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