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