an386.c

C编译器 ,简单的一个C语言的编译器。

/*
 * 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
 *
 */
/*
 * Register analysis
 */
#include        <stdio.h>
#include        "expr.h"
#include        "c.h"
#include        "gen386.h"
#include 				"diag.h"

/* pc-relative expressions not optimized */
extern AMODE    push[], pop[];
extern OCODE    *peep_tail;
extern SYM *currentfunc;
extern int prm_stackcheck,prm_linkreg;
extern int floatregs,dataregs,addrregs;
extern long framedepth,stackdepth;
extern int cf_maxfloat, cf_maxaddress,cf_maxdata,cf_freeaddress,cf_freedata,cf_freefloat;
extern CSE       *olist;         /* list of optimizable expressions */

long lc_maxauto;
int  fsave_mask,save_mask;
void reserveregs(int *datareg, int *addreg, int *floatreg)
/*
 * Reserve regs goes through and reserves a register for variables with
 * the REGISTER keyword.  Note that it currently does register allocation
 * backwards...  NOT the standard I suspect.
 */
{
	CSE *csp = olist;

	while (csp) {
		switch (csp->exp->nodetype) {
								case en_floatref:
								case en_doubleref:
								case en_longdoubleref:
										break;
                case en_b_ref:
                case en_w_ref:
                case en_l_ref:
                case en_ub_ref:
                case en_uw_ref:
								case en_ul_ref:
										if (csp->exp->v.p[0]->nodetype != en_autoreg)		
											break;
								  		if (csp->exp->nodetype == en_floatref || csp->exp->nodetype == en_doubleref 
												|| csp->exp->nodetype == en_longdoubleref) {
											}
            			    else if( (csp->duses <= csp->uses / 4) && (*datareg < cf_maxdata) &&dataregs)
                        csp->reg = (*datareg)++;
			                else if(!(csp->size ==-1 || csp->size ==1) && (*addreg < cf_maxaddress) && addrregs) {
                        csp->reg = (*addreg)++;
											}
											if (csp->reg != -1) {
												((SYM *)csp->exp->v.p[0]->v.p[0])->inreg = TRUE;
												((SYM *)csp->exp->v.p[0]->v.p[0])->value.i = -csp->reg;
											}
											break;
		}
		csp = csp->next;
	}
}	

void allocate(int datareg, int addreg, int floatreg, SNODE *block )
/*
 *      allocate will allocate registers for the expressions that have
 *      a high enough desirability.  It also puts the function
 * header, consisting of saved registers and stack decrments for local
 * variables
 */
{       CSE      *csp;
        ENODE    *exptr;
        unsigned      mask, rmask,i,fmask,frmask,size;
        AMODE    *ap, *ap2;
				framedepth = 4;
        mask = 0;
				rmask = 0;
				fmask = frmask = 0;
				for (i=cf_freedata; i < datareg; i++) {
						rmask = rmask | (1 << (15 - i));
                        mask = mask | (1 << i);
				}
				for (i=cf_freeaddress+16; i < addreg; i++) {
						rmask = rmask | (1 << (23 - i));
                        mask = mask | (1 << (i-8));
				}
        while( bsort(&olist) );         /* sort the expression list */
        csp = olist;
        while( csp != 0 ) {
						if (csp->reg == -1 && !(csp->exp->cflags & DF_VOL) && !csp->voidf) {
                if( desire(csp) < 3 )
                        csp->reg = -1;
								else {
									if (csp->exp->nodetype == en_rcon || csp->exp->nodetype == en_fcon || csp->exp->nodetype == en_lrcon
								  			|| csp->exp->nodetype == en_floatref || csp->exp->nodetype ==en_doubleref
												|| csp->exp->nodetype == en_longdoubleref) {
									}
            			else if( (csp->duses <= csp->uses / 4) && (datareg < cf_maxdata) &&dataregs)
                  	csp->reg = (datareg)++;
	                else if( (!(csp->size == 1 || csp->size == -1) || csp->exp->nodetype == en_icon) && (addreg < cf_maxaddress) && addrregs) {
  	                csp->reg = (addreg)++;
									}
								}
						}
            if( csp->reg != -1 )
				{
						if (lvalue(csp->exp) && !((SYM *)csp->exp->v.p[0]->v.p[0])->funcparm) {
							((SYM *)csp->exp->v.p[0]->v.p[0])->inreg = TRUE;
							((SYM *)csp->exp->v.p[0]->v.p[0])->value.i = -csp->reg;
						}
						if (csp->reg < 16) {
							rmask = rmask | (1 << (15 - csp->reg));
                        mask = mask | (1 << csp->reg);
						}
						if (csp->reg < 32) {
							rmask = rmask | (1 << (23 - csp->reg));
                        mask = mask | (1 << (csp->reg-8));
						}
						else {
							frmask = frmask | (1 << (39 - csp->reg));
              fmask = fmask | (1 << (csp->reg-32));
						}
				}
                csp = csp->next;
                }
				allocstack();								/* Allocate stack space for the local vars */
				if (prm_linkreg && (lc_maxauto || currentfunc->tp->lst.head && currentfunc->tp->lst.head != (SYM *)-1)) {
					gen_code(op_enter,4,make_immed(lc_maxauto),make_immed(0));
				}
				if (currentfunc->intflag) {
					gen_code(op_pushad,0,0,0);
					stackdepth = 4*8;
				}
        else
				  if( mask != 0 ) 
							pushregs(rmask);
        save_mask = mask;
				if (fmask!=0)
				fsave_mask = fmask;
				
				if (!prm_linkreg && lc_maxauto) {
					gen_code(op_sub,4,makedreg(ESP), make_immed(lc_maxauto));
				}
				stackdepth +=lc_maxauto;
				framedepth +=stackdepth;
				stackdepth = 0;
				if (prm_stackcheck) {
					AMODE *ap1;
					ap = set_symbol("_stackerror",1);
					ap1 = set_symbol("_stackbottom",0);
					ap1->mode = am_direct;
					gen_code(op_cmp,4,makedreg(ESP),ap1);
					gen_code(op_jb,0,ap,0);
				}
}
void loadregs(void)
/*
 * initialize allocated registers
 */
{       CSE      *csp;
        ENODE    *exptr;
        unsigned      mask, rmask,i,fmask,frmask,size;
        AMODE    *ap, *ap2;
        csp = olist;
        while( csp != 0 ) {
								int sz;
                if( csp->reg != -1 )
                        {               /* see if preload needed */
                        exptr = csp->exp;
                        if( !lvalue(exptr) || ((SYM *)exptr->v.p[0]->v.p[0])->funcparm )
                                {
																exptr = csp->exp;
                                initstack();
																sz = csp->size;
                                ap = gen_expr(exptr,F_ALL,sz);
                                if( csp->reg < 16 ) {
																	if (ap->mode == am_dreg)
																		peep_tail->oper1->preg = csp->reg;
																	else {
                                        ap2 = makedreg(csp->reg);
																				if (ap->mode == am_immed || sz == 4 || sz == -4)
                                					gen_code(op_mov,4,ap2,ap);
																				else
																					if (sz < 0)
																						gen_code2(op_movsx,-4,sz,ap2,ap);
																					else
																						gen_code2(op_movzx,4,sz,ap2,ap);
																	}
																}
                                else
																	if (csp->reg < 32) {
																		if (ap->mode == am_dreg)
																			peep_tail->oper1->preg = csp->reg - 12;
																		else {
  	                                      ap2 = makedreg(csp->reg - 12);
																					if (ap->mode == am_immed || sz == 4 || sz == -4)
  	                              					gen_code(op_mov,4,ap2,ap);
																					else
																						if (sz < 0)
																							gen_code2(op_movsx,-4,sz,ap2,ap);
																						else
																							gen_code2(op_movzx,4,sz,ap2,ap);