/* VAX descriptor table for ACK target optimizer,
 * Prolog prototype
 */

/* tunable constants-> */

MAXOP			4;
MAXLINELEN		50;
LABEL_STARTER		'L';
OPC_TERMINATOR		'	';

%%;

ZERO		{strcmp(VAL,"$0") == 0};
ONE		{strcmp(VAL,"$1") == 0};
M_ONE		{strcmp(VAL,"$-1") == 0};
CONST		{VAL[0] == '$'};
NUM,NUM1	{is_number(VAL)};
REG		{is_register(VAL)};
SREG		{is_scratchreg(VAL)};
LAB,LAB2	{VAL[0] == 'L'};
A,B		{no_side_effects(VAL) };
X,Y,LOG		{TRUE};

%%;

movab 1(X),X			->	incl X;
movab -1(X),X			->	decl X;

movzbw ZERO,X			->	clrw X;
movzbl ZERO,X			->	clrl X;
movb ZERO,X			->	clrb X;
movw ZERO,X			->	clrw X;
movl ZERO,X			->	clrl X;
cvtbw ZERO,X			->	clrw X;
cvtww ZERO,X			->	clrw X;
cvtbl ZERO,X			->	clrl X;
cvtwl ZERO,X			->	clrl X;

/* change 3-operand instructions to 2-operand instructions */

addw3 X,Y,Y			->	addw2 X,Y;
addl3 X,Y,Y			->	addl2 X,Y;
addf3 X,Y,Y			->	addf2 X,Y;
addd3 X,Y,Y			->	addd2 X,Y;

addw3 X,Y,X			->	addw2 Y,X;
addl3 X,Y,X			->	addl2 Y,X;
addf3 X,Y,X			->	addf2 Y,X;
addd3 X,Y,X			->	addd2 Y,X;

subw3 X,Y,Y			->	subw2 X,Y;
subl3 X,Y,Y			->	subl2 X,Y;
subf3 X,Y,Y			->	subf2 X,Y;
subd3 X,Y,Y			->	subd2 X,Y;

mulw3 X,Y,Y			->	mulw2 X,Y;
mull3 X,Y,Y			->	mull2 X,Y;
mulf3 X,Y,Y			->	mulf2 X,Y;
muld3 X,Y,Y			->	muld2 X,Y;

mulw3 X,Y,X			->	mulw2 Y,X;
mull3 X,Y,X			->	mull2 Y,X;
mulf3 X,Y,X			->	mulf2 Y,X;
muld3 X,Y,X			->	muld2 Y,X;

divw3 X,Y,Y			->	divw2 X,Y;
divl3 X,Y,Y			->	divl2 X,Y;
divf3 X,Y,Y			->	divf2 X,Y;
divd3 X,Y,Y			->	divd2 X,Y;

xorw3 X,Y,Y			->	xorw2 X,Y;
xorl3 X,Y,Y			->	xorl2 X,Y;

bisw3 X,Y,Y			->	bisw2 X,Y;
bisl3 X,Y,Y			->	bisl2 X,Y;
bisw3 X,Y,X			->	bisw2 Y,X;
bisl3 X,Y,X			->	bisl2 Y,X;

bicw3 X,Y,Y			->	bicw2 X,Y;
bicl3 X,Y,Y			->	bicl2 X,Y;

/* eliminate negative constants */

addw2 $-NUM,X			->	subw2 $NUM,X;
addl2 $-NUM,X			->	subl2 $NUM,X;
addw3 $-NUM,X,Y			->	subw3 $NUM,X,Y;
addl3 $-NUM,X,Y			->	subl3 $NUM,X,Y;
addw3 X,$-NUM,Y			->	subw3 $NUM,X,Y;
addl3 X,$-NUM,Y			->	subl3 $NUM,X,Y;

subw2 $-NUM,X			->	addw2 $NUM,X;
subl2 $-NUM,X			->	addl2 $NUM,X;
subw3 $-NUM,X,Y			->	addw3 $NUM,X,Y;
subl3 $-NUM,X,Y			->	addl3 $NUM,X,Y;

/* use special instructions */

addw2 ONE,X			->	incw X;
addl2 ONE,X			->	incl X;
subw2 ONE,X			->	decw X;
subl2 ONE,X			->	decl X;

addw2 M_ONE,X			->	decw X;
addl2 M_ONE,X			->	decl X;
subw2 M_ONE,X			->	incw X;
subl2 M_ONE,X			->	incl X;

bitw $NUM,A : jneq LAB
	{is_poweroftwo(NUM,LOG)}->	jbs $LOG,A,LAB;
bitl $NUM,A : jneq LAB
	{is_poweroftwo(NUM,LOG)}->	jbs $LOG,A,LAB;
bitw $NUM,A : jeql LAB
	{is_poweroftwo(NUM,LOG)}->	jbc $LOG,A,LAB;
bitl $NUM,A : jeql LAB
	{is_poweroftwo(NUM,LOG)}->	jbc $LOG,A,LAB;
bitw ONE,A : jneq LAB		->	jlbs A,LAB;
bitl ONE,A : jneq LAB		->	jlbs A,LAB;
bitw ONE,A : jneq LAB		->	jlbc A,LAB;
bitl ONE,A : jneq LAB		->	jlbc A,LAB;
ashl $-NUM,A,REG : bicw2 $~NUM1,REG
	{is_p2m1(NUM1,LOG)}	->	extzv $NUM,$LOG,A,REG;
ashl $-NUM,A,REG : bicl2 $~NUM1,REG
	{is_p2m1(NUM1,LOG)}	->	extzv $NUM,$LOG,A,REG;

/* stack optimizations */

movl (sp)+,X : pushl X		->	movl (sp),X;
tstw (sp)+ : movw X,-(sp)	->	movw X,(sp);
tstl (sp)+ : movl X,-(sp)	->	movl X,(sp);
tstw (sp)+ : clrw -(sp)		->	clrw (sp);
tstl (sp)+ : clrl -(sp)		->	clrl (sp);
tstw (sp)+ : movzbw X,-(sp)	->	movzbw X,(sp);
tstl (sp)+ : movzbl X,-(sp)	->	movzbl X,(sp);
tstw (sp)+ : cvtbw X,-(sp)	->	cvtbw X,(sp);
tstl (sp)+ : cvtbl X,-(sp)	->	cvtbl X,(sp);
tstw (sp)+ : tstw X		->	movw X,(sp)+;
tstl (sp)+ : tstl X		->	movl X,(sp)+;
tstl (sp)+ : pushl X		->	movl X,(sp);
tstl (sp)+ : pushab X		->	movab X,(sp);
tstl (sp)+ : pushaw X		->	movaw X,(sp);
tstl (sp)+ : pushal X		->	moval X,(sp);
tstl (sp)+ : pushaq X		->	movaq X,(sp);

/* push constants */

clrw -(sp) : movw $NUM,-(sp)	->	pushl $NUM;
clrw -(sp) : mnegw $NUM, -(sp)	->	movzwl $-NUM,-(sp);
clrw -(sp) : movw X,-(sp)	->	movzwl X,-(sp);
clrw -(sp) : cvtbw $NUM,-(sp)	->	pushl $NUM;
clrw -(sp) : cvtbw CONST,-(sp)	->	movzwl CONST,-(sp);

/* compare with zero */

cmpb X,ZERO 			->	tstb X;
cmpw X,ZERO 			->	tstw X;
cmpl X,ZERO 			->	tstl X;
cmpb ZERO,X : jneq LAB		->	tstb X: jneq LAB;
cmpw ZERO,X : jneq LAB		->	tstw X: jneq LAB;
cmpl ZERO,X : jneq LAB		->	tstl X: jneq LAB;

cmpb ZERO,X : jeql LAB		->	tstb X: jeql LAB;
cmpw ZERO,X : jeql LAB		->	tstw X: jeql LAB;
cmpl ZERO,X : jeql LAB		->	tstl X: jeql LAB;

cmpb ZERO,X : jgtr LAB		->	tstb X: jlss LAB;
cmpw ZERO,X : jgtr LAB		->	tstw X: jlss LAB;
cmpl ZERO,X : jgtr LAB		->	tstl X: jlss LAB;

cmpb ZERO,X : jlss LAB		->	tstb X: jgtr LAB;
cmpw ZERO,X : jlss LAB		->	tstw X: jgtr LAB;
cmpl ZERO,X : jlss LAB		->	tstl X: jgtr LAB;

cmpb ZERO,X : jgeq LAB		->	tstb X: jleq LAB;
cmpw ZERO,X : jgeq LAB		->	tstw X: jleq LAB;
cmpl ZERO,X : jgeq LAB		->	tstl X: jleq LAB;

cmpb ZERO,X : jleq LAB		->	tstb X: jgeq LAB;
cmpw ZERO,X : jleq LAB		->	tstw X: jgeq LAB;
cmpl ZERO,X : jleq LAB		->	tstl X: jgeq LAB;

/* compare with -1 */

cmpw M_ONE,SREG : jeql LAB	->	incw SREG : jeql LAB;
cmpl M_ONE,SREG : jeql LAB	->	incl SREG : jeql LAB;
cmpw M_ONE,SREG : jneq LAB	->	incw SREG : jneq LAB;
cmpl M_ONE,SREG : jneq LAB	->	incl SREG : jneq LAB;

/* eliminate redundant tests */

movw X,A : tstw A		->	movw X,A;
movl X,A : tstl A		->	movl X,A;
movw A,X : tstw A		->	movw A,X;
movl A,X : tstl A		->	movl A,X;

/* skip over jumps */

jeql LAB : jbr LAB2 : labdef LAB ->	jneq LAB2 : labdef LAB;
jgeq LAB : jbr LAB2 : labdef LAB ->	jlss LAB2 : labdef LAB;
jgtr LAB : jbr LAB2 : labdef LAB ->	jleq LAB2 : labdef LAB;
jlss LAB : jbr LAB2 : labdef LAB ->	jgeq LAB2 : labdef LAB;
jleq LAB : jbr LAB2 : labdef LAB ->	jgtr LAB2 : labdef LAB;
jneq LAB : jbr LAB2 : labdef LAB ->	jeql LAB2 : labdef LAB;

/* Register propagation */

movl REG,A : ANY *A		->	movl REG,A : ANY (REG);
movl REG,A : ANY *A,X		->	movl REG,A : ANY (REG),X;
movl REG,A : ANY X,*A		->	movl REG,A : ANY X,(REG);
movl REG,A : ANY *A,X,Y		->	movl REG,A : ANY (REG),X,Y;
movl REG,A : ANY X,*A,Y		->	movl REG,A : ANY X,(REG),Y;
movl REG,A : ANY X,Y,*A		->	movl REG,A : ANY X,Y,(REG);


%%;

/* Auxiliary routines: */

int is_number(s)
	register char *s;
{
	while (*s >= '0' && *s <= '9') s++;
	return *s == '\0';
}

int is_poweroftwo(s,t)
	char *s,*t;
{
	long	arg, pow;
	register int i;

	arg = atol(s);
	pow = 1;
	i = 0;
	while (pow > 0) {
		if (pow == arg) {
			sprintf(t,"%d",i);
			return 1;
		}
		pow <<= 1;
		i++;
	}
	return 0;
}

int is_p2m1(s,t)
	char *s,*t;
{
	long arg;
	char buf[MAXLINELEN];

	arg = atol(s)+1;
	sprintf(buf,"%ld",arg);
	return is_poweroftwo(buf,t);
}

int no_side_effects(s)
	register char *s;
{

	for(;;) {
		switch(*s++) {
			case '\0': return TRUE;
			case '-':  if (*s == '(') return FALSE; break;
			case ')':  if (*s == '+') return FALSE; break;
		}
	}
	/* NOTREACHED */
}

int is_register(s)
	register char *s;
{
	if (*s++ == 'r' && *s >= '0' && *s <= '9') {
		if (*s++ == '1' && (*s == '0' || *s == '1')) s++;
		return *s == '\0';
	}
	return FALSE;
}

int is_scratchreg(s)
	register char *s;
{
	return *s++ == 'r' && *s >= '0' && *s++ <= '3' && *s == '\0';
}