/* 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; }