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

				a = AMOVFD;
			break;
		case TFLOAT:
			a = AMOVDF;
			if(ft == TFLOAT)
				a = AMOVF;
			break;
		case TINT:
		case TUINT:
		case TLONG:
		case TULONG:
		case TIND:
		case TSHORT:
		case TUSHORT:
		case TCHAR:
		case TUCHAR:
			if(fproundflg) {
				/* convert f, t */
				regalloc(&nod, f, Z);
				gins(AMOVDW, f, &nod);
				if(ft == TFLOAT)
					p->as = AMOVFW;
				gins(AMOVW, &nod, t);
				regfree(&nod);
				gins(AMOVW, t, t);
				return;
			}
			regalloc(&nod1, &regnode, Z);
			regalloc(&nod2, &regnode, Z);

			/* movw fcr, rx */
			gins(AMOVW, Z, &nod1);
			p->from.type = D_FCREG;
			p->from.reg = 31;

			/* nop */
			gins(ANOR, nodconst(0), nodconst(0));
			p->to.type = D_REG;
			p->to.reg = 0;

			/* nop */
			gins(ANOR, nodconst(0), nodconst(0));
			p->to.type = D_REG;
			p->to.reg = 0;

			/* or $3, rx, ry */
			gins(AOR, nodconst(3), &nod2);
			p->reg = nod1.reg;

			/* xor $2, ry */
			gins(AXOR, nodconst(2), &nod2);

			/* movw ry, fcr */
			gins(AMOVW, &nod2, Z);
			p->to.type = D_FCREG;
			p->to.reg = 31;

			/* nop */
			gins(ANOR, nodconst(0), nodconst(0));
			p->to.type = D_REG;
			p->to.reg = 0;

			/* nop */
			gins(ANOR, nodconst(0), nodconst(0));
			p->to.type = D_REG;
			p->to.reg = 0;

			/* convert f, t */
			regalloc(&nod, f, Z);
			gins(AMOVDW, f, &nod);
			if(ft == TFLOAT)
				p->as = AMOVFW;
			gins(AMOVW, &nod, t);
			regfree(&nod);
			gins(AMOVW, t, t);

			/* movw rx, fcr */
			gins(AMOVW, &nod1, Z);
			p->to.type = D_FCREG;
			p->to.reg = 31;

			/* nop */
			gins(ANOR, nodconst(0), nodconst(0));
			p->to.type = D_REG;
			p->to.reg = 0;

			/* nop */
			gins(ANOR, nodconst(0), nodconst(0));
			p->to.type = D_REG;
			p->to.reg = 0;

			regfree(&nod1);
			regfree(&nod2);
			return;
		}
		break;
	case TINT:
	case TUINT:
	case TLONG:
	case TULONG:
	case TIND:
		switch(tt) {
		case TDOUBLE:
		case TVLONG:
			gins(AMOVW, f, t);
			gins(AMOVWD, t, t);
			if(ft == TULONG || ft == TUINT) {
				regalloc(&nod, t, Z);
				gins(ACMPGED, t, Z);
				p->reg = FREGZERO;
				gins(ABFPT, Z, Z);
				p1 = p;
				gins(AMOVD, nodfconst(4294967296.), &nod);
				gins(AADDD, &nod, t);
				patch(p1, pc);
				regfree(&nod);
			}
			return;
		case TFLOAT:
			gins(AMOVW, f, t);
			gins(AMOVWF, t, t);
			if(ft == TULONG || ft == TUINT) {
				regalloc(&nod, t, Z);
				gins(ACMPGEF, t, Z);
				p->reg = FREGZERO;
				gins(ABFPT, Z, Z);
				p1 = p;
				gins(AMOVF, nodfconst(4294967296.), &nod);
				gins(AADDF, &nod, t);
				patch(p1, pc);
				regfree(&nod);
			}
			return;
		case TINT:
		case TUINT:
		case TLONG:
		case TULONG:
		case TIND:
		case TSHORT:
		case TUSHORT:
		case TCHAR:
		case TUCHAR:
			a = AMOVW;
			break;
		}
		break;
	case TSHORT:
		switch(tt) {
		case TDOUBLE:
		case TVLONG:
			regalloc(&nod, f, Z);
			gins(AMOVH, f, &nod);
			gins(AMOVW, &nod, t);
			gins(AMOVWD, t, t);
			regfree(&nod);
			return;
		case TFLOAT:
			regalloc(&nod, f, Z);
			gins(AMOVH, f, &nod);
			gins(AMOVW, &nod, t);
			gins(AMOVWF, t, t);
			regfree(&nod);
			return;
		case TINT:
		case TUINT:
		case TLONG:
		case TULONG:
		case TIND:
			a = AMOVH;
			break;
		case TSHORT:
		case TUSHORT:
		case TCHAR:
		case TUCHAR:
			a = AMOVW;
			break;
		}
		break;
	case TUSHORT:
		switch(tt) {
		case TDOUBLE:
		case TVLONG:
			regalloc(&nod, f, Z);
			gins(AMOVHU, f, &nod);
			gins(AMOVW, &nod, t);
			gins(AMOVWD, t, t);
			regfree(&nod);
			return;
		case TFLOAT:
			regalloc(&nod, f, Z);
			gins(AMOVHU, f, &nod);
			gins(AMOVW, &nod, t);
			gins(AMOVWF, t, t);
			regfree(&nod);
			return;
		case TINT:
		case TUINT:
		case TLONG:
		case TULONG:
		case TIND:
			a = AMOVHU;
			break;
		case TSHORT:
		case TUSHORT:
		case TCHAR:
		case TUCHAR:
			a = AMOVW;
			break;
		}
		break;
	case TCHAR:
		switch(tt) {
		case TDOUBLE:
		case TVLONG:
			regalloc(&nod, f, Z);
			gins(AMOVB, f, &nod);
			gins(AMOVW, &nod, t);
			gins(AMOVWD, t, t);
			regfree(&nod);
			return;
		case TFLOAT:
			regalloc(&nod, f, Z);
			gins(AMOVB, f, &nod);
			gins(AMOVW, &nod, t);
			gins(AMOVWF, t, t);
			regfree(&nod);
			return;
		case TINT:
		case TUINT:
		case TLONG:
		case TULONG:
		case TIND:
		case TSHORT:
		case TUSHORT:
			a = AMOVB;
			break;
		case TCHAR:
		case TUCHAR:
			a = AMOVW;
			break;
		}
		break;
	case TUCHAR:
		switch(tt) {
		case TDOUBLE:
		case TVLONG:
			regalloc(&nod, f, Z);
			gins(AMOVBU, f, &nod);
			gins(AMOVW, &nod, t);
			gins(AMOVWD, t, t);
			regfree(&nod);
			return;
		case TFLOAT:
			regalloc(&nod, f, Z);
			gins(AMOVBU, f, &nod);
			gins(AMOVW, &nod, t);
			gins(AMOVWF, t, t);
			regfree(&nod);
			return;
		case TINT:
		case TUINT:
		case TLONG:
		case TULONG:
		case TIND:
		case TSHORT:
		case TUSHORT:
			a = AMOVBU;
			break;
		case TCHAR:
		case TUCHAR:
			a = AMOVW;
			break;
		}
		break;
	}
	if(a == AGOK)
		diag(Z, "bad opcode in gmove %T -> %T", f->type, t->type);
	if(a == AMOVW || a == AMOVF || a == AMOVD)
	if(samaddr(f, t))
		return;
	gins(a, f, t);
}

void
gins(int a, Node *f, Node *t)
{

	nextpc();
	p->as = a;
	if(f != Z)
		naddr(f, &p->from);
	if(t != Z)
		naddr(t, &p->to);
	if(debug['g'])
		print("%P\n", p);
}

void
gopcode(int o, Node *f1, Node *f2, Node *t)
{
	int a, et;
	Adr ta;

	et = TLONG;
	if(f1 != Z && f1->type != T)
		et = f1->type->etype;
	a = AGOK;
	switch(o) {
	case OAS:
		gmove(f1, t);
		return;

	case OASADD:
	case OADD:
		a = AADDU;
		if(et == TFLOAT)
			a = AADDF;
		else
		if(et == TDOUBLE || et == TVLONG)
			a = AADDD;
		break;

	case OASSUB:
	case OSUB:
		a = ASUBU;
		if(et == TFLOAT)
			a = ASUBF;
		else
		if(et == TDOUBLE || et == TVLONG)
			a = ASUBD;
		break;

	case OASOR:
	case OOR:
		a = AOR;
		break;

	case OASAND:
	case OAND:
		a = AAND;
		break;

	case OASXOR:
	case OXOR:
		a = AXOR;
		break;

	case OASLSHR:
	case OLSHR:
		a = ASRL;
		break;

	case OASASHR:
	case OASHR:
		a = ASRA;
		break;

	case OASASHL:
	case OASHL:
		a = ASLL;
		break;

	case OFUNC:
		a = AJAL;
		break;

	case OCOND:
		a = ASGTU;
		break;

	case OCOMMA:
		a = ASGT;
		break;

	case OASMUL:
	case OMUL:
		if(et == TFLOAT) {
			a = AMULF;
			break;
		} else
		if(et == TDOUBLE || et == TVLONG) {
			a = AMULD;
			break;
		}
		a = AMUL;
		goto muldiv;

	case OASDIV:
	case ODIV:
		if(et == TFLOAT) {
			a = ADIVF;
			break;
		} else
		if(et == TDOUBLE || et == TVLONG) {
			a = ADIVD;
			break;
		}
		a = ADIV;
		goto muldiv;

	case OASMOD:
	case OMOD:
		a = ADIV;
		o = OMOD;
		goto muldiv;

	case OASLMUL:
	case OLMUL:
		a = AMULU;
		goto muldiv;

	case OASLMOD:
	case OLMOD:
		a = ADIVU;
		o = OMOD;
		goto muldiv;

	case OASLDIV:
	case OLDIV:
		a = ADIVU;
		goto muldiv;

	muldiv:
		nextpc();
		naddr(f1, &p->from);
		if(f2 == Z)
			raddr(t, p);
		else
			raddr(f2, p);
		p->as = a;
		if(debug['g'])
			print("%P\n", p);

		nextpc();
		p->as = AMOVW;
		a = D_LO;
		if(o == OMOD)
			a = D_HI;
		p->from.type = a;
		naddr(t, &p->to);
		if(debug['g'])
			print("%P\n", p);
		return;

	case OEQ:
		if(!typefd[et]) {
			a = ABEQ;
			break;
		}

	case ONE:
		if(!typefd[et]) {
			a = ABNE;
			break;
		}

	case OLT:
	case OLE:
	case OGE:
	case OGT:
		if(typefd[et]) {
			nextpc();
			if(et == TFLOAT) {
				a = ACMPGTF;
				if(o == OEQ || o == ONE)
					a = ACMPEQF;
				else
				if(o == OLT || o == OGE)
					a = ACMPGEF;
			} else {
				a = ACMPGTD;
				if(o == OEQ || o == ONE)
					a = ACMPEQD;
				else
				if(o == OLT || o == OGE)
					a = ACMPGED;
			}
			p->as = a;
			naddr(f1, &p->from);
			raddr(f2, p);
			if(debug['g'])
				print("%P\n", p);
			nextpc();
			a = ABFPF;
			if(o == OEQ || o == OGE || o == OGT)
				a = ABFPT;
			p->as = a;
			if(debug['g'])
				print("%P\n", p);
			return;
		}
		if(vconst(f1) == 0 || vconst(f2) == 0) {
			if(vconst(f1) == 0) {
				o = invrel[relindex(o)];
				f1 = f2;
			}
			switch(o) {
			case OLT:
				a = ABLTZ;
				break;
			case OLE:
				a = ABLEZ;
				break;
			case OGE:
				a = ABGEZ;
				break;
			case OGT:
				a = ABGTZ;
				break;
			}
			f2 = Z;
			break;
		}

	case OLO:
	case OLS:
	case OHS:
	case OHI:
		nextpc();
		if(o == OLE || o == OGT || o == OLS || o == OHI) {
			naddr(f1, &p->from);
			raddr(f2, p);
		} else {
			naddr(f2, &p->from);
			raddr(f1, p);
		}
		naddr(&regnode, &p->to);
		p->to.reg = tmpreg();
		a = ASGT;
		if(o == OLO || o == OLS || o == OHS || o == OHI)
			a = ASGTU;
		p->as = a;
		if(debug['g'])
			print("%P\n", p);

		nextpc();
		naddr(&regnode, &p->from);
		p->from.reg = tmpreg();
		a = ABEQ;
		if(o == OLT || o == OGT || o == OLO || o == OHI)
			a = ABNE;
		p->as = a;
		if(debug['g'])
			print("%P\n", p);
		return;
	}
	if(a == AGOK)
		diag(Z, "bad in gopcode %O", o);
	nextpc();
	p->as = a;
	if(f1 != Z)
		naddr(f1, &p->from);
	if(f2 != Z) {
		naddr(f2, &ta);
		p->reg = ta.reg;
		if(ta.type == D_CONST && ta.offset == 0)
			p->reg = REGZERO;
	}
	if(t != Z)
		naddr(t, &p->to);
	if(debug['g'])
		print("%P\n", p);
}

int
samaddr(Node *f, Node *t)
{

	if(f->op != t->op)
		return 0;
	switch(f->op) {

	case OREGISTER:
		if(f->reg != t->reg)
			break;
		return 1;
	}
	return 0;
}

void
gbranch(int o)
{
	int a;

	a = AGOK;
	switch(o) {
	case ORETURN:
		a = ARET;
		break;
	case OGOTO:
		a = AJMP;
		break;
	}
	nextpc();
	if(a == AGOK) {
		diag(Z, "bad in gbranch %O",  o);
		nextpc();
	}
	p->as = a;
}

void
patch(Prog *op, long pc)
{

	op->to.offset = pc;
	op->to.type = D_BRANCH;
}

void
gpseudo(int a, Sym *s, Node *n)
{

	nextpc();
	p->as = a;
	p->from.type = D_OREG;
	p->from.sym = s;
	p->reg = (profileflg ? 0 : NOPROF);
	p->from.name = D_EXTERN;
	if(s->class == CSTATIC)
		p->from.name = D_STATIC;
	naddr(n, &p->to);
	if(a == ADATA || a == AGLOBL)
		pc--;
}

int
sconst(Node *n)
{
	vlong vv;

	if(n->op == OCONST) {
		if(!typefd[n->type->etype]) {
			vv = n->vconst;
			if(vv >= (vlong)(-32766) && vv < (vlong)32766)
				return 1;
		}
	}
	return 0;
}

int
sval(long v)
{
	if(v >= -32766L && v < 32766L)
		return 1;
	return 0;
}

long
exreg(Type *t)
{
	long o;

	if(typechlp[t->etype]) {
		if(exregoffset <= 16)
			return 0;
		o = exregoffset;
		exregoffset--;
		return o;
	}
	if(typefd[t->etype]) {
		if(exfregoffset <= 16)
			return 0;
		o = exfregoffset + NREG;
		exfregoffset--;
		return o;
	}
	return 0;
}

schar	ewidth[NTYPE] =
{
	-1,		/* [TXXX] */
	SZ_CHAR,	/* [TCHAR] */
	SZ_CHAR,	/* [TUCHAR] */
	SZ_SHORT,	/* [TSHORT] */
	SZ_SHORT,	/* [TUSHORT] */
	SZ_INT,		/* [TINT] */
	SZ_INT,		/* [TUINT] */
	SZ_LONG,	/* [TLONG] */
	SZ_LONG,	/* [TULONG] */
	SZ_VLONG,	/* [TVLONG] */
	SZ_VLONG,	/* [TUVLONG] */
	SZ_FLOAT,	/* [TFLOAT] */
	SZ_DOUBLE,	/* [TDOUBLE] */
	SZ_IND,		/* [TIND] */
	0,		/* [TFUNC] */
	-1,		/* [TARRAY] */
	0,		/* [TVOID] */
	-1,		/* [TSTRUCT] */
	-1,		/* [TUNION] */
	SZ_INT,		/* [TENUM] */
};

long	ncast[NTYPE] =
{
	0,				/* [TXXX] */
	BCHAR|BUCHAR,			/* [TCHAR] */
	BCHAR|BUCHAR,			/* [TUCHAR] */
	BSHORT|BUSHORT,			/* [TSHORT] */
	BSHORT|BUSHORT,			/* [TUSHORT] */
	BINT|BUINT|BLONG|BULONG|BIND,	/* [TINT] */
	BINT|BUINT|BLONG|BULONG|BIND,	/* [TUINT] */
	BINT|BUINT|BLONG|BULONG|BIND,	/* [TLONG] */
	BINT|BUINT|BLONG|BULONG|BIND,	/* [TULONG] */
	BVLONG|BUVLONG,			/* [TVLONG] */
	BVLONG|BUVLONG,			/* [TUVLONG] */
	BFLOAT,				/* [TFLOAT] */
	BDOUBLE,			/* [TDOUBLE] */
	BLONG|BULONG|BIND,		/* [TIND] */
	0,				/* [TFUNC] */
	0,				/* [TARRAY] */
	0,				/* [TVOID] */
	BSTRUCT,			/* [TSTRUCT] */
	BUNION,				/* [TUNION] */
	0,				/* [TENUM] */
};