rust/src/comp/middle/trans_closure.rs

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import core::ctypes::c_uint;
import syntax::ast;
import syntax::ast_util;
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import lib::llvm::llvm;
import llvm::{ValueRef, TypeRef};
import trans_common::*;
import trans_build::*;
import trans::*;
import middle::freevars::{get_freevars, freevar_info};
import option::{some, none};
import back::abi;
import syntax::codemap::span;
import syntax::print::pprust::expr_to_str;
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import back::link::{
mangle_internal_name_by_path,
mangle_internal_name_by_path_and_seq};
import util::ppaux::ty_to_str;
import trans::{
trans_shared_malloc,
type_of_inner,
node_id_type,
INIT,
trans_shared_free,
drop_ty,
new_sub_block_ctxt,
load_if_immediate,
dest
};
import shape::{size_of};
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// ___Good to know (tm)__________________________________________________
//
// The layout of a closure environment in memory is
// roughly as follows:
//
// struct closure_box {
// unsigned ref_count; // only used for shared environments
// type_desc *tydesc; // descriptor for the "struct closure_box" type
// type_desc *bound_tdescs[]; // bound descriptors
// struct {
// upvar1_t upvar1;
// ...
// upvarN_t upvarN;
// } bound_data;
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// };
//
// Note that the closure carries a type descriptor that describes the
// closure itself. Trippy. This is needed because the precise types
// of the closed over data are lost in the closure type (`fn(T)->U`),
// so if we need to take/drop, we must know what data is in the upvars
// and so forth. This struct is defined in the code in mk_closure_tys()
// below.
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//
// The allocation strategy for this closure depends on the closure
// type. For a sendfn, the closure (and the referenced type
// descriptors) will be allocated in the exchange heap. For a fn, the
// closure is allocated in the task heap and is reference counted.
// For a block, the closure is allocated on the stack. Note that in
// all cases we allocate space for a ref count just to make our lives
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// easier when upcasting to fn(T)->U, in the shape code, and so
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// forth.
//
// ## Opaque Closures ##
//
// One interesting part of closures is that they encapsulate the data
// that they close over. So when I have a ptr to a closure, I do not
// know how many type descriptors it contains nor what upvars are
// captured within. That means I do not know precisely how big it is
// nor where its fields are located. This is called an "opaque
// closure".
//
// Typically an opaque closure suffices because I only manipulate it
// by ptr. The routine trans_common::T_opaque_cbox_ptr() returns an
// appropriate type for such an opaque closure; it allows access to the
// first two fields, but not the others.
//
// But sometimes, such as when cloning or freeing a closure, we need
// to know the full information. That is where the type descriptor
// that defines the closure comes in handy. We can use its take and
// drop glue functions to allocate/free data as needed.
//
// ## Subtleties concerning alignment ##
//
// You'll note that the closure_box structure is a flat structure with
// four fields. In some ways, it would be more convenient to use a nested
// structure like so:
//
// struct {
// int;
// struct {
// type_desc*;
// type_desc*[];
// bound_data;
// } }
//
// This would be more convenient because it would allow us to use more
// of the existing infrastructure: we could treat the inner struct as
// a type and then hvae a boxed variant (which would add the int) etc.
// However, there is one subtle problem with this: grouping the latter
// 3 fields into an inner struct causes the alignment of the entire
// struct to be the max alignment of the bound_data. This will
// therefore vary from closure to closure. That would mean that we
// cannot reliably locate the initial type_desc* in an opaque closure!
// That's definitely a bad thing. Therefore, I have elected to create
// a flat structure, even though it means some mild amount of code
// duplication (however, we used to do it the other way, and we were
// jumping through about as many hoops just trying to wedge a ref
// count into a unique pointer, so it's kind of a wash in the end).
//
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// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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enum environment_value {
// Evaluate expr and store result in env (used for bind).
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env_expr(@ast::expr),
// Copy the value from this llvm ValueRef into the environment.
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env_copy(ValueRef, ty::t, lval_kind),
// Move the value from this llvm ValueRef into the environment.
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env_move(ValueRef, ty::t, lval_kind),
// Access by reference (used for blocks).
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env_ref(ValueRef, ty::t, lval_kind),
}
fn ev_to_str(ccx: @crate_ctxt, ev: environment_value) -> str {
alt ev {
env_expr(ex) { expr_to_str(ex) }
env_copy(v, t, lk) { #fmt("copy(%s,%s)", val_str(ccx.tn, v),
ty_to_str(ccx.tcx, t)) }
env_move(v, t, lk) { #fmt("move(%s,%s)", val_str(ccx.tn, v),
ty_to_str(ccx.tcx, t)) }
env_ref(v, t, lk) { #fmt("ref(%s,%s)", val_str(ccx.tn, v),
ty_to_str(ccx.tcx, t)) }
}
}
fn mk_tydesc_ty(tcx: ty::ctxt, ck: ty::closure_kind) -> ty::t {
ret alt ck {
ty::ck_block | ty::ck_box { ty::mk_type(tcx) }
ty::ck_uniq { ty::mk_send_type(tcx) }
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};
}
// Given a closure ty, emits a corresponding tuple ty
fn mk_closure_tys(tcx: ty::ctxt,
ck: ty::closure_kind,
ty_params: [fn_ty_param],
bound_values: [environment_value])
-> (ty::t, ty::t, [ty::t]) {
let bound_tys = [];
let tydesc_ty =
mk_tydesc_ty(tcx, ck);
// Compute the closed over tydescs
let param_ptrs = [];
for tp in ty_params {
param_ptrs += [tydesc_ty];
option::may(tp.dicts) {|dicts|
for dict in dicts { param_ptrs += [tydesc_ty]; }
}
}
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// Compute the closed over data
for bv in bound_values {
bound_tys += [alt bv {
env_copy(_, t, _) { t }
env_move(_, t, _) { t }
env_ref(_, t, _) { t }
env_expr(e) { ty::expr_ty(tcx, e) }
}];
}
let bound_data_ty = ty::mk_tup(tcx, bound_tys);
let norc_tys = [tydesc_ty, ty::mk_tup(tcx, param_ptrs), bound_data_ty];
// closure_norc_ty == everything but ref count
//
// This is a hack to integrate with the cycle coll. When you
// allocate memory in the task-local space, you are expected to
// provide a descriptor for that memory which excludes the ref
// count. That's what this represents. However, this really
// assumes a type setup like [uint, data] where data can be a
// struct. We don't use that structure here because we don't want
// to alignment of the first few fields being bound up in the
// alignment of the bound data, as would happen if we laid out
// that way. For now this should be fine but ultimately we need
// to modify CC code or else modify box allocation interface to be
// a bit more flexible, perhaps taking a vec of tys in the box
// (which for normal rust code is always of length 1).
let closure_norc_ty = ty::mk_tup(tcx, norc_tys);
#debug["closure_norc_ty=%s", ty_to_str(tcx, closure_norc_ty)];
// closure_ty == ref count, data tydesc, typarams, bound data
let closure_ty = ty::mk_tup(tcx, [ty::mk_int(tcx)] + norc_tys);
#debug["closure_ty=%s", ty_to_str(tcx, closure_norc_ty)];
ret (closure_ty, closure_norc_ty, bound_tys);
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}
fn allocate_cbox(bcx: @block_ctxt,
ck: ty::closure_kind,
cbox_ty: ty::t,
cbox_norc_ty: ty::t)
-> (@block_ctxt, ValueRef, [ValueRef]) {
let ccx = bcx_ccx(bcx);
let alloc_in_heap = fn@(bcx: @block_ctxt,
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xchgheap: bool,
&temp_cleanups: [ValueRef])
-> (@block_ctxt, ValueRef) {
// n.b. If you are wondering why we don't use
// trans_malloc_boxed() or alloc_uniq(), see the section about
// "Subtleties concerning alignment" in the big comment at the
// top of the file.
let {bcx, val:llsz} = size_of(bcx, cbox_ty);
let ti = none;
let tydesc_ty = if xchgheap { cbox_ty } else { cbox_norc_ty };
let {bcx, val:lltydesc} =
get_tydesc(bcx, tydesc_ty, true, ti).result;
let malloc = {
if xchgheap { ccx.upcalls.shared_malloc}
else { ccx.upcalls.malloc }
};
let box = Call(bcx, malloc, [llsz, lltydesc]);
add_clean_free(bcx, box, xchgheap);
temp_cleanups += [box];
(bcx, box)
};
// Allocate the box:
let temp_cleanups = [];
let (bcx, box, rc) = alt ck {
ty::ck_box {
let (bcx, box) = alloc_in_heap(bcx, false, temp_cleanups);
(bcx, box, 1)
}
ty::ck_uniq {
let (bcx, box) = alloc_in_heap(bcx, true, temp_cleanups);
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(bcx, box, 0x12345678) // use arbitrary value for debugging
}
ty::ck_block {
let {bcx, val: box} = trans::alloc_ty(bcx, cbox_ty);
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(bcx, box, 0x12345678) // use arbitrary value for debugging
}
};
// Initialize ref count
let box = PointerCast(bcx, box, T_opaque_cbox_ptr(ccx));
let ref_cnt = GEPi(bcx, box, [0, abi::box_rc_field_refcnt]);
Store(bcx, C_int(ccx, rc), ref_cnt);
ret (bcx, box, temp_cleanups);
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}
type closure_result = {
llbox: ValueRef, // llvalue of ptr to closure
cbox_ty: ty::t, // type of the closure data
bcx: @block_ctxt // final bcx
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};
fn cast_if_we_can(bcx: @block_ctxt, llbox: ValueRef, t: ty::t) -> ValueRef {
let ccx = bcx_ccx(bcx);
if check type_has_static_size(ccx, t) {
let llty = type_of(ccx, bcx.sp, t);
ret PointerCast(bcx, llbox, llty);
} else {
ret llbox;
}
}
// Given a block context and a list of tydescs and values to bind
// construct a closure out of them. If copying is true, it is a
// heap allocated closure that copies the upvars into environment.
// Otherwise, it is stack allocated and copies pointers to the upvars.
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fn store_environment(
bcx: @block_ctxt, lltyparams: [fn_ty_param],
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bound_values: [environment_value],
ck: ty::closure_kind)
-> closure_result {
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fn maybe_clone_tydesc(bcx: @block_ctxt,
ck: ty::closure_kind,
td: ValueRef) -> ValueRef {
ret alt ck {
ty::ck_block | ty::ck_box {
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td
}
ty::ck_uniq {
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Call(bcx, bcx_ccx(bcx).upcalls.create_shared_type_desc, [td])
}
};
}
let ccx = bcx_ccx(bcx);
let tcx = bcx_tcx(bcx);
// compute the shape of the closure
let (cbox_ty, cbox_norc_ty, bound_tys) =
mk_closure_tys(tcx, ck, lltyparams, bound_values);
// allocate closure in the heap
let (bcx, llbox, temp_cleanups) =
allocate_cbox(bcx, ck, cbox_ty, cbox_norc_ty);
// store data tydesc.
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alt ck {
ty::ck_box | ty::ck_uniq {
let bound_tydesc = GEPi(bcx, llbox, [0, abi::cbox_elt_tydesc]);
let ti = none;
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let {result:closure_td, _} =
trans::get_tydesc(bcx, cbox_ty, true, ti);
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trans::lazily_emit_tydesc_glue(bcx, abi::tydesc_field_take_glue, ti);
trans::lazily_emit_tydesc_glue(bcx, abi::tydesc_field_drop_glue, ti);
trans::lazily_emit_tydesc_glue(bcx, abi::tydesc_field_free_glue, ti);
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bcx = closure_td.bcx;
let td = maybe_clone_tydesc(bcx, ck, closure_td.val);
Store(bcx, td, bound_tydesc);
}
ty::ck_block { /* skip this for blocks, not really relevant */ }
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}
// cbox_ty has the form of a tuple: (a, b, c) we want a ptr to a
// tuple. This could be a ptr in uniq or a box or on stack,
// whatever.
let cboxptr_ty = ty::mk_ptr(tcx, {ty:cbox_ty, mut:ast::imm});
let llbox = cast_if_we_can(bcx, llbox, cboxptr_ty);
check type_is_tup_like(bcx, cbox_ty);
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// If necessary, copy tydescs describing type parameters into the
// appropriate slot in the closure.
let {bcx:bcx, val:ty_params_slot} =
GEP_tup_like(bcx, cbox_ty, llbox, [0, abi::cbox_elt_ty_params]);
let off = 0;
for tp in lltyparams {
let cloned_td = maybe_clone_tydesc(bcx, ck, tp.desc);
Store(bcx, cloned_td, GEPi(bcx, ty_params_slot, [0, off]));
off += 1;
option::may(tp.dicts, {|dicts|
for dict in dicts {
let cast = PointerCast(bcx, dict, val_ty(cloned_td));
Store(bcx, cast, GEPi(bcx, ty_params_slot, [0, off]));
off += 1;
}
});
}
// Copy expr values into boxed bindings.
// Silly check
vec::iteri(bound_values) { |i, bv|
if (!ccx.sess.opts.no_asm_comments) {
add_comment(bcx, #fmt("Copy %s into closure",
ev_to_str(ccx, bv)));
}
let bound_data = GEP_tup_like_1(bcx, cbox_ty, llbox,
[0, abi::cbox_elt_bindings,
i as int]);
bcx = bound_data.bcx;
let bound_data = bound_data.val;
alt bv {
env_expr(e) {
bcx = trans::trans_expr_save_in(bcx, e, bound_data);
add_clean_temp_mem(bcx, bound_data, bound_tys[i]);
temp_cleanups += [bound_data];
}
env_copy(val, ty, owned) {
let val1 = load_if_immediate(bcx, val, ty);
bcx = trans::copy_val(bcx, INIT, bound_data, val1, ty);
}
env_copy(val, ty, owned_imm) {
bcx = trans::copy_val(bcx, INIT, bound_data, val, ty);
}
env_copy(_, _, temporary) {
fail "Cannot capture temporary upvar";
}
env_move(val, ty, kind) {
let src = {bcx:bcx, val:val, kind:kind};
bcx = move_val(bcx, INIT, bound_data, src, ty);
}
env_ref(val, ty, owned) {
Store(bcx, val, bound_data);
}
env_ref(val, ty, owned_imm) {
let addr = do_spill_noroot(bcx, val);
Store(bcx, addr, bound_data);
}
env_ref(_, _, temporary) {
fail "Cannot capture temporary upvar";
}
}
}
for cleanup in temp_cleanups { revoke_clean(bcx, cleanup); }
ret {llbox: llbox, cbox_ty: cbox_ty, bcx: bcx};
}
// Given a context and a list of upvars, build a closure. This just
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// collects the upvars and packages them up for store_environment.
fn build_closure(bcx0: @block_ctxt,
cap_vars: [capture::capture_var],
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ck: ty::closure_kind)
-> closure_result {
// If we need to, package up the iterator body to call
let env_vals = [];
let bcx = bcx0;
let tcx = bcx_tcx(bcx);
// Package up the captured upvars
vec::iter(cap_vars) { |cap_var|
let lv = trans_local_var(bcx, cap_var.def);
let nid = ast_util::def_id_of_def(cap_var.def).node;
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let ty = ty::node_id_to_monotype(tcx, nid);
alt cap_var.mode {
capture::cap_ref {
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assert ck == ty::ck_block;
ty = ty::mk_mut_ptr(tcx, ty);
env_vals += [env_ref(lv.val, ty, lv.kind)];
}
capture::cap_copy {
env_vals += [env_copy(lv.val, ty, lv.kind)];
}
capture::cap_move {
env_vals += [env_move(lv.val, ty, lv.kind)];
}
capture::cap_drop {
bcx = drop_ty(bcx, lv.val, ty);
}
}
}
ret store_environment(bcx, copy bcx.fcx.lltyparams, env_vals, ck);
}
// Given an enclosing block context, a new function context, a closure type,
// and a list of upvars, generate code to load and populate the environment
// with the upvars and type descriptors.
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fn load_environment(enclosing_cx: @block_ctxt,
fcx: @fn_ctxt,
cbox_ty: ty::t,
cap_vars: [capture::capture_var],
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ck: ty::closure_kind) {
let bcx = new_raw_block_ctxt(fcx, fcx.llloadenv);
let ccx = bcx_ccx(bcx);
let tcx = bcx_tcx(bcx);
let sp = bcx.sp;
let cboxptr_ty = ty::mk_ptr(tcx, {ty:cbox_ty, mut:ast::imm});
check (type_has_static_size(ccx, cboxptr_ty));
let llty = type_of(ccx, sp, cboxptr_ty);
let llclosure = PointerCast(bcx, fcx.llenv, llty);
// Populate the type parameters from the environment. We need to
// do this first because the tydescs are needed to index into
// the bindings if they are dynamically sized.
let lltydescs = GEPi(bcx, llclosure, [0, abi::cbox_elt_ty_params]);
let off = 0;
for tp in copy enclosing_cx.fcx.lltyparams {
let tydesc = Load(bcx, GEPi(bcx, lltydescs, [0, off]));
off += 1;
let dicts = option::map(tp.dicts, {|dicts|
let rslt = [];
for dict in dicts {
let dict = Load(bcx, GEPi(bcx, lltydescs, [0, off]));
rslt += [PointerCast(bcx, dict, T_ptr(T_dict()))];
off += 1;
}
rslt
});
fcx.lltyparams += [{desc: tydesc, dicts: dicts}];
}
// Populate the upvars from the environment.
let path = [0, abi::cbox_elt_bindings];
let i = 0u;
vec::iter(cap_vars) { |cap_var|
alt cap_var.mode {
capture::cap_drop { /* ignore */ }
_ {
check type_is_tup_like(bcx, cbox_ty);
let upvarptr = GEP_tup_like(
bcx, cbox_ty, llclosure, path + [i as int]);
bcx = upvarptr.bcx;
let llupvarptr = upvarptr.val;
alt ck {
ty::ck_block { llupvarptr = Load(bcx, llupvarptr); }
ty::ck_uniq | ty::ck_box { }
}
let def_id = ast_util::def_id_of_def(cap_var.def);
fcx.llupvars.insert(def_id.node, llupvarptr);
i += 1u;
}
}
}
}
fn trans_expr_fn(bcx: @block_ctxt,
proto: ast::proto,
decl: ast::fn_decl,
body: ast::blk,
sp: span,
id: ast::node_id,
cap_clause: ast::capture_clause,
dest: dest) -> @block_ctxt {
if dest == ignore { ret bcx; }
let ccx = bcx_ccx(bcx), bcx = bcx;
let fty = node_id_type(ccx, id);
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let llfnty = type_of_fn_from_ty(ccx, sp, fty, []);
let sub_cx = extend_path(bcx.fcx.lcx, ccx.names("anon"));
let s = mangle_internal_name_by_path(ccx, sub_cx.path);
let llfn = decl_internal_cdecl_fn(ccx.llmod, s, llfnty);
register_fn(ccx, sp, sub_cx.path, "anon fn", [], id);
let trans_closure_env = fn@(ck: ty::closure_kind) -> ValueRef {
let cap_vars = capture::compute_capture_vars(
ccx.tcx, id, proto, cap_clause);
let {llbox, cbox_ty, bcx} = build_closure(bcx, cap_vars, ck);
trans_closure(sub_cx, sp, decl, body, llfn, no_self, [], id, {|fcx|
load_environment(bcx, fcx, cbox_ty, cap_vars, ck);
});
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llbox
};
let closure = alt proto {
ast::proto_any | ast::proto_block { trans_closure_env(ty::ck_block) }
ast::proto_box { trans_closure_env(ty::ck_box) }
ast::proto_uniq { trans_closure_env(ty::ck_uniq) }
ast::proto_bare {
let closure = C_null(T_opaque_cbox_ptr(ccx));
trans_closure(sub_cx, sp, decl, body, llfn, no_self, [],
id, {|_fcx|});
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closure
}
};
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fill_fn_pair(bcx, get_dest_addr(dest), llfn, closure);
ret bcx;
}
fn trans_bind(cx: @block_ctxt, f: @ast::expr, args: [option::t<@ast::expr>],
id: ast::node_id, dest: dest) -> @block_ctxt {
let f_res = trans_callee(cx, f);
ret trans_bind_1(cx, ty::expr_ty(bcx_tcx(cx), f), f_res, args,
ty::node_id_to_type(bcx_tcx(cx), id), dest);
}
fn trans_bind_1(cx: @block_ctxt, outgoing_fty: ty::t,
f_res: lval_maybe_callee,
args: [option::t<@ast::expr>], pair_ty: ty::t,
dest: dest) -> @block_ctxt {
let bound: [@ast::expr] = [];
for argopt: option::t<@ast::expr> in args {
alt argopt { none { } some(e) { bound += [e]; } }
}
let bcx = f_res.bcx;
if dest == ignore {
for ex in bound { bcx = trans_expr(bcx, ex, ignore); }
ret bcx;
}
// Figure out which tydescs we need to pass, if any.
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let (outgoing_fty_real, lltydescs, param_bounds) = alt f_res.generic {
none { (outgoing_fty, [], @[]) }
some(ginfo) {
let tds = [], orig = 0u;
vec::iter2(ginfo.tydescs, *ginfo.param_bounds) {|td, bounds|
tds += [td];
for bound in *bounds {
alt bound {
ty::bound_iface(_) {
let dict = trans_impl::get_dict(
bcx, option::get(ginfo.origins)[orig]);
tds += [PointerCast(bcx, dict.val, val_ty(td))];
orig += 1u;
bcx = dict.bcx;
}
_ {}
}
}
}
lazily_emit_all_generic_info_tydesc_glues(cx, ginfo);
(ginfo.item_type, tds, ginfo.param_bounds)
}
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};
if vec::len(bound) == 0u && vec::len(lltydescs) == 0u {
// Trivial 'binding': just return the closure
let lv = lval_maybe_callee_to_lval(f_res, pair_ty);
bcx = lv.bcx;
ret memmove_ty(bcx, get_dest_addr(dest), lv.val, pair_ty);
}
let closure = alt f_res.env {
null_env { none }
_ { let (_, cl) = maybe_add_env(cx, f_res); some(cl) }
};
// FIXME: should follow from a precondition on trans_bind_1
let ccx = bcx_ccx(cx);
check (type_has_static_size(ccx, outgoing_fty));
// Arrange for the bound function to live in the first binding spot
// if the function is not statically known.
let (env_vals, target_res) = alt closure {
some(cl) {
// Cast the function we are binding to be the type that the
// closure will expect it to have. The type the closure knows
// about has the type parameters substituted with the real types.
let sp = cx.sp;
let llclosurety = T_ptr(type_of(ccx, sp, outgoing_fty));
let src_loc = PointerCast(bcx, cl, llclosurety);
([env_copy(src_loc, pair_ty, owned)], none)
}
none { ([], some(f_res.val)) }
};
// Actually construct the closure
let {llbox, cbox_ty, bcx} = store_environment(
bcx, vec::map(lltydescs, {|d| {desc: d, dicts: none}}),
env_vals + vec::map(bound, {|x| env_expr(x)}),
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ty::ck_box);
// Make thunk
let llthunk =
trans_bind_thunk(cx.fcx.lcx, cx.sp, pair_ty, outgoing_fty_real, args,
cbox_ty, *param_bounds, target_res);
// Fill the function pair
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fill_fn_pair(bcx, get_dest_addr(dest), llthunk.val, llbox);
ret bcx;
}
fn make_null_test(
in_bcx: @block_ctxt,
ptr: ValueRef,
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blk: fn(@block_ctxt) -> @block_ctxt)
-> @block_ctxt {
let not_null_bcx = new_sub_block_ctxt(in_bcx, "not null");
let next_bcx = new_sub_block_ctxt(in_bcx, "next");
let null_test = IsNull(in_bcx, ptr);
CondBr(in_bcx, null_test, next_bcx.llbb, not_null_bcx.llbb);
let not_null_bcx = blk(not_null_bcx);
Br(not_null_bcx, next_bcx.llbb);
ret next_bcx;
}
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fn make_fn_glue(
cx: @block_ctxt,
v: ValueRef,
t: ty::t,
glue_fn: fn@(@block_ctxt, v: ValueRef, t: ty::t) -> @block_ctxt)
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-> @block_ctxt {
let bcx = cx;
let tcx = bcx_tcx(cx);
let fn_env = fn@(ck: ty::closure_kind) -> @block_ctxt {
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let box_cell_v = GEPi(cx, v, [0, abi::fn_field_box]);
let box_ptr_v = Load(cx, box_cell_v);
make_null_test(cx, box_ptr_v) {|bcx|
let closure_ty = ty::mk_opaque_closure_ptr(tcx, ck);
glue_fn(bcx, box_cell_v, closure_ty)
}
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};
ret alt ty::struct(tcx, t) {
ty::ty_native_fn(_, _) | ty::ty_fn({proto: ast::proto_bare, _}) { bcx }
ty::ty_fn({proto: ast::proto_block, _}) { bcx }
ty::ty_fn({proto: ast::proto_any, _}) { bcx }
ty::ty_fn({proto: ast::proto_uniq, _}) { fn_env(ty::ck_uniq) }
ty::ty_fn({proto: ast::proto_box, _}) { fn_env(ty::ck_box) }
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_ { fail "make_fn_glue invoked on non-function type" }
};
}
fn make_opaque_cbox_take_glue(
bcx: @block_ctxt,
ck: ty::closure_kind,
cboxptr: ValueRef) // ptr to ptr to the opaque closure
-> @block_ctxt {
// Easy cases:
alt ck {
ty::ck_block { ret bcx; }
ty::ck_box { ret incr_refcnt_of_boxed(bcx, Load(bcx, cboxptr)); }
ty::ck_uniq { /* hard case: */ }
}
// Hard case, a deep copy:
let ccx = bcx_ccx(bcx);
let llopaquecboxty = T_opaque_cbox_ptr(ccx);
let cbox_in = Load(bcx, cboxptr);
make_null_test(bcx, cbox_in) {|bcx|
// Load the size from the type descr found in the cbox
let cbox_in = PointerCast(bcx, cbox_in, llopaquecboxty);
let tydescptr = GEPi(bcx, cbox_in, [0, abi::cbox_elt_tydesc]);
let tydesc = Load(bcx, tydescptr);
let tydesc = PointerCast(bcx, tydesc, T_ptr(ccx.tydesc_type));
let sz = Load(bcx, GEPi(bcx, tydesc, [0, abi::tydesc_field_size]));
// Allocate memory, update original ptr, and copy existing data
let malloc = ccx.upcalls.shared_malloc;
let cbox_out = Call(bcx, malloc, [sz, tydesc]);
let cbox_out = PointerCast(bcx, cbox_out, llopaquecboxty);
let {bcx, val: _} = call_memmove(bcx, cbox_out, cbox_in, sz);
Store(bcx, cbox_out, cboxptr);
// Take the data in the tuple
let ti = none;
call_tydesc_glue_full(bcx, cbox_out, tydesc,
abi::tydesc_field_take_glue, ti);
bcx
}
}
fn make_opaque_cbox_drop_glue(
bcx: @block_ctxt,
ck: ty::closure_kind,
cboxptr: ValueRef) // ptr to the opaque closure
-> @block_ctxt {
alt ck {
ty::ck_block { bcx }
ty::ck_box {
decr_refcnt_maybe_free(bcx, Load(bcx, cboxptr),
ty::mk_opaque_closure_ptr(bcx_tcx(bcx), ck))
}
ty::ck_uniq {
free_ty(bcx, Load(bcx, cboxptr),
ty::mk_opaque_closure_ptr(bcx_tcx(bcx), ck))
}
}
}
fn make_opaque_cbox_free_glue(
bcx: @block_ctxt,
ck: ty::closure_kind,
cbox: ValueRef) // ptr to the opaque closure
-> @block_ctxt {
alt ck {
ty::ck_block { ret bcx; }
ty::ck_box | ty::ck_uniq { /* hard cases: */ }
}
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let ccx = bcx_ccx(bcx);
let tcx = bcx_tcx(bcx);
make_null_test(bcx, cbox) {|bcx|
// Load the type descr found in the cbox
let lltydescty = T_ptr(ccx.tydesc_type);
let cbox = PointerCast(bcx, cbox, T_opaque_cbox_ptr(ccx));
let tydescptr = GEPi(bcx, cbox, [0, abi::cbox_elt_tydesc]);
let tydesc = Load(bcx, tydescptr);
let tydesc = PointerCast(bcx, tydesc, lltydescty);
// Null out the type descr in the cbox. This is subtle:
// we will be freeing the data in the cbox, and we may need the
// information in the type descr to guide the GEP_tup_like process
// etc if generic types are involved. So we null it out at first
// then free it manually below.
Store(bcx, C_null(lltydescty), tydescptr);
// Drop the tuple data then free the descriptor
let ti = none;
call_tydesc_glue_full(bcx, cbox, tydesc,
abi::tydesc_field_drop_glue, ti);
// Free the ty descr (if necc) and the box itself
alt ck {
ty::ck_block { fail "Impossible"; }
ty::ck_box {
trans_free_if_not_gc(bcx, cbox)
}
ty::ck_uniq {
let bcx = free_ty(bcx, tydesc, mk_tydesc_ty(tcx, ck));
trans_shared_free(bcx, cbox)
}
}
}
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}
// pth is cx.path
fn trans_bind_thunk(cx: @local_ctxt,
sp: span,
incoming_fty: ty::t,
outgoing_fty: ty::t,
args: [option::t<@ast::expr>],
cbox_ty: ty::t,
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param_bounds: [ty::param_bounds],
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target_fn: option::t<ValueRef>)
-> {val: ValueRef, ty: TypeRef} {
// If we supported constraints on record fields, we could make the
// constraints for this function:
/*
: returns_non_ty_var(ccx, outgoing_fty),
type_has_static_size(ccx, incoming_fty) ->
*/
// but since we don't, we have to do the checks at the beginning.
let ccx = cx.ccx;
let tcx = ccx_tcx(ccx);
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check type_has_static_size(ccx, incoming_fty);
// Here we're not necessarily constructing a thunk in the sense of
// "function with no arguments". The result of compiling 'bind f(foo,
// bar, baz)' would be a thunk that, when called, applies f to those
// arguments and returns the result. But we're stretching the meaning of
// the word "thunk" here to also mean the result of compiling, say, 'bind
// f(foo, _, baz)', or any other bind expression that binds f and leaves
// some (or all) of the arguments unbound.
// Here, 'incoming_fty' is the type of the entire bind expression, while
// 'outgoing_fty' is the type of the function that is having some of its
// arguments bound. If f is a function that takes three arguments of type
// int and returns int, and we're translating, say, 'bind f(3, _, 5)',
// then outgoing_fty is the type of f, which is (int, int, int) -> int,
// and incoming_fty is the type of 'bind f(3, _, 5)', which is int -> int.
// Once translated, the entire bind expression will be the call f(foo,
// bar, baz) wrapped in a (so-called) thunk that takes 'bar' as its
// argument and that has bindings of 'foo' to 3 and 'baz' to 5 and a
// pointer to 'f' all saved in its environment. So, our job is to
// construct and return that thunk.
// Give the thunk a name, type, and value.
let s: str = mangle_internal_name_by_path_and_seq(ccx, cx.path, "thunk");
let llthunk_ty: TypeRef = get_pair_fn_ty(type_of(ccx, sp, incoming_fty));
let llthunk: ValueRef = decl_internal_cdecl_fn(ccx.llmod, s, llthunk_ty);
// Create a new function context and block context for the thunk, and hold
// onto a pointer to the first block in the function for later use.
let fcx = new_fn_ctxt(cx, sp, llthunk);
let bcx = new_top_block_ctxt(fcx);
let lltop = bcx.llbb;
// Since we might need to construct derived tydescs that depend on
// our bound tydescs, we need to load tydescs out of the environment
// before derived tydescs are constructed. To do this, we load them
// in the load_env block.
let l_bcx = new_raw_block_ctxt(fcx, fcx.llloadenv);
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// The 'llenv' that will arrive in the thunk we're creating is an
// environment that will contain the values of its arguments and a pointer
// to the original function. So, let's create one of those:
// The llenv pointer needs to be the correct size. That size is
// 'cbox_ty', which was determined by trans_bind.
let cboxptr_ty = ty::mk_ptr(tcx, {ty:cbox_ty, mut:ast::imm});
check type_has_static_size(ccx, cboxptr_ty);
let llclosure_ptr_ty = type_of(ccx, sp, cboxptr_ty);
let llclosure = PointerCast(l_bcx, fcx.llenv, llclosure_ptr_ty);
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// "target", in this context, means the function that's having some of its
// arguments bound and that will be called inside the thunk we're
// creating. (In our running example, target is the function f.) Pick
// out the pointer to the target function from the environment. The
// target function lives in the first binding spot.
let (lltargetfn, lltargetenv, starting_idx) = alt target_fn {
some(fptr) {
(fptr, llvm::LLVMGetUndef(T_opaque_cbox_ptr(ccx)), 0)
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}
none {
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// Silly check
check type_is_tup_like(bcx, cbox_ty);
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let {bcx: cx, val: pair} =
GEP_tup_like(bcx, cbox_ty, llclosure,
[0, abi::cbox_elt_bindings, 0]);
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let lltargetenv =
Load(cx, GEPi(cx, pair, [0, abi::fn_field_box]));
let lltargetfn = Load
(cx, GEPi(cx, pair, [0, abi::fn_field_code]));
bcx = cx;
(lltargetfn, lltargetenv, 1)
}
};
// And then, pick out the target function's own environment. That's what
// we'll use as the environment the thunk gets.
// Get f's return type, which will also be the return type of the entire
// bind expression.
let outgoing_ret_ty = ty::ty_fn_ret(cx.ccx.tcx, outgoing_fty);
// Get the types of the arguments to f.
let outgoing_args = ty::ty_fn_args(cx.ccx.tcx, outgoing_fty);
// The 'llretptr' that will arrive in the thunk we're creating also needs
// to be the correct type. Cast it to f's return type, if necessary.
let llretptr = fcx.llretptr;
let ccx = cx.ccx;
if ty::type_contains_params(ccx.tcx, outgoing_ret_ty) {
check non_ty_var(ccx, outgoing_ret_ty);
let llretty = type_of_inner(ccx, sp, outgoing_ret_ty);
llretptr = PointerCast(bcx, llretptr, T_ptr(llretty));
}
// Set up the three implicit arguments to the thunk.
let llargs: [ValueRef] = [llretptr, lltargetenv];
// Copy in the type parameters.
check type_is_tup_like(l_bcx, cbox_ty);
let {bcx: l_bcx, val: param_record} =
GEP_tup_like(l_bcx, cbox_ty, llclosure,
[0, abi::cbox_elt_ty_params]);
let off = 0;
for param in param_bounds {
let dsc = Load(l_bcx, GEPi(l_bcx, param_record, [0, off])),
dicts = none;
llargs += [dsc];
off += 1;
for bound in *param {
alt bound {
ty::bound_iface(_) {
let dict = Load(l_bcx, GEPi(l_bcx, param_record, [0, off]));
dict = PointerCast(l_bcx, dict, T_ptr(T_dict()));
llargs += [dict];
off += 1;
dicts = some(alt dicts {
none { [dict] }
some(ds) { ds + [dict] }
});
}
_ {}
}
}
fcx.lltyparams += [{desc: dsc, dicts: dicts}];
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}
let a: uint = 2u; // retptr, env come first
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let b: int = starting_idx;
let outgoing_arg_index: uint = 0u;
let llout_arg_tys: [TypeRef] =
type_of_explicit_args(cx.ccx, sp, outgoing_args);
for arg: option::t<@ast::expr> in args {
let out_arg = outgoing_args[outgoing_arg_index];
let llout_arg_ty = llout_arg_tys[outgoing_arg_index];
alt arg {
// Arg provided at binding time; thunk copies it from
// closure.
some(e) {
// Silly check
check type_is_tup_like(bcx, cbox_ty);
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let bound_arg =
GEP_tup_like(bcx, cbox_ty, llclosure,
[0, abi::cbox_elt_bindings, b]);
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bcx = bound_arg.bcx;
let val = bound_arg.val;
if out_arg.mode == ast::by_val { val = Load(bcx, val); }
if out_arg.mode == ast::by_copy {
let {bcx: cx, val: alloc} = alloc_ty(bcx, out_arg.ty);
bcx = memmove_ty(cx, alloc, val, out_arg.ty);
bcx = take_ty(bcx, alloc, out_arg.ty);
val = alloc;
}
// If the type is parameterized, then we need to cast the
// type we actually have to the parameterized out type.
if ty::type_contains_params(cx.ccx.tcx, out_arg.ty) {
val = PointerCast(bcx, val, llout_arg_ty);
}
llargs += [val];
b += 1;
}
// Arg will be provided when the thunk is invoked.
none {
let arg: ValueRef = llvm::LLVMGetParam(llthunk, a as c_uint);
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if ty::type_contains_params(cx.ccx.tcx, out_arg.ty) {
arg = PointerCast(bcx, arg, llout_arg_ty);
}
llargs += [arg];
a += 1u;
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}
}
outgoing_arg_index += 1u;
}
// Cast the outgoing function to the appropriate type.
// This is necessary because the type of the function that we have
// in the closure does not know how many type descriptors the function
// needs to take.
let ccx = bcx_ccx(bcx);
let lltargetty =
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type_of_fn_from_ty(ccx, sp, outgoing_fty, param_bounds);
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lltargetfn = PointerCast(bcx, lltargetfn, T_ptr(lltargetty));
Call(bcx, lltargetfn, llargs);
build_return(bcx);
finish_fn(fcx, lltop);
ret {val: llthunk, ty: llthunk_ty};
}