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/* $OpenBSD: optim.c,v 1.3 2008/04/11 20:45:52 stefan Exp $ */
/*
* Copyright(C) Caldera International Inc. 2001-2002. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* Redistributions of source code and documentation must retain the above
* copyright notice, this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright
* notice, this list of conditionsand the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed or owned by Caldera
* International, Inc.
* Neither the name of Caldera International, Inc. nor the names of other
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* USE OF THE SOFTWARE PROVIDED FOR UNDER THIS LICENSE BY CALDERA
* INTERNATIONAL, INC. AND CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL CALDERA INTERNATIONAL, INC. BE LIABLE
* FOR ANY DIRECT, INDIRECT INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OFLIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
# include "pass1.h"
# define SWAP(p,q) {sp=p; p=q; q=sp;}
# define RCON(p) (p->n_right->n_op==ICON)
# define RO(p) p->n_right->n_op
# define RV(p) p->n_right->n_lval
# define LCON(p) (p->n_left->n_op==ICON)
# define LO(p) p->n_left->n_op
# define LV(p) p->n_left->n_lval
int oflag = 0;
/* remove left node */
static NODE *
zapleft(NODE *p)
{
NODE *q;
q = p->n_left;
nfree(p->n_right);
nfree(p);
return q;
}
/*
* fortran function arguments
*/
static NODE *
fortarg(NODE *p)
{
if( p->n_op == CM ){
p->n_left = fortarg( p->n_left );
p->n_right = fortarg( p->n_right );
return(p);
}
while( ISPTR(p->n_type) ){
p = buildtree( UMUL, p, NIL );
}
return( optim(p) );
}
/* mapping relationals when the sides are reversed */
short revrel[] ={ EQ, NE, GE, GT, LE, LT, UGE, UGT, ULE, ULT };
/*
* local optimizations, most of which are probably
* machine independent
*/
NODE *
optim(NODE *p)
{
int o, ty;
NODE *sp, *q;
int i;
TWORD t;
t = BTYPE(p->n_type);
if( oflag ) return(p);
ty = coptype(p->n_op);
if( ty == LTYPE ) return(p);
if( ty == BITYPE ) p->n_right = optim(p->n_right);
p->n_left = optim(p->n_left);
/* collect constants */
again: o = p->n_op;
switch(o){
case SCONV:
case PCONV:
return( clocal(p) );
case FORTCALL:
p->n_right = fortarg( p->n_right );
break;
case ADDROF:
if (LO(p) == TEMP)
return p;
if( LO(p) != NAME ) cerror( "& error" );
if( !andable(p->n_left) ) return(p);
LO(p) = ICON;
setuleft:
/* paint over the type of the left hand side with the type of the top */
p->n_left->n_type = p->n_type;
p->n_left->n_df = p->n_df;
p->n_left->n_sue = p->n_sue;
q = p->n_left;
nfree(p);
return q;
case UMUL:
if( LO(p) != ICON ) break;
LO(p) = NAME;
goto setuleft;
case RS:
if (LO(p) == RS && RCON(p->n_left) && RCON(p)) {
/* two right-shift by constants */
RV(p) += RV(p->n_left);
p->n_left = zapleft(p->n_left);
}
#if 0
else if (LO(p) == LS && RCON(p->n_left) && RCON(p)) {
RV(p) -= RV(p->n_left);
if (RV(p) < 0)
o = p->n_op = LS, RV(p) = -RV(p);
p->n_left = zapleft(p->n_left);
}
#endif
if (RO(p) == ICON) {
if (RV(p) < 0) {
RV(p) = -RV(p);
p->n_op = LS;
goto again;
}
#ifdef notyet /* must check for side effects, --a >> 32; */
if (RV(p) >= tsize(p->n_type, p->n_df, p->n_sue) &&
ISUNSIGNED(p->n_type)) { /* ignore signed shifts */
/* too many shifts */
tfree(p->n_left);
nfree(p->n_right);
p->n_op = ICON; p->n_lval = 0; p->n_sp = NULL;
} else
#endif
/* avoid larger shifts than type size */
if (RV(p) >= p->n_sue->suesize) {
RV(p) = RV(p) % p->n_sue->suesize;
werror("shift larger than type");
}
if (RV(p) == 0)
p = zapleft(p);
}
break;
case LS:
if (LO(p) == LS && RCON(p->n_left) && RCON(p)) {
/* two left-shift by constants */
RV(p) += RV(p->n_left);
p->n_left = zapleft(p->n_left);
}
#if 0
else if (LO(p) == RS && RCON(p->n_left) && RCON(p)) {
RV(p) -= RV(p->n_left);
p->n_left = zapleft(p->n_left);
}
#endif
if (RO(p) == ICON) {
if (RV(p) < 0) {
RV(p) = -RV(p);
p->n_op = RS;
goto again;
}
#ifdef notyet /* must check for side effects */
if (RV(p) >= tsize(p->n_type, p->n_df, p->n_sue)) {
/* too many shifts */
tfree(p->n_left);
nfree(p->n_right);
p->n_op = ICON; p->n_lval = 0; p->n_sp = NULL;
} else
#endif
/* avoid larger shifts than type size */
if (RV(p) >= p->n_sue->suesize) {
RV(p) = RV(p) % p->n_sue->suesize;
werror("shift larger than type");
}
if (RV(p) == 0)
p = zapleft(p);
}
break;
case MINUS:
if (LCON(p) && RCON(p) && p->n_left->n_sp == p->n_right->n_sp) {
/* link-time constants, but both are the same */
/* solve it now by forgetting the symbols */
p->n_left->n_sp = p->n_right->n_sp = NULL;
}
if( !nncon(p->n_right) ) break;
RV(p) = -RV(p);
o = p->n_op = PLUS;
case MUL:
case PLUS:
case AND:
case OR:
case ER:
/* commutative ops; for now, just collect constants */
/* someday, do it right */
if( nncon(p->n_left) || ( LCON(p) && !RCON(p) ) )
SWAP( p->n_left, p->n_right );
/* make ops tower to the left, not the right */
if( RO(p) == o ){
NODE *t1, *t2, *t3;
t1 = p->n_left;
sp = p->n_right;
t2 = sp->n_left;
t3 = sp->n_right;
/* now, put together again */
p->n_left = sp;
sp->n_left = t1;
sp->n_right = t2;
p->n_right = t3;
}
if(o == PLUS && LO(p) == MINUS && RCON(p) && RCON(p->n_left) &&
conval(p->n_right, MINUS, p->n_left->n_right)){
zapleft:
q = p->n_left->n_left;
nfree(p->n_left->n_right);
nfree(p->n_left);
p->n_left = q;
}
if( RCON(p) && LO(p)==o && RCON(p->n_left) &&
conval( p->n_right, o, p->n_left->n_right ) ){
goto zapleft;
}
else if( LCON(p) && RCON(p) && conval( p->n_left, o, p->n_right ) ){
zapright:
nfree(p->n_right);
q = makety(p->n_left, p->n_type, p->n_qual,
p->n_df, p->n_sue);
nfree(p);
return clocal(q);
}
/* change muls to shifts */
if( o == MUL && nncon(p->n_right) && (i=ispow2(RV(p)))>=0){
if( i == 0 ) { /* multiplication by 1 */
goto zapright;
}
o = p->n_op = LS;
p->n_right->n_type = INT;
p->n_right->n_df = NULL;
RV(p) = i;
}
/* change +'s of negative consts back to - */
if( o==PLUS && nncon(p->n_right) && RV(p)<0 ){
RV(p) = -RV(p);
o = p->n_op = MINUS;
}
/* remove ops with RHS 0 */
if ((o == PLUS || o == MINUS || o == OR || o == ER) &&
nncon(p->n_right) && RV(p) == 0) {
goto zapright;
}
break;
case DIV:
if( nncon( p->n_right ) && p->n_right->n_lval == 1 )
goto zapright;
if (LCON(p) && RCON(p) && conval(p->n_left, DIV, p->n_right))
goto zapright;
if (RCON(p) && ISUNSIGNED(p->n_type) && (i=ispow2(RV(p))) > 0) {
p->n_op = RS;
RV(p) = i;
q = p->n_right;
if(tsize(q->n_type, q->n_df, q->n_sue) > SZINT)
p->n_right = makety(q, INT, 0, 0, MKSUE(INT));
break;
}
break;
case MOD:
if (RCON(p) && ISUNSIGNED(p->n_type) && ispow2(RV(p)) > 0) {
p->n_op = AND;
RV(p) = RV(p) -1;
break;
}
break;
case EQ:
case NE:
case LT:
case LE:
case GT:
case GE:
case ULT:
case ULE:
case UGT:
case UGE:
if( !LCON(p) ) break;
/* exchange operands */
sp = p->n_left;
p->n_left = p->n_right;
p->n_right = sp;
p->n_op = revrel[p->n_op - EQ ];
break;
}
return(p);
}
int
ispow2(CONSZ c)
{
int i;
if( c <= 0 || (c&(c-1)) ) return(-1);
for( i=0; c>1; ++i) c >>= 1;
return(i);
}
int
nncon( p ) NODE *p; {
/* is p a constant without a name */
return( p->n_op == ICON && p->n_sp == NULL );
}
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