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Sketching trans_anon_obj.

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This commit is contained in:
Lindsey Kuper 2011-06-09 18:15:55 -07:00
parent 40e3a9fcbc
commit c51c6ba354
1 changed files with 219 additions and 7 deletions
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226
src/comp/middle/trans.rs
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@ -5701,7 +5701,7 @@ fn trans_expr_out(&@block_ctxt cx, &@ast::expr e, out_method output)
}
case (ast::expr_anon_obj(?anon_obj, ?tps, ?odid, ?ann)) {
ret trans_anon_obj(cx, e.span, anon_obj, tps, odid, ann);
ret trans_anon_obj(cx, e.span, anon_obj, tps, odid.ctor, ann);
}
case (_) {
@ -6352,12 +6352,27 @@ fn recv_val(&@block_ctxt cx, ValueRef lhs, &@ast::expr rhs,
wrapped inner object.
*/
fn trans_anon_obj(&@block_ctxt cx, &span sp,
// trans_anon_obj: create (and return!) an LLVM function that is the object
// constructor for the anonymous object being translated.
//
// This code differs from trans_obj in that, rather than creating an object
// constructor function and putting it in the generated code as an object
// item, we are instead "inlining" the construction of the object.
fn trans_anon_obj(@block_ctxt cx, &span sp,
&ast::anon_obj anon_obj,
&vec[ast::ty_param] ty_params,
&ast::obj_def_ids oid,
ast::def_id oid,
&ast::ann ann) -> result {
auto ccx = cx.fcx.lcx.ccx;
// A crate_ctxt has an item_ids hashmap, which has all of the def_ids of
// everything in the crate. By looking up a def_id, you can get the
// ValueRef of that item.
auto llctor_decl = ccx.item_ids.get(oid);
// If with_obj (the object being extended) exists, translate it, producing
// a result.
let option::t[result] with_obj_val = none[result];
alt (anon_obj.with_obj) {
case (none) { }
@ -6369,25 +6384,222 @@ fn trans_anon_obj(&@block_ctxt cx, &span sp,
}
}
// If the anonymous object we're translating adds any additional fields,
// they'll become the arguments to the function we're creating.
// FIXME (part of issue #417): all of the following code is copypasta from
// trans_obj for translating the anonymous wrapper object. Eventually we
// should abstract this code out of trans_anon_obj and trans_obj.
// For the anon obj's additional fields, if any exist, translate object
// constructor arguments to function arguments.
let option::t[vec[ast::obj_field]] addtl_fields
= none[vec[ast::obj_field]];
let vec[ast::obj_field] addtl_fields = [];
let vec[ast::arg] addtl_fn_args = [];
alt (anon_obj.fields) {
case (none) { }
case (some(?fields)) {
addtl_fields = fields;
for (ast::obj_field f in fields) {
addtl_fn_args += [rec(mode=ast::alias, ty=f.ty,
ident=f.ident, id=f.id)];
}
}
}
auto fcx = new_fn_ctxt(cx.fcx.lcx, sp, llctor_decl);
// TODO: everything else.
// Both regular arguments and type parameters are handled here.
create_llargs_for_fn_args(fcx, ast::proto_fn,
none[ty_self_pair],
ret_ty_of_fn(ccx, ann),
addtl_fn_args, ty_params);
let vec[ty::arg] arg_tys = arg_tys_of_fn(ccx, ann);
copy_args_to_allocas(fcx, addtl_fn_args, arg_tys);
cx.fcx.lcx.ccx.sess.unimpl("support for anonymous objects");
// Create the first block context in the function and keep a handle on it
// to pass to finish_fn later.
auto bcx = new_top_block_ctxt(fcx);
auto lltop = bcx.llbb;
// Pick up the type of this object by looking at our own output type, that
// is, the output type of the object constructor we're building.
auto self_ty = ret_ty_of_fn(ccx, ann);
auto llself_ty = type_of(ccx, sp, self_ty);
// Set up the two-word pair that we're going to return from the object
// constructor we're building. The two elements of this pair will be a
// vtable pointer and a body pointer. (llretptr already points to the
// place where this two-word pair should go; it was pre-allocated by the
// caller of the function.)
auto pair = bcx.fcx.llretptr;
// Grab onto the first and second elements of the pair.
// abi::obj_field_vtbl and abi::obj_field_box simply specify words 0 and 1
// of 'pair'.
auto pair_vtbl = bcx.build.GEP(pair,
[C_int(0),
C_int(abi::obj_field_vtbl)]);
auto pair_box = bcx.build.GEP(pair,
[C_int(0),
C_int(abi::obj_field_box)]);
// Make a vtable for this object: a static array of pointers to functions.
// It will be located in the read-only memory of the executable we're
// creating and will contain ValueRefs for all of this object's methods.
// create_vtbl returns a pointer to the vtable, which we store.
// create_vtbl() wants an ast::_obj and all we have is an
// ast::anon_obj, so we need to roll our own.
let ast::_obj wrapper_obj = rec(
fields = addtl_fields,
methods = anon_obj.methods,
dtor = none[@ast::method]);
auto vtbl = create_vtbl(cx.fcx.lcx, llself_ty, self_ty, wrapper_obj,
ty_params);
bcx.build.Store(vtbl, pair_vtbl);
// FIXME (part of issue #417): This vtable needs to contain "forwarding
// slots" for the methods that exist in the with_obj, as well. How do we
// do that?
// Next we have to take care of the other half of the pair we're
// returning: a boxed (reference-counted) tuple containing a tydesc,
// typarams, and fields.
// FIXME (part of issue #417): Because this is an anonymous object, we
// also have to fill in the with_obj field of this tuple.
let TypeRef llbox_ty = T_opaque_obj_ptr(ccx.tn);
// FIXME: we should probably also allocate a box for empty objs that have
// a dtor, since otherwise they are never dropped, and the dtor never
// runs.
if (vec::len[ast::ty_param](ty_params) == 0u &&
vec::len[ty::arg](arg_tys) == 0u) {
// If the object we're translating has no fields or type parameters,
// there's not much to do.
// Store null into pair, if no args or typarams.
bcx.build.Store(C_null(llbox_ty), pair_box);
} else {
// Otherwise, we have to synthesize a big structural type for the
// object body.
let vec[ty::t] obj_fields = [];
for (ty::arg a in arg_tys) {
vec::push[ty::t](obj_fields, a.ty);
}
// Tuple type for fields: [field, ...]
let ty::t fields_ty = ty::mk_imm_tup(ccx.tcx, obj_fields);
// Tuple type for typarams: [typaram, ...]
auto tydesc_ty = ty::mk_type(ccx.tcx);
let vec[ty::t] tps = [];
for (ast::ty_param tp in ty_params) {
vec::push[ty::t](tps, tydesc_ty);
}
let ty::t typarams_ty = ty::mk_imm_tup(ccx.tcx, tps);
// Tuple type for body: [tydesc_ty, [typaram, ...], [field, ...]]
let ty::t body_ty = ty::mk_imm_tup(ccx.tcx,
[tydesc_ty,
typarams_ty,
fields_ty]);
// Hand this type we've synthesized off to trans_malloc_boxed, which
// allocates a box, including space for a refcount.
auto box = trans_malloc_boxed(bcx, body_ty);
bcx = box.bcx;
// mk_imm_box throws a refcount into the type we're synthesizing, so
// that it looks like: [rc, [tydesc_ty, [typaram, ...], [field, ...]]]
let ty::t boxed_body_ty = ty::mk_imm_box(ccx.tcx, body_ty);
// Grab onto the refcount and body parts of the box we allocated.
auto rc = GEP_tup_like(bcx, boxed_body_ty, box.val,
[0,
abi::box_rc_field_refcnt]);
bcx = rc.bcx;
auto body = GEP_tup_like(bcx, boxed_body_ty, box.val,
[0, abi::box_rc_field_body]);
bcx = body.bcx;
bcx.build.Store(C_int(1), rc.val);
// Put together a tydesc for the body, so that the object can later be
// freed by calling through its tydesc.
// Every object (not just those with type parameters) needs to have a
// tydesc to describe its body, since all objects have unknown type to
// the user of the object. So the tydesc is needed to keep track of
// the types of the object's fields, so that the fields can be freed
// later.
auto body_tydesc =
GEP_tup_like(bcx, body_ty, body.val,
[0, abi::obj_body_elt_tydesc]);
bcx = body_tydesc.bcx;
auto ti = none[@tydesc_info];
auto body_td = get_tydesc(bcx, body_ty, true, ti);
lazily_emit_tydesc_glue(bcx, abi::tydesc_field_drop_glue, ti);
lazily_emit_tydesc_glue(bcx, abi::tydesc_field_free_glue, ti);
bcx = body_td.bcx;
bcx.build.Store(body_td.val, body_tydesc.val);
// Copy the object's type parameters and fields into the space we
// allocated for the object body. (This is something like saving the
// lexical environment of a function in its closure: the "captured
// typarams" are any type parameters that are passed to the object
// constructor and are then available to the object's methods.
// Likewise for the object's fields.)
// Copy typarams into captured typarams.
auto body_typarams =
GEP_tup_like(bcx, body_ty, body.val,
[0, abi::obj_body_elt_typarams]);
bcx = body_typarams.bcx;
let int i = 0;
for (ast::ty_param tp in ty_params) {
auto typaram = bcx.fcx.lltydescs.(i);
auto capture = GEP_tup_like(bcx, typarams_ty, body_typarams.val,
[0, i]);
bcx = capture.bcx;
bcx = copy_val(bcx, INIT, capture.val, typaram, tydesc_ty).bcx;
i += 1;
}
// Copy args into body fields.
auto body_fields =
GEP_tup_like(bcx, body_ty, body.val,
[0, abi::obj_body_elt_fields]);
bcx = body_fields.bcx;
i = 0;
for (ast::obj_field f in wrapper_obj.fields) {
auto arg = bcx.fcx.llargs.get(f.id);
arg = load_if_immediate(bcx, arg, arg_tys.(i).ty);
auto field = GEP_tup_like(bcx, fields_ty, body_fields.val,
[0, i]);
bcx = field.bcx;
bcx = copy_val(bcx, INIT, field.val, arg, arg_tys.(i).ty).bcx;
i += 1;
}
// Store box ptr in outer pair.
auto p = bcx.build.PointerCast(box.val, llbox_ty);
bcx.build.Store(p, pair_box);
}
bcx.build.RetVoid();
// Insert the mandatory first few basic blocks before lltop.
finish_fn(fcx, lltop);
// Return the object we built.
ret res(bcx, pair);
}
fn init_local(&@block_ctxt cx, &@ast::local local) -> result {