ref: e5c045851833cfd6b4a8a3326131caf5a406410b
dir: /cc1/fold.c/
/* See LICENSE file for copyright and license details. */
static char sccsid[] = "@(#) ./cc1/fold.c";
#include <stdio.h>
#include <stdlib.h>
#include "../inc/cc.h"
#include "cc1.h"
TUINT
ones(int nbytes)
{
TUINT v;
for (v = 0; nbytes--; v |= 255)
v <<= 8;
return v;
}
static int
addi(TINT l, TINT r, Type *tp)
{
struct limits *lim = getlimits(tp);
TINT max = lim->max.i, min = -lim->min.i;
if (l < 0 && r < 0 && l >= min - r ||
l == 0 ||
r == 0 ||
l < 0 && r > 0 ||
l > 0 && r < 0 ||
l > 0 && r > 0 && l <= max - r) {
return 1;
}
warn("overflow in constant expression");
return 0;
}
static int
addf(TFLOAT l, TFLOAT r, Type *tp)
{
struct limits *lim = getlimits(tp);
TFLOAT max = lim->max.f, min = lim->min.f;
if (l < 0 && r < 0 && l >= min - r ||
l == 0 ||
r == 0 ||
l < 0 && r > 0 ||
l > 0 && r < 0 ||
l > 0 && r > 0 && l <= max - r) {
return 1;
}
warn("overflow in constant expression");
return 0;
}
static int
subi(TINT l, TINT r, Type *tp)
{
return addi(l, -r, tp);
}
static int
subf(TFLOAT l, TFLOAT r, Type *tp)
{
return addf(l, -r, tp);
}
static int
muli(TINT l, TINT r, Type *tp)
{
struct limits *lim = getlimits(tp);
TINT max = lim->max.i, min = -lim->min.i;
if (l > -1 && l <= 1 ||
r > -1 && r <= 1 ||
l < 0 && r < 0 && -l <= max/-r ||
l < 0 && r > 0 && l >= min/r ||
l > 0 && r < 0 && r >= min/l ||
l > 0 && r > 0 && l <= max/r) {
return 1;
}
warn("overflow in constant expression");
return 0;
}
static int
mulf(TFLOAT l, TFLOAT r, Type *tp)
{
struct limits *lim = getlimits(tp);
TFLOAT max = lim->max.f, min = lim->min.f;
if (l > -1 && l <= 1 ||
r > -1 && r <= 1 ||
l < 0 && r < 0 && -l <= max/-r ||
l < 0 && r > 0 && l >= min/r ||
l > 0 && r < 0 && r >= min/l ||
l > 0 && r > 0 && l <= max/r) {
return 1;
}
warn("overflow in constant expression");
return 0;
}
static int
divi(TINT l, TINT r, Type *tp)
{
struct limits *lim = getlimits(tp);
if (r == 0 || l == -lim->min.i && r == -1) {
warn("overflow in constant expression");
return 0;
}
return 1;
}
static int
divf(TFLOAT l, TFLOAT r, Type *tp)
{
struct limits *lim = getlimits(tp);
if (l < 0) l = -l;
if (r < 0) r = -r;
if (r == 0.0 || r < 1.0 && l > lim->max.f * r) {
warn("overflow in constant expression");
return 0;
}
return 1;
}
static int
lshi(TINT l, TINT r, Type *tp)
{
if (r < 0 || r >= tp->size * 8) {
warn("shifting %d bits is undefined", r);
return 0;
}
return muli(l, 1 << r, tp);
}
static int
rshi(TINT l, TINT r, Type *tp)
{
if (r < 0 || r >= tp->size * 8) {
warn("shifting %d bits is undefined", r);
return 0;
}
return 1;
}
static int
foldint(int op, Symbol *res, TINT l, TINT r)
{
TINT i;
Type *tp = res->type;
int (*validate)(TINT, TINT, Type *tp);
switch (op) {
case OADD: validate = addi; break;
case OSUB: validate = subi; break;
case OMUL: validate = muli; break;
case ODIV: validate = divi; break;
case OSHL: validate = lshi; break;
case OSHR: validate = rshi; break;
case OMOD: validate = divi; break;
default: validate = NULL; break;
}
if (validate && !(*validate)(l, r, tp))
return 0;
switch (op) {
case OADD: i = l + r; break;
case OSUB: i = l - r; break;
case OMUL: i = l * r; break;
case ODIV: i = l / r; break;
case OMOD: i = l % r; break;
case OSHL: i = l << r; break;
case OSHR: i = l >> r; break;
case OBAND: i = l & r; break;
case OBXOR: i = l ^ r; break;
case OBOR: i = l | r; break;
case OAND: i = l && r; break;
case OOR: i = l || r; break;
case OLT: i = l < r; break;
case OGT: i = l > r; break;
case OGE: i = l >= r; break;
case OLE: i = l <= r; break;
case OEQ: i = l == r; break;
case ONE: i = l != r; break;
case ONEG: i = !l; break;
case OSNEG: i = -l; break;
case OCPL: i = ~l; break;
default: return 0;
}
res->u.i = i;
return 1;
}
static int
folduint(int op, Symbol *res, TUINT l, TUINT r)
{
TINT i;
TUINT u;
switch (op) {
case OADD: u = l + r; break;
case OSUB: u = l - r; break;
case OMUL: u = l * r; break;
case ODIV: u = l / r; break;
case OMOD: u = l % r; break;
case OSHL: u = l << r; break;
case OSHR: u = l >> r; break;
case OBAND: u = l & r; break;
case OBXOR: u = l ^ r; break;
case OBOR: u = l | r; break;
case ONEG: u = !l; break;
case OSNEG: u = -l; break;
case OCPL: u = ~l; break;
case OAND: i = l && r; goto sign;
case OOR: i = l || r; goto sign;
case OLT: i = l < r; goto sign;
case OGT: i = l > r; goto sign;
case OGE: i = l >= r; goto sign;
case OLE: i = l <= r; goto sign;
case OEQ: i = l == r; goto sign;
case ONE: i = l != r; goto sign;
default: return 0;
}
res->u.u = u & ones(res->type->size);
return 1;
sign:
res->u.i = i;
return 1;
}
static int
foldfloat(int op, Symbol *res, TFLOAT l, TFLOAT r)
{
TFLOAT f;
TINT i;
int (*validate)(TFLOAT, TFLOAT, Type *tp);
switch (op) {
case OADD: validate = addf; break;
case OSUB: validate = subf; break;
case OMUL: validate = mulf; break;
case ODIV: validate = divf; break;
default: validate = NULL; break;
}
if (validate && !(*validate)(l, r, res->type))
return 0;
switch (op) {
case OADD: f = l + r; break;
case OSUB: f = l - r; break;
case OMUL: f = l * r; break;
case ODIV: f = l / r; break;
case OLT: i = l < r; goto comparison;
case OGT: i = l > r; goto comparison;
case OGE: i = l >= r; goto comparison;
case OLE: i = l <= r; goto comparison;
case OEQ: i = l == r; goto comparison;
case ONE: i = l != r; goto comparison;
default: return 0;
}
res->u.f = f;
return 1;
comparison:
res->u.i = i;
return 1;
}
static Node *
foldconst(int type, int op, Type *tp, Symbol *ls, Symbol *rs)
{
Symbol *sym, aux;
TINT i;
TUINT u;
TFLOAT f;
aux.type = tp;
switch (type) {
case INT:
i = (rs) ? rs->u.i : 0;
if (!foldint(op, &aux, ls->u.i, i))
return NULL;
break;
case UNSIGNED:
u = (rs) ? rs->u.u : 0u;
if (!folduint(op, &aux, ls->u.u, u))
return NULL;
break;
case FLOAT:
f = (rs) ? rs->u.f : 0.0;
if (!foldfloat(op, &aux, ls->u.f, f))
return NULL;
break;
}
sym = newsym(NS_IDEN, NULL);
sym->type = tp;
sym->u = aux.u;
return constnode(sym);
}
static Node *
fold(int op, Type *tp, Node *lp, Node *rp)
{
Symbol *rs, *ls;
Node *np;
Type *optype;
int type;
if ((op == ODIV || op == OMOD) && cmpnode(rp, 0)) {
warn("division by 0");
return NULL;
}
/*
* Return if any of the children is no constant,
* or it is a constant generated when
* the address of a static variable is taken
* (when we don't know the physical address so
* we cannot fold it)
*/
if (!(lp->flags & NCONST) || !lp->sym ||
rp && (!(rp->flags & NCONST) || !rp->sym)) {
return NULL;
}
optype = lp->type;
ls = lp->sym;
rs = (rp) ? rp->sym : NULL;
switch (type = optype->op) {
case ENUM:
case INT:
if (!(optype->prop & TSIGNED))
type = UNSIGNED;
case PTR:
case FLOAT:
if ((np = foldconst(type, op, tp, ls, rs)) != NULL)
break;
default:
return NULL;
}
freetree(lp);
freetree(rp);
return np;
}
static void
commutative(int *op, Node **lp, Node **rp)
{
Node *l = *lp, *r = *rp, *aux;
if (r == NULL || r->flags & NCONST || !(l->flags & NCONST))
return;
switch (*op) {
case OLT:
case OGT:
case OGE:
case OLE:
*op = negop(*op);
case OEQ:
case ONE:
case OADD:
case OMUL:
case OBAND:
case OBXOR:
case OBOR:
aux = l;
l = r;
r = aux;
break;
}
*rp = r;
*lp = l;
}
static Node *
identity(int *op, Node *lp, Node *rp)
{
int iszeror, isoner, istruer;
int iszerol, isonel, istruel;
if (!rp)
return NULL;
iszeror = cmpnode(rp, 0);
isoner = cmpnode(rp, 1),
istruer = !iszeror && rp->flags & NCONST;
iszerol = cmpnode(lp, 0);
isonel = cmpnode(lp, 1),
istruel = !iszerol && lp->flags & NCONST;
switch (*op) {
case OOR:
/*
* 1 || i => 1 (free right)
* i || 0 => i (free right)
* 0 || i => i (free left)
* i || 1 => i,1 (comma)
*/
if (isonel | iszeror)
goto free_right;
if (iszerol)
goto free_left;
if (isoner)
goto change_to_comma;
return NULL;
case OAND:
/*
* 0 && i => 0 (free right)
* i && 1 => i (free right)
* 1 && i => i (free left)
* i && 0 => i,0 (comma)
*/
if (iszerol | isoner)
goto free_right;
if (isonel)
goto free_left;
if (iszeror)
goto change_to_comma;
return NULL;
case OSHL:
case OSHR:
/*
* i >> 0 => i (free right)
* i << 0 => i (free right)
* 0 >> i => 0 (free right)
* 0 << i => 0 (free right)
*/
if (iszeror | iszerol)
goto free_right;
return NULL;
case OBXOR:
case OADD:
case OBOR:
case OSUB:
/*
* i + 0 => i
* i - 0 => i
* i | 0 => i
* i ^ 0 => i
*/
if (iszeror)
goto free_right;
return NULL;
case OMUL:
/*
* i * 0 => i,0
* i * 1 => i
*/
if (iszeror)
goto change_to_comma;
if (isoner)
goto free_right;
return NULL;
case ODIV:
/* i / 1 => i */
if (isoner)
goto free_right;
return NULL;
case OBAND:
/* i & ~0 => i */
if (cmpnode(rp, -1))
goto free_right;
return NULL;
case OMOD:
/* i % 1 => i,1 */
if (isoner)
goto change_to_comma;
default:
return NULL;
}
free_right:
freetree(rp);
return lp;
free_left:
freetree(lp);
return rp;
change_to_comma:
*op = OCOMMA;
return NULL;
}
static Node *
foldternary(int op, Type *tp, Node *cond, Node *body)
{
Node *np;
if (!(cond->flags & NCONST))
return node(op, tp, cond, body);
if (cmpnode(cond, 0)) {
np = body->right;
freetree(body->left);
} else {
np = body->left;
freetree(body->right);
}
freetree(cond);
free(body);
return np;
}
/*
* TODO: transform simplify in a recursivity
* function, because we are losing optimization
* chances
*/
Node *
simplify(int op, Type *tp, Node *lp, Node *rp)
{
Node *np;
if (op == OASK)
return foldternary(op, tp, lp, rp);
commutative(&op, &lp, &rp);
if ((np = fold(op, tp, lp, rp)) != NULL)
return np;
if ((np = identity(&op, lp, rp)) != NULL)
return np;
return node(op, tp, lp, rp);
}
/* TODO: check validity of types */
Node *
castcode(Node *np, Type *newtp)
{
TUINT negmask, mask, u;
Type *oldtp = np->type;
Symbol aux, *sym, *osym = np->sym;
if (!(np->flags & NCONST))
goto noconstant;
switch (newtp->op) {
case PTR:
case INT:
case ENUM:
switch (oldtp->op) {
case PTR:
case INT:
case ENUM:
u = (oldtp->prop & TSIGNED) ? osym->u.i : osym->u.u;
break;
case FLOAT:
oldtp = newtp;
u = osym->u.f;
break;
default:
goto noconstant;
}
mask = ones(newtp->size);
if (newtp->prop & TSIGNED) {
negmask = ~mask;
if (u & (negmask >> 1) & mask)
u |= negmask;
aux.u.i = u;
} else {
aux.u.u = u & mask;
}
break;
case FLOAT:
/* FIXME: The cast can be from another float type */
aux.u.f = (oldtp->prop & TSIGNED) ? osym->u.i : osym->u.u;
break;
default:
goto noconstant;
}
sym = newsym(NS_IDEN, NULL);
np->type = sym->type = newtp;
np->sym = sym;
sym->u = aux.u;
return np;
noconstant:
return node(OCAST, newtp, np, NULL);
}