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