Ejemplo n.º 1
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;
			p->reg = r2;

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

			r = r2;
			t++;

		case ADATA:
		case AGLOBL:
		case ANAME:
		case ASIGNAME:
		case ALOCALS:
		case ATYPE:
			p = p->link;
		}
	}
	
	// byte, word arithmetic elimination.
	elimshortmov(r);

	// constant propagation
	// find MOV $con,R followed by
	// another MOV $con,R without
	// setting R in the interim
	for(r=firstr; r!=R; 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", firstr);

	t = 0;
	for(r=firstr; r!=R; 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(r)) {
					excise(r);
					t++;
				} else
				if(subprop(r) && copyprop(r)) {
					excise(r);
					t++;
				}
			}
			break;

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

		case AADDL:
		case AADDQ:
		case AADDW:
			if(p->from.type != D_CONST || needc(p->link))
				break;
			if(p->from.offset == -1){
				if(p->as == AADDQ)
					p->as = ADECQ;
				else
				if(p->as == AADDL)
					p->as = ADECL;
				else
					p->as = ADECW;
				p->from = zprog.from;
				break;
			}
			if(p->from.offset == 1){
				if(p->as == AADDQ)
					p->as = AINCQ;
				else if(p->as == AADDL)
					p->as = AINCL;
				else
					p->as = AINCW;
				p->from = zprog.from;
				break;
			}
			break;

		case ASUBL:
		case ASUBQ:
		case ASUBW:
			if(p->from.type != D_CONST || needc(p->link))
				break;
			if(p->from.offset == -1) {
				if(p->as == ASUBQ)
					p->as = AINCQ;
				else
				if(p->as == ASUBL)
					p->as = AINCL;
				else
					p->as = AINCW;
				p->from = zprog.from;
				break;
			}
			if(p->from.offset == 1){
				if(p->as == ASUBQ)
					p->as = ADECQ;
				else
				if(p->as == ASUBL)
					p->as = ADECL;
				else
					p->as = ADECW;
				p->from = zprog.from;
				break;
			}
			break;
		}
	}
	if(t)
		goto loop1;

	// MOVLQZX removal.
	// The MOVLQZX exists to avoid being confused for a
	// MOVL that is just copying 32-bit data around during
	// copyprop.  Now that copyprop is done, remov MOVLQZX R1, R2
	// if it is dominated by an earlier ADDL/MOVL/etc into R1 that
	// will have already cleared the high bits.
	//
	// MOVSD removal.
	// We never use packed registers, so a MOVSD between registers
	// can be replaced by MOVAPD, which moves the pair of float64s
	// instead of just the lower one.  We only use the lower one, but
	// the processor can do better if we do moves using both.
	for(r=firstr; r!=R; r=r->link) {
		p = r->prog;
		if(p->as == AMOVLQZX)
		if(regtyp(&p->from))
		if(p->from.type == p->to.type)
		if(prevl(r, p->from.type))
			excise(r);
		
		if(p->as == AMOVSD)
		if(regtyp(&p->from))
		if(regtyp(&p->to))
			p->as = AMOVAPD;
	}

	// load pipelining
	// push any load from memory as early as possible
	// to give it time to complete before use.
	for(r=firstr; r!=R; r=r->link) {
		p = r->prog;
		switch(p->as) {
		case AMOVB:
		case AMOVW:
		case AMOVL:
		case AMOVQ:
		case AMOVLQZX:
			if(regtyp(&p->to) && !regconsttyp(&p->from))
				pushback(r);
		}
	}
}
Ejemplo n.º 2
0
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++;
					}
				}
			}
			break;

		case AADDL:
		case AADDQ:
		case AADDW:
			if(p->from.type != D_CONST || needc(p->link))
				break;
			if(p->from.offset == -1){
				if(p->as == AADDQ)
					p->as = ADECQ;
				else
				if(p->as == AADDL)
					p->as = ADECL;
				else
					p->as = ADECW;
				p->from = zprog.from;
				break;
			}
			if(p->from.offset == 1){
				if(p->as == AADDQ)
					p->as = AINCQ;
				else if(p->as == AADDL)
					p->as = AINCL;
				else
					p->as = AINCW;
				p->from = zprog.from;
				break;
			}
			break;

		case ASUBL:
		case ASUBQ:
		case ASUBW:
			if(p->from.type != D_CONST || needc(p->link))
				break;
			if(p->from.offset == -1) {
				if(p->as == ASUBQ)
					p->as = AINCQ;
				else
				if(p->as == ASUBL)
					p->as = AINCL;
				else
					p->as = AINCW;
				p->from = zprog.from;
				break;
			}
			if(p->from.offset == 1){
				if(p->as == ASUBQ)
					p->as = ADECQ;
				else
				if(p->as == ASUBL)
					p->as = ADECL;
				else
					p->as = ADECW;
				p->from = zprog.from;
				break;
			}
			break;
		}
	}
	if(t)
		goto loop1;

	// MOVLQZX removal.
	// The MOVLQZX exists to avoid being confused for a
	// MOVL that is just copying 32-bit data around during
	// copyprop.  Now that copyprop is done, remov MOVLQZX R1, R2
	// if it is dominated by an earlier ADDL/MOVL/etc into R1 that
	// will have already cleared the high bits.
	//
	// MOVSD removal.
	// We never use packed registers, so a MOVSD between registers
	// can be replaced by MOVAPD, which moves the pair of float64s
	// instead of just the lower one.  We only use the lower one, but
	// the processor can do better if we do moves using both.
	for(r=g->start; r!=nil; r=r->link) {
		p = r->prog;
		if(p->as == AMOVLQZX)
		if(regtyp(&p->from))
		if(p->from.type == p->to.type)
		if(prevl(r, p->from.type))
			excise(r);
		
		if(p->as == AMOVSD)
		if(regtyp(&p->from))
		if(regtyp(&p->to))
			p->as = AMOVAPD;
	}

	// load pipelining
	// push any load from memory as early as possible
	// to give it time to complete before use.
	for(r=g->start; r!=nil; r=r->link) {
		p = r->prog;
		switch(p->as) {
		case AMOVB:
		case AMOVW:
		case AMOVL:
		case AMOVQ:
		case AMOVLQZX:
			if(regtyp(&p->to) && !regconsttyp(&p->from))
				pushback(r);
		}
	}

	flowend(g);
}
Ejemplo n.º 3
0
// movb elimination.
// movb is simulated by the linker
// when a register other than ax, bx, cx, dx
// is used, so rewrite to other instructions
// when possible.  a movb into a register
// can smash the entire 32-bit register without
// causing any trouble.
static void
elimshortmov(Reg *r)
{
	Prog *p;

	USED(r);
	for(r=firstr; r!=R; r=r->link) {
		p = r->prog;
		if(regtyp(&p->to)) {
			switch(p->as) {
			case AINCB:
			case AINCW:
				p->as = AINCQ;
				break;
			case ADECB:
			case ADECW:
				p->as = ADECQ;
				break;
			case ANEGB:
			case ANEGW:
				p->as = ANEGQ;
				break;
			case ANOTB:
			case ANOTW:
				p->as = ANOTQ;
				break;
			}
			if(regtyp(&p->from) || p->from.type == D_CONST) {
				// move or artihmetic into partial register.
				// from another register or constant can be movl.
				// we don't switch to 64-bit arithmetic if it can
				// change how the carry bit is set (and the carry bit is needed).
				switch(p->as) {
				case AMOVB:
				case AMOVW:
					p->as = AMOVQ;
					break;
				case AADDB:
				case AADDW:
					if(!needc(p->link))
						p->as = AADDQ;
					break;
				case ASUBB:
				case ASUBW:
					if(!needc(p->link))
						p->as = ASUBQ;
					break;
				case AMULB:
				case AMULW:
					p->as = AMULQ;
					break;
				case AIMULB:
				case AIMULW:
					p->as = AIMULQ;
					break;
				case AANDB:
				case AANDW:
					p->as = AANDQ;
					break;
				case AORB:
				case AORW:
					p->as = AORQ;
					break;
				case AXORB:
				case AXORW:
					p->as = AXORQ;
					break;
				case ASHLB:
				case ASHLW:
					p->as = ASHLQ;
					break;
				}
			} else if(p->from.type >= D_NONE) {
				// explicit zero extension, but don't
				// do that if source is a byte register
				// (only AH can occur and it's forbidden).
				switch(p->as) {
				case AMOVB:
					p->as = AMOVBQZX;
					break;
				case AMOVW:
					p->as = AMOVWQZX;
					break;
				}
			}
		}
	}
}
Ejemplo n.º 4
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;
			p->reg = r2;

			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;
		}
	}

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

	t = 0;
	for(r=firstr; r!=R; 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(r)) {
					excise(r);
					t++;
				} else
				if(subprop(r) && copyprop(r)) {
					excise(r);
					t++;
				}
			}
			break;

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

		case AADDL:
		case AADDQ:
		case AADDW:
			if(p->from.type != D_CONST || needc(p->link))
				break;
			if(p->from.offset == -1){
				if(p->as == AADDQ)
					p->as = ADECQ;
				else
				if(p->as == AADDL)
					p->as = ADECL;
				else
					p->as = ADECW;
				p->from = zprog.from;
				break;
			}
			if(p->from.offset == 1){
				if(p->as == AADDQ)
					p->as = AINCQ;
				else if(p->as == AADDL)
					p->as = AINCL;
				else
					p->as = AINCW;
				p->from = zprog.from;
				break;
			}
			break;

		case ASUBL:
		case ASUBQ:
		case ASUBW:
			if(p->from.type != D_CONST || needc(p->link))
				break;
			if(p->from.offset == -1) {
				if(p->as == ASUBQ)
					p->as = AINCQ;
				else
				if(p->as == ASUBL)
					p->as = AINCL;
				else
					p->as = AINCW;
				p->from = zprog.from;
				break;
			}
			if(p->from.offset == 1){
				if(p->as == ASUBQ)
					p->as = ADECQ;
				else
				if(p->as == ASUBL)
					p->as = ADECL;
				else
					p->as = ADECW;
				p->from = zprog.from;
				break;
			}
			break;
		}
	}
	if(t)
		goto loop1;
}
Ejemplo n.º 5
0
Archivo: peep.c Proyecto: gnanderson/go
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;
            }
    }

    pc = 0;	/* speculating it won't kill */

loop1:

    t = 0;
    for(r=firstr; r!=R; r=r->link) {
        p = r->prog;
        switch(p->as) {
        case AMOVL:
            if(regtyp(&p->to))
                if(regtyp(&p->from)) {
                    if(copyprop(r)) {
                        excise(r);
                        t++;
                    }
                    if(subprop(r) && copyprop(r)) {
                        excise(r);
                        t++;
                    }
                }
            break;

        case AMOVBLSX:
        case AMOVBLZX:
        case AMOVWLSX:
        case AMOVWLZX:
            if(regtyp(&p->to)) {
                r1 = uniqs(r);
                if(r1 != R) {
                    p1 = r1->prog;
                    if(p->as == p1->as && p->to.type == p1->from.type)
                        p1->as = AMOVL;
                }
            }
            break;
        case AADDL:
        case AADDW:
            if(p->from.type != D_CONST || needc(p->link))
                break;
            if(p->from.offset == -1) {
                if(p->as == AADDL)
                    p->as = ADECL;
                else
                    p->as = ADECW;
                p->from = zprog.from;
            }
            else if(p->from.offset == 1) {
                if(p->as == AADDL)
                    p->as = AINCL;
                else
                    p->as = AINCW;
                p->from = zprog.from;
            }
            break;
        case ASUBL:
        case ASUBW:
            if(p->from.type != D_CONST || needc(p->link))
                break;
            if(p->from.offset == -1) {
                if(p->as == ASUBL)
                    p->as = AINCL;
                else
                    p->as = AINCW;
                p->from = zprog.from;
            }
            else if(p->from.offset == 1) {
                if(p->as == ASUBL)
                    p->as = ADECL;
                else
                    p->as = ADECW;
                p->from = zprog.from;
            }
            break;
        }
    }
    if(t)
        goto loop1;
}
Ejemplo n.º 6
0
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:
			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 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 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 AADDL:
		case AADDW:
			if(p->from.type != D_CONST || needc(p->link))
				break;
			if(p->from.offset == -1){
				if(p->as == AADDL)
					p->as = ADECL;
				else
					p->as = ADECW;
				p->from = zprog.from;
				break;
			}
			if(p->from.offset == 1){
				if(p->as == AADDL)
					p->as = AINCL;
				else
					p->as = AINCW;
				p->from = zprog.from;
				break;
			}
			break;

		case ASUBL:
		case ASUBW:
			if(p->from.type != D_CONST || needc(p->link))
				break;
			if(p->from.offset == -1) {
				if(p->as == ASUBL)
					p->as = AINCL;
				else
					p->as = AINCW;
				p->from = zprog.from;
				break;
			}
			if(p->from.offset == 1){
				if(p->as == ASUBL)
					p->as = ADECL;
				else
					p->as = ADECW;
				p->from = zprog.from;
				break;
			}
			break;
		}
	}
	if(t)
		goto loop1;

	// MOVSD removal.
	// We never use packed registers, so a MOVSD between registers
	// can be replaced by MOVAPD, which moves the pair of float64s
	// instead of just the lower one.  We only use the lower one, but
	// the processor can do better if we do moves using both.
	for(r=g->start; r!=nil; r=r->link) {
		p = r->prog;
		if(p->as == AMOVSD)
		if(regtyp(&p->from))
		if(regtyp(&p->to))
			p->as = AMOVAPD;
	}
	
	flowend(g);
}
Ejemplo n.º 7
0
// movb elimination.
// movb is simulated by the linker
// when a register other than ax, bx, cx, dx
// is used, so rewrite to other instructions
// when possible.  a movb into a register
// can smash the entire 64-bit register without
// causing any trouble.
static void
elimshortmov(Graph *g)
{
	Prog *p;
	Flow *r;

	for(r=g->start; r!=nil; r=r->link) {
		p = r->prog;
		if(regtyp(&p->to)) {
			switch(p->as) {
			case AINCB:
			case AINCW:
				p->as = AINCL;
				break;
			case ADECB:
			case ADECW:
				p->as = ADECL;
				break;
			case ANEGB:
			case ANEGW:
				p->as = ANEGL;
				break;
			case ANOTB:
			case ANOTW:
				p->as = ANOTL;
				break;
			}
			if(regtyp(&p->from) || p->from.type == D_CONST) {
				// move or artihmetic into partial register.
				// from another register or constant can be movl.
				// we don't switch to 32-bit arithmetic if it can
				// change how the carry bit is set (and the carry bit is needed).
				switch(p->as) {
				case AMOVB:
				case AMOVW:
					p->as = AMOVL;
					break;
				case AADDB:
				case AADDW:
					if(!needc(p->link))
						p->as = AADDL;
					break;
				case ASUBB:
				case ASUBW:
					if(!needc(p->link))
						p->as = ASUBL;
					break;
				case AMULB:
				case AMULW:
					p->as = AMULL;
					break;
				case AIMULB:
				case AIMULW:
					p->as = AIMULL;
					break;
				case AANDB:
				case AANDW:
					p->as = AANDL;
					break;
				case AORB:
				case AORW:
					p->as = AORL;
					break;
				case AXORB:
				case AXORW:
					p->as = AXORL;
					break;
				case ASHLB:
				case ASHLW:
					p->as = ASHLL;
					break;
				}
			} else {
				// explicit zero extension
				switch(p->as) {
				case AMOVB:
					p->as = AMOVBLZX;
					break;
				case AMOVW:
					p->as = AMOVWLZX;
					break;
				}
			}
		}
	}
}
Ejemplo n.º 8
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;
			p->reg = r2;

			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;
		}
	}

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

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

		case AMOVB:
		case AMOVW:
		case AMOVL:
		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", firstr);

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

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

		case AADDL:
		case AADDW:
			if(p->from.type != D_CONST || needc(p->link))
				break;
			if(p->from.offset == -1){
				if(p->as == AADDL)
					p->as = ADECL;
				else
					p->as = ADECW;
				p->from = zprog.from;
				break;
			}
			if(p->from.offset == 1){
				if(p->as == AADDL)
					p->as = AINCL;
				else
					p->as = AINCW;
				p->from = zprog.from;
				break;
			}
			break;

		case ASUBL:
		case ASUBW:
			if(p->from.type != D_CONST || needc(p->link))
				break;
			if(p->from.offset == -1) {
				if(p->as == ASUBL)
					p->as = AINCL;
				else
					p->as = AINCW;
				p->from = zprog.from;
				break;
			}
			if(p->from.offset == 1){
				if(p->as == ASUBL)
					p->as = ADECL;
				else
					p->as = ADECW;
				p->from = zprog.from;
				break;
			}
			break;
		}
	}
	if(t)
		goto loop1;

	// MOVSD removal.
	// We never use packed registers, so a MOVSD between registers
	// can be replaced by MOVAPD, which moves the pair of float64s
	// instead of just the lower one.  We only use the lower one, but
	// the processor can do better if we do moves using both.
	for(r=firstr; r!=R; r=r->link) {
		p = r->prog;
		if(p->as == AMOVSD)
		if(regtyp(&p->from))
		if(regtyp(&p->to))
			p->as = AMOVAPD;
	}
}