val) {}
116  virtual Value *Codegen();
117};
118
119/// VariableExprAST - Expression class for referencing a variable, like "a".
120class VariableExprAST : public ExprAST {
121  std::string Name;
122public:
123  VariableExprAST(const std::string &name) : Name(name) {}
124  virtual Value *Codegen();
125};
126
127/// UnaryExprAST - Expression class for a unary operator.
128class UnaryExprAST : public ExprAST {
129  char Opcode;
130  ExprAST *Operand;
131public:
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.
138class BinaryExprAST : public ExprAST {
139  char Op;
140  ExprAST *LHS, *RHS;
141public:
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.
148class CallExprAST : public ExprAST {
149  std::string Callee;
150  std::vector<ExprAST*> Args;
151public:
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.
158class IfExprAST : public ExprAST {
159  ExprAST *Cond, *Then, *Else;
160public:
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.
167class ForExprAST : public ExprAST {
168  std::string VarName;
169  ExprAST *Start, *End, *Step, *Body;
170public:
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.
180class PrototypeAST {
181  std::string Name;
182  std::vector<std::string> Args;
183  bool isOperator;
184  unsigned Precedence;  // Precedence if a binary op.
185public:
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.
204class FunctionAST {
205  PrototypeAST *Proto;
206  ExprAST *Body;
207public:
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.
221static int CurTok;
222static int getNextToken() {
223  return CurTok = gettok();
224}
225
226/// BinopPrecedence - This holds the precedence for each binary operator that is
227/// defined.
228static std::map<char, int> BinopPrecedence;
229
230/// GetTokPrecedence - Get the precedence of the pending binary operator token.
231static 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.
242ExprAST *Error(const char *Str) { fprintf(stderr, "Error: %s\n", Str);return 0;}
243PrototypeAST *ErrorP(const char *Str) { Error(Str); return 0; }
244FunctionAST *ErrorF(const char *Str) { Error(Str); return 0; }
245
246static ExprAST *ParseExpression();
247
248/// identifierexpr
249///   ::= identifier
250///   ::= identifier '(' expression* ')'
251static 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
283static ExprAST *ParseNumberExpr() {
284  ExprAST *Result = new NumberExprAST(NumVal);
285  getNextToken(); // consume the number
286  return Result;
287}
288
289/// parenexpr ::= '(' expression ')'
290static 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
302static 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
328static 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
375static 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
389static 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)*
404static 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///
438static 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)
449static 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
511static 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
522static 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
532static PrototypeAST *ParseExtern() {
533  getNextToken();  // eat extern.
534  return ParsePrototype();
535}
536
537//===----------------------------------------------------------------------===//
538// Code Generation
539//===----------------------------------------------------------------------===//
540
541static Module *TheModule;
542static IRBuilder<> Builder(getGlobalContext());
543static std::map<std::string, Value*> NamedValues;
544static FunctionPassManager *TheFPM;
545
546Value *ErrorV(const char *Str) { Error(Str); return 0; }
547
548Value *NumberExprAST::Codegen() {
549  return ConstantFP::get(getGlobalContext(), APFloat(Val));
550}
551
552Value *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
558Value *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
569Value *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, "binop");
593}
594
595Value *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, "calltmp");
612}
613
614Value *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
665Value *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
758Function *PrototypeAST::Codegen() {
759  // Make the function type:  double(double,double) etc.
760  std::vector<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
800Function *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
840static ExecutionEngine *TheExecutionEngine;
841
842static 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
854static 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
866static 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 | ';'
885static 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.
903extern "C"
904double 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.
910extern "C"
911double printd(double X) {
912  printf("%f\n", X);
913  return 0;
914}
915
916//===----------------------------------------------------------------------===//
917// Main driver code.
918//===----------------------------------------------------------------------===//
919
920int 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}
977