/* Look for simple "left" identities like 0+x, 1*x, etc. */
static int
expr_can_destroy_int_left(yasm_expr_op op, yasm_intnum *intn)
{
int iszero = yasm_intnum_is_zero(intn);
return ((yasm_intnum_is_pos1(intn) && op == YASM_EXPR_MUL) ||
(iszero && op == YASM_EXPR_ADD) ||
(yasm_intnum_is_neg1(intn) && op == YASM_EXPR_AND) ||
(!iszero && op == YASM_EXPR_LAND) ||
(iszero && op == YASM_EXPR_OR) ||
(iszero && op == YASM_EXPR_LOR));
}
/* Look for simple "right" identities like x+|-0, x*&/1 */
static int
expr_can_destroy_int_right(yasm_expr_op op, yasm_intnum *intn)
{
int iszero = yasm_intnum_is_zero(intn);
int ispos1 = yasm_intnum_is_pos1(intn);
return ((ispos1 && op == YASM_EXPR_MUL) ||
(ispos1 && op == YASM_EXPR_DIV) ||
(iszero && op == YASM_EXPR_ADD) ||
(iszero && op == YASM_EXPR_SUB) ||
(yasm_intnum_is_neg1(intn) && op == YASM_EXPR_AND) ||
(!iszero && op == YASM_EXPR_LAND) ||
(iszero && op == YASM_EXPR_OR) ||
(iszero && op == YASM_EXPR_LOR) ||
(iszero && op == YASM_EXPR_SHL) ||
(iszero && op == YASM_EXPR_SHR));
}
int
yasm_value_finalize(yasm_value *value, yasm_bytecode *precbc)
{
if (!value->abs)
return 0;
value->abs = yasm_expr__level_tree(value->abs, 1, 1, 0, 0, NULL, NULL);
/* quit early if there was an issue in simplify() */
if (yasm_error_occurred())
return 1;
/* Strip top-level AND masking to an all-1s mask the same size
* of the value size. This allows forced avoidance of overflow warnings.
*/
if (value->abs->op == YASM_EXPR_AND) {
int term;
/* Calculate 1<<size - 1 value */
yasm_intnum *mask = yasm_intnum_create_uint(1);
yasm_intnum *mask_tmp = yasm_intnum_create_uint(value->size);
yasm_intnum_calc(mask, YASM_EXPR_SHL, mask_tmp);
yasm_intnum_set_uint(mask_tmp, 1);
yasm_intnum_calc(mask, YASM_EXPR_SUB, mask_tmp);
yasm_intnum_destroy(mask_tmp);
/* Walk terms and delete matching masks */
for (term=value->abs->numterms-1; term>=0; term--) {
if (value->abs->terms[term].type == YASM_EXPR_INT &&
yasm_intnum_compare(value->abs->terms[term].data.intn,
mask) == 0) {
/* Delete the intnum */
yasm_intnum_destroy(value->abs->terms[term].data.intn);
/* Slide everything to its right over by 1 */
if (term != value->abs->numterms-1) /* if it wasn't last.. */
memmove(&value->abs->terms[term],
&value->abs->terms[term+1],
(value->abs->numterms-1-term)*
sizeof(yasm_expr__item));
/* Update numterms */
value->abs->numterms--;
/* Indicate warnings have been disabled */
value->no_warn = 1;
}
}
if (value->abs->numterms == 1)
value->abs->op = YASM_EXPR_IDENT;
yasm_intnum_destroy(mask);
}
/* Handle trivial (IDENT) cases immediately */
if (value->abs->op == YASM_EXPR_IDENT) {
switch (value->abs->terms[0].type) {
case YASM_EXPR_INT:
if (yasm_intnum_is_zero(value->abs->terms[0].data.intn)) {
yasm_expr_destroy(value->abs);
value->abs = NULL;
}
return 0;
case YASM_EXPR_REG:
case YASM_EXPR_FLOAT:
return 0;
case YASM_EXPR_SYM:
value->rel = value->abs->terms[0].data.sym;
yasm_expr_destroy(value->abs);
value->abs = NULL;
return 0;
case YASM_EXPR_EXPR:
/* Bring up lower values. */
while (value->abs->op == YASM_EXPR_IDENT
&& value->abs->terms[0].type == YASM_EXPR_EXPR) {
yasm_expr *sube = value->abs->terms[0].data.expn;
yasm_xfree(value->abs);
value->abs = sube;
}
break;
default:
yasm_internal_error(N_("unexpected expr term type"));
}
}
if (value_finalize_scan(value, value->abs, precbc, 0))
return 1;
value->abs = yasm_expr__level_tree(value->abs, 1, 1, 0, 0, NULL, NULL);
/* Simplify 0 in abs to NULL */
if (value->abs->op == YASM_EXPR_IDENT
&& value->abs->terms[0].type == YASM_EXPR_INT
&& yasm_intnum_is_zero(value->abs->terms[0].data.intn)) {
yasm_expr_destroy(value->abs);
value->abs = NULL;
}
return 0;
}
