rust/src/rustc/middle/trans/impl.rs

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import ctypes::c_uint;
import base::*;
import common::*;
import type_of::*;
import build::*;
import driver::session::session;
import syntax::{ast, ast_util};
import metadata::csearch;
import back::{link, abi};
import lib::llvm::llvm;
import lib::llvm::{ValueRef, TypeRef};
import lib::llvm::llvm::LLVMGetParam;
import ast_map::{path, path_mod, path_name};
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// Translation functionality related to impls and ifaces
//
// Terminology:
// vtable: a table of function pointers pointing to method wrappers
// of an impl that implements an iface
// dict: a record containing a vtable pointer along with pointers to
// all tydescs and other dicts needed to run methods in this vtable
// (i.e. corresponding to the type parameters of the impl)
// wrapper: a function that takes a dict as first argument, along
// with the method-specific tydescs for a method (and all
// other args the method expects), which fetches the extra
// tydescs and dicts from the dict, splices them into the
// arglist, and calls through to the actual method
//
// Generic functions take, along with their normal arguments, a number
// of extra tydesc and dict arguments -- one tydesc for each type
// parameter, one dict (following the tydesc in the arg order) for
// each interface bound on a type parameter.
//
// Most dicts are completely static, and are allocated and filled at
// compile time. Dicts that depend on run-time values (tydescs or
// dicts for type parameter types) are built at run-time, and interned
// through upcall_intern_dict in the runtime. This means that dict
// pointers are self-contained things that do not need to be cleaned
// up.
//
// The trans_constants pass in trans.rs outputs the vtables. Typeck
// annotates nodes with information about the methods and dicts that
// are referenced (ccx.method_map and ccx.dict_map).
fn trans_impl(ccx: crate_ctxt, path: path, name: ast::ident,
methods: [@ast::method], id: ast::node_id,
tps: [ast::ty_param]) {
let sub_path = path + [path_name(name)];
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for m in methods {
alt ccx.item_ids.find(m.id) {
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some(llfn) {
let m_bounds = param_bounds(ccx, tps + m.tps);
trans_fn(ccx, sub_path + [path_name(m.ident)], m.decl, m.body,
llfn, impl_self(ty::node_id_to_type(ccx.tcx, id)),
m_bounds, none, m.id, none);
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}
_ {
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ccx.sess.bug("unbound id in trans_impl");
}
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}
}
}
fn trans_self_arg(bcx: block, base: @ast::expr) -> result {
let basety = expr_ty(bcx, base);
let m_by_ref = ast::expl(ast::by_ref);
let temp_cleanups = [];
let result = trans_arg_expr(bcx, {mode: m_by_ref, ty: basety},
T_ptr(type_of_or_i8(bcx.ccx(), basety)), base,
temp_cleanups);
// by-ref self argument should not require cleanup in the case of
// other arguments failing:
assert temp_cleanups == [];
ret result;
}
fn trans_method_callee(bcx: block, callee_id: ast::node_id,
self: @ast::expr, origin: typeck::method_origin)
-> lval_maybe_callee {
alt origin {
typeck::method_static(did) {
trans_static_callee(bcx, callee_id, self, did, none)
}
typeck::method_param(iid, off, p, b) {
alt bcx.fcx.param_substs {
some(substs) {
trans_monomorphized_callee(bcx, callee_id, self,
iid, off, p, b, substs)
}
none {
trans_param_callee(bcx, callee_id, self, iid, off, p, b)
}
}
}
typeck::method_iface(iid, off) {
trans_iface_callee(bcx, callee_id, self, iid, off)
}
}
}
// Method callee where the method is statically known
fn trans_static_callee(bcx: block, callee_id: ast::node_id,
base: @ast::expr, did: ast::def_id,
substs: option<([ty::t], typeck::dict_res)>)
-> lval_maybe_callee {
let {bcx, val} = trans_self_arg(bcx, base);
{env: self_env(val, node_id_type(bcx, base.id))
with lval_static_fn(bcx, did, callee_id, substs)}
}
fn wrapper_fn_ty(ccx: crate_ctxt, dict_ty: TypeRef, fty: ty::t,
tps: @[ty::param_bounds]) -> {ty: ty::t, llty: TypeRef} {
let bare_fn_ty = type_of_fn_from_ty(ccx, fty, *tps);
let {inputs, output} = llfn_arg_tys(bare_fn_ty);
{ty: fty, llty: T_fn([dict_ty] + inputs, output)}
}
fn trans_vtable_callee(bcx: block, env: callee_env, dict: ValueRef,
callee_id: ast::node_id, iface_id: ast::def_id,
n_method: uint) -> lval_maybe_callee {
let bcx = bcx, ccx = bcx.ccx(), tcx = ccx.tcx;
let method = ty::iface_methods(tcx, iface_id)[n_method];
let method_ty = ty::mk_fn(tcx, method.fty);
let {ty: fty, llty: llfty} =
wrapper_fn_ty(ccx, val_ty(dict), method_ty, method.tps);
let vtable = PointerCast(bcx, Load(bcx, GEPi(bcx, dict, [0, 0])),
T_ptr(T_array(T_ptr(llfty), n_method + 1u)));
let mptr = Load(bcx, GEPi(bcx, vtable, [0, n_method as int]));
let generic = generic_none;
if (*method.tps).len() > 0u || ty::type_has_params(fty) {
let tydescs = [], tis = [];
let tptys = node_id_type_params(bcx, callee_id);
for t in vec::tail_n(tptys, tptys.len() - (*method.tps).len()) {
let ti = none;
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let td = get_tydesc(bcx, t, true, ti);
tis += [ti];
tydescs += [td.val];
bcx = td.bcx;
}
generic = generic_full({item_type: fty,
static_tis: tis,
tydescs: tydescs,
param_bounds: method.tps,
origins: ccx.maps.dict_map.find(callee_id)});
}
{bcx: bcx, val: mptr, kind: owned,
env: env,
generic: generic}
}
fn trans_monomorphized_callee(bcx: block, callee_id: ast::node_id,
base: @ast::expr, iface_id: ast::def_id,
n_method: uint, n_param: uint, n_bound: uint,
substs: param_substs) -> lval_maybe_callee {
alt find_dict_in_fn_ctxt(substs, n_param, n_bound) {
typeck::dict_static(impl_did, tys, sub_origins) {
let tcx = bcx.tcx();
if impl_did.crate != ast::local_crate {
ret trans_param_callee(bcx, callee_id, base, iface_id,
n_method, n_param, n_bound);
}
let mname = ty::iface_methods(tcx, iface_id)[n_method].ident;
let mth = alt check tcx.items.get(impl_did.node) {
ast_map::node_item(@{node: ast::item_impl(_, _, _, ms), _}, _) {
option::get(vec::find(ms, {|m| m.ident == mname}))
}
};
ret trans_static_callee(bcx, callee_id, base,
ast_util::local_def(mth.id),
some((tys, sub_origins)));
}
typeck::dict_iface(iid) {
ret trans_iface_callee(bcx, callee_id, base, iid, n_method);
}
typeck::dict_param(n_param, n_bound) {
fail "dict_param left in monomorphized function's dict substs";
}
}
}
// Method callee where the dict comes from a type param
fn trans_param_callee(bcx: block, callee_id: ast::node_id,
base: @ast::expr, iface_id: ast::def_id, n_method: uint,
n_param: uint, n_bound: uint) -> lval_maybe_callee {
let {bcx, val} = trans_self_arg(bcx, base);
let dict = option::get(bcx.fcx.lltyparams[n_param].dicts)[n_bound];
trans_vtable_callee(bcx, dict_env(dict, val), dict,
callee_id, iface_id, n_method)
}
// Method callee where the dict comes from a boxed iface
fn trans_iface_callee(bcx: block, callee_id: ast::node_id,
base: @ast::expr, iface_id: ast::def_id, n_method: uint)
-> lval_maybe_callee {
let {bcx, val} = trans_temp_expr(bcx, base);
let dict = Load(bcx, PointerCast(bcx, GEPi(bcx, val, [0, 0]),
T_ptr(T_ptr(T_dict()))));
let box = Load(bcx, GEPi(bcx, val, [0, 1]));
// FIXME[impl] I doubt this is alignment-safe
let self = GEPi(bcx, box, [0, abi::box_field_body]);
trans_vtable_callee(bcx, dict_env(dict, self), dict,
callee_id, iface_id, n_method)
}
fn llfn_arg_tys(ft: TypeRef) -> {inputs: [TypeRef], output: TypeRef} {
let out_ty = llvm::LLVMGetReturnType(ft);
let n_args = llvm::LLVMCountParamTypes(ft);
let args = vec::init_elt(n_args as uint, 0 as TypeRef);
unsafe { llvm::LLVMGetParamTypes(ft, vec::unsafe::to_ptr(args)); }
{inputs: args, output: out_ty}
}
fn trans_vtable(ccx: crate_ctxt, id: ast::node_id, name: str,
ptrs: [ValueRef]) {
let tbl = C_struct(ptrs);
let vt_gvar = str::as_buf(name, {|buf|
llvm::LLVMAddGlobal(ccx.llmod, val_ty(tbl), buf)
});
llvm::LLVMSetInitializer(vt_gvar, tbl);
llvm::LLVMSetGlobalConstant(vt_gvar, lib::llvm::True);
ccx.item_ids.insert(id, vt_gvar);
ccx.item_symbols.insert(id, name);
}
fn find_dict_in_fn_ctxt(ps: param_substs, n_param: uint, n_bound: uint)
-> typeck::dict_origin {
let dict_off = n_bound, i = 0u;
// Dicts are stored in a flat array, finding the right one is
// somewhat awkward
for bounds in *ps.bounds {
i += 1u;
if i >= n_param { break; }
for bound in *bounds {
alt bound { ty::bound_iface(_) { dict_off += 1u; } _ {} }
}
}
option::get(ps.dicts)[dict_off]
}
fn resolve_dicts_in_fn_ctxt(fcx: fn_ctxt, dicts: typeck::dict_res)
-> option<typeck::dict_res> {
let result = [];
for dict in *dicts {
result += [alt dict {
typeck::dict_static(iid, tys, sub) {
alt resolve_dicts_in_fn_ctxt(fcx, sub) {
some(sub) {
let tys = alt fcx.param_substs {
some(substs) {
vec::map(tys, {|t|
ty::substitute_type_params(fcx.ccx.tcx, substs.tys, t)
})
}
_ { tys }
};
typeck::dict_static(iid, tys, sub)
}
none { ret none; }
}
}
typeck::dict_param(n_param, n_bound) {
alt fcx.param_substs {
some(substs) {
find_dict_in_fn_ctxt(substs, n_param, n_bound)
}
none { ret none; }
}
}
_ { dict }
}];
}
some(@result)
}
fn trans_wrapper(ccx: crate_ctxt, pt: path, llfty: TypeRef,
fill: fn(ValueRef, block) -> block)
-> ValueRef {
let name = link::mangle_internal_name_by_path(ccx, pt);
let llfn = decl_internal_cdecl_fn(ccx.llmod, name, llfty);
let fcx = new_fn_ctxt(ccx, [], llfn, none);
let bcx = top_scope_block(fcx, none), lltop = bcx.llbb;
let bcx = fill(llfn, bcx);
build_return(bcx);
finish_fn(fcx, lltop);
ret llfn;
}
fn trans_impl_wrapper(ccx: crate_ctxt, pt: path,
extra_tps: [ty::param_bounds], real_fn: ValueRef)
-> ValueRef {
let {inputs: real_args, output: real_ret} =
llfn_arg_tys(llvm::LLVMGetElementType(val_ty(real_fn)));
let extra_ptrs = [];
for tp in extra_tps {
extra_ptrs += [T_ptr(ccx.tydesc_type)];
for bound in *tp {
alt bound {
ty::bound_iface(_) { extra_ptrs += [T_ptr(T_dict())]; }
_ {}
}
}
}
let env_ty = T_ptr(T_struct([T_ptr(T_i8())] + extra_ptrs));
let n_extra_ptrs = extra_ptrs.len();
let wrap_args = [T_ptr(T_dict())] +
vec::slice(real_args, 0u, first_tp_arg) +
vec::slice(real_args, first_tp_arg + n_extra_ptrs, real_args.len());
let llfn_ty = T_fn(wrap_args, real_ret);
trans_wrapper(ccx, pt, llfn_ty, {|llfn, bcx|
let dict = PointerCast(bcx, LLVMGetParam(llfn, 0 as c_uint), env_ty);
// retptr, self
let args = [LLVMGetParam(llfn, 1 as c_uint),
LLVMGetParam(llfn, 2 as c_uint)];
let i = 0u;
// saved tydescs/dicts
while i < n_extra_ptrs {
i += 1u;
args += [load_inbounds(bcx, dict, [0, i as int])];
}
// the rest of the parameters
let j = 3u as c_uint;
let params_total = llvm::LLVMCountParamTypes(llfn_ty);
while j < params_total {
args += [LLVMGetParam(llfn, j)];
j += 1u as c_uint;
}
Call(bcx, real_fn, args);
bcx
})
}
fn trans_impl_vtable(ccx: crate_ctxt, pt: path,
iface_id: ast::def_id, ms: [@ast::method],
tps: [ast::ty_param], it: @ast::item) {
let new_pt = pt + [path_name(it.ident), path_name(int::str(it.id)),
path_name("wrap")];
let extra_tps = param_bounds(ccx, tps);
let ptrs = vec::map(*ty::iface_methods(ccx.tcx, iface_id), {|im|
alt vec::find(ms, {|m| m.ident == im.ident}) {
some(m) {
let target = ccx.item_ids.get(m.id);
trans_impl_wrapper(ccx, new_pt + [path_name(m.ident)],
extra_tps, target)
}
_ {
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ccx.sess.span_bug(it.span, "no matching method \
in trans_impl_vtable");
}
}
});
let s = link::mangle_internal_name_by_path(
ccx, new_pt + [path_name("!vtable")]);
trans_vtable(ccx, it.id, s, ptrs);
}
fn trans_iface_wrapper(ccx: crate_ctxt, pt: path, m: ty::method,
n: uint) -> ValueRef {
let {llty: llfty, _} = wrapper_fn_ty(ccx, T_ptr(T_i8()),
ty::mk_fn(ccx.tcx, m.fty), m.tps);
trans_wrapper(ccx, pt, llfty, {|llfn, bcx|
let param = PointerCast(bcx, LLVMGetParam(llfn, 2u as c_uint),
T_ptr(T_opaque_iface(ccx)));
let dict = Load(bcx, GEPi(bcx, param, [0, 0]));
let box = Load(bcx, GEPi(bcx, param, [0, 1]));
let self = GEPi(bcx, box, [0, abi::box_field_body]);
let vtable = PointerCast(bcx, Load(bcx, GEPi(bcx, dict, [0, 0])),
T_ptr(T_array(T_ptr(llfty), n + 1u)));
let mptr = Load(bcx, GEPi(bcx, vtable, [0, n as int]));
let args = [PointerCast(bcx, dict, T_ptr(T_i8())),
LLVMGetParam(llfn, 1u as c_uint),
PointerCast(bcx, self, T_opaque_cbox_ptr(ccx))];
let i = 3u as c_uint, total = llvm::LLVMCountParamTypes(llfty);
while i < total {
args += [LLVMGetParam(llfn, i)];
i += 1u as c_uint;
}
Call(bcx, mptr, args);
bcx
})
}
fn trans_iface_vtable(ccx: crate_ctxt, pt: path, it: @ast::item) {
let new_pt = pt + [path_name(it.ident), path_name(int::str(it.id))];
let i_did = ast_util::local_def(it.id), i = 0u;
let ptrs = vec::map(*ty::iface_methods(ccx.tcx, i_did), {|m|
let w = trans_iface_wrapper(ccx, new_pt + [path_name(m.ident)], m, i);
i += 1u;
w
});
let s = link::mangle_internal_name_by_path(
ccx, new_pt + [path_name("!vtable")]);
trans_vtable(ccx, it.id, s, ptrs);
}
fn dict_is_static(tcx: ty::ctxt, origin: typeck::dict_origin) -> bool {
alt origin {
typeck::dict_static(_, ts, origs) {
vec::all(ts, {|t| !ty::type_has_params(t)}) &&
vec::all(*origs, {|o| dict_is_static(tcx, o)})
}
typeck::dict_iface(_) { true }
_ { false }
}
}
fn get_dict(bcx: block, origin: typeck::dict_origin) -> result {
let ccx = bcx.ccx();
alt origin {
typeck::dict_static(impl_did, tys, sub_origins) {
if dict_is_static(ccx.tcx, origin) {
ret rslt(bcx, get_static_dict(bcx, origin));
}
let {bcx, ptrs} = get_dict_ptrs(bcx, origin);
let pty = T_ptr(T_i8()), dict_ty = T_array(pty, ptrs.len());
let dict = alloca(bcx, dict_ty), i = 0;
for ptr in ptrs {
Store(bcx, PointerCast(bcx, ptr, pty), GEPi(bcx, dict, [0, i]));
i += 1;
}
dict = Call(bcx, ccx.upcalls.intern_dict,
[C_uint(ccx, ptrs.len()),
PointerCast(bcx, dict, T_ptr(T_dict()))]);
rslt(bcx, dict)
}
typeck::dict_param(n_param, n_bound) {
rslt(bcx, option::get(bcx.fcx.lltyparams[n_param].dicts)[n_bound])
}
typeck::dict_iface(did) {
ret rslt(bcx, get_static_dict(bcx, origin));
}
}
}
fn dict_id(tcx: ty::ctxt, origin: typeck::dict_origin) -> dict_id {
alt origin {
typeck::dict_static(did, ts, origs) {
let d_params = [], orig = 0u;
if ts.len() == 0u { ret @{def: did, params: d_params}; }
let impl_params = ty::lookup_item_type(tcx, did).bounds;
vec::iter2(ts, *impl_params) {|t, bounds|
d_params += [dict_param_ty(t)];
for bound in *bounds {
alt bound {
ty::bound_iface(_) {
d_params += [dict_param_dict(dict_id(tcx, origs[orig]))];
orig += 1u;
}
_ {}
}
}
}
@{def: did, params: d_params}
}
typeck::dict_iface(did) {
@{def: did, params: []}
}
_ {
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tcx.sess.bug("unexpected dict_param in dict_id");
}
}
}
fn get_static_dict(bcx: block, origin: typeck::dict_origin)
-> ValueRef {
let ccx = bcx.ccx();
let id = dict_id(ccx.tcx, origin);
alt ccx.dicts.find(id) {
some(d) { ret d; }
none {}
}
let ptrs = C_struct(get_dict_ptrs(bcx, origin).ptrs);
let name = ccx.names("dict");
let gvar = str::as_buf(name, {|buf|
llvm::LLVMAddGlobal(ccx.llmod, val_ty(ptrs), buf)
});
llvm::LLVMSetGlobalConstant(gvar, lib::llvm::True);
llvm::LLVMSetInitializer(gvar, ptrs);
lib::llvm::SetLinkage(gvar, lib::llvm::InternalLinkage);
let cast = llvm::LLVMConstPointerCast(gvar, T_ptr(T_dict()));
ccx.dicts.insert(id, cast);
cast
}
fn get_dict_ptrs(bcx: block, origin: typeck::dict_origin)
-> {bcx: block, ptrs: [ValueRef]} {
let ccx = bcx.ccx();
fn get_vtable(ccx: crate_ctxt, did: ast::def_id) -> ValueRef {
if did.crate == ast::local_crate {
ccx.item_ids.get(did.node)
} else {
let name = csearch::get_symbol(ccx.sess.cstore, did);
get_extern_const(ccx.externs, ccx.llmod, name, T_ptr(T_i8()))
}
}
alt origin {
typeck::dict_static(impl_did, tys, sub_origins) {
let impl_params = ty::lookup_item_type(ccx.tcx, impl_did).bounds;
let ptrs = [get_vtable(ccx, impl_did)];
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let origin = 0u, bcx = bcx;
vec::iter2(*impl_params, tys) {|param, ty|
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let rslt = get_tydesc_simple(bcx, ty, true);
ptrs += [rslt.val];
bcx = rslt.bcx;
for bound in *param {
alt bound {
ty::bound_iface(_) {
let res = get_dict(bcx, sub_origins[origin]);
ptrs += [res.val];
bcx = res.bcx;
origin += 1u;
}
_ {}
}
}
}
{bcx: bcx, ptrs: ptrs}
}
typeck::dict_iface(did) {
{bcx: bcx, ptrs: [get_vtable(ccx, did)]}
}
_ {
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bcx.tcx().sess.bug("unexpected dict_param in get_dict_ptrs");
}
}
}
fn trans_cast(bcx: block, val: @ast::expr, id: ast::node_id, dest: dest)
-> block {
if dest == ignore { ret trans_expr(bcx, val, ignore); }
let ccx = bcx.ccx();
let v_ty = expr_ty(bcx, val);
let {bcx, box, body} = trans_malloc_boxed(bcx, v_ty);
add_clean_free(bcx, box, false);
bcx = trans_expr_save_in(bcx, val, body);
revoke_clean(bcx, box);
let result = get_dest_addr(dest);
Store(bcx, box, PointerCast(bcx, GEPi(bcx, result, [0, 1]),
T_ptr(val_ty(box))));
let {bcx, val: dict} = get_dict(bcx, ccx.maps.dict_map.get(id)[0]);
Store(bcx, dict, PointerCast(bcx, GEPi(bcx, result, [0, 0]),
T_ptr(val_ty(dict))));
bcx
}