gstmt386.c

编译原理这门课确实不是很容易

/*
 * 68K/386 32-bit C compiler.
 *
 * copyright (c) 1997, David Lindauer
 * 
 * This compiler is intended for educational use.  It may not be used
 * for profit without the express written consent of the author.
 *
 * It may be freely redistributed, as long as this notice remains intact
 * and either the original sources or derived sources 
 * are distributed along with any executables derived from the originals.
 *
 * The author is not responsible for any damages that may arise from use
 * of this software, either idirect or consequential.
 *
 * v1.35 March 1997
 * David Lindauer, [e-mail]
 *
 * Credits to Mathew Brandt for original K&R C compiler
 *
 */
#include        <stdio.h>
#include        "expr.h"
#include        "c.h"
#include        "gen386.h"
#include 				"diag.h"

extern TABLE gsyms;
extern int stdaddrsize;
extern int global_flag;
extern int fsave_mask, save_mask;
extern TYP              stdfunc;
extern struct amode     push[], pop[];
extern OCODE *peep_tail, *peep_head, *peep_insert;
extern long stackdepth,framedepth;
extern SYM *currentfunc;
extern int regs[3];
extern int prm_cplusplus,prm_linkreg;
extern int firstlabel, nextlabel;
extern long lc_maxauto;

int funcfloat;

static int     breaklab;
static int     contlab;
static int     retlab;
static int diddef;
static long gswitchbottom, gswitchcount;
static long gswitchtop;

AMODE    *makedreg(int r)
/*
 *      make an address reference to a data register.
 */
{       AMODE    *ap;
        ap = xalloc(sizeof(AMODE));
        ap->mode = am_dreg;
        ap->preg = r;
        return ap;
}

AMODE    *makefreg(int r)
/*
 *      make an address reference to a data register.
 */
{       AMODE    *ap;
        ap = xalloc(sizeof(AMODE));
        ap->mode = am_freg;
        ap->preg = r;
        return ap;
}

AMODE    *make_direct(int i)
/*
 *      make a direct reference to an immediate value.
 */
{       return make_offset(makenode(en_icon,(char *)i,0));
}

AMODE    *make_strlab(char *s)
/*
 *      generate a direct reference to a string label.
 */
{       AMODE    *ap;
        ap = xalloc(sizeof(AMODE));
        ap->mode = am_direct;
        ap->offset = makenode(en_nacon,s,0);
        return ap;
}

void genwhile(SNODE *stmt)
/*
 *      generate code to evaluate a while statement.
 */
{       int     lab1, lab2, lab3;
        initstack();            /* initialize temp registers */
        lab1 = contlab;         /* save old continue label */
        contlab = nextlabel++;  /* new continue label */
        if( stmt->s1 != 0 )      /* has block */
                {
        				lab2 = breaklab;        /* save old break label */
                breaklab = nextlabel++;
								gen_code(op_jmp,0,make_label(contlab),0);
								lab3 = nextlabel++;
								gen_label(lab3);
                genstmt(stmt->s1);
								gen_label(contlab);
								if (stmt->lst)
		 							gen_line(stmt->lst);
                initstack();
                truejp(stmt->exp,lab3);
                gen_label(breaklab);
                breaklab = lab2;        /* restore old break label */
                }
        else					        /* no loop code */
                {
								if (stmt->lst)
		 							gen_line(stmt->lst);
        				gen_label(contlab);
                initstack();
                truejp(stmt->exp,contlab);
                }
        contlab = lab1;         /* restore old continue label */
}

void gen_for(SNODE *stmt)
/*
 *      generate code to evaluate a for loop
 */
{       int     old_break, old_cont, exit_label, loop_label;
        old_break = breaklab;
        old_cont = contlab;
        loop_label = nextlabel++;
        exit_label = nextlabel++;
        contlab = nextlabel++;
        initstack();
        if( stmt->label != 0 )
                gen_expr(stmt->label,F_ALL | F_NOVALUE
                        ,natural_size(stmt->label));
				
        gen_code(op_jmp,0,make_label(contlab),0);
        gen_label(loop_label);
        if( stmt->s1 != 0 ) {
								breaklab = exit_label;
                genstmt(stmt->s1);
				}
        initstack();
        if( stmt->s2 != 0 )
                gen_expr(stmt->s2,F_ALL | F_NOVALUE,natural_size(stmt->s2));
				gen_label(contlab);
				if (stmt->lst)
		 			gen_line(stmt->lst);
        initstack();
        if( stmt->exp != 0 )
                truejp(stmt->exp,loop_label);
				else
						gen_code(op_jmp,0,make_label(loop_label),0);
				gen_label(exit_label);
 				breaklab = old_break;
				contlab = old_cont;
}

void genif(SNODE *stmt)
/*
 *      generate code to evaluate an if statement.
 */
{       int     lab1, lab2;
        lab1 = nextlabel++;     /* else label */
        lab2 = nextlabel++;     /* exit label */
        initstack();            /* clear temps */
        falsejp(stmt->exp,lab1);
        genstmt(stmt->s1);
        if( stmt->s2 != 0 )             /* else part exists */
                {
                gen_code(op_jmp,0,make_label(lab2),0);
                gen_label(lab1);
                genstmt(stmt->s2);
                gen_label(lab2);
                }
        else                            /* no else code */
                gen_label(lab1);
}

void gendo(SNODE *stmt)
/*
 *      generate code for a do - while loop.
 */
{       int     oldcont, oldbreak;
        oldcont = contlab;
        oldbreak = breaklab;
        contlab = nextlabel++;
        gen_label(contlab);
        if( stmt->s1 != 0 && stmt->s1->next != 0 )
                {
                breaklab = nextlabel++;
                genstmt(stmt->s1);      /* generate body */
                initstack();
                truejp(stmt->exp,contlab);
                gen_label(breaklab);
                }
        else
                {
                genstmt(stmt->s1);
                initstack();
                truejp(stmt->exp,contlab);
                }
        breaklab = oldbreak;
        contlab = oldcont;
}

AMODE *set_symbol(char *name,int flag)
{
	SYM *sp;
	AMODE *ap;
        sp = gsearch(name);
        if( sp == 0 )
                {
                ++global_flag;
                sp = xalloc(sizeof(SYM));
                sp->tp = &stdfunc;
                sp->name = name;
								if (flag)
									sp->storage_class = sc_externalfunc;
								else
                	sp->storage_class = sc_external;
								sp->extflag = 1;
                insert(sp,&gsyms);
                --global_flag;
                }
				ap = make_strlab(name);
				ap->mode = am_immed;
	return ap;
}
void call_library(char *lib_name)
/*
 *      generate a call to a library routine.
 */
{
				AMODE *ap;
				ap = set_symbol(lib_name,1);
        gen_code(op_call,0,ap,0);
}

int analyzeswitch(SNODE *stmt)
{
	gswitchbottom = 0x7fffffff;
	gswitchtop = 0x80000000;
	gswitchcount = 0;
	stmt = stmt->s1;
	while (stmt) {
		if (!stmt->s2) {
			gswitchcount++;
			if ((long)stmt->label < gswitchbottom)
				gswitchbottom = (int)stmt->label;
			if ((long)stmt->label > gswitchtop)
				gswitchtop = (int)stmt->label;
		}
		stmt = stmt->next;
	}
	gswitchtop++;
	if (gswitchcount == 0)
		return(0);
	if (gswitchcount > 3)
		if (gswitchcount*10/(gswitchtop-gswitchbottom) >= 8)
			return(1);
	return(2);
}
void bingen(int lower, int avg, int higher,AMODE *ap1, int deflab, int size,long * switchids,int * switchlabels,int *switchbinlabels)
{
	AMODE *ap2 = make_immed(switchids[avg]);
	AMODE *ap3 = make_label(switchlabels[avg]);
	if (switchbinlabels[avg] != -1)
		gen_label(switchbinlabels[avg]);
	gen_code(op_cmp,4,ap1,ap2);
	gen_code(op_je,0,ap3,0);
	if (avg == lower) {
		ap3 = make_label(deflab);
		gen_code(op_jmp,0,ap3,0);
	}
	else {
		int avg1 = (lower + avg)/2;
		int avg2 = (higher + avg+1)/2;
		if (avg+1 < higher) 
			ap3 = make_label(switchbinlabels[avg2]=nextlabel++);
		else
			ap3 = make_label(deflab);
		if (size < 0)
			gen_code(op_jg,0,ap3,0);
		else
			gen_code(op_ja,0,ap3,0);
		bingen(lower,avg1,avg,ap1,deflab,size,switchids,switchlabels,switchbinlabels);
		if (avg+1 < higher)
			bingen(avg+1,avg2,higher,ap1,deflab,size,switchids,switchlabels,switchbinlabels);
	}
}
void genbinaryswitch(SNODE *stmt, int deflab)
{
	int curlab, i=0,j,size = natural_size(stmt->exp);
	AMODE *ap1;
  long switchbottom=gswitchbottom, switchcount=gswitchcount;
  long switchtop=gswitchtop;
  int *switchlabels=0;
  long *switchids=0;
  int *switchbinlabels=0;
	curlab = nextlabel++;
  initstack();
  ap1 = gen_expr(stmt->exp,F_DREG,4);
	global_flag++;
		switchlabels = xalloc((switchcount) * sizeof(int));
		switchbinlabels = xalloc((switchcount) * sizeof(int));
		switchids = xalloc((switchcount) * sizeof(long));
	global_flag--;
	stmt = stmt->s1;
	while (stmt) {
                if( stmt->s2 )          /* default case ? */
                        {
                        stmt->label = (SNODE *) deflab;
												diddef = TRUE;
                        }
                else
                        {
												switchlabels[i] = curlab;
												switchbinlabels[i] = -1;
												switchids[i++] = (int)stmt->label;
												stmt->label = (SNODE *)curlab;
                        }
                if( stmt->next != 0 )
                        curlab = nextlabel++;
                stmt = stmt->next;