driver.cc

PL/0源码

//////////////////////////////////////////////////////////////////////////////
//
//  PL/0 compiler.
//
//  Designed by Michael Scott for CSC 252/452 at the University of
//  Rochester, summer 1992.
//
//  Changed by Michal Cierniak to generate MIPS code and perform some
//  optimizations, fall 1993.
//
//  Translated into C++ by Galen C. Hunt, fall 1994.
//

#include <string>
#include <strstream>
#include "inpbuf.h"
#include "scanner.h"
#include "parser.h"
#include "symtab.h"
#include "attributes.h"
#include "codegen.h"
#include "mips.h"
#include "optimize.h"

static char     input_file[128] = "";         // use stdin by default
static char     output_file[128] = "plzero.s";
//  Default if source file not specified; otherwise build name from source.


////////
//  Remind the user how the compiler is supposed to be invoked then die.
//
static void usage_msg(string error)
{
    die_compiler(error + "\n\n"
        + "Usage:\n"
        + "  pl0 [-C] [-g] [-spim] [-sgi] [-O[+-][pc]] [file.0]\n"
        + "Options:\n"
        + "  -C    : Generate comments in assembly code.\n"
        + "  -g    : Generate code with debugging symbol.\n"
        + "  -spim : Generate spim assembly code (default).\n"
        + "  -sgi  : Generate SGI assembly code.\n"
        + "  -O+p  : Enable peephole optimization (default).\n"
        + "  -O-p  : Disable peephole optimization.\n"
        + "  -O+c  : Enable constant evaluation (default).\n"
        + "  -O-c  : Disable constant evaluation.\n");
}

////////
//  Parse command-line arguments.
//
static void parse_arguments(int argc, char **argv)
{
    char *      a;
    int         i;
    bool        toggle;
    string      error("Invalid option: ");

    for (i = 1; i < argc; i++) {
        a = argv[i];
        if (a[0] == '\0')
            usage_msg(error + "null string");
        if (a[1] == '\0')  {
            usage_msg(error + a);
        }
        if (a[0] == '-')  {
            switch (a[1]) {
            case 'C': generate_comments = true; break;
            case 'g': generate_debug_code = true; break;
            case 's':
                if (a[2] == '\0'){
                    usage_msg(error + a);
                }
                switch (a[2]) {
                case 'p' : compiler_target = T_SPIM; break;
                case 'g' : compiler_target = T_SGI; break;
                default:
                    usage_msg(error + a);
                    break;
                }
                break;
            case 'O':
                if (a[2] == '\0' || a[3] == '\0')  {
                    usage_msg(error + a);
                }
                switch (a[2]) {
                case '+' : toggle = true; break;
                case '-' : toggle = false; break;
                default:
                    usage_msg(error + a);
                    break;
                }
                switch (a[3]) {
                case 'p' : g_peep_hole_optimize = toggle; break;
                case 'c' : evaluate_consts = toggle; break;
                default:
                    usage_msg(error + a);
                } //case a[4]
                break;
            default:
                break;
            }
        }
        else { //must be input file name
            if (strlen(a) < 3) {
                usage_msg(error + a);
            }
            if (a[strlen(a)-2] != '.' || a[strlen(a)-1] != '0') {
                error = "File name does not end with `.0': ";
                usage_msg(error + a);
            }
            strcpy(input_file, a);
            strcpy(output_file, a);
            output_file[strlen(a)-1] = 's';
        }
    }
}

////////
//  Takes care of all initialization that could be done when the PL/0 compiler
//  was compiled.
//
static void initialize(void)
{
    int st_num_terminals = init_scanner();
    int pt_num_terminals = init_parser();
    assert(st_num_terminals == pt_num_terminals);
        // Scanner and parser should recognize the same number of terminals.
        // If you ever get this message you haven't used mungegrammar
        // correctly.  Check for bugs in your Makefile.

    init_input_buffer();
    init_symbol_table();
}

int main(int argc, char **argv)
{
    ifstream ins;                   // lifetime must be all of main
    parse_arguments(argc, argv);
    if (input_file[0] != '\0') {
        ins.open(input_file);
        if (!ins) {
            die_compiler(string("Unable to open input file: ")
                + string(input_file));
        }
        cin = ins;
            // read input_file as if it were standard input
    }

    initialize();

    parse();
    // dump_syntax_tree (ast_root); // For debugging only.

    if (ast_root) {
        ast_root->check_semantics(global_scope);
        // dump_syntax_tree (ast_root); // For debugging only.
    }

    if (compile_ok) {
        ast_root = optimize_syntax_tree(ast_root);
        // dump_syntax_tree (ast_root); // For debugging only.
    }

    finalize_input_buffer();

    if (compile_ok) {
        // dump_syntax_tree (ast_root); // For debugging only.
        generate_code (output_file);
        // dump_symbol_table(); // For debugging only.
    }
    else
        cout << "No code generated, due to errors.\n";

    return 0;
}

//  End of File