CMM

Introduction

CMM (C Minus Minus) language compiler and VM.

Dependencies

• C++17 compiler
• boost

Installation

To compile CMM, make sure the location is in the CMM/src directory and simply run the following commands:

make

The executable file CMM will be created in CMM/bin/CMM.

In addition, "make debug" is used to compile with the debug mode:

make debug

Use "make clean" to remove the installation:

make clean

Getting Help

Command "CMM -h" or "CMM --help" is used to get the help information:

================================================================================

CMM
===

    CMM (C Minus Minus) Language Compiler And VM.

================================================================================

Usage:
  -h [ --help ]         show this help message and exit
  -c arg                Input CMM File Path
  -s arg                Output ASM File Path
  -o arg (=a.out)       Output Byte Code File Path
  -r arg                Input Byte Code File Path (For Running)

Sample files

There are two sample code files written by the CMM language in the CMM/test/testA.cmm and the CMM/test/testB.cmm.

CMM Language Grammar

Here is the CMM language grammar in EBNF format:

1. Program ::= DeclList

2. DeclList ::= Decl { Decl }

3. Decl ::= VarDecl
          | FuncDecl

4. VarDecl ::= Type ID [ '[' NUM ']' ] ';'

5. Type ::= int
          | void

6. FuncDecl ::= Type ID '(' Params ')' CompoundStmt

7. Params ::= [ ParamList ]

8. ParamList ::= Param { ',' Param }

9. Param ::= Type ID [ '[' ']' ]

10. CompoundStmt ::= '{' LocalDecl StmtList '}'

11. LocalDecl ::= { VarDecl }

12. StmtList ::= { Stmt }

13. Stmt ::= ExprStmt
           | CompoundStmt
           | IfStmt
           | WhileStmt
           | ReturnStmt

14. ExprStmt ::= [ Expr ] ';'

15. IfStmt ::= if '(' Expr ')' Stmt [ else Stmt ]

16. WhileStmt ::= while '(' Expr ')' Stmt

17. ReturnStmt ::= return [ Expr ] ';'

18. Expr ::= Var '=' Expr
           | SimpleExpr

19. Var ::= ID [ '[' Expr ']' ]

20. SimpleExpr ::= AddExpr [ RelOp AddExpr ]

21. RelOp ::= '<'
            | '<='
            | '>'
            | '>='
            | '=='
            | '!='

22. AddExpr ::= Term { AddOp Term }

23. AddOp ::= '+'
            | '-'

24. Term ::= Factor { MulOp Factor }

25. MulOp ::= '*'
            | '/'

26. Factor ::= '(' Expr ')'
             | Var
             | Call
             | NUM

27. Call ::= ID '(' [ ArgList ] ')'

28. ArgList ::= Expr { ',' Expr }

VM

Here is the VM model of the CMM language:

+----+    +----+
| SS |    | CS |
+----+    +----+
| .. |    | .. |
+----+    +----+    +----+
| .. |    | .. | <= | IP |
+----+    +----+    +----+
  ..        ..

CMM VM use only one SS to store all the data.

Instruction Set

Here is the instruction set and the fake code of each instruction of the CMM language:

Instruction	Fake Code
LDC N	SS[0] = N
LD	SS[0] = SS[SS[1] - SS[0]]
ALD	SS[0] = SS[SS[0]]
ST	SS[SS[1] - SS[0]] = SS.TOP()
AST	SS[SS[0]] = SS.TOP()
PUSH	SS.PUSH(SS[0])
POP	SS.POP()
JMP N	IP += N
JZ N	if (SS[0] == 0) IP += N
ADD	SS[0] = SS.TOP() + SS[0]
SUB	SS[0] = SS.TOP() - SS[0]
MUL	SS[0] = SS.TOP() * SS[0]
DIV	SS[0] = SS.TOP() / SS[0]
LT	SS[0] = SS.TOP() < SS[0]
LE	SS[0] = SS.TOP() <= SS[0]
GT	SS[0] = SS.TOP() > SS[0]
GE	SS[0] = SS.TOP() >= SS[0]
EQ	SS[0] = SS.TOP() == SS[0]
NE	SS[0] = SS.TOP() != SS[0]
IN	scanf("%d", &SS[0])
OUT	printf("%d\n", SS[0])
ADDR N	SS[0] = SS.SIZE() - N
CALL N	SS.PUSH(SS[1]); SS[1] = SS.SIZE(); SS.PUSH(IP); IP += N
RET	IP = SS.POP(); SS[1] = SS.POP()