#include "gc.h" static intneedc(Prog *p){	while(p != P) {		switch(p->as) {		case AADCL:		case ASBBL:		case ARCRL:			return 1;		case AADDL:		case ASUBL:		case AJMP:		case ARET:		case ACALL:			return 0;		default:			if(p->to.type == D_BRANCH)				return 0;		}		p = p->link;	}	return 0;} voidpeep(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;} voidexcise(Reg *r){	Prog *p; 	p = r->prog;	p->as = ANOP;	p->from = zprog.from;	p->to = zprog.to;} Reg*uniqp(Reg *r){	Reg *r1; 	r1 = r->p1;	if(r1 == R) {		r1 = r->p2;		if(r1 == R || r1->p2link != R)			return R;	} else		if(r->p2 != R)			return R;	return r1;} Reg*uniqs(Reg *r){	Reg *r1; 	r1 = r->s1;	if(r1 == R) {		r1 = r->s2;		if(r1 == R)			return R;	} else		if(r->s2 != R)			return R;	return r1;} intregtyp(Adr *a){	int t; 	t = a->type;	if(t >= D_AX && t <= D_DI)		return 1;	return 0;} /* * the idea is to substitute * one register for another * from one MOV to another *	MOV	a, R0 *	ADD	b, R0	/ no use of R1 *	MOV	R0, R1 * would be converted to *	MOV	a, R1 *	ADD	b, R1 *	MOV	R1, R0 * hopefully, then the former or latter MOV * will be eliminated by copy propagation. */intsubprop(Reg *r0){	Prog *p;	Adr *v1, *v2;	Reg *r;	int t; 	p = r0->prog;	v1 = &p->from;	if(!regtyp(v1))		return 0;	v2 = &p->to;	if(!regtyp(v2))		return 0;	for(r=uniqp(r0); r!=R; r=uniqp(r)) {		if(uniqs(r) == R)			break;		p = r->prog;		switch(p->as) {		case ACALL:			return 0; 		case AIMULL:		case AIMULW:			if(p->to.type != D_NONE)				break; 		case ADIVB:		case ADIVL:		case ADIVW:		case AIDIVB:		case AIDIVL:		case AIDIVW:		case AIMULB:		case AMULB:		case AMULL:		case AMULW: 		case AROLB:		case AROLL:		case AROLW:		case ARORB:		case ARORL:		case ARORW:		case ASALB:		case ASALL:		case ASALW:		case ASARB:		case ASARL:		case ASARW:		case ASHLB:		case ASHLL:		case ASHLW:		case ASHRB:		case ASHRL:		case ASHRW: 		case AREP:		case AREPN: 		case ACWD:		case ACDQ: 		case AMOVSL:		case AFSTSW:			return 0; 		case AMOVL:			if(p->to.type == v1->type)				goto gotit;			break;		}		if(copyau(&p->from, v2) ||		   copyau(&p->to, v2))			break;		if(copysub(&p->from, v1, v2, 0) ||		   copysub(&p->to, v1, v2, 0))			break;	}	return 0; gotit:	copysub(&p->to, v1, v2, 1);	if(debug['P']) {		print("gotit: %D->%D\n%P", v1, v2, r->prog);		if(p->from.type == v2->type)			print(" excise");		print("\n");	}	for(r=uniqs(r); r!=r0; r=uniqs(r)) {		p = r->prog;		copysub(&p->from, v1, v2, 1);		copysub(&p->to, v1, v2, 1);		if(debug['P'])			print("%P\n", r->prog);	}	t = v1->type;	v1->type = v2->type;	v2->type = t;	if(debug['P'])		print("%P last\n", r->prog);	return 1;} /* * The idea is to remove redundant copies. *	v1->v2	F=0 *	(use v2	s/v2/v1/)* *	set v1	F=1 *	use v2	return fail *	----------------- *	v1->v2	F=0 *	(use v2	s/v2/v1/)* *	set v1	F=1 *	set v2	return success */intcopyprop(Reg *r0){	Prog *p;	Adr *v1, *v2;	Reg *r; 	p = r0->prog;	v1 = &p->from;	v2 = &p->to;	if(copyas(v1, v2))		return 1;	for(r=firstr; r!=R; r=r->link)		r->active = 0;	return copy1(v1, v2, r0->s1, 0);} intcopy1(Adr *v1, Adr *v2, Reg *r, int f){	int t;	Prog *p; 	if(r->active) {		if(debug['P'])			print("act set; return 1\n");		return 1;	}	r->active = 1;	if(debug['P'])		print("copy %D->%D f=%d\n", v1, v2, f);	for(; r != R; r = r->s1) {		p = r->prog;		if(debug['P'])			print("%P", p);		if(!f && uniqp(r) == R) {			f = 1;			if(debug['P'])				print("; merge; f=%d", f);		}		t = copyu(p, v2, A);		switch(t) {		case 2:	/* rar, cant split */			if(debug['P'])				print("; %D rar; return 0\n", v2);			return 0; 		case 3:	/* set */			if(debug['P'])				print("; %D set; return 1\n", v2);			return 1; 		case 1:	/* used, substitute */		case 4:	/* use and set */			if(f) {				if(!debug['P'])					return 0;				if(t == 4)					print("; %D used+set and f=%d; return 0\n", v2, f);				else					print("; %D used and f=%d; return 0\n", v2, f);				return 0;			}			if(copyu(p, v2, v1)) {				if(debug['P'])					print("; sub fail; return 0\n");				return 0;			}			if(debug['P'])				print("; sub %D/%D", v2, v1);			if(t == 4) {				if(debug['P'])					print("; %D used+set; return 1\n", v2);				return 1;			}			break;		}		if(!f) {			t = copyu(p, v1, A);			if(!f && (t == 2 || t == 3 || t == 4)) {				f = 1;				if(debug['P'])					print("; %D set and !f; f=%d", v1, f);			}		}		if(debug['P'])			print("\n");		if(r->s2)			if(!copy1(v1, v2, r->s2, f))				return 0;	}	return 1;} /* * return * 1 if v only used (and substitute), * 2 if read-alter-rewrite * 3 if set * 4 if set and used * 0 otherwise (not touched) */intcopyu(Prog *p, Adr *v, Adr *s){ 	switch(p->as) { 	default:		if(debug['P'])			print("unknown op %A\n", p->as);		return 2; 	case ANEGB:	case ANEGW:	case ANEGL:	case ANOTB:	case ANOTW:	case ANOTL:		if(copyas(&p->to, v))			return 2;		break; 	case ALEAL:	/* lhs addr, rhs store */		if(copyas(&p->from, v))			return 2;  	case ANOP:	/* rhs store */	case AMOVL:	case AMOVBLSX:	case AMOVBLZX:	case AMOVWLSX:	case AMOVWLZX:		if(copyas(&p->to, v)) {			if(s != A)				return copysub(&p->from, v, s, 1);			if(copyau(&p->from, v))				return 4;			return 3;		}		goto caseread; 	case AROLB:	case AROLL:	case AROLW:	case ARORB:	case ARORL:	case ARORW:	case ASALB:	case ASALL:	case ASALW:	case ASARB:	case ASARL:	case ASARW:	case ASHLB:	case ASHLL:	case ASHLW:	case ASHRB:	case ASHRL:	case ASHRW:		if(copyas(&p->to, v))			return 2;		if(copyas(&p->from, v))			if(p->from.type == D_CX)				return 2;		goto caseread; 	case AADDB:	/* rhs rar */	case AADDL:

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