/*
* Determine if a value is known to be constant at compile-time and
* hence that PCC can perform constant-folding on expressions involving
* that value.
*/
static NODE *
builtin_constant_p(const struct bitable *bt, NODE *a)
{
void putjops(NODE *p, void *arg);
NODE *f;
int isconst;
walkf(a, putjops, 0);
for (f = a; f->n_op == COMOP; f = f->n_right)
;
isconst = nncon(f);
tfree(a);
return bcon(isconst);
}
/*
* Determine if a value is known to be constant at compile-time and
* hence that PCC can perform constant-folding on expressions involving
* that value.
*/
static NODE *
builtin_constant_p(NODE *f, NODE *a, TWORD rt)
{
void putjops(NODE *p, void *arg);
int isconst;
tfree(f);
walkf(a, putjops, 0);
for (f = a; f->n_op == COMOP; f = f->n_right)
;
isconst = nncon(f);
tfree(a);
return bcon(isconst);
}
/* clocal() is called to do local transformations on
* an expression tree preparitory to its being
* written out in intermediate code.
*
* the major essential job is rewriting the
* automatic variables and arguments in terms of
* REG and OREG nodes
* conversion ops which are not necessary are also clobbered here
* in addition, any special features (such as rewriting
* exclusive or) are easily handled here as well
*/
NODE *
clocal(NODE *p)
{
register struct symtab *q;
register NODE *r, *l;
register int o;
register int m;
TWORD t;
#ifdef PCC_DEBUG
if (xdebug) {
printf("clocal: %p\n", p);
fwalk(p, eprint, 0);
}
#endif
switch( o = p->n_op ){
case NAME:
if ((q = p->n_sp) == NULL)
return p; /* Nothing to care about */
switch (q->sclass) {
case PARAM:
case AUTO:
/* fake up a structure reference */
r = block(REG, NIL, NIL, PTR+STRTY, 0, 0);
slval(r, 0);
r->n_rval = FPREG;
p = stref(block(STREF, r, p, 0, 0, 0));
break;
case USTATIC:
if (kflag == 0)
break;
/* FALLTHROUGH */
case STATIC:
#ifdef TLS
if (q->sflags & STLS) {
p = tlsref(p);
break;
}
#endif
break;
case REGISTER:
p->n_op = REG;
slval(p, 0);
p->n_rval = q->soffset;
break;
case EXTERN:
case EXTDEF:
if (q->sflags & STLS) {
p = tlsref(p);
break;
}
if (kflag == 0 || statinit)
break;
if (blevel > 0)
p = picext(p);
break;
}
break;
case UCALL:
case USTCALL:
/* For now, always clear eax */
l = block(REG, NIL, NIL, INT, 0, 0);
regno(l) = RAX;
p->n_right = clocal(buildtree(ASSIGN, l, bcon(0)));
p->n_op -= (UCALL-CALL);
break;
case SCONV:
/* Special-case shifts */
if (p->n_type == LONG && (l = p->n_left)->n_op == LS &&
l->n_type == INT && l->n_right->n_op == ICON) {
p->n_left = l->n_left;
p = buildtree(LS, p, l->n_right);
nfree(l);
break;
}
l = p->n_left;
/* Float conversions may need extra casts */
if (p->n_type == FLOAT || p->n_type == DOUBLE ||
p->n_type == LDOUBLE) {
if (l->n_type < INT || l->n_type == BOOL) {
p->n_left = block(SCONV, l, NIL,
ISUNSIGNED(l->n_type) ? UNSIGNED : INT,
l->n_df, l->n_ap);
break;
}
}
if (p->n_type == l->n_type) {
nfree(p);
return l;
}
if ((p->n_type & TMASK) == 0 && (l->n_type & TMASK) == 0 &&
tsize(p->n_type, p->n_df, p->n_ap) ==
tsize(l->n_type, l->n_df, l->n_ap)) {
if (p->n_type != FLOAT && p->n_type != DOUBLE &&
l->n_type != FLOAT && l->n_type != DOUBLE &&
l->n_type != LDOUBLE && p->n_type != LDOUBLE) {
if (l->n_op == NAME || l->n_op == UMUL ||
l->n_op == TEMP) {
l->n_type = p->n_type;
nfree(p);
return l;
}
}
}
if (DEUNSIGN(p->n_type) == INT && DEUNSIGN(l->n_type) == INT &&
coptype(l->n_op) == BITYPE && l->n_op != COMOP &&
l->n_op != QUEST && l->n_op != ASSIGN) {
l->n_type = p->n_type;
nfree(p);
return l;
}
o = l->n_op;
m = p->n_type;
if (o == ICON) {
CONSZ val = glval(l);
/* if named constant and pointer, allow cast
to long/ulong */
if (!nncon(l) && (l->n_type & TMASK) &&
(m == LONG || m == ULONG)) {
l->n_type = m;
l->n_ap = 0;
return nfree(p);
}
if (ISPTR(l->n_type) && !nncon(l))
break; /* cannot convert named pointers */
if (!ISPTR(m)) /* Pointers don't need to be conv'd */
switch (m) {
case BOOL:
val = nncon(l) ? (val != 0) : 1;
slval(l, val);
l->n_sp = NULL;
break;
case CHAR:
slval(l, (char)val);
break;
case UCHAR:
slval(l, val & 0377);
break;
case SHORT:
slval(l, (short)val);
break;
case USHORT:
slval(l, val & 0177777);
break;
case UNSIGNED:
slval(l, val & 0xffffffff);
break;
case INT:
slval(l, (int)val);
break;
case LONG:
case LONGLONG:
slval(l, (long long)val);
break;
case ULONG:
case ULONGLONG:
slval(l, val);
break;
case VOID:
break;
case LDOUBLE:
case DOUBLE:
case FLOAT:
l->n_op = FCON;
l->n_dcon = fltallo();
FCAST(l->n_dcon)->fp = val;
break;
default:
cerror("unknown type %d", m);
}
l->n_type = m;
l->n_ap = NULL;
nfree(p);
return l;
} else if (l->n_op == FCON) {
CONSZ lv;
if (p->n_type == BOOL)
lv = !FLOAT_ISZERO(FCAST(l->n_dcon));
else {
FLOAT_FP2INT(lv, FCAST(l->n_dcon), m);
}
slval(l, lv);
l->n_sp = NULL;
l->n_op = ICON;
l->n_type = m;
l->n_ap = NULL;
nfree(p);
return clocal(l);
}
if ((p->n_type == CHAR || p->n_type == UCHAR ||
p->n_type == SHORT || p->n_type == USHORT) &&
(l->n_type == FLOAT || l->n_type == DOUBLE ||
l->n_type == LDOUBLE)) {
p = block(SCONV, p, NIL, p->n_type, p->n_df, p->n_ap);
p->n_left->n_type = INT;
return p;
}
break;
case MOD:
case DIV:
if (o == DIV && p->n_type != CHAR && p->n_type != SHORT)
break;
if (o == MOD && p->n_type != CHAR && p->n_type != SHORT)
break;
/* make it an int division by inserting conversions */
p->n_left = makety(p->n_left, INT, 0, 0, 0);
p->n_right = makety(p->n_right, INT, 0, 0, 0);
p = makety(p, p->n_type, 0, 0, 0);
p->n_left->n_type = INT;
break;
case FORCE:
/* put return value in return reg */
p->n_op = ASSIGN;
p->n_right = p->n_left;
p->n_left = block(REG, NIL, NIL, p->n_type, 0, 0);
t = p->n_type;
if (ISITY(t))
t = t - (FIMAG-FLOAT);
p->n_left->n_rval = p->n_left->n_type == BOOL ?
RETREG(CHAR) : RETREG(t);
break;
case LS:
case RS:
/* shift count must be in a char */
if (p->n_right->n_type == CHAR || p->n_right->n_type == UCHAR)
break;
p->n_right = makety(p->n_right, CHAR, 0, 0, 0);
break;
}
#ifdef PCC_DEBUG
if (xdebug) {
printf("clocal end: %p\n", p);
fwalk(p, eprint, 0);
}
#endif
return(p);
}
/*
* local optimizations, most of which are probably
* machine independent
*/
NODE *
optim(NODE *p)
{
int o, ty;
NODE *sp, *q;
OFFSZ sz;
int i;
if (odebug) 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:
if (concast(p->n_left, p->n_type)) {
q = p->n_left;
nfree(p);
p = q;
break;
}
/* FALLTHROUGH */
case PCONV:
if (p->n_type != VOID)
p = clocal(p);
break;
case FORTCALL:
p->n_right = fortarg( p->n_right );
break;
case ADDROF:
if (LO(p) == TEMP)
break;
if( LO(p) != NAME ) cerror( "& error" );
if( !andable(p->n_left) && !statinit)
break;
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_ap = p->n_ap;
q = p->n_left;
nfree(p);
p = q;
break;
case NOT:
case UMINUS:
case COMPL:
if (LCON(p) && conval(p->n_left, o, p->n_left))
p = nfree(p);
break;
case UMUL:
/* Do not discard ADDROF TEMP's */
if (LO(p) == ADDROF && LO(p->n_left) != TEMP) {
q = p->n_left->n_left;
nfree(p->n_left);
nfree(p);
p = q;
break;
}
if( LO(p) != ICON ) break;
LO(p) = NAME;
goto setuleft;
case RS:
if (LCON(p) && RCON(p) && conval(p->n_left, o, p->n_right))
goto zapright;
sz = tsize(p->n_type, p->n_df, p->n_ap);
if (LO(p) == RS && RCON(p->n_left) && RCON(p) &&
(RV(p) + RV(p->n_left)) < sz) {
/* 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) >= sz) {
RV(p) = RV(p) % sz;
werror("shift larger than type");
}
if (RV(p) == 0)
p = zapleft(p);
}
break;
case LS:
if (LCON(p) && RCON(p) && conval(p->n_left, o, p->n_right))
goto zapright;
sz = tsize(p->n_type, p->n_df, p->n_ap);
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) >= sz) {
RV(p) = RV(p) % sz;
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:
/*
* Check for u=(x-y)+z; where all vars are pointers to
* the same struct. This has two advantages:
* 1: avoid a mul+div
* 2: even if not allowed, people may get surprised if this
* calculation do not give correct result if using
* unaligned structs.
*/
if (p->n_type == INTPTR && RCON(p) &&
LO(p) == DIV && RCON(p->n_left) &&
RV(p) == RV(p->n_left) &&
LO(p->n_left) == MINUS) {
q = p->n_left->n_left;
if (q->n_left->n_type == PTR+STRTY &&
q->n_right->n_type == PTR+STRTY &&
strmemb(q->n_left->n_ap) ==
strmemb(q->n_right->n_ap)) {
p = zapleft(p);
p = zapleft(p);
}
}
/* FALLTHROUGH */
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;
sp->n_type = p->n_type;
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_ap);
nfree(p);
p = clocal(q);
break;
}
/* 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_ap) > SZINT)
p->n_right = makety(q, INT, 0, 0, 0);
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;
#ifdef notyet
case ASSIGN:
/* Simple test to avoid two branches */
if (RO(p) != NE)
break;
q = p->n_right;
if (RCON(q) && RV(q) == 0 && LO(q) == AND &&
RCON(q->n_left) && (i = ispow2(RV(q->n_left))) &&
q->n_left->n_type == INT) {
q->n_op = RS;
RV(q) = i;
}
break;
#endif
}
return(p);
}
