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
  -i arg                Input CMM File Path
  -o arg (=a.out)       Output ASM File Path
  -r arg                Input ASM 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 ::= Decl { Decl }

2. Decl ::= VarDecl
          | FuncDecl

3. VarDecl ::= Type ID [ '[' Number ']' ] ';'

4. Type ::= int
          | void

5. FuncDecl ::= Type ID '(' ParamList ')' '{' LocalDecl StmtList '}'

6. ParamList ::= [ Param { ',' Param } ]

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

8. LocalDecl ::= { VarDecl }

9. StmtList ::= { Stmt }

10. Stmt ::= ExprStmt
           | IfStmt
           | WhileStmt
           | ReturnStmt

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

12. IfStmt ::= if '(' Expr ')' '{' StmtList '}' [ else '{' StmtList '}' ]

13. WhileStmt ::= while '(' Expr ')' '{' StmtList '}'

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

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

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

17. SimpleExpr ::= AddExpr [ RelOp AddExpr ]

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

19. AddExpr ::= Term { AddOp Term }

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

21. Term ::= Factor { MulOp Factor }

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

23. Factor ::= '(' Expr ')'
             | Number
             | Call
             | Var

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

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

VM

Here is the VM model of the CMM language:

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

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