C++ regtyp函数代码示例

/*
 * substitute s for v in a
 * return failure to substitute
 */
int
copysub(Adr *a, Adr *v, Adr *s, int f)
{
	int t;

	if(copyas(a, v)) {
		t = s->type;
		if(t >= D_AX && t <= D_R15 || t >= D_X0 && t <= D_X0+15) {
			if(f)
				a->type = t;
		}
		return 0;
	}
	if(regtyp(v)) {
		t = v->type;
		if(a->type == t+D_INDIR) {
			if((s->type == D_BP || s->type == D_R13) && a->index != D_NONE)
				return 1;	/* can't use BP-base with index */
			if(f)
				a->type = s->type+D_INDIR;
//			return 0;
		}
		if(a->index == t) {
			if(f)
				a->index = s->type;
			return 0;
		}
		return 0;
	}
	return 0;
}

int
smallindir(Addr *a, Addr *reg)
{
	return regtyp(reg) &&
		a->type == D_INDIR + reg->type &&
		a->index == D_NONE &&
		0 <= a->offset && a->offset < 4096;
}

/*
 * direct reference,
 * could be set/use depending on
 * semantics
 */
int
copyas(Adr *a, Adr *v)
{

	if(regtyp(v))
		if(a->type == v->type)
		if(a->reg == v->reg)
			return 1;
	return 0;
}

void
nilopt(Prog *firstp)
{
	NilFlow *r;
	Prog *p;
	Graph *g;
	int ncheck, nkill;

	g = flowstart(firstp, sizeof(NilFlow));
	if(g == nil)
		return;

	if(debug_checknil > 1 /* || strcmp(curfn->nname->sym->name, "f1") == 0 */)
		dumpit("nilopt", g->start, 0);

	ncheck = 0;
	nkill = 0;
	for(r = (NilFlow*)g->start; r != nil; r = (NilFlow*)r->f.link) {
		p = r->f.prog;
		if(p->as != ACHECKNIL || !regtyp(&p->from))
			continue;
		ncheck++;
		if(stackaddr(&p->from)) {
			if(debug_checknil && p->lineno > 1)
				warnl(p->lineno, "removed nil check of SP address");
			r->kill = 1;
			continue;
		}
		nilwalkfwd(r);
		if(r->kill) {
			if(debug_checknil && p->lineno > 1)
				warnl(p->lineno, "removed nil check before indirect");
			continue;
		}
		nilwalkback(r);
		if(r->kill) {
			if(debug_checknil && p->lineno > 1)
				warnl(p->lineno, "removed repeated nil check");
			continue;
		}
	}
	
	for(r = (NilFlow*)g->start; r != nil; r = (NilFlow*)r->f.link) {
		if(r->kill) {
			nkill++;
			excise(&r->f);
		}
	}

	flowend(g);
	
	if(debug_checknil > 1)
		print("%S: removed %d of %d nil checks\n", curfn->nname->sym, nkill, ncheck);
}

/*
 * direct reference,
 * could be set/use depending on
 * semantics
 */
int
copyas(Adr *a, Adr *v)
{
	if(a->type != v->type)
		return 0;
	if(regtyp(v))
		return 1;
	if(v->type == D_AUTO || v->type == D_PARAM)
		if(v->offset == a->offset)
			return 1;
	return 0;
}

int
copyau1(Prog *p, Adr *v)
{

	if(regtyp(v))
		if(p->from.type == v->type || p->to.type == v->type)
		if(p->reg == v->reg) {
			if(a2type(p) != v->type)
				print("botch a2type %P\n", p);
			return 1;
		}
	return 0;
}

/*
 * either direct or indirect
 */
int
copyau(Adr *a, Adr *v)
{

	if(copyas(a, v))
		return 1;
	if(regtyp(v)) {
		if(a->type-D_INDIR == v->type)
			return 1;
		if(a->index == v->type)
			return 1;
	}
	return 0;
}

static int
regconsttyp(Adr *a)
{
	if(regtyp(a))
		return 1;
	switch(a->type) {
	case D_CONST:
	case D_FCONST:
	case D_SCONST:
	case D_ADDR:
		return 1;
	}
	return 0;
}

/*
 * direct reference,
 * could be set/use depending on
 * semantics
 */
static int
copyas(Adr *a, Adr *v)
{
	if(D_AL <= a->type && a->type <= D_BL)
		fatal("use of byte register");
	if(D_AL <= v->type && v->type <= D_BL)
		fatal("use of byte register");

	if(a->type != v->type)
		return 0;
	if(regtyp(v))
		return 1;
	if(v->type == D_AUTO || v->type == D_PARAM)
		if(v->offset == a->offset)
			return 1;
	return 0;
}

/*
 * direct reference,
 * could be set/use depending on
 * semantics
 */
int
copyas(Adr *a, Adr *v)
{

	if(regtyp(v)) {
		if(a->type == v->type)
		if(a->reg == v->reg)
			return 1;
	} else if(v->type == D_CONST) {		/* for constprop */
		if(a->type == v->type)
		if(a->name == v->name)
		if(a->sym == v->sym)
		if(a->reg == v->reg)
		if(a->offset == v->offset)
			return 1;
	}
	return 0;
}

/*
 * compare v to the center
 * register in p (p->reg)
 * the trick is that this
 * register might be D_REG
 * D_FREG. there are basically
 * two cases,
 *	ADD r,r,r
 *	CMP r,r,
 */
static int
copyau1(Prog *p, Adr *v)
{

	if(regtyp(v))
	if(p->reg == v->reg) {
		if(p->to.type != D_NONE) {
			if(v->type == p->to.type)
				return 1;
			return 0;
		}
		if(p->from.type != D_NONE) {
			if(v->type == p->from.type)
				return 1;
			return 0;
		}
		print("copyau1: can't tell %P\n", p);
	}
	return 0;
}

static void
nilwalkfwd(NilFlow *rcheck)
{
	NilFlow *r;
	Prog *p;
	ProgInfo info;
	
	// If the path down from rcheck dereferences the address
	// (possibly with a small offset) before writing to memory
	// and before any subsequent checks, it's okay to wait for
	// that implicit check. Only consider this basic block to
	// avoid problems like:
	//	_ = *x // should panic
	//	for {} // no writes but infinite loop may be considered visible
	for(r = (NilFlow*)uniqs(&rcheck->f); r != nil; r = (NilFlow*)uniqs(&r->f)) {
		p = r->f.prog;
		proginfo(&info, p);
		
		if((info.flags & LeftRead) && smallindir(&p->from, &rcheck->f.prog->from)) {
			rcheck->kill = 1;
			return;
		}
		if((info.flags & (RightRead|RightWrite)) && smallindir(&p->to, &rcheck->f.prog->from)) {
			rcheck->kill = 1;
			return;
		}
		
		// Stop if another nil check happens.
		if(p->as == ACHECKNIL)
			return;
		// Stop if value is lost.
		if((info.flags & RightWrite) && sameaddr(&p->to, &rcheck->f.prog->from))
			return;
		// Stop if memory write.
		if((info.flags & RightWrite) && !regtyp(&p->to))
			return;
	}
}

/*
 * either direct or indirect
 */
int
copyau(Adr *a, Adr *v)
{

	if(copyas(a, v)) {
		if(debug['P'] && debug['v'])
			print("\tcopyau: copyas returned 1\n");
		return 1;
	}
	if(regtyp(v)) {
		if(a->type-D_INDIR == v->type) {
			if(debug['P'] && debug['v'])
				print("\tcopyau: found indir use - return 1\n");
			return 1;
		}
		if(a->index == v->type) {
			if(debug['P'] && debug['v'])
				print("\tcopyau: found index use - return 1\n");
			return 1;
		}
	}
	return 0;
}

void
peep(void)
{
	Reg *r, *r1, *r2;
	Prog *p, *p1;
	int t;
/*
 * complete R structure
 */
	t = 0;
	for(r=firstr; r!=R; r=r1) {
		r1 = r->link;
		if(r1 == R)
			break;
		p = r->prog->link;
		while(p != r1->prog)
		switch(p->as) {
		default:
			r2 = rega();
			r->link = r2;
			r2->link = r1;

			r2->prog = p;
			r2->p1 = r;
			r->s1 = r2;
			r2->s1 = r1;
			r1->p1 = r2;

			r = r2;
			t++;

		case ADATA:
		case AGLOBL:
		case ANAME:
		case ASIGNAME:
			p = p->link;
		}
	}

loop1:
	t = 0;
	for(r=firstr; r!=R; r=r->link) {
		p = r->prog;
		if(p->as == AMOVW || p->as == AFMOVS || p->as == AFMOVD)
		if(regtyp(&p->to)) {
			if(regtyp(&p->from))
			if(p->from.type == p->to.type) {
				if(copyprop(r)) {
					excise(r);
					t++;
				} else
				if(subprop(r) && copyprop(r)) {
					excise(r);
					t++;
				}
			}
			if(regzer(&p->from))
			if(p->to.type == D_REG) {
				p->from.type = D_REG;
				p->from.reg = REGZERO;
				if(copyprop(r)) {
					excise(r);
					t++;
				} else
				if(subprop(r) && copyprop(r)) {
					excise(r);
					t++;
				}
			}
		}
	}
	if(t)
		goto loop1;
	/*
	 * look for MOVB x,R; MOVB R,R
	 */
	for(r=firstr; r!=R; r=r->link) {
		p = r->prog;
		switch(p->as) {
		default:
			continue;
		case AMOVH:
		case AMOVHZ:
		case AMOVB:
		case AMOVBZ:
			if(p->to.type != D_REG)
				continue;
			break;
		}
		r1 = r->link;
		if(r1 == R)
			continue;
		p1 = r1->prog;
		if(p1->as != p->as)
			continue;
		if(p1->from.type != D_REG || p1->from.reg != p->to.reg)
			continue;
		if(p1->to.type != D_REG || p1->to.reg != p->to.reg)
			continue;
		excise(r1);
//.........这里部分代码省略.........

void
peep(Prog *firstp)
{
	Flow *r, *r1;
	Graph *g;
	Prog *p, *p1;
	int t;

	g = flowstart(firstp, sizeof(Flow));
	if(g == nil)
		return;
	for(r=g->start, t=0; r!=nil; r=r->link, t++)
		r->active = t;

	// byte, word arithmetic elimination.
	elimshortmov(g);

	// constant propagation
	// find MOV $con,R followed by
	// another MOV $con,R without
	// setting R in the interim
	for(r=g->start; r!=nil; r=r->link) {
		p = r->prog;
		switch(p->as) {
		case ALEAL:
		case ALEAQ:
			if(regtyp(&p->to))
			if(p->from.sym != S)
			if(p->from.index == D_NONE || p->from.index == D_CONST)
				conprop(r);
			break;

		case AMOVB:
		case AMOVW:
		case AMOVL:
		case AMOVQ:
		case AMOVSS:
		case AMOVSD:
			if(regtyp(&p->to))
			if(p->from.type == D_CONST)
				conprop(r);
			break;
		}
	}

loop1:
	if(debug['P'] && debug['v'])
		dumpit("loop1", g->start, 0);

	t = 0;
	for(r=g->start; r!=nil; r=r->link) {
		p = r->prog;
		switch(p->as) {
		case AMOVL:
		case AMOVQ:
		case AMOVSS:
		case AMOVSD:
			if(regtyp(&p->to))
			if(regtyp(&p->from)) {
				if(copyprop(g, r)) {
					excise(r);
					t++;
				} else
				if(subprop(r) && copyprop(g, r)) {
					excise(r);
					t++;
				}
			}
			break;

		case AMOVBLZX:
		case AMOVWLZX:
		case AMOVBLSX:
		case AMOVWLSX:
			if(regtyp(&p->to)) {
				r1 = rnops(uniqs(r));
				if(r1 != nil) {
					p1 = r1->prog;
					if(p->as == p1->as && p->to.type == p1->from.type){
						p1->as = AMOVL;
						t++;
					}
				}
			}
			break;

		case AMOVBQSX:
		case AMOVBQZX:
		case AMOVWQSX:
		case AMOVWQZX:
		case AMOVLQSX:
		case AMOVLQZX:
		case AMOVQL:
			if(regtyp(&p->to)) {
				r1 = rnops(uniqs(r));
				if(r1 != nil) {
					p1 = r1->prog;
					if(p->as == p1->as && p->to.type == p1->from.type){
						p1->as = AMOVQ;
						t++;
//.........这里部分代码省略.........