NJU Compiler of C--

Here is a compiler of C-- developed by Fqr as a project of course "Principles and Techniques of Compilers" in Nanjing University. This compiler is able to compile C-- source code into MIPS assembly code, which could be executed on SPIM Simulator.

Syntax of C--

Generally speaking, C-- looks like C, but there are some differences:

• You can only define variables at the beginning of funcitons.
• All variables are global, which means the variables in different functions are not allowed to have the same name.
• You can only use While-loop in C--, For-loop and For-each are not supported.
• Struct and high-dimension array are allowed in the process of syntax check. But they are not supported currectly at the process of generating assembly code.
• Pointer and type char are not supported, so you cannot handle string using C--.
• Structure and high-dimentsion array can not be used as return value and parameters.
• Some designs cause that recursion is not supported currenctly, but it will be fixed in the future.

Example of C-- Code

struct my_struct{
    int val;
    int list[10];
};

int main(){
    struct my_struct test[10];
    int i=0;
    while(i<10){
        int j=0;
        while(j<10){
            test[i].list[j] = read();
            j=j+1;
        }
        i=i+1;
    }

    i=0;
    while(i<10){
        int j=0;
        test[i].val = 0;
        while(j<10){
            test[i].val = test[i].val + test[i].list[j];
            j=j+1;
        }
        write(test[i].val);
        i=i+1;
    }
    return 0;
}

How to use

You can use make command to compile project and you will get a parser file which is executable.

Use:

./parser test.cmm out.s

to compile C-- code. test.cmm is C-- source code and out.s is the name of target file. Then you can run out.s on QtSPIM.

TODOs

1. Of course variables should not be global, it is so Anti-human.
2. Support of struct and high dimension array.
3. Better algorithm to sellect Registers and optimize intermediate reprensentation.
4. More operations of structure and high-dimentsion array, such as using them as parameters.
5. I know there are still a lot of bugs in my project. If you find any of them please contact me, it will be so helpful that I can fix them accordingly.