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// The "shape" of a type is best defined as "how a value of a type looks from
// the standpoint of a certain built-in operation".
//
// This is used to collapse take/drop glues that would otherwise be
// separate. For instance, a boxed tuple of 3 ints and a boxed tuple of 3
// uints look the same as far as reference count manipulation is concerned, so
// they get the same shape so that their reference count glues can be
// collapsed together. To give another example, an int and float have the
// same (nonexistent!) glue as far as reference counting is concerned, since
// they aren't reference counted.
import front::ast;
import middle::trans::variant_info;
import middle::ty;
type variant_getter = fn(&ast::def_id) -> vec[variant_info];
// Reference counting shapes.
tag rc_shape {
rs_none; // No reference count.
rs_ref; // Reference counted box.
rs_pair; // Pair of code/const ptr + rc box.
rs_tag(vec[vec[@rc_shape]]); // Discriminated union.
rs_tup(vec[@rc_shape]); // Tuple.
}
fn rc_shape_of(&ty::ctxt tcx, variant_getter getter, ty::t t) -> rc_shape {
alt (ty::struct(tcx, t)) {
// TODO: Or-patterns
case (ty::ty_nil) { ret rs_none; }
case (ty::ty_bool) { ret rs_none; }
case (ty::ty_int) { ret rs_none; }
case (ty::ty_uint) { ret rs_none; }
case (ty::ty_machine(_)) { ret rs_none; }
case (ty::ty_char) { ret rs_none; }
case (ty::ty_str) { ret rs_none; }
case (ty::ty_tag(?did, ?params)) {
let vec[vec[@rc_shape]] result = vec();
auto vinfos = getter(did);
for (variant_info vinfo in vinfos) {
let vec[@rc_shape] variant_rcs = vec();
for (ty::t typ in vinfo.args) {
auto ty_1 = ty::bind_params_in_type(tcx, typ);
ty_1 = ty::substitute_type_params(tcx, params, ty_1);
variant_rcs += vec(@rc_shape_of(tcx, getter, ty_1));
}
result += vec(variant_rcs);
}
ret rs_tag(result);
}
case (ty::ty_box(_)) { ret rs_ref; }
case (ty::ty_vec(_)) { ret rs_ref; }
case (ty::ty_port(_)) { ret rs_ref; }
case (ty::ty_chan(_)) { ret rs_ref; }
case (ty::ty_task) { ret rs_ref; }
case (ty::ty_tup(?mts)) {
let vec[@rc_shape] result = vec();
for (ty::mt tm in mts) {
result += vec(@rc_shape_of(tcx, getter, tm.ty));
}
ret rs_tup(result);
}
case (ty::ty_rec(?fields)) {
let vec[@rc_shape] result = vec();
for (ty::field fld in fields) {
result += vec(@rc_shape_of(tcx, getter, fld.mt.ty));
}
ret rs_tup(result);
}
case (ty::ty_fn(_, _, _)) { ret rs_pair; }
case (ty::ty_native_fn(_, _, _)) { ret rs_pair; }
case (ty::ty_obj(_)) { ret rs_pair; }
case (ty::ty_var(_)) { log_err "var in rc_shape_of()"; fail; }
case (ty::ty_local(_)) {
log_err "local in rc_shape_of()";
fail;
}
case (ty::ty_param(_)) {
log_err "param in rc_shape_of()";
fail;
}
case (ty::ty_bound_param(_)) {
log_err "bound param in rc::shape_of()";
fail;
}
case (ty::ty_type) { ret rs_ref; }
case (ty::ty_native) { ret rs_none; }
}
}
//
// Local Variables:
// mode: rust
// fill-column: 78;
// indent-tabs-mode: nil
// c-basic-offset: 4
// buffer-file-coding-system: utf-8-unix
// compile-command: "make -k -C $RBUILD 2>&1 | sed -e 's/\\/x\\//x:\\//g'";
// End:
//
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