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      1 #include "llvm/ADT/STLExtras.h"
      2 #include "llvm/ADT/Triple.h"
      3 #include "llvm/Analysis/Passes.h"
      4 #include "llvm/ExecutionEngine/ExecutionEngine.h"
      5 #include "llvm/ExecutionEngine/MCJIT.h"
      6 #include "llvm/ExecutionEngine/SectionMemoryManager.h"
      7 #include "llvm/IR/DIBuilder.h"
      8 #include "llvm/IR/DataLayout.h"
      9 #include "llvm/IR/DerivedTypes.h"
     10 #include "llvm/IR/IRBuilder.h"
     11 #include "llvm/IR/LLVMContext.h"
     12 #include "llvm/IR/LegacyPassManager.h"
     13 #include "llvm/IR/Module.h"
     14 #include "llvm/IR/Verifier.h"
     15 #include "llvm/Support/Host.h"
     16 #include "llvm/Support/TargetSelect.h"
     17 #include "llvm/Transforms/Scalar.h"
     18 #include <cctype>
     19 #include <cstdio>
     20 #include <iostream>
     21 #include <map>
     22 #include <string>
     23 #include <vector>
     24 using namespace llvm;
     25 
     26 //===----------------------------------------------------------------------===//
     27 // Lexer
     28 //===----------------------------------------------------------------------===//
     29 
     30 // The lexer returns tokens [0-255] if it is an unknown character, otherwise one
     31 // of these for known things.
     32 enum Token {
     33   tok_eof = -1,
     34 
     35   // commands
     36   tok_def = -2,
     37   tok_extern = -3,
     38 
     39   // primary
     40   tok_identifier = -4,
     41   tok_number = -5,
     42 
     43   // control
     44   tok_if = -6,
     45   tok_then = -7,
     46   tok_else = -8,
     47   tok_for = -9,
     48   tok_in = -10,
     49 
     50   // operators
     51   tok_binary = -11,
     52   tok_unary = -12,
     53 
     54   // var definition
     55   tok_var = -13
     56 };
     57 
     58 std::string getTokName(int Tok) {
     59   switch (Tok) {
     60   case tok_eof:
     61     return "eof";
     62   case tok_def:
     63     return "def";
     64   case tok_extern:
     65     return "extern";
     66   case tok_identifier:
     67     return "identifier";
     68   case tok_number:
     69     return "number";
     70   case tok_if:
     71     return "if";
     72   case tok_then:
     73     return "then";
     74   case tok_else:
     75     return "else";
     76   case tok_for:
     77     return "for";
     78   case tok_in:
     79     return "in";
     80   case tok_binary:
     81     return "binary";
     82   case tok_unary:
     83     return "unary";
     84   case tok_var:
     85     return "var";
     86   }
     87   return std::string(1, (char)Tok);
     88 }
     89 
     90 namespace {
     91 class PrototypeAST;
     92 class ExprAST;
     93 }
     94 static IRBuilder<> Builder(getGlobalContext());
     95 struct DebugInfo {
     96   DICompileUnit TheCU;
     97   DIType DblTy;
     98   std::vector<DIScope *> LexicalBlocks;
     99   std::map<const PrototypeAST *, DIScope> FnScopeMap;
    100 
    101   void emitLocation(ExprAST *AST);
    102   DIType getDoubleTy();
    103 } KSDbgInfo;
    104 
    105 static std::string IdentifierStr; // Filled in if tok_identifier
    106 static double NumVal;             // Filled in if tok_number
    107 struct SourceLocation {
    108   int Line;
    109   int Col;
    110 };
    111 static SourceLocation CurLoc;
    112 static SourceLocation LexLoc = { 1, 0 };
    113 
    114 static int advance() {
    115   int LastChar = getchar();
    116 
    117   if (LastChar == '\n' || LastChar == '\r') {
    118     LexLoc.Line++;
    119     LexLoc.Col = 0;
    120   } else
    121     LexLoc.Col++;
    122   return LastChar;
    123 }
    124 
    125 /// gettok - Return the next token from standard input.
    126 static int gettok() {
    127   static int LastChar = ' ';
    128 
    129   // Skip any whitespace.
    130   while (isspace(LastChar))
    131     LastChar = advance();
    132 
    133   CurLoc = LexLoc;
    134 
    135   if (isalpha(LastChar)) { // identifier: [a-zA-Z][a-zA-Z0-9]*
    136     IdentifierStr = LastChar;
    137     while (isalnum((LastChar = advance())))
    138       IdentifierStr += LastChar;
    139 
    140     if (IdentifierStr == "def")
    141       return tok_def;
    142     if (IdentifierStr == "extern")
    143       return tok_extern;
    144     if (IdentifierStr == "if")
    145       return tok_if;
    146     if (IdentifierStr == "then")
    147       return tok_then;
    148     if (IdentifierStr == "else")
    149       return tok_else;
    150     if (IdentifierStr == "for")
    151       return tok_for;
    152     if (IdentifierStr == "in")
    153       return tok_in;
    154     if (IdentifierStr == "binary")
    155       return tok_binary;
    156     if (IdentifierStr == "unary")
    157       return tok_unary;
    158     if (IdentifierStr == "var")
    159       return tok_var;
    160     return tok_identifier;
    161   }
    162 
    163   if (isdigit(LastChar) || LastChar == '.') { // Number: [0-9.]+
    164     std::string NumStr;
    165     do {
    166       NumStr += LastChar;
    167       LastChar = advance();
    168     } while (isdigit(LastChar) || LastChar == '.');
    169 
    170     NumVal = strtod(NumStr.c_str(), 0);
    171     return tok_number;
    172   }
    173 
    174   if (LastChar == '#') {
    175     // Comment until end of line.
    176     do
    177       LastChar = advance();
    178     while (LastChar != EOF && LastChar != '\n' && LastChar != '\r');
    179 
    180     if (LastChar != EOF)
    181       return gettok();
    182   }
    183 
    184   // Check for end of file.  Don't eat the EOF.
    185   if (LastChar == EOF)
    186     return tok_eof;
    187 
    188   // Otherwise, just return the character as its ascii value.
    189   int ThisChar = LastChar;
    190   LastChar = advance();
    191   return ThisChar;
    192 }
    193 
    194 //===----------------------------------------------------------------------===//
    195 // Abstract Syntax Tree (aka Parse Tree)
    196 //===----------------------------------------------------------------------===//
    197 namespace {
    198 
    199 std::ostream &indent(std::ostream &O, int size) {
    200   return O << std::string(size, ' ');
    201 }
    202 
    203 /// ExprAST - Base class for all expression nodes.
    204 class ExprAST {
    205   SourceLocation Loc;
    206 
    207 public:
    208   int getLine() const { return Loc.Line; }
    209   int getCol() const { return Loc.Col; }
    210   ExprAST(SourceLocation Loc = CurLoc) : Loc(Loc) {}
    211   virtual std::ostream &dump(std::ostream &out, int ind) {
    212     return out << ':' << getLine() << ':' << getCol() << '\n';
    213   }
    214   virtual ~ExprAST() {}
    215   virtual Value *Codegen() = 0;
    216 };
    217 
    218 /// NumberExprAST - Expression class for numeric literals like "1.0".
    219 class NumberExprAST : public ExprAST {
    220   double Val;
    221 
    222 public:
    223   NumberExprAST(double val) : Val(val) {}
    224   std::ostream &dump(std::ostream &out, int ind) override {
    225     return ExprAST::dump(out << Val, ind);
    226   }
    227   Value *Codegen() override;
    228 };
    229 
    230 /// VariableExprAST - Expression class for referencing a variable, like "a".
    231 class VariableExprAST : public ExprAST {
    232   std::string Name;
    233 
    234 public:
    235   VariableExprAST(SourceLocation Loc, const std::string &name)
    236       : ExprAST(Loc), Name(name) {}
    237   const std::string &getName() const { return Name; }
    238   std::ostream &dump(std::ostream &out, int ind) override {
    239     return ExprAST::dump(out << Name, ind);
    240   }
    241   Value *Codegen() override;
    242 };
    243 
    244 /// UnaryExprAST - Expression class for a unary operator.
    245 class UnaryExprAST : public ExprAST {
    246   char Opcode;
    247   ExprAST *Operand;
    248 
    249 public:
    250   UnaryExprAST(char opcode, ExprAST *operand)
    251       : Opcode(opcode), Operand(operand) {}
    252   std::ostream &dump(std::ostream &out, int ind) override {
    253     ExprAST::dump(out << "unary" << Opcode, ind);
    254     Operand->dump(out, ind + 1);
    255     return out;
    256   }
    257   Value *Codegen() override;
    258 };
    259 
    260 /// BinaryExprAST - Expression class for a binary operator.
    261 class BinaryExprAST : public ExprAST {
    262   char Op;
    263   ExprAST *LHS, *RHS;
    264 
    265 public:
    266   BinaryExprAST(SourceLocation Loc, char op, ExprAST *lhs, ExprAST *rhs)
    267       : ExprAST(Loc), Op(op), LHS(lhs), RHS(rhs) {}
    268   std::ostream &dump(std::ostream &out, int ind) override {
    269     ExprAST::dump(out << "binary" << Op, ind);
    270     LHS->dump(indent(out, ind) << "LHS:", ind + 1);
    271     RHS->dump(indent(out, ind) << "RHS:", ind + 1);
    272     return out;
    273   }
    274   Value *Codegen() override;
    275 };
    276 
    277 /// CallExprAST - Expression class for function calls.
    278 class CallExprAST : public ExprAST {
    279   std::string Callee;
    280   std::vector<ExprAST *> Args;
    281 
    282 public:
    283   CallExprAST(SourceLocation Loc, const std::string &callee,
    284               std::vector<ExprAST *> &args)
    285       : ExprAST(Loc), Callee(callee), Args(args) {}
    286   std::ostream &dump(std::ostream &out, int ind) override {
    287     ExprAST::dump(out << "call " << Callee, ind);
    288     for (ExprAST *Arg : Args)
    289       Arg->dump(indent(out, ind + 1), ind + 1);
    290     return out;
    291   }
    292   Value *Codegen() override;
    293 };
    294 
    295 /// IfExprAST - Expression class for if/then/else.
    296 class IfExprAST : public ExprAST {
    297   ExprAST *Cond, *Then, *Else;
    298 
    299 public:
    300   IfExprAST(SourceLocation Loc, ExprAST *cond, ExprAST *then, ExprAST *_else)
    301       : ExprAST(Loc), Cond(cond), Then(then), Else(_else) {}
    302   std::ostream &dump(std::ostream &out, int ind) override {
    303     ExprAST::dump(out << "if", ind);
    304     Cond->dump(indent(out, ind) << "Cond:", ind + 1);
    305     Then->dump(indent(out, ind) << "Then:", ind + 1);
    306     Else->dump(indent(out, ind) << "Else:", ind + 1);
    307     return out;
    308   }
    309   Value *Codegen() override;
    310 };
    311 
    312 /// ForExprAST - Expression class for for/in.
    313 class ForExprAST : public ExprAST {
    314   std::string VarName;
    315   ExprAST *Start, *End, *Step, *Body;
    316 
    317 public:
    318   ForExprAST(const std::string &varname, ExprAST *start, ExprAST *end,
    319              ExprAST *step, ExprAST *body)
    320       : VarName(varname), Start(start), End(end), Step(step), Body(body) {}
    321   std::ostream &dump(std::ostream &out, int ind) override {
    322     ExprAST::dump(out << "for", ind);
    323     Start->dump(indent(out, ind) << "Cond:", ind + 1);
    324     End->dump(indent(out, ind) << "End:", ind + 1);
    325     Step->dump(indent(out, ind) << "Step:", ind + 1);
    326     Body->dump(indent(out, ind) << "Body:", ind + 1);
    327     return out;
    328   }
    329   Value *Codegen() override;
    330 };
    331 
    332 /// VarExprAST - Expression class for var/in
    333 class VarExprAST : public ExprAST {
    334   std::vector<std::pair<std::string, ExprAST *> > VarNames;
    335   ExprAST *Body;
    336 
    337 public:
    338   VarExprAST(const std::vector<std::pair<std::string, ExprAST *> > &varnames,
    339              ExprAST *body)
    340       : VarNames(varnames), Body(body) {}
    341 
    342   std::ostream &dump(std::ostream &out, int ind) override {
    343     ExprAST::dump(out << "var", ind);
    344     for (const auto &NamedVar : VarNames)
    345       NamedVar.second->dump(indent(out, ind) << NamedVar.first << ':', ind + 1);
    346     Body->dump(indent(out, ind) << "Body:", ind + 1);
    347     return out;
    348   }
    349   Value *Codegen() override;
    350 };
    351 
    352 /// PrototypeAST - This class represents the "prototype" for a function,
    353 /// which captures its argument names as well as if it is an operator.
    354 class PrototypeAST {
    355   std::string Name;
    356   std::vector<std::string> Args;
    357   bool isOperator;
    358   unsigned Precedence; // Precedence if a binary op.
    359   int Line;
    360 
    361 public:
    362   PrototypeAST(SourceLocation Loc, const std::string &name,
    363                const std::vector<std::string> &args, bool isoperator = false,
    364                unsigned prec = 0)
    365       : Name(name), Args(args), isOperator(isoperator), Precedence(prec),
    366         Line(Loc.Line) {}
    367 
    368   bool isUnaryOp() const { return isOperator && Args.size() == 1; }
    369   bool isBinaryOp() const { return isOperator && Args.size() == 2; }
    370 
    371   char getOperatorName() const {
    372     assert(isUnaryOp() || isBinaryOp());
    373     return Name[Name.size() - 1];
    374   }
    375 
    376   unsigned getBinaryPrecedence() const { return Precedence; }
    377 
    378   Function *Codegen();
    379 
    380   void CreateArgumentAllocas(Function *F);
    381   const std::vector<std::string> &getArgs() const { return Args; }
    382 };
    383 
    384 /// FunctionAST - This class represents a function definition itself.
    385 class FunctionAST {
    386   PrototypeAST *Proto;
    387   ExprAST *Body;
    388 
    389 public:
    390   FunctionAST(PrototypeAST *proto, ExprAST *body) : Proto(proto), Body(body) {}
    391 
    392   std::ostream &dump(std::ostream &out, int ind) {
    393     indent(out, ind) << "FunctionAST\n";
    394     ++ind;
    395     indent(out, ind) << "Body:";
    396     return Body ? Body->dump(out, ind) : out << "null\n";
    397   }
    398 
    399   Function *Codegen();
    400 };
    401 } // end anonymous namespace
    402 
    403 //===----------------------------------------------------------------------===//
    404 // Parser
    405 //===----------------------------------------------------------------------===//
    406 
    407 /// CurTok/getNextToken - Provide a simple token buffer.  CurTok is the current
    408 /// token the parser is looking at.  getNextToken reads another token from the
    409 /// lexer and updates CurTok with its results.
    410 static int CurTok;
    411 static int getNextToken() { return CurTok = gettok(); }
    412 
    413 /// BinopPrecedence - This holds the precedence for each binary operator that is
    414 /// defined.
    415 static std::map<char, int> BinopPrecedence;
    416 
    417 /// GetTokPrecedence - Get the precedence of the pending binary operator token.
    418 static int GetTokPrecedence() {
    419   if (!isascii(CurTok))
    420     return -1;
    421 
    422   // Make sure it's a declared binop.
    423   int TokPrec = BinopPrecedence[CurTok];
    424   if (TokPrec <= 0)
    425     return -1;
    426   return TokPrec;
    427 }
    428 
    429 /// Error* - These are little helper functions for error handling.
    430 ExprAST *Error(const char *Str) {
    431   fprintf(stderr, "Error: %s\n", Str);
    432   return 0;
    433 }
    434 PrototypeAST *ErrorP(const char *Str) {
    435   Error(Str);
    436   return 0;
    437 }
    438 FunctionAST *ErrorF(const char *Str) {
    439   Error(Str);
    440   return 0;
    441 }
    442 
    443 static ExprAST *ParseExpression();
    444 
    445 /// identifierexpr
    446 ///   ::= identifier
    447 ///   ::= identifier '(' expression* ')'
    448 static ExprAST *ParseIdentifierExpr() {
    449   std::string IdName = IdentifierStr;
    450 
    451   SourceLocation LitLoc = CurLoc;
    452 
    453   getNextToken(); // eat identifier.
    454 
    455   if (CurTok != '(') // Simple variable ref.
    456     return new VariableExprAST(LitLoc, IdName);
    457 
    458   // Call.
    459   getNextToken(); // eat (
    460   std::vector<ExprAST *> Args;
    461   if (CurTok != ')') {
    462     while (1) {
    463       ExprAST *Arg = ParseExpression();
    464       if (!Arg)
    465         return 0;
    466       Args.push_back(Arg);
    467 
    468       if (CurTok == ')')
    469         break;
    470 
    471       if (CurTok != ',')
    472         return Error("Expected ')' or ',' in argument list");
    473       getNextToken();
    474     }
    475   }
    476 
    477   // Eat the ')'.
    478   getNextToken();
    479 
    480   return new CallExprAST(LitLoc, IdName, Args);
    481 }
    482 
    483 /// numberexpr ::= number
    484 static ExprAST *ParseNumberExpr() {
    485   ExprAST *Result = new NumberExprAST(NumVal);
    486   getNextToken(); // consume the number
    487   return Result;
    488 }
    489 
    490 /// parenexpr ::= '(' expression ')'
    491 static ExprAST *ParseParenExpr() {
    492   getNextToken(); // eat (.
    493   ExprAST *V = ParseExpression();
    494   if (!V)
    495     return 0;
    496 
    497   if (CurTok != ')')
    498     return Error("expected ')'");
    499   getNextToken(); // eat ).
    500   return V;
    501 }
    502 
    503 /// ifexpr ::= 'if' expression 'then' expression 'else' expression
    504 static ExprAST *ParseIfExpr() {
    505   SourceLocation IfLoc = CurLoc;
    506 
    507   getNextToken(); // eat the if.
    508 
    509   // condition.
    510   ExprAST *Cond = ParseExpression();
    511   if (!Cond)
    512     return 0;
    513 
    514   if (CurTok != tok_then)
    515     return Error("expected then");
    516   getNextToken(); // eat the then
    517 
    518   ExprAST *Then = ParseExpression();
    519   if (Then == 0)
    520     return 0;
    521 
    522   if (CurTok != tok_else)
    523     return Error("expected else");
    524 
    525   getNextToken();
    526 
    527   ExprAST *Else = ParseExpression();
    528   if (!Else)
    529     return 0;
    530 
    531   return new IfExprAST(IfLoc, Cond, Then, Else);
    532 }
    533 
    534 /// forexpr ::= 'for' identifier '=' expr ',' expr (',' expr)? 'in' expression
    535 static ExprAST *ParseForExpr() {
    536   getNextToken(); // eat the for.
    537 
    538   if (CurTok != tok_identifier)
    539     return Error("expected identifier after for");
    540 
    541   std::string IdName = IdentifierStr;
    542   getNextToken(); // eat identifier.
    543 
    544   if (CurTok != '=')
    545     return Error("expected '=' after for");
    546   getNextToken(); // eat '='.
    547 
    548   ExprAST *Start = ParseExpression();
    549   if (Start == 0)
    550     return 0;
    551   if (CurTok != ',')
    552     return Error("expected ',' after for start value");
    553   getNextToken();
    554 
    555   ExprAST *End = ParseExpression();
    556   if (End == 0)
    557     return 0;
    558 
    559   // The step value is optional.
    560   ExprAST *Step = 0;
    561   if (CurTok == ',') {
    562     getNextToken();
    563     Step = ParseExpression();
    564     if (Step == 0)
    565       return 0;
    566   }
    567 
    568   if (CurTok != tok_in)
    569     return Error("expected 'in' after for");
    570   getNextToken(); // eat 'in'.
    571 
    572   ExprAST *Body = ParseExpression();
    573   if (Body == 0)
    574     return 0;
    575 
    576   return new ForExprAST(IdName, Start, End, Step, Body);
    577 }
    578 
    579 /// varexpr ::= 'var' identifier ('=' expression)?
    580 //                    (',' identifier ('=' expression)?)* 'in' expression
    581 static ExprAST *ParseVarExpr() {
    582   getNextToken(); // eat the var.
    583 
    584   std::vector<std::pair<std::string, ExprAST *> > VarNames;
    585 
    586   // At least one variable name is required.
    587   if (CurTok != tok_identifier)
    588     return Error("expected identifier after var");
    589 
    590   while (1) {
    591     std::string Name = IdentifierStr;
    592     getNextToken(); // eat identifier.
    593 
    594     // Read the optional initializer.
    595     ExprAST *Init = 0;
    596     if (CurTok == '=') {
    597       getNextToken(); // eat the '='.
    598 
    599       Init = ParseExpression();
    600       if (Init == 0)
    601         return 0;
    602     }
    603 
    604     VarNames.push_back(std::make_pair(Name, Init));
    605 
    606     // End of var list, exit loop.
    607     if (CurTok != ',')
    608       break;
    609     getNextToken(); // eat the ','.
    610 
    611     if (CurTok != tok_identifier)
    612       return Error("expected identifier list after var");
    613   }
    614 
    615   // At this point, we have to have 'in'.
    616   if (CurTok != tok_in)
    617     return Error("expected 'in' keyword after 'var'");
    618   getNextToken(); // eat 'in'.
    619 
    620   ExprAST *Body = ParseExpression();
    621   if (Body == 0)
    622     return 0;
    623 
    624   return new VarExprAST(VarNames, Body);
    625 }
    626 
    627 /// primary
    628 ///   ::= identifierexpr
    629 ///   ::= numberexpr
    630 ///   ::= parenexpr
    631 ///   ::= ifexpr
    632 ///   ::= forexpr
    633 ///   ::= varexpr
    634 static ExprAST *ParsePrimary() {
    635   switch (CurTok) {
    636   default:
    637     return Error("unknown token when expecting an expression");
    638   case tok_identifier:
    639     return ParseIdentifierExpr();
    640   case tok_number:
    641     return ParseNumberExpr();
    642   case '(':
    643     return ParseParenExpr();
    644   case tok_if:
    645     return ParseIfExpr();
    646   case tok_for:
    647     return ParseForExpr();
    648   case tok_var:
    649     return ParseVarExpr();
    650   }
    651 }
    652 
    653 /// unary
    654 ///   ::= primary
    655 ///   ::= '!' unary
    656 static ExprAST *ParseUnary() {
    657   // If the current token is not an operator, it must be a primary expr.
    658   if (!isascii(CurTok) || CurTok == '(' || CurTok == ',')
    659     return ParsePrimary();
    660 
    661   // If this is a unary operator, read it.
    662   int Opc = CurTok;
    663   getNextToken();
    664   if (ExprAST *Operand = ParseUnary())
    665     return new UnaryExprAST(Opc, Operand);
    666   return 0;
    667 }
    668 
    669 /// binoprhs
    670 ///   ::= ('+' unary)*
    671 static ExprAST *ParseBinOpRHS(int ExprPrec, ExprAST *LHS) {
    672   // If this is a binop, find its precedence.
    673   while (1) {
    674     int TokPrec = GetTokPrecedence();
    675 
    676     // If this is a binop that binds at least as tightly as the current binop,
    677     // consume it, otherwise we are done.
    678     if (TokPrec < ExprPrec)
    679       return LHS;
    680 
    681     // Okay, we know this is a binop.
    682     int BinOp = CurTok;
    683     SourceLocation BinLoc = CurLoc;
    684     getNextToken(); // eat binop
    685 
    686     // Parse the unary expression after the binary operator.
    687     ExprAST *RHS = ParseUnary();
    688     if (!RHS)
    689       return 0;
    690 
    691     // If BinOp binds less tightly with RHS than the operator after RHS, let
    692     // the pending operator take RHS as its LHS.
    693     int NextPrec = GetTokPrecedence();
    694     if (TokPrec < NextPrec) {
    695       RHS = ParseBinOpRHS(TokPrec + 1, RHS);
    696       if (RHS == 0)
    697         return 0;
    698     }
    699 
    700     // Merge LHS/RHS.
    701     LHS = new BinaryExprAST(BinLoc, BinOp, LHS, RHS);
    702   }
    703 }
    704 
    705 /// expression
    706 ///   ::= unary binoprhs
    707 ///
    708 static ExprAST *ParseExpression() {
    709   ExprAST *LHS = ParseUnary();
    710   if (!LHS)
    711     return 0;
    712 
    713   return ParseBinOpRHS(0, LHS);
    714 }
    715 
    716 /// prototype
    717 ///   ::= id '(' id* ')'
    718 ///   ::= binary LETTER number? (id, id)
    719 ///   ::= unary LETTER (id)
    720 static PrototypeAST *ParsePrototype() {
    721   std::string FnName;
    722 
    723   SourceLocation FnLoc = CurLoc;
    724 
    725   unsigned Kind = 0; // 0 = identifier, 1 = unary, 2 = binary.
    726   unsigned BinaryPrecedence = 30;
    727 
    728   switch (CurTok) {
    729   default:
    730     return ErrorP("Expected function name in prototype");
    731   case tok_identifier:
    732     FnName = IdentifierStr;
    733     Kind = 0;
    734     getNextToken();
    735     break;
    736   case tok_unary:
    737     getNextToken();
    738     if (!isascii(CurTok))
    739       return ErrorP("Expected unary operator");
    740     FnName = "unary";
    741     FnName += (char)CurTok;
    742     Kind = 1;
    743     getNextToken();
    744     break;
    745   case tok_binary:
    746     getNextToken();
    747     if (!isascii(CurTok))
    748       return ErrorP("Expected binary operator");
    749     FnName = "binary";
    750     FnName += (char)CurTok;
    751     Kind = 2;
    752     getNextToken();
    753 
    754     // Read the precedence if present.
    755     if (CurTok == tok_number) {
    756       if (NumVal < 1 || NumVal > 100)
    757         return ErrorP("Invalid precedecnce: must be 1..100");
    758       BinaryPrecedence = (unsigned)NumVal;
    759       getNextToken();
    760     }
    761     break;
    762   }
    763 
    764   if (CurTok != '(')
    765     return ErrorP("Expected '(' in prototype");
    766 
    767   std::vector<std::string> ArgNames;
    768   while (getNextToken() == tok_identifier)
    769     ArgNames.push_back(IdentifierStr);
    770   if (CurTok != ')')
    771     return ErrorP("Expected ')' in prototype");
    772 
    773   // success.
    774   getNextToken(); // eat ')'.
    775 
    776   // Verify right number of names for operator.
    777   if (Kind && ArgNames.size() != Kind)
    778     return ErrorP("Invalid number of operands for operator");
    779 
    780   return new PrototypeAST(FnLoc, FnName, ArgNames, Kind != 0, BinaryPrecedence);
    781 }
    782 
    783 /// definition ::= 'def' prototype expression
    784 static FunctionAST *ParseDefinition() {
    785   getNextToken(); // eat def.
    786   PrototypeAST *Proto = ParsePrototype();
    787   if (Proto == 0)
    788     return 0;
    789 
    790   if (ExprAST *E = ParseExpression())
    791     return new FunctionAST(Proto, E);
    792   return 0;
    793 }
    794 
    795 /// toplevelexpr ::= expression
    796 static FunctionAST *ParseTopLevelExpr() {
    797   SourceLocation FnLoc = CurLoc;
    798   if (ExprAST *E = ParseExpression()) {
    799     // Make an anonymous proto.
    800     PrototypeAST *Proto =
    801         new PrototypeAST(FnLoc, "main", std::vector<std::string>());
    802     return new FunctionAST(Proto, E);
    803   }
    804   return 0;
    805 }
    806 
    807 /// external ::= 'extern' prototype
    808 static PrototypeAST *ParseExtern() {
    809   getNextToken(); // eat extern.
    810   return ParsePrototype();
    811 }
    812 
    813 //===----------------------------------------------------------------------===//
    814 // Debug Info Support
    815 //===----------------------------------------------------------------------===//
    816 
    817 static DIBuilder *DBuilder;
    818 
    819 DIType DebugInfo::getDoubleTy() {
    820   if (DblTy)
    821     return DblTy;
    822 
    823   DblTy = DBuilder->createBasicType("double", 64, 64, dwarf::DW_ATE_float);
    824   return DblTy;
    825 }
    826 
    827 void DebugInfo::emitLocation(ExprAST *AST) {
    828   if (!AST)
    829     return Builder.SetCurrentDebugLocation(DebugLoc());
    830   MDScope *Scope;
    831   if (LexicalBlocks.empty())
    832     Scope = TheCU;
    833   else
    834     Scope = *LexicalBlocks.back();
    835   Builder.SetCurrentDebugLocation(
    836       DebugLoc::get(AST->getLine(), AST->getCol(), Scope));
    837 }
    838 
    839 static MDSubroutineType *CreateFunctionType(unsigned NumArgs, DIFile Unit) {
    840   SmallVector<Metadata *, 8> EltTys;
    841   DIType DblTy = KSDbgInfo.getDoubleTy();
    842 
    843   // Add the result type.
    844   EltTys.push_back(DblTy);
    845 
    846   for (unsigned i = 0, e = NumArgs; i != e; ++i)
    847     EltTys.push_back(DblTy);
    848 
    849   DITypeArray EltTypeArray = DBuilder->getOrCreateTypeArray(EltTys);
    850   return DBuilder->createSubroutineType(Unit, EltTypeArray);
    851 }
    852 
    853 //===----------------------------------------------------------------------===//
    854 // Code Generation
    855 //===----------------------------------------------------------------------===//
    856 
    857 static Module *TheModule;
    858 static std::map<std::string, AllocaInst *> NamedValues;
    859 static legacy::FunctionPassManager *TheFPM;
    860 
    861 Value *ErrorV(const char *Str) {
    862   Error(Str);
    863   return 0;
    864 }
    865 
    866 /// CreateEntryBlockAlloca - Create an alloca instruction in the entry block of
    867 /// the function.  This is used for mutable variables etc.
    868 static AllocaInst *CreateEntryBlockAlloca(Function *TheFunction,
    869                                           const std::string &VarName) {
    870   IRBuilder<> TmpB(&TheFunction->getEntryBlock(),
    871                    TheFunction->getEntryBlock().begin());
    872   return TmpB.CreateAlloca(Type::getDoubleTy(getGlobalContext()), 0,
    873                            VarName.c_str());
    874 }
    875 
    876 Value *NumberExprAST::Codegen() {
    877   KSDbgInfo.emitLocation(this);
    878   return ConstantFP::get(getGlobalContext(), APFloat(Val));
    879 }
    880 
    881 Value *VariableExprAST::Codegen() {
    882   // Look this variable up in the function.
    883   Value *V = NamedValues[Name];
    884   if (V == 0)
    885     return ErrorV("Unknown variable name");
    886 
    887   KSDbgInfo.emitLocation(this);
    888   // Load the value.
    889   return Builder.CreateLoad(V, Name.c_str());
    890 }
    891 
    892 Value *UnaryExprAST::Codegen() {
    893   Value *OperandV = Operand->Codegen();
    894   if (OperandV == 0)
    895     return 0;
    896 
    897   Function *F = TheModule->getFunction(std::string("unary") + Opcode);
    898   if (F == 0)
    899     return ErrorV("Unknown unary operator");
    900 
    901   KSDbgInfo.emitLocation(this);
    902   return Builder.CreateCall(F, OperandV, "unop");
    903 }
    904 
    905 Value *BinaryExprAST::Codegen() {
    906   KSDbgInfo.emitLocation(this);
    907 
    908   // Special case '=' because we don't want to emit the LHS as an expression.
    909   if (Op == '=') {
    910     // Assignment requires the LHS to be an identifier.
    911     VariableExprAST *LHSE = dynamic_cast<VariableExprAST *>(LHS);
    912     if (!LHSE)
    913       return ErrorV("destination of '=' must be a variable");
    914     // Codegen the RHS.
    915     Value *Val = RHS->Codegen();
    916     if (Val == 0)
    917       return 0;
    918 
    919     // Look up the name.
    920     Value *Variable = NamedValues[LHSE->getName()];
    921     if (Variable == 0)
    922       return ErrorV("Unknown variable name");
    923 
    924     Builder.CreateStore(Val, Variable);
    925     return Val;
    926   }
    927 
    928   Value *L = LHS->Codegen();
    929   Value *R = RHS->Codegen();
    930   if (L == 0 || R == 0)
    931     return 0;
    932 
    933   switch (Op) {
    934   case '+':
    935     return Builder.CreateFAdd(L, R, "addtmp");
    936   case '-':
    937     return Builder.CreateFSub(L, R, "subtmp");
    938   case '*':
    939     return Builder.CreateFMul(L, R, "multmp");
    940   case '<':
    941     L = Builder.CreateFCmpULT(L, R, "cmptmp");
    942     // Convert bool 0/1 to double 0.0 or 1.0
    943     return Builder.CreateUIToFP(L, Type::getDoubleTy(getGlobalContext()),
    944                                 "booltmp");
    945   default:
    946     break;
    947   }
    948 
    949   // If it wasn't a builtin binary operator, it must be a user defined one. Emit
    950   // a call to it.
    951   Function *F = TheModule->getFunction(std::string("binary") + Op);
    952   assert(F && "binary operator not found!");
    953 
    954   Value *Ops[] = { L, R };
    955   return Builder.CreateCall(F, Ops, "binop");
    956 }
    957 
    958 Value *CallExprAST::Codegen() {
    959   KSDbgInfo.emitLocation(this);
    960 
    961   // Look up the name in the global module table.
    962   Function *CalleeF = TheModule->getFunction(Callee);
    963   if (CalleeF == 0)
    964     return ErrorV("Unknown function referenced");
    965 
    966   // If argument mismatch error.
    967   if (CalleeF->arg_size() != Args.size())
    968     return ErrorV("Incorrect # arguments passed");
    969 
    970   std::vector<Value *> ArgsV;
    971   for (unsigned i = 0, e = Args.size(); i != e; ++i) {
    972     ArgsV.push_back(Args[i]->Codegen());
    973     if (ArgsV.back() == 0)
    974       return 0;
    975   }
    976 
    977   return Builder.CreateCall(CalleeF, ArgsV, "calltmp");
    978 }
    979 
    980 Value *IfExprAST::Codegen() {
    981   KSDbgInfo.emitLocation(this);
    982 
    983   Value *CondV = Cond->Codegen();
    984   if (CondV == 0)
    985     return 0;
    986 
    987   // Convert condition to a bool by comparing equal to 0.0.
    988   CondV = Builder.CreateFCmpONE(
    989       CondV, ConstantFP::get(getGlobalContext(), APFloat(0.0)), "ifcond");
    990 
    991   Function *TheFunction = Builder.GetInsertBlock()->getParent();
    992 
    993   // Create blocks for the then and else cases.  Insert the 'then' block at the
    994   // end of the function.
    995   BasicBlock *ThenBB =
    996       BasicBlock::Create(getGlobalContext(), "then", TheFunction);
    997   BasicBlock *ElseBB = BasicBlock::Create(getGlobalContext(), "else");
    998   BasicBlock *MergeBB = BasicBlock::Create(getGlobalContext(), "ifcont");
    999 
   1000   Builder.CreateCondBr(CondV, ThenBB, ElseBB);
   1001 
   1002   // Emit then value.
   1003   Builder.SetInsertPoint(ThenBB);
   1004 
   1005   Value *ThenV = Then->Codegen();
   1006   if (ThenV == 0)
   1007     return 0;
   1008 
   1009   Builder.CreateBr(MergeBB);
   1010   // Codegen of 'Then' can change the current block, update ThenBB for the PHI.
   1011   ThenBB = Builder.GetInsertBlock();
   1012 
   1013   // Emit else block.
   1014   TheFunction->getBasicBlockList().push_back(ElseBB);
   1015   Builder.SetInsertPoint(ElseBB);
   1016 
   1017   Value *ElseV = Else->Codegen();
   1018   if (ElseV == 0)
   1019     return 0;
   1020 
   1021   Builder.CreateBr(MergeBB);
   1022   // Codegen of 'Else' can change the current block, update ElseBB for the PHI.
   1023   ElseBB = Builder.GetInsertBlock();
   1024 
   1025   // Emit merge block.
   1026   TheFunction->getBasicBlockList().push_back(MergeBB);
   1027   Builder.SetInsertPoint(MergeBB);
   1028   PHINode *PN =
   1029       Builder.CreatePHI(Type::getDoubleTy(getGlobalContext()), 2, "iftmp");
   1030 
   1031   PN->addIncoming(ThenV, ThenBB);
   1032   PN->addIncoming(ElseV, ElseBB);
   1033   return PN;
   1034 }
   1035 
   1036 Value *ForExprAST::Codegen() {
   1037   // Output this as:
   1038   //   var = alloca double
   1039   //   ...
   1040   //   start = startexpr
   1041   //   store start -> var
   1042   //   goto loop
   1043   // loop:
   1044   //   ...
   1045   //   bodyexpr
   1046   //   ...
   1047   // loopend:
   1048   //   step = stepexpr
   1049   //   endcond = endexpr
   1050   //
   1051   //   curvar = load var
   1052   //   nextvar = curvar + step
   1053   //   store nextvar -> var
   1054   //   br endcond, loop, endloop
   1055   // outloop:
   1056 
   1057   Function *TheFunction = Builder.GetInsertBlock()->getParent();
   1058 
   1059   // Create an alloca for the variable in the entry block.
   1060   AllocaInst *Alloca = CreateEntryBlockAlloca(TheFunction, VarName);
   1061 
   1062   KSDbgInfo.emitLocation(this);
   1063 
   1064   // Emit the start code first, without 'variable' in scope.
   1065   Value *StartVal = Start->Codegen();
   1066   if (StartVal == 0)
   1067     return 0;
   1068 
   1069   // Store the value into the alloca.
   1070   Builder.CreateStore(StartVal, Alloca);
   1071 
   1072   // Make the new basic block for the loop header, inserting after current
   1073   // block.
   1074   BasicBlock *LoopBB =
   1075       BasicBlock::Create(getGlobalContext(), "loop", TheFunction);
   1076 
   1077   // Insert an explicit fall through from the current block to the LoopBB.
   1078   Builder.CreateBr(LoopBB);
   1079 
   1080   // Start insertion in LoopBB.
   1081   Builder.SetInsertPoint(LoopBB);
   1082 
   1083   // Within the loop, the variable is defined equal to the PHI node.  If it
   1084   // shadows an existing variable, we have to restore it, so save it now.
   1085   AllocaInst *OldVal = NamedValues[VarName];
   1086   NamedValues[VarName] = Alloca;
   1087 
   1088   // Emit the body of the loop.  This, like any other expr, can change the
   1089   // current BB.  Note that we ignore the value computed by the body, but don't
   1090   // allow an error.
   1091   if (Body->Codegen() == 0)
   1092     return 0;
   1093 
   1094   // Emit the step value.
   1095   Value *StepVal;
   1096   if (Step) {
   1097     StepVal = Step->Codegen();
   1098     if (StepVal == 0)
   1099       return 0;
   1100   } else {
   1101     // If not specified, use 1.0.
   1102     StepVal = ConstantFP::get(getGlobalContext(), APFloat(1.0));
   1103   }
   1104 
   1105   // Compute the end condition.
   1106   Value *EndCond = End->Codegen();
   1107   if (EndCond == 0)
   1108     return EndCond;
   1109 
   1110   // Reload, increment, and restore the alloca.  This handles the case where
   1111   // the body of the loop mutates the variable.
   1112   Value *CurVar = Builder.CreateLoad(Alloca, VarName.c_str());
   1113   Value *NextVar = Builder.CreateFAdd(CurVar, StepVal, "nextvar");
   1114   Builder.CreateStore(NextVar, Alloca);
   1115 
   1116   // Convert condition to a bool by comparing equal to 0.0.
   1117   EndCond = Builder.CreateFCmpONE(
   1118       EndCond, ConstantFP::get(getGlobalContext(), APFloat(0.0)), "loopcond");
   1119 
   1120   // Create the "after loop" block and insert it.
   1121   BasicBlock *AfterBB =
   1122       BasicBlock::Create(getGlobalContext(), "afterloop", TheFunction);
   1123 
   1124   // Insert the conditional branch into the end of LoopEndBB.
   1125   Builder.CreateCondBr(EndCond, LoopBB, AfterBB);
   1126 
   1127   // Any new code will be inserted in AfterBB.
   1128   Builder.SetInsertPoint(AfterBB);
   1129 
   1130   // Restore the unshadowed variable.
   1131   if (OldVal)
   1132     NamedValues[VarName] = OldVal;
   1133   else
   1134     NamedValues.erase(VarName);
   1135 
   1136   // for expr always returns 0.0.
   1137   return Constant::getNullValue(Type::getDoubleTy(getGlobalContext()));
   1138 }
   1139 
   1140 Value *VarExprAST::Codegen() {
   1141   std::vector<AllocaInst *> OldBindings;
   1142 
   1143   Function *TheFunction = Builder.GetInsertBlock()->getParent();
   1144 
   1145   // Register all variables and emit their initializer.
   1146   for (unsigned i = 0, e = VarNames.size(); i != e; ++i) {
   1147     const std::string &VarName = VarNames[i].first;
   1148     ExprAST *Init = VarNames[i].second;
   1149 
   1150     // Emit the initializer before adding the variable to scope, this prevents
   1151     // the initializer from referencing the variable itself, and permits stuff
   1152     // like this:
   1153     //  var a = 1 in
   1154     //    var a = a in ...   # refers to outer 'a'.
   1155     Value *InitVal;
   1156     if (Init) {
   1157       InitVal = Init->Codegen();
   1158       if (InitVal == 0)
   1159         return 0;
   1160     } else { // If not specified, use 0.0.
   1161       InitVal = ConstantFP::get(getGlobalContext(), APFloat(0.0));
   1162     }
   1163 
   1164     AllocaInst *Alloca = CreateEntryBlockAlloca(TheFunction, VarName);
   1165     Builder.CreateStore(InitVal, Alloca);
   1166 
   1167     // Remember the old variable binding so that we can restore the binding when
   1168     // we unrecurse.
   1169     OldBindings.push_back(NamedValues[VarName]);
   1170 
   1171     // Remember this binding.
   1172     NamedValues[VarName] = Alloca;
   1173   }
   1174 
   1175   KSDbgInfo.emitLocation(this);
   1176 
   1177   // Codegen the body, now that all vars are in scope.
   1178   Value *BodyVal = Body->Codegen();
   1179   if (BodyVal == 0)
   1180     return 0;
   1181 
   1182   // Pop all our variables from scope.
   1183   for (unsigned i = 0, e = VarNames.size(); i != e; ++i)
   1184     NamedValues[VarNames[i].first] = OldBindings[i];
   1185 
   1186   // Return the body computation.
   1187   return BodyVal;
   1188 }
   1189 
   1190 Function *PrototypeAST::Codegen() {
   1191   // Make the function type:  double(double,double) etc.
   1192   std::vector<Type *> Doubles(Args.size(),
   1193                               Type::getDoubleTy(getGlobalContext()));
   1194   FunctionType *FT =
   1195       FunctionType::get(Type::getDoubleTy(getGlobalContext()), Doubles, false);
   1196 
   1197   Function *F =
   1198       Function::Create(FT, Function::ExternalLinkage, Name, TheModule);
   1199 
   1200   // If F conflicted, there was already something named 'Name'.  If it has a
   1201   // body, don't allow redefinition or reextern.
   1202   if (F->getName() != Name) {
   1203     // Delete the one we just made and get the existing one.
   1204     F->eraseFromParent();
   1205     F = TheModule->getFunction(Name);
   1206 
   1207     // If F already has a body, reject this.
   1208     if (!F->empty()) {
   1209       ErrorF("redefinition of function");
   1210       return 0;
   1211     }
   1212 
   1213     // If F took a different number of args, reject.
   1214     if (F->arg_size() != Args.size()) {
   1215       ErrorF("redefinition of function with different # args");
   1216       return 0;
   1217     }
   1218   }
   1219 
   1220   // Set names for all arguments.
   1221   unsigned Idx = 0;
   1222   for (Function::arg_iterator AI = F->arg_begin(); Idx != Args.size();
   1223        ++AI, ++Idx)
   1224     AI->setName(Args[Idx]);
   1225 
   1226   // Create a subprogram DIE for this function.
   1227   DIFile Unit = DBuilder->createFile(KSDbgInfo.TheCU->getFilename(),
   1228                                      KSDbgInfo.TheCU->getDirectory());
   1229   MDScope *FContext = Unit;
   1230   unsigned LineNo = Line;
   1231   unsigned ScopeLine = Line;
   1232   DISubprogram SP = DBuilder->createFunction(
   1233       FContext, Name, StringRef(), Unit, LineNo,
   1234       CreateFunctionType(Args.size(), Unit), false /* internal linkage */,
   1235       true /* definition */, ScopeLine, DebugNode::FlagPrototyped, false, F);
   1236 
   1237   KSDbgInfo.FnScopeMap[this] = SP;
   1238   return F;
   1239 }
   1240 
   1241 /// CreateArgumentAllocas - Create an alloca for each argument and register the
   1242 /// argument in the symbol table so that references to it will succeed.
   1243 void PrototypeAST::CreateArgumentAllocas(Function *F) {
   1244   Function::arg_iterator AI = F->arg_begin();
   1245   for (unsigned Idx = 0, e = Args.size(); Idx != e; ++Idx, ++AI) {
   1246     // Create an alloca for this variable.
   1247     AllocaInst *Alloca = CreateEntryBlockAlloca(F, Args[Idx]);
   1248 
   1249     // Create a debug descriptor for the variable.
   1250     DIScope *Scope = KSDbgInfo.LexicalBlocks.back();
   1251     DIFile Unit = DBuilder->createFile(KSDbgInfo.TheCU->getFilename(),
   1252                                        KSDbgInfo.TheCU->getDirectory());
   1253     DIVariable D = DBuilder->createLocalVariable(dwarf::DW_TAG_arg_variable,
   1254                                                  *Scope, Args[Idx], Unit, Line,
   1255                                                  KSDbgInfo.getDoubleTy(), Idx);
   1256 
   1257     DBuilder->insertDeclare(Alloca, D, DBuilder->createExpression(),
   1258                             DebugLoc::get(Line, 0, *Scope),
   1259                             Builder.GetInsertBlock());
   1260 
   1261     // Store the initial value into the alloca.
   1262     Builder.CreateStore(AI, Alloca);
   1263 
   1264     // Add arguments to variable symbol table.
   1265     NamedValues[Args[Idx]] = Alloca;
   1266   }
   1267 }
   1268 
   1269 Function *FunctionAST::Codegen() {
   1270   NamedValues.clear();
   1271 
   1272   Function *TheFunction = Proto->Codegen();
   1273   if (TheFunction == 0)
   1274     return 0;
   1275 
   1276   // Push the current scope.
   1277   KSDbgInfo.LexicalBlocks.push_back(&KSDbgInfo.FnScopeMap[Proto]);
   1278 
   1279   // Unset the location for the prologue emission (leading instructions with no
   1280   // location in a function are considered part of the prologue and the debugger
   1281   // will run past them when breaking on a function)
   1282   KSDbgInfo.emitLocation(nullptr);
   1283 
   1284   // If this is an operator, install it.
   1285   if (Proto->isBinaryOp())
   1286     BinopPrecedence[Proto->getOperatorName()] = Proto->getBinaryPrecedence();
   1287 
   1288   // Create a new basic block to start insertion into.
   1289   BasicBlock *BB = BasicBlock::Create(getGlobalContext(), "entry", TheFunction);
   1290   Builder.SetInsertPoint(BB);
   1291 
   1292   // Add all arguments to the symbol table and create their allocas.
   1293   Proto->CreateArgumentAllocas(TheFunction);
   1294 
   1295   KSDbgInfo.emitLocation(Body);
   1296 
   1297   if (Value *RetVal = Body->Codegen()) {
   1298     // Finish off the function.
   1299     Builder.CreateRet(RetVal);
   1300 
   1301     // Pop off the lexical block for the function.
   1302     KSDbgInfo.LexicalBlocks.pop_back();
   1303 
   1304     // Validate the generated code, checking for consistency.
   1305     verifyFunction(*TheFunction);
   1306 
   1307     // Optimize the function.
   1308     TheFPM->run(*TheFunction);
   1309 
   1310     return TheFunction;
   1311   }
   1312 
   1313   // Error reading body, remove function.
   1314   TheFunction->eraseFromParent();
   1315 
   1316   if (Proto->isBinaryOp())
   1317     BinopPrecedence.erase(Proto->getOperatorName());
   1318 
   1319   // Pop off the lexical block for the function since we added it
   1320   // unconditionally.
   1321   KSDbgInfo.LexicalBlocks.pop_back();
   1322 
   1323   return 0;
   1324 }
   1325 
   1326 //===----------------------------------------------------------------------===//
   1327 // Top-Level parsing and JIT Driver
   1328 //===----------------------------------------------------------------------===//
   1329 
   1330 static ExecutionEngine *TheExecutionEngine;
   1331 
   1332 static void HandleDefinition() {
   1333   if (FunctionAST *F = ParseDefinition()) {
   1334     if (!F->Codegen()) {
   1335       fprintf(stderr, "Error reading function definition:");
   1336     }
   1337   } else {
   1338     // Skip token for error recovery.
   1339     getNextToken();
   1340   }
   1341 }
   1342 
   1343 static void HandleExtern() {
   1344   if (PrototypeAST *P = ParseExtern()) {
   1345     if (!P->Codegen()) {
   1346       fprintf(stderr, "Error reading extern");
   1347     }
   1348   } else {
   1349     // Skip token for error recovery.
   1350     getNextToken();
   1351   }
   1352 }
   1353 
   1354 static void HandleTopLevelExpression() {
   1355   // Evaluate a top-level expression into an anonymous function.
   1356   if (FunctionAST *F = ParseTopLevelExpr()) {
   1357     if (!F->Codegen()) {
   1358       fprintf(stderr, "Error generating code for top level expr");
   1359     }
   1360   } else {
   1361     // Skip token for error recovery.
   1362     getNextToken();
   1363   }
   1364 }
   1365 
   1366 /// top ::= definition | external | expression | ';'
   1367 static void MainLoop() {
   1368   while (1) {
   1369     switch (CurTok) {
   1370     case tok_eof:
   1371       return;
   1372     case ';':
   1373       getNextToken();
   1374       break; // ignore top-level semicolons.
   1375     case tok_def:
   1376       HandleDefinition();
   1377       break;
   1378     case tok_extern:
   1379       HandleExtern();
   1380       break;
   1381     default:
   1382       HandleTopLevelExpression();
   1383       break;
   1384     }
   1385   }
   1386 }
   1387 
   1388 //===----------------------------------------------------------------------===//
   1389 // "Library" functions that can be "extern'd" from user code.
   1390 //===----------------------------------------------------------------------===//
   1391 
   1392 /// putchard - putchar that takes a double and returns 0.
   1393 extern "C" double putchard(double X) {
   1394   putchar((char)X);
   1395   return 0;
   1396 }
   1397 
   1398 /// printd - printf that takes a double prints it as "%f\n", returning 0.
   1399 extern "C" double printd(double X) {
   1400   printf("%f\n", X);
   1401   return 0;
   1402 }
   1403 
   1404 //===----------------------------------------------------------------------===//
   1405 // Main driver code.
   1406 //===----------------------------------------------------------------------===//
   1407 
   1408 int main() {
   1409   InitializeNativeTarget();
   1410   InitializeNativeTargetAsmPrinter();
   1411   InitializeNativeTargetAsmParser();
   1412   LLVMContext &Context = getGlobalContext();
   1413 
   1414   // Install standard binary operators.
   1415   // 1 is lowest precedence.
   1416   BinopPrecedence['='] = 2;
   1417   BinopPrecedence['<'] = 10;
   1418   BinopPrecedence['+'] = 20;
   1419   BinopPrecedence['-'] = 20;
   1420   BinopPrecedence['*'] = 40; // highest.
   1421 
   1422   // Prime the first token.
   1423   getNextToken();
   1424 
   1425   // Make the module, which holds all the code.
   1426   std::unique_ptr<Module> Owner = make_unique<Module>("my cool jit", Context);
   1427   TheModule = Owner.get();
   1428 
   1429   // Add the current debug info version into the module.
   1430   TheModule->addModuleFlag(Module::Warning, "Debug Info Version",
   1431                            DEBUG_METADATA_VERSION);
   1432 
   1433   // Darwin only supports dwarf2.
   1434   if (Triple(sys::getProcessTriple()).isOSDarwin())
   1435     TheModule->addModuleFlag(llvm::Module::Warning, "Dwarf Version", 2);
   1436 
   1437   // Construct the DIBuilder, we do this here because we need the module.
   1438   DBuilder = new DIBuilder(*TheModule);
   1439 
   1440   // Create the compile unit for the module.
   1441   // Currently down as "fib.ks" as a filename since we're redirecting stdin
   1442   // but we'd like actual source locations.
   1443   KSDbgInfo.TheCU = DBuilder->createCompileUnit(
   1444       dwarf::DW_LANG_C, "fib.ks", ".", "Kaleidoscope Compiler", 0, "", 0);
   1445 
   1446   // Create the JIT.  This takes ownership of the module.
   1447   std::string ErrStr;
   1448   TheExecutionEngine =
   1449       EngineBuilder(std::move(Owner))
   1450           .setErrorStr(&ErrStr)
   1451           .setMCJITMemoryManager(llvm::make_unique<SectionMemoryManager>())
   1452           .create();
   1453   if (!TheExecutionEngine) {
   1454     fprintf(stderr, "Could not create ExecutionEngine: %s\n", ErrStr.c_str());
   1455     exit(1);
   1456   }
   1457 
   1458   legacy::FunctionPassManager OurFPM(TheModule);
   1459 
   1460   // Set up the optimizer pipeline.  Start with registering info about how the
   1461   // target lays out data structures.
   1462   TheModule->setDataLayout(*TheExecutionEngine->getDataLayout());
   1463 #if 0
   1464   // Provide basic AliasAnalysis support for GVN.
   1465   OurFPM.add(createBasicAliasAnalysisPass());
   1466   // Promote allocas to registers.
   1467   OurFPM.add(createPromoteMemoryToRegisterPass());
   1468   // Do simple "peephole" optimizations and bit-twiddling optzns.
   1469   OurFPM.add(createInstructionCombiningPass());
   1470   // Reassociate expressions.
   1471   OurFPM.add(createReassociatePass());
   1472   // Eliminate Common SubExpressions.
   1473   OurFPM.add(createGVNPass());
   1474   // Simplify the control flow graph (deleting unreachable blocks, etc).
   1475   OurFPM.add(createCFGSimplificationPass());
   1476   #endif
   1477   OurFPM.doInitialization();
   1478 
   1479   // Set the global so the code gen can use this.
   1480   TheFPM = &OurFPM;
   1481 
   1482   // Run the main "interpreter loop" now.
   1483   MainLoop();
   1484 
   1485   TheFPM = 0;
   1486 
   1487   // Finalize the debug info.
   1488   DBuilder->finalize();
   1489 
   1490   // Print out all of the generated code.
   1491   TheModule->dump();
   1492 
   1493   return 0;
   1494 }
   1495