Compiler Term Project

1
Compiler Term Project

• MilkTea
• a simplified C to Java Compiler
• NTUCSIE,
• B86506010 ???
• B86506054 ???

2
Scanner

• ??? Scanner ?? flex ??
• ??????
• ???????Hand Coding,??????flex???,????regular
  expression,???escape character???(?\\?\
  ),??????code???????
• ????????escape character

3
Scanner(continue)

• ?? Identifier ??,???? Parser ???? Conflict, ????
  Semantic-Feedback Scanning,?? Scanning ????
  Semantic ??????????,???IDENTIFIER?FIDENTIFIER?TIDE
  NTIFIER,code????

4
Scanner(continue)

• a-zA-Z_a-zA-Z0-9_
• yylval.StringValue new
  TString(yytext)
• if (IsTypeName(yylval.StringValue)
  )
• return TIDENTIFIER
• else if (IsFuncName(yylval.StringV
  alue))
• return FIDENTIFIER
• else
• return IDENTIFIER

5
Scanner(continue)

• System support functions ? scanner ??????,????
  Symbol Table ?????????,? printint, printfloat,
  malloc ?,??????????

6
Parser

• Parser ?? bison ??,???? LR-parsing,?????? C ?????
  Conflict,????
• If-then-else,? Dangling-else ?????
  bison(yacc)?????? precedence ????????? ELSE (?
  shift)? Rule ?????? ELSE (? reduce)?????

7
Parser(continue)

• Struct Dec List, Func Dec List, GlobalVar Dec
  List, Func Body List???,??????????(struct
  IDENTIFIER)?? parser ?? lookahead ??????????
  reduce/reduce conflict????? Grammar
• Program StructDecList FuncDecList
  GlobalVarDecList FuncBodyList
• StructDecList Lambda StructDecList StructDec
• ???? LR Grammar,?????? Modify ???? Grammar

8
Parser(continued)

• Program InfoList
• InfoList Lambda InfoList Info
• Info StructDec FuncDec GlobalVarDec
  FuncBody
• ??? Semantic ??? check ??? Program ?????????????

9
Parser(continued)

• ???? Pointer ?????,?????????? Conflict
• Complex x
• Ab
• ??? C ????????????,????? scanner ??? IDENTIFIER
  ???????????? Semantics ???????
• struct Complex x

10
Semantics

• Semantics ?????????,??? SymbolTable ???????
• ??? Symbol Table ????? Hash Table,??? Scope ?????
  Symbol Table ????,?? Variable binding ???????
  Display ????????
• ? Type?GlobalVar?FuncDec??? GlobalSymbTbl ?,????
  Scanner ? IDENTIFIER ??????
• Symbol Table ??? Symbol Attribute ??
  Object-oriented ????? RTTI ???? Attribute ?????
  Symbol

11
Semantics(continued)

• Type ???? Symbol Table ?? Key ???,????
  Object-oriented ? RTTI???????????? Type ? Pointer
  Attribute ?? Original Type ??????(???? Original
  Type ?,Primitive Type/Struct Type ????
  TypeWithPointer)
• Array Type ???? Base ? Length,????? Pointer

12
Semantics(continued)

• ????? Expression???? Expression ????
• ??? Java VM ???,? Stack Variable
  ?????????????,????????? Local Variable?
• ????????,?? Expression SubTerm ??????????Stack(???
  ????????)???????,???? Do Operation
  ???,?????????,?? Modify ? Action Symbol ???

13
Semantics(continued)

• Add Exp1 Exp1 need to be generated here
  Exp2 Exp2 generated, do add
• ?????????,?? Exp1 ? Exp2 ? Type ??? Exp1 ?? Type
  Coercion ???? do add ???? Exp1 Swap ???do
  coercion?Swap ???do add?
• ??,?? Expression Record ????? Expression
  ???(Var?Owner on Stack ?Field?Array Info on Stack
  ? ArrayPos?Value on Stack)????? Expression
  ???????(?? Assignment ?? Load)

14
Semantics(continued)

• ?? C ?,?????? Assignment ??? Expression,?? JVM
  ?,?? Assign ???????? Stack ?,???? Modify ? Assign
  ?????
• Make sure the location of assgnment is known
• Dup the location of assignment
• Do assign
• Do load

15
Semantics(continued)

• ??,C ?? Logic Expression ?? Short-cut
  Evaluation,?? Evaluate Logic Expression
  ????????????????????????? if ? label ????
• ????? Control Structure????? Code ?????,?????
  Control Structure ? Code Generation ?????? C
  ????????,??????

16
Semantics(continued)

• if(Exp) State
• Exp0 .EndIf
• State
• EndIf

• if(Exp) State1 else State2
• Exp0 . EndIf
• State1
• EndIf
• . EndElse
• StartElse
• State2
• EndElse

17

• while(Exp) State
• StartWhile(continue)
• Exp0 . EndWhile
• State
• . StartWhile
• EndWhile(break)

• do State while(Exp)
• StartDo(continue)
• State
• Exp!0 . StartDo
• EndDo(break)

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Semantics(continue)

• for(E1E2E3) State
• E1
• Check
• E2
• . StartFor/EndFor
• UpDate(continue)
• E3
• . Check
• StartFor
• State
• . UpDate
• EndFor(break)

• switch(E1) Lstate
• Branched as many ifs
• break to end of switch

19
Semantics

• ??????? Semantics ???
• Object Allocation as in C
• Copy initializer of structures similar to C
• Struct Type Pointer accessing