txt.c

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

#include "gc.h"

void
ginit(void)
{
	int i;
	Type *t;

	thechar = '8';
	thestring = "386";
	exregoffset = 0;
	exfregoffset = 0;
	listinit();
	nstring = 0;
	mnstring = 0;
	nrathole = 0;
	pc = 0;
	breakpc = -1;
	continpc = -1;
	cases = C;
	firstp = P;
	lastp = P;
	tfield = types[TLONG];

	zprog.link = P;
	zprog.as = AGOK;
	zprog.from.type = D_NONE;
	zprog.from.index = D_NONE;
	zprog.from.scale = 0;
	zprog.to = zprog.from;

	regnode.op = OREGISTER;
	regnode.class = CEXREG;
	regnode.reg = REGTMP;
	regnode.complex = 0;
	regnode.addable = 11;
	regnode.type = types[TLONG];

	fregnode0 = regnode;
	fregnode0.reg = D_F0;
	fregnode0.type = types[TDOUBLE];

	fregnode1 = fregnode0;
	fregnode1.reg = D_F0+1;

	constnode.op = OCONST;
	constnode.class = CXXX;
	constnode.complex = 0;
	constnode.addable = 20;
	constnode.type = types[TLONG];

	fconstnode.op = OCONST;
	fconstnode.class = CXXX;
	fconstnode.complex = 0;
	fconstnode.addable = 20;
	fconstnode.type = types[TDOUBLE];

	nodsafe = new(ONAME, Z, Z);
	nodsafe->sym = slookup(".safe");
	nodsafe->type = types[TINT];
	nodsafe->etype = types[TINT]->etype;
	nodsafe->class = CAUTO;
	complex(nodsafe);

	t = typ(TARRAY, types[TCHAR]);
	symrathole = slookup(".rathole");
	symrathole->class = CGLOBL;
	symrathole->type = t;

	nodrat = new(ONAME, Z, Z);
	nodrat->sym = symrathole;
	nodrat->type = types[TIND];
	nodrat->etype = TVOID;
	nodrat->class = CGLOBL;
	complex(nodrat);
	nodrat->type = t;

	nodret = new(ONAME, Z, Z);
	nodret->sym = slookup(".ret");
	nodret->type = types[TIND];
	nodret->etype = TIND;
	nodret->class = CPARAM;
	nodret = new(OIND, nodret, Z);
	complex(nodret);

	com64init();

	for(i=0; i<nelem(reg); i++) {
		reg[i] = 1;
		if(i >= D_AX && i <= D_DI && i != D_SP)
			reg[i] = 0;
	}
}

void
gclean(void)
{
	int i;
	Sym *s;

	reg[D_SP]--;
	for(i=D_AX; i<=D_DI; i++)
		if(reg[i])
			diag(Z, "reg %R left allocated", i);
	while(mnstring)
		outstring("", 1L);
	symstring->type->width = nstring;
	symrathole->type->width = nrathole;
	for(i=0; i<NHASH; i++)
	for(s = hash[i]; s != S; s = s->link) {
		if(s->type == T)
			continue;
		if(s->type->width == 0)
			continue;
		if(s->class != CGLOBL && s->class != CSTATIC)
			continue;
		if(s->type == types[TENUM])
			continue;
		gpseudo(AGLOBL, s, nodconst(s->type->width));
	}
	nextpc();
	p->as = AEND;
	outcode();
}

void
nextpc(void)
{

	p = alloc(sizeof(*p));
	*p = zprog;
	p->lineno = nearln;
	pc++;
	if(firstp == P) {
		firstp = p;
		lastp = p;
		return;
	}
	lastp->link = p;
	lastp = p;
}

void
gargs(Node *n, Node *tn1, Node *tn2)
{
	long regs;
	Node fnxargs[20], *fnxp;

	regs = cursafe;

	fnxp = fnxargs;
	garg1(n, tn1, tn2, 0, &fnxp);	/* compile fns to temps */

	curarg = 0;
	fnxp = fnxargs;
	garg1(n, tn1, tn2, 1, &fnxp);	/* compile normal args and temps */

	cursafe = regs;
}

int nareg(void)
{
	int i, n;

	n = 0;
	for(i=D_AX; i<=D_DI; i++)
		if(reg[i] == 0)
			n++;
	return n;
}

void
garg1(Node *n, Node *tn1, Node *tn2, int f, Node **fnxp)
{
	Node nod;

	if(n == Z)
		return;
	if(n->op == OLIST) {
		garg1(n->left, tn1, tn2, f, fnxp);
		garg1(n->right, tn1, tn2, f, fnxp);
		return;
	}
	if(f == 0) {
		if(n->complex >= FNX) {
			regsalloc(*fnxp, n);
			nod = znode;
			nod.op = OAS;
			nod.left = *fnxp;
			nod.right = n;
			nod.type = n->type;
			cgen(&nod, Z);
			(*fnxp)++;
		}
		return;
	}
	if(typesu[n->type->etype] || typev[n->type->etype]) {
		regaalloc(tn2, n);
		if(n->complex >= FNX) {
			sugen(*fnxp, tn2, n->type->width);
			(*fnxp)++;
		} else
			sugen(n, tn2, n->type->width);
		return;
	}
	if(REGARG>=0 && curarg == 0 && typeilp[n->type->etype]) {
		regaalloc1(tn1, n);
		if(n->complex >= FNX) {
			cgen(*fnxp, tn1);
			(*fnxp)++;
		} else
			cgen(n, tn1);
		return;
	}
	if(vconst(n) == 0) {
		regaalloc(tn2, n);
		gmove(n, tn2);
		return;
	}
	regalloc(tn1, n, Z);
	if(n->complex >= FNX) {
		cgen(*fnxp, tn1);
		(*fnxp)++;
	} else
		cgen(n, tn1);
	regaalloc(tn2, n);
	gmove(tn1, tn2);
	regfree(tn1);
}

Node*
nodconst(long v)
{
	constnode.vconst = v;
	return &constnode;
}

Node*
nodfconst(double d)
{
	fconstnode.fconst = d;
	return &fconstnode;
}

int
isreg(Node *n, int r)
{

	if(n->op == OREGISTER)
		if(n->reg == r)
			return 1;
	return 0;
}

int
nodreg(Node *n, Node *nn, int r)
{

	*n = regnode;
	n->reg = r;
	if(reg[r] == 0)
		return 0;
	if(nn != Z) {
		n->type = nn->type;
		n->lineno = nn->lineno;
		if(nn->op == OREGISTER)
		if(nn->reg == r)
			return 0;
	}
	return 1;
}

void
regret(Node *n, Node *nn)
{
	int r;

	r = REGRET;
	if(typefd[nn->type->etype])
		r = FREGRET;
	nodreg(n, nn, r);
	reg[r]++;
}

void
regalloc(Node *n, Node *tn, Node *o)
{
	int i;

	switch(tn->type->etype) {
	case TCHAR:
	case TUCHAR:
	case TSHORT:
	case TUSHORT:
	case TINT:
	case TUINT:
	case TLONG:
	case TULONG:
	case TIND:
		if(o != Z && o->op == OREGISTER) {
			i = o->reg;
			if(i >= D_AX && i <= D_DI)
				goto out;
		}
		for(i=D_AX; i<=D_DI; i++)
			if(reg[i] == 0)
				goto out;
		diag(tn, "out of fixed registers");
abort();
		goto err;

	case TFLOAT:
	case TDOUBLE:
	case TVLONG:
		i = D_F0;
		goto out;
	}
	diag(tn, "unknown type in regalloc: %T", tn->type);
err:
	i = 0;
out:
	if(i)
		reg[i]++;
	nodreg(n, tn, i);
//print("+ %R %d\n", i, reg[i]);
}

void
regialloc(Node *n, Node *tn, Node *o)
{
	Node nod;

	nod = *tn;
	nod.type = types[TIND];
	regalloc(n, &nod, o);
}

void
regfree(Node *n)
{
	int i;

	i = 0;
	if(n->op != OREGISTER && n->op != OINDREG)
		goto err;
	i = n->reg;
	if(i < 0 || i >= sizeof(reg))
		goto err;
	if(reg[i] <= 0)
		goto err;
	reg[i]--;
//print("- %R %d\n", i, reg[i]);
	return;
err:
	diag(n, "error in regfree: %R", i);
}

void
regsalloc(Node *n, Node *nn)
{
	cursafe = align(cursafe, nn->type, Aaut3);
	maxargsafe = maxround(maxargsafe, cursafe+curarg);
	*n = *nodsafe;
	n->xoffset = -(stkoff + cursafe);
	n->type = nn->type;
	n->etype = nn->type->etype;
	n->lineno = nn->lineno;
}

void
regaalloc1(Node *n, Node *nn)
{
	USED(nn);

	if(REGARG < 0) {
		diag(n, "regaalloc1");
		return;
	}
/* not reached 
	nodreg(n, nn, REGARG);
	reg[REGARG]++;
	curarg = align(curarg, nn->type, Aarg1);
	curarg = align(curarg, nn->type, Aarg2);
	maxargsafe = maxround(maxargsafe, cursafe+curarg);
*/
}

void
regaalloc(Node *n, Node *nn)
{
	curarg = align(curarg, nn->type, Aarg1);
	*n = *nn;
	n->op = OINDREG;
	n->reg = REGSP;
	n->xoffset = curarg;
	n->complex = 0;
	n->addable = 20;
	curarg = align(curarg, nn->type, Aarg2);
	maxargsafe = maxround(maxargsafe, cursafe+curarg);
}

void
regind(Node *n, Node *nn)
{

	if(n->op != OREGISTER) {
		diag(n, "regind not OREGISTER");
		return;
	}
	n->op = OINDREG;
	n->type = nn->type;
}

void
naddr(Node *n, Adr *a)
{
	long v;

	a->type = D_NONE;
	if(n == Z)
		return;
	switch(n->op) {
	default:
	bad:
		diag(n, "bad in naddr: %O %D", n->op, a);
//prtree(n, "naddr");
		break;

	case OREGISTER:
		a->type = n->reg;
		a->sym = S;
		break;


	case OIND:
		naddr(n->left, a);
		if(a->type >= D_AX && a->type <= D_DI)
			a->type += D_INDIR;
		else
		if(a->type == D_CONST)
			a->type = D_NONE+D_INDIR;
		else
		if(a->type == D_ADDR) {
			a->type = a->index;
			a->index = D_NONE;
		} else
			goto bad;
		break;

	case OINDEX:
		a->type = idx.ptr;
		if(n->left->op == OADDR || n->left->op == OCONST)
			naddr(n->left, a);
		if(a->type >= D_AX && a->type <= D_DI)
			a->type += D_INDIR;
		else
		if(a->type == D_CONST)
			a->type = D_NONE+D_INDIR;
		else
		if(a->type == D_ADDR) {
			a->type = a->index;
			a->index = D_NONE;
		} else
			goto bad;
		a->index = idx.reg;
		a->scale = n->scale;
		a->offset += n->xoffset;
		break;

	case OINDREG:
		a->type = n->reg+D_INDIR;
		a->sym = S;
		a->offset = n->xoffset;
		break;

	case ONAME:
		a->etype = n->etype;
		a->type = D_STATIC;
		a->sym = n->sym;
		a->offset = n->xoffset;
		if(n->class == CSTATIC)
			break;
		if(n->class == CEXTERN || n->class == CGLOBL) {
			a->type = D_EXTERN;
			break;
		}
		if(n->class == CAUTO) {
			a->type = D_AUTO;
			break;
		}
		if(n->class == CPARAM) {
			a->type = D_PARAM;
			break;
		}
		goto bad;

	case OCONST:
		if(typefd[n->type->etype]) {
			a->type = D_FCONST;
			a->dval = n->fconst;
			break;
		}
		a->sym = S;
		a->type = D_CONST;
		a->offset = n->vconst;
		break;

	case OADDR:
		naddr(n->left, a);
		if(a->type >= D_INDIR) {
			a->type -= D_INDIR;
			break;
		}
		if(a->type == D_EXTERN || a->type == D_STATIC ||
		   a->type == D_AUTO || a->type == D_PARAM)
			if(a->index == D_NONE) {
				a->index = a->type;
				a->type = D_ADDR;
				break;
			}
		goto bad;

	case OADD:
		if(n->right->op == OCONST) {
			v = n->right->vconst;
			naddr(n->left, a);
		} else
		if(n->left->op == OCONST) {
			v = n->left->vconst;
			naddr(n->right, a);
		} else
			goto bad;
		a->offset += v;
		break;

	}
}

#define	CASE(a,b)	((a<<8)|(b<<0))

void
gmove(Node *f, Node *t)
{
	int ft, tt, a;
	Node nod, nod1;
	Prog *p1;

	ft = f->type->etype;
	tt = t->type->etype;
	if(debug['M'])
		print("gop: %O %O[%s],%O[%s]\n", OAS,
			f->op, tnames[ft], t->op, tnames[tt]);
	if(typefd[ft] && f->op == OCONST) {
		if(f->fconst == 0)
			gins(AFLDZ, Z, Z);
		else
		if(f->fconst == 1)
			gins(AFLD1, Z, Z);
		else
			gins(AFMOVD, f, &fregnode0);
		gmove(&fregnode0, t);
		return;
	}
/*
 * load
 */
	if(f->op == ONAME || f->op == OINDREG ||
	   f->op == OIND || f->op == OINDEX)
	switch(ft) {
	case TCHAR:
		a = AMOVBLSX;
		goto ld;
	case TUCHAR:
		a = AMOVBLZX;
		goto ld;
	case TSHORT:
		if(typefd[tt]) {
			gins(AFMOVW, f, &fregnode0);
			gmove(&fregnode0, t);
			return;
		}
		a = AMOVWLSX;
		goto ld;
	case TUSHORT:
		a = AMOVWLZX;
		goto ld;
	case TINT:
	case TUINT:
	case TLONG:
	case TULONG:
	case TIND:
		if(typefd[tt]) {
			gins(AFMOVL, f, &fregnode0);
			gmove(&fregnode0, t);
			return;
		}
		a = AMOVL;

	ld:
		regalloc(&nod, f, t);
		nod.type = types[TLONG];
		gins(a, f, &nod);
		gmove(&nod, t);
		regfree(&nod);
		return;

	case TFLOAT:
		gins(AFMOVF, f, t);
		return;
	case TDOUBLE:
		gins(AFMOVD, f, t);
		return;
	case TVLONG:
		gins(AFMOVV, f, t);
		return;
	}

/*
 * store
 */
	if(t->op == ONAME || t->op == OINDREG ||
	   t->op == OIND || t->op == OINDEX)
	switch(tt) {
	case TCHAR:
	case TUCHAR:
		a = AMOVB;	goto st;
	case TSHORT:
	case TUSHORT:
		a = AMOVW;	goto st;
	case TINT:
	case TUINT:
	case TLONG:
	case TULONG:
	case TIND:
		a = AMOVL;	goto st;

	st:
		if(f->op == OCONST) {
			gins(a, f, t);
			return;
		}
		regalloc(&nod, t, f);
		gmove(f, &nod);
		gins(a, &nod, t);
		regfree(&nod);
		return;

	case TFLOAT:
		gins(AFMOVFP, f, t);
		return;
	case TDOUBLE:
		gins(AFMOVDP, f, t);
		return;
	case TVLONG:
		gins(AFMOVVP, f, t);
		return;
	}

/*
 * convert
 */
	switch(CASE(ft,tt)) {
	default:
/*
 * integer to integer
 ********
		a = AGOK;	break;

	case CASE(	TCHAR,	TCHAR):
	case CASE(	TUCHAR,	TCHAR):
	case CASE(	TSHORT,	TCHAR):
	case CASE(	TUSHORT,TCHAR):
	case CASE(	TINT,	TCHAR):
	case CASE(	TUINT,	TCHAR):
	case CASE(	TLONG,	TCHAR):
	case CASE(	TULONG,	TCHAR):
	case CASE(	TIND,	TCHAR):

	case CASE(	TCHAR,	TUCHAR):
	case CASE(	TUCHAR,	TUCHAR):
	case CASE(	TSHORT,	TUCHAR):
	case CASE(	TUSHORT,TUCHAR):
	case CASE(	TINT,	TUCHAR):
	case CASE(	TUINT,	TUCHAR):
	case CASE(	TLONG,	TUCHAR):
	case CASE(	TULONG,	TUCHAR):
	case CASE(	TIND,	TUCHAR):

	case CASE(	TSHORT,	TSHORT):
	case CASE(	TUSHORT,TSHORT):
	case CASE(	TINT,	TSHORT):
	case CASE(	TUINT,	TSHORT):
	case CASE(	TLONG,	TSHORT):
	case CASE(	TULONG,	TSHORT):
	case CASE(	TIND,	TSHORT):

	case CASE(	TSHORT,	TUSHORT):
	case CASE(	TUSHORT,TUSHORT):
	case CASE(	TINT,	TUSHORT):
	case CASE(	TUINT,	TUSHORT):
	case CASE(	TLONG,	TUSHORT):
	case CASE(	TULONG,	TUSHORT):
	case CASE(	TIND,	TUSHORT):

	case CASE(	TINT,	TINT):