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/*	@(#) optim.c: 1.3 1/12/84	*/

# include "mfile1.h"

# define ISCON(p) (p->in.op==ICON)

int opdebug = 0;
NODE *doptim();

NODE *
aadjust( p, adj )
register NODE *p; 
register adj;
{
	/* try to adjust p by adj bits */
	register NODE *q;
	adj = BITOOR(adj);
	switch( p->tn.op )
	{
	case ICON:
		p->tn.lval += adj;
		return( p );
	default:
		/* construct a + node */
mkplus:
		return( block( PLUS, p, bcon(adj), p->fn.type,
		p->fn.cdim, p->fn.csiz ) );
	case PLUS:
		q = p->in.right;
		if( q->tn.op != ICON ) goto mkplus;
		q->tn.lval += adj;
		return( p );
	case MINUS:
		q = p->in.right;
		if( q->tn.op != ICON ) goto mkplus;
		q->tn.lval -= adj;
		return( p );
	}
}

adjust( p, adj )
register NODE *p; 
register adj;
{
	/* handle adjustment of scalars by adj bits */

	switch( p->tn.op )
	{
	case NAME:
	case VAUTO:
	case VPARAM:
		p->tn.lval += BITOOR(adj);
		return( 1 );
	case STAR:
		p->in.left = aadjust( p->in.left, adj );
		return( 1 );
	default:
		return( 0 );
	}
}

# ifdef NOSIMPSTR
# ifndef MYSIMPSTR
simpstr( d, s ) 
{
	  return( STRTY ); 
}
# endif
# else
TWORD
simpstr( d, s ) 
{
	/* return STRTY if not, and CHAR, INT, SHORT, or LONG if simple */
	register sz, al;

	sz = tsize( STRTY, d, s );
	al = talign( STRTY, s );
	if( sz == SZINT /*&& !( al % ALINT)*/ ) return( INT );
	else if( sz == SZCHAR /*&& !( al % ALCHAR)*/ ) return( CHAR );
	else if( sz == SZLONG /*&& !( al % ALLONG)*/ ) return( LONG );
	else if( sz == SZSHORT /*&& !( al % ALSHORT)*/ ) return( SHORT );
	return( STRTY );
}
# endif

tydown( p )
NODE *p; 
{
	/* reflect the type of p downwards, as appropriate */
	/* the type is typically getting smaller */
	/* returns 1 if it makes a real change */

	TWORD t;
	NODE *l, *r;
	int flag;

#ifndef NODBG
	if( opdebug ) 
	{
		printf( "tydown(%d) called with:\n", p-node );
		eprint( p );
	}
#endif
	t = p->tn.type;
	if( ISPTR(t) || ISARY(t) ) return(0);

	/* work these types down into the tree */

	flag = 0;

	switch( p->tn.op ) 
	{

	case AND:
	case OR:
	case PLUS:
	case MINUS:
	case ER:
	case COMOP:
#ifndef NODBG
		if( opdebug ) 
		{
			printf( "tydown:\n" );
			eprint( p );
		}
#endif
		r = p->in.right;
		if( bigsize(r->tn.type) > bigsize(p->tn.type ) ) 
		{
			r = makety( r, t, 0, (int) t );
			tydown( r );
			p->in.right = doptim( r );
#ifndef NODBG
			if( opdebug ) 
			{
				printf( "tydown(%d), after doptim(R):\n",
				p-node );
				eprint(p);
			}
#endif
			flag = 1;
		}
		if( p->tn.op == COMOP ) return( flag );
		/* FALLTHRU */

	case UNARY MINUS:
	case COMPL:
		l = p->in.left;
		if( bigsize(l->tn.type) > bigsize(p->tn.type ) ) 
		{
			l = makety( l, t, 0, (int) t );
			tydown( l );
			p->in.left = doptim( l );
#ifndef NODBG
			if( opdebug ) 
			{
				printf( "tydown(%d), after doptim(L):\n",
				p-node );
				eprint(p);
			}
#endif
			flag = 1;
		}
		return(flag);
	}
	return( 0 );			/* no change */
}

# ifndef MYCONVERT
NODE *
sconvert( p )
register NODE *p; 
{
	register TWORD t, lt;
	register NODE *l;
	register o;

	/* optimize CONV nodes */
	/* the unsigned-ness is ignored */
	/* if the CONV involves floats or doubles, retain unless null */
	/* if the CONV makes things bigger, retain */
	/* if the CONV keeps things the same size, just paint the type */
	/* if the CONV makes things smaller, adjust the addressing with
	** memory references, and paint the new type 
	*/
	/* if a pointer is being converted, convert as if it were PTRTYPE */
	/* finally, if CONV converts a constant, do it in place */
again:
#ifndef NODBG
	if( opdebug ) 
	{
		printf( "sconvert(%d) called:\n", p-node );
		eprint( p );
	}
#endif
	if( p->tn.op != CONV ) cerror( "sconvert" );
	l = p->in.left;
	t = p->tn.type;
	lt = l->tn.type;
	o = l->tn.op;

	if( o == FCON )
	{
		/* for a floating point const, paint type,
		** round when it is output */
		if( t == FLOAT || t == DOUBLE ) goto paint;
		/* otherwise, convert it to long and treat as long conversion */
		l->tn.op = ICON;
		l->tn.lval = l->fpn.dval;  /* MACHINE-DEPENDENT CONVERSION */
		l->tn.rval = NONAME;
		goto icon;
	}

	if( o==CONV && cbigger( l ) )
	{
merge:
		p->in.left = l->in.left;
		l->tn.op = FREE;
		tydown( p );
		goto again;
	}
	if( t == lt && (t == DOUBLE || t == FLOAT) )
	    goto paint;			/* float over float, double over double */
	if(	t==FLOAT || t==DOUBLE || t == VOID
	    || lt==FLOAT || lt==DOUBLE ) return( p );

	if( ISUNSIGNED(t) ) t = DEUNSIGN(t);
	if( ISUNSIGNED(lt) ) lt = DEUNSIGN(lt);
	if( ISPTR(lt) )
# ifdef MEMONLY
		if( o==STAR || o==NAME || o==VAUTO || o==VPARAM )
# endif
			lt = PTRTYPE;
	if( t == lt ) goto paint;
	if( ISPTR(lt) || ISARY(lt) ) return(p);

	if( o == ICON )
	{
icon:
		l->tn.lval = ccast( l->tn.lval, p->tn.type );
paint:
		l->tn.type = p->tn.type;
		l->fn.csiz = p->fn.csiz;
		l->fn.cdim = p->fn.cdim;
		p->tn.op = FREE;
		if( tydown(l) ) 
		{
			l = doptim(l);
		}
		return( l );
	}
	if( cbigger(p) ) return( p );
	/* p makes things smaller */
	if( o==CONV )
	{
		/* two conversions in a row: the second makes things smaller */
		/* make them into one */
		goto merge;
	}
	if( o==STAR || o==NAME || o==VAUTO || o==VPARAM ) 
	{
		/* memory reference: determine the adjustment */
# ifdef RTOLBYTES
# ifdef LOWINT
		if( lt == LONG ) if( !adjust( l, LOWINT )) cerror( "adj" );
# endif
# else 
		register adj = 0;
		if( lt == LONG ) adj = SZLONG;
		else if( lt == INT ) adj = SZINT;
		else if( lt == SHORT ) adj = SZSHORT;
		else cerror( "sconv:lt 0%o", lt );
		if( t == INT ) adj -= SZINT;
		else if( t == SHORT ) adj -= SZSHORT;
		else if( t == CHAR ) adj -= SZCHAR;
		else cerror( "sconv:t 0%o", t );
# ifdef LOWINT
		if( lt == LONG ) adj += LOWINT;
# endif
		if( adj ) if( !adjust( l, adj ) ) cerror( "adj1" );
# endif
	}

	/* other cases are where it is computed into a reg; */
	/* simply paint the type */
	/* must avoid clobbering the type for assignment nodes */
	/* however, we must copy (e.g., apply the CONV) for register vars */
	/* also, can't paint type over fields */
	if( o == REG || asgop(o) || o == FLD ) return( p );
	goto paint;
}
# endif

NODE *
pvconvert( p )
register NODE *p; 
{
	/* p is a CONV node; convert */
	/* this does something only when the descendent is not a ptr */
	register NODE *l;
	register int o;
	l = p->in.left;
	if( ISPTR( l->tn.type ) ) return( clocal(p) );
# ifdef MEMONLY
	o = l->tn.op;
	if( o==STAR || o==NAME || o==VAUTO || o==VPARAM || o==ICON )
# endif
	{
		 /* optimize this reference */
		/* sconvert and optimize to PTRTYPE */
		l = makety( l, PTRTYPE, 0, PTRTYPE );
		if( l->tn.op == CONV ) l = sconvert( l );
		l->tn.type = p->tn.type;
		l->fn.cdim = p->fn.cdim;
		l->fn.csiz = p->fn.csiz;
		p->tn.op = FREE;
		p = l;
	}
	return( clocal(p) );
}

NODE *
fortarg( p )
register NODE *p; 
{
	/* fortran function arguments */

	if( p->in.op == CM )
	{
		p->in.left = fortarg( p->in.left );
		p->in.right = fortarg( p->in.right );
		return(p);
	}
	while( ISPTR(p->in.type) )
	{
		p = buildtree( STAR, p, NIL );
	}
	return( optim(p) );
}

/* mapping relationals when the sides are reversed */
short revrel[] =
{
	 EQ, NE, GE, GT, LE, LT, UGE, UGT, ULE, ULT 
};

#ifndef NODBG
#define REPORT(x) if(opdebug){printf( "optim did\n"); eprint(x);}
#else
# define REPORT(x)
#endif
NODE *
doptim(p)
register NODE *p; 
{
	/* local optimizations, most of which are machine independent */
	/* doptim is called for each node by optim; it assumes that
	** the children of p are already optimized 
	*/
	/* p is not a leaf */
	register NODE *l, *r, *sp;
	register o, i;
	register TWORD t;

#ifndef NODBG
	if( opdebug ) 
	{
		printf( "doptim called on:\n" );
		eprint(p);
	}
#endif

	if( (t=BTYPE(p->in.type))==ENUMTY || t==MOETY ) econvert(p);
	switch( optype( o = p->tn.op ) ) 
	{
	case BITYPE:
		r = p->in.right;
		/* FALLTHRU */
	case UTYPE:
		l = p->in.left;
		break;
	case LTYPE:
		/* nothing more to do (after doing the enum stuff) */
		return( p );
	}
	sp = conval( p );
	/* return only if conval did something */
	if( sp != p ) return( doptim(sp) );
#ifndef NODBG
	if( opdebug ) 
	{
		printf( "doptim works on:\n" );
		eprint(p);
	}
#endif
	switch(o)
	{
	case COMOP:	/* maybe simpstr changed the type of the right */
		if(p->in.type != r->in.type) {
			p->in.type = r->in.type;
			/* anything else? */
			REPORT(p);
		}
		return(p);
	case CONV:
		/* someday, make pvconvert and sconvert the same */
		return( ISPTR(p->tn.type)?pvconvert(p):sconvert(p) );
	case ASG PLUS:
	case ASG MINUS:
	case ASG AND:
	case ASG OR:
	case ASG ER:
	case ASG LS:
	case ASG RS:
	case ASG MUL:
	case ASG DIV:
	case ASG MOD:
		/* if conversion ops on the lhs, transfer them to the rhs */
		t = l->in.type;

		/* (CONV A) op= B  into A op= (CONV B)
		** this only holds if the result depends only on the
		** low order part of B (e.g., that part of B that
		** is the width of A
		** this is not true for /=, %=, or floats */

		if( l->tn.op == CONV && t!=FLOAT && t!=DOUBLE
			&& o!=ASG DIV && o != ASG MOD )
		{
			p->in.left = l->in.left;
			l->tn.op = FREE;
			l = l->in.left;
			r = makety( r, p->in.type, p->fn.cdim, p->fn.csiz );
			p->in.right = doptim( r );
		}
		if( !nncon(r) ) break;  /* no more optimization */
		/* get rid of 0 ops that don't change anything... */
		if( !r->tn.lval && (o==ASG PLUS || o==ASG MINUS || o==ASG OR ||
		    o==ASG ER || o==ASG LS || o==ASG RS) )
		{
			/* the answer is the lhs */
			goto bless;
		}
		if( r->tn.lval == 1 && (o==ASG MUL || o==ASG DIV) ) 
		{
			/* the answer is the lhs */
			goto bless;
		}
		if( (i = ispow2( r->tn.lval ))>=0 && o==ASG MUL ) 
		{
			o = p->in.op = ASG LS;
			r->tn.lval = i;
		}
		break;
	case LS:
	case RS:
		if( !nncon(r) || r->tn.lval )
			break;  /* do nothing */
		goto bless;  /* shifts by 0 */
	case FORTCALL:
		p->in.right = fortarg( r );
		break;
	case UNARY AND:
		switch( l->tn.op ) 
		{
		case STAR:
			/* fake up to use setuleft */
			l->tn.op = FREE;
			l=l->in.left;
			goto setuleft;
		case VAUTO:
		case VPARAM:
		case TEMP:
			/* the next two lines come from short structs */
		case CALL:
		case UNARY CALL:
			break;

		case RNODE:
# ifdef ARGSRET
			/* RNODE disappears if structure simple */
			if( simpstr( p->fn.cdim, p->fn.csiz ) == STRTY ) 
			{
				/* complicated: make it look like first arg */
				l->tn.op = VPARAM;
				l->tn.lval = BITOOR(ARGINIT);
				l->tn.rval = NONAME;
			}
			break;
#else
# ifdef STATSRET
			/* simple structures will disappear */
			if( simpstr( p->fn.cdim, p->fn.csiz ) != STRTY ) break;
			/* otherwise, make & RNODE into ICON for static area */
			l->tn.rval = -strftn;
# else
			break; /* & of RNODE is just fine */
#endif
#endif
		case NAME:
# ifdef ANDABLE
			if( !ANDABLE(l) ) return(p);
# endif
			l->tn.op = ICON;
setuleft:
			/* set the type of lhs with the type of the top */
			l->in.type = p->in.type;
			l->fn.cdim = p->fn.cdim;
			l->fn.csiz = p->fn.csiz;
			p->in.op = FREE;
			REPORT(l);
			return( l );
		default:
			cerror( "& error" );
		}
		break;
	case STCALL:
	case UNARY STCALL:
		/* use l in case return type overwritten */
		t = simpstr( l->fn.cdim, l->fn.csiz );
		if( t != STRTY ) 
		{
			/* take some care to keep the types OK */
			/* the type of the return might well have been
			** overwritten by (say) a structure reference 
			*/
			/* MAY NOT BE QUITE RIGHT IF TWO FLAVORS OF PTR */
			l = p;
			p->tn.type = DECREF( p->tn.type );
			p = buildtree( UNARY AND, l, NIL );
			if( o == STCALL ) l->tn.op = CALL;
			else l->tn.op = UNARY CALL;
			l->fn.type = l->fn.csiz = t;
			l->fn.cdim = 0;
		}
		break;
	case STAR:
		if( p->tn.type == STRTY || p->tn.type == UNIONTY ) 
		{
			p->tn.op = FREE;
			REPORT(l);
			return( l );
		}
		if( l->tn.op == UNARY AND && !callop(l->in.left->tn.op) ) 
		{
			/* & of call used in structure optimization */
			/* fake up to use setuleft */
			l->tn.op = FREE;
			l = l->in.left;
			goto setuleft;
		}
		if( l->tn.op != ICON ) break;
		l->tn.op = NAME;
		goto setuleft;
	case MINUS:
		if( !nncon(r) ) break;
		r->tn.lval = - r->tn.lval;
		o = p->in.op = PLUS;
	case MUL:
	case PLUS:
	case AND:
	case OR:
	case ER:
		/* commutative ops; for now, just collect constants */
		/* someday, do it right */
		if( o==r->tn.op || nncon(l) || ( ISCON(l) && !ISCON(r) ) ) 
		{
			/* make ops tower to the left, not the right */
			/* also, put constants on the right */
			sp = l;
			l = p->in.left = r;
			r = p->in.right = sp;
		}
		/* do (A + C1) + C2, etc. */
		/* the number of special cases is horrifying */
		/* many bugs have been found here; this code is very cautious */
		/* (A + C1) + C2, where C2 can be a ptr, C1 not */
		if( o==PLUS && l->tn.op==PLUS && ISCON(r) &&
		    nncon(l->in.right) )
		{
			p->in.left = l->in.left;
			l->tn.op = FREE;
			l = l->in.right;
			r->tn.lval += l->tn.lval;
			l->tn.op = FREE;
			return( doptim( p ) );
		}
		/* (A + C1) + C2, where C1 can be a ptr, C2 not */
		if( o==PLUS && l->tn.op==PLUS && nncon(r) &&
		    ISCON(l->in.right) )
		{
			l->in.right->tn.lval += r->tn.lval;
			goto bless;  /* return l as the result */
		}
		/* (A - C1) + C2, where C2 can be a ptr, C1 not */
		if( o==PLUS && l->tn.op==MINUS && ISCON(r) &&
		    nncon(l->in.right) )
		{
			p->in.left = l->in.left;
			l->tn.op = FREE;
			l = l->in.right;
			r->tn.lval -= l->tn.lval;
			l->tn.op = FREE;
			return( doptim( p ) );
		}
		/* (&A)+C */
		if( o==PLUS && l->tn.op == UNARY AND && ISCON(r) ) 
		{
			switch( l->in.left->tn.op ) 
			{
			case NAME:
			case VPARAM:
			case VAUTO:
				l->in.left->tn.lval += r->tn.lval;
				goto bless;
			}
		}
		/* change muls to shifts */
		if( o==MUL && nncon(r) && (i=ispow2(r->tn.lval))>=0)
		{
			if( i == 0 )
			{
				 /* multiplication by 1 */
bless:
				/* return l, with the type of p */
				l = makety( l, p->tn.type, p->fn.cdim,
				p->fn.csiz );
				r->tn.op = FREE;
				p->tn.op = FREE;
				/* if a conversion op was added, optimize */
				l = doptim( l );
#ifndef NODBG
				if( opdebug ) 
				{
					printf( "optim replaces op1 (%d) by:\n",
					p-node );
					eprint(l);
				}
#endif
				return( l );
			}
			o = p->in.op = LS;
			r->tn.lval = i;
		}
		/* change +'s of negative consts back to - */
		if( o==PLUS && nncon(r) && r->tn.lval<0 )
		{
			r->tn.lval = -r->tn.lval;
			o = p->in.op = MINUS;
		}
		if( nncon(r) && !r->tn.lval && (o==PLUS||o==MINUS) )
		{
			/* get rid of add or subtract of 0 */
			goto bless;
		}
# ifdef PTRLEFT
		if( o==PLUS && ISPTR(p->tn.type) && ISPTR(r->tn.type)
# ifdef CONSRIGHT
		    && r->tn.op != ICON
# endif
		    ) 
		{
			 sp = l; 
			p->in.left = r; 
			p->in.right = sp; 
		}
# endif
# ifdef PTRRIGHT
		if( o==PLUS && ISPTR(p->tn.type) && ISPTR(l->tn.type)
# ifdef CONSRIGHT
		    && r->tn.op != ICON
# endif
		    ) 
		{
			 sp = l; 
			p->in.left = r; 
			p->in.right = sp; 
		}
# endif
		break;
	case DIV:
		if( nncon( r ) && r->tn.lval == 1 ) goto bless;
		break;
	case EQ:
	case NE:
	case LT:
	case LE:
	case GT:
	case GE:
	case ULT:
	case ULE:
	case UGT:
	case UGE:
		if( ISCON(l) && !ISCON(r) )
		{
			/* exchange operands */
			p->in.op = revrel[p->in.op - EQ ];
			sp = l;
			l = p->in.left = r;
			r = p->in.right = sp;
		}
		break;
	case STASG:
		if( (t=simpstr( p->fn.cdim, p->fn.csiz ) ) != STRTY ) 
		{
			/* rewrite = as simpler */
			if( ISPTR(r->tn.type) ) 
			{
				r = buildtree( STAR, r, NIL );
				r->fn.type = r->fn.csiz = t;
				r->fn.cdim = 0;
				p->in.right = r = doptim( r );
			}
			l = buildtree( STAR, l, NIL );
			l->fn.type = l->fn.csiz = t;
			l->fn.cdim = 0;
			p->in.left = l = doptim( l );
			p->fn.type = p->fn.csiz = t;
			p->fn.cdim = 0;
			p->fn.op = ASSIGN;
			return( p );
		}
	case STARG:
		if( (t=simpstr( p->fn.cdim, p->fn.csiz ) ) != STRTY ) 
		{
			/* rewrite as simpler */
			if( ISPTR(l->fn.type) ) 
			{
				l = buildtree( STAR, l, NIL );
				l->fn.type = l->fn.csiz = t;
				l->fn.cdim = 0;
				p->in.left = l = doptim( l );
			}
			p->fn.type = p->fn.csiz = (t==LONG ? LONG : INT);
			p->fn.cdim = 0;
			p->fn.op = FUNARG;
			return( p );
		}
# ifdef ENDSTRUCT
		p->in.left = aadjust( l, p->stn.stsize );
# endif
		break;
	}
	return(p);
}

NODE *
optim( p )
register NODE *p; 
{
	switch( optype( p->tn.op ) )
	{
	case BITYPE:
		p->in.right = optim( p->in.right );
		/* FALLTHRU */
	case UTYPE:
		p->in.left = optim( p->in.left );
	}
	return( doptim( p ) );
}

ispow2( c ) 
register CONSZ c; 
{
	register i;
	if( c <= 0 || (c&(c-1)) ) return(-1);
	for( i=0; c>1; ++i) c >>= 1;
	return(i);
}

nncon( p )
register NODE *p; 
{
	/* is p a constant without a name */
	return( p->tn.op == ICON && p->tn.rval == NONAME && !ISPTR(p->tn.type));
}

/* some routines for debugging and tree transformation */
#ifndef MYOFFCON
NODE *
offcon( off, t, d, s )
OFFSZ off; 
TWORD t; 
{
	/* return a node, for structure references, which is suitable for
	** being added to a pointer of type t, in order to be off bits offset
	** into a structure 
	*/
	register NODE *p;

	/* t, d, and s are the type, dimension offset, and size offset */
	/* in general they may be necessary for offcon */
	p = bcon(0);
	p->tn.lval = BITOOR(off);
	p->fn.type = p->fn.csiz = PTRTYPE;
	return(p);
}
# endif

bccode()
{
	/* called just before executing code */
	/* beware: called several times if there is auto. initialization */
# ifdef MYBCCODE
	MYBCCODE;
# endif
	p2bbeg( autooff, regvar );
}

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