librustc: Permit by-value-self methods to be invoked on objects

referenced by boxes.

This is done by creating a shim function that handles the cleanup of the
box properly.

Closes #10672.
This commit is contained in:
Patrick Walton 2014-06-28 12:55:17 -07:00
parent 94343da1bd
commit 68ead460f9
7 changed files with 309 additions and 21 deletions

View File

@ -1220,7 +1220,7 @@ pub fn init_function<'a>(fcx: &'a FunctionContext<'a>,
// - new_fn_ctxt
// - trans_args
fn arg_kind(cx: &FunctionContext, t: ty::t) -> datum::Rvalue {
pub fn arg_kind(cx: &FunctionContext, t: ty::t) -> datum::Rvalue {
use middle::trans::datum::{ByRef, ByValue};
datum::Rvalue {

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@ -159,6 +159,14 @@ impl<'a> Builder<'a> {
attributes: &[(uint, u64)])
-> ValueRef {
self.count_insn("invoke");
debug!("Invoke {} with args ({})",
self.ccx.tn.val_to_str(llfn),
args.iter()
.map(|&v| self.ccx.tn.val_to_str(v))
.collect::<Vec<String>>()
.connect(", "));
unsafe {
let v = llvm::LLVMBuildInvoke(self.llbuilder,
llfn,

View File

@ -16,7 +16,9 @@
* closure.
*/
use arena::TypedArena;
use back::abi;
use back::link;
use driver::session;
use lib::llvm::ValueRef;
use lib::llvm::llvm;
@ -33,28 +35,26 @@ use middle::trans::cleanup::CleanupMethods;
use middle::trans::common;
use middle::trans::common::*;
use middle::trans::datum::*;
use middle::trans::datum::Datum;
use middle::trans::datum::{Datum, KindOps};
use middle::trans::expr;
use middle::trans::glue;
use middle::trans::inline;
use middle::trans::foreign;
use middle::trans::meth;
use middle::trans::monomorphize;
use middle::trans::type_::Type;
use middle::trans::type_of;
use middle::trans::foreign;
use middle::ty;
use middle::typeck;
use middle::typeck::coherence::make_substs_for_receiver_types;
use middle::typeck::MethodCall;
use util::ppaux::Repr;
use middle::trans::type_::Type;
use std::gc::Gc;
use syntax::ast;
use synabi = syntax::abi;
use syntax::ast_map;
use std::gc::Gc;
pub struct MethodData {
pub llfn: ValueRef,
pub llself: ValueRef,
@ -224,6 +224,134 @@ fn resolve_default_method_vtables(bcx: &Block,
param_vtables
}
/// Translates the adapter that deconstructs a `Box<Trait>` object into
/// `Trait` so that a by-value self method can be called.
pub fn trans_unboxing_shim(bcx: &Block,
llshimmedfn: ValueRef,
method: &ty::Method,
method_id: ast::DefId,
substs: subst::Substs)
-> ValueRef {
let _icx = push_ctxt("trans_unboxing_shim");
let ccx = bcx.ccx();
let tcx = bcx.tcx();
// Transform the self type to `Box<self_type>`.
let self_type = *method.fty.sig.inputs.get(0);
let boxed_self_type = ty::mk_uniq(tcx, self_type);
let boxed_function_type = ty::FnSig {
binder_id: method.fty.sig.binder_id,
inputs: method.fty.sig.inputs.iter().enumerate().map(|(i, typ)| {
if i == 0 {
boxed_self_type
} else {
*typ
}
}).collect(),
output: method.fty.sig.output,
variadic: false,
};
let boxed_function_type = ty::BareFnTy {
fn_style: method.fty.fn_style,
abi: method.fty.abi,
sig: boxed_function_type,
};
let boxed_function_type =
ty::mk_bare_fn(tcx, boxed_function_type).subst(tcx, &substs);
let function_type =
ty::mk_bare_fn(tcx, method.fty.clone()).subst(tcx, &substs);
let function_name = tcx.map.with_path(method_id.node, |path| {
link::mangle_internal_name_by_path_and_seq(path, "unboxing_shim")
});
let llfn = decl_internal_rust_fn(ccx,
boxed_function_type,
function_name.as_slice());
let block_arena = TypedArena::new();
let empty_param_substs = param_substs::empty();
let return_type = ty::ty_fn_ret(boxed_function_type);
let fcx = new_fn_ctxt(ccx,
llfn,
-1,
false,
return_type,
&empty_param_substs,
None,
&block_arena);
init_function(&fcx, false, return_type);
// Create the substituted versions of the self type.
let mut bcx = fcx.entry_bcx.borrow().clone().unwrap();
let arg_scope = fcx.push_custom_cleanup_scope();
let arg_scope_id = cleanup::CustomScope(arg_scope);
let boxed_arg_types = ty::ty_fn_args(boxed_function_type);
let boxed_self_type = *boxed_arg_types.get(0);
let arg_types = ty::ty_fn_args(function_type);
let self_type = *arg_types.get(0);
let boxed_self_kind = arg_kind(&fcx, boxed_self_type);
// Create a datum for self.
let llboxedself = unsafe {
llvm::LLVMGetParam(fcx.llfn, fcx.arg_pos(0) as u32)
};
let llboxedself = Datum::new(llboxedself,
boxed_self_type,
boxed_self_kind);
let boxed_self =
unpack_datum!(bcx,
llboxedself.to_lvalue_datum_in_scope(bcx,
"boxedself",
arg_scope_id));
// This `Load` is needed because lvalue data are always by-ref.
let llboxedself = Load(bcx, boxed_self.val);
let llself = if type_is_immediate(ccx, self_type) {
let llboxedself = Load(bcx, llboxedself);
immediate_rvalue(llboxedself, self_type)
} else {
let llself = rvalue_scratch_datum(bcx, self_type, "self");
memcpy_ty(bcx, llself.val, llboxedself, self_type);
llself
};
// Make sure we don't free the box twice!
boxed_self.kind.post_store(bcx, boxed_self.val, boxed_self_type);
// Schedule a cleanup to free the box.
fcx.schedule_free_value(arg_scope_id,
llboxedself,
cleanup::HeapExchange,
self_type);
// Now call the function.
let mut llshimmedargs = vec!(llself.val);
for i in range(1, arg_types.len()) {
llshimmedargs.push(unsafe {
llvm::LLVMGetParam(fcx.llfn, fcx.arg_pos(i) as u32)
});
}
bcx = trans_call_inner(bcx,
None,
function_type,
|bcx, _| {
Callee {
bcx: bcx,
data: Fn(llshimmedfn),
}
},
ArgVals(llshimmedargs.as_slice()),
match fcx.llretptr.get() {
None => None,
Some(llretptr) => Some(expr::SaveIn(llretptr)),
}).bcx;
bcx = fcx.pop_and_trans_custom_cleanup_scope(bcx, arg_scope);
finish_fn(&fcx, bcx);
llfn
}
pub fn trans_fn_ref_with_vtables(
bcx: &Block, //

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@ -492,14 +492,24 @@ fn emit_vtable_methods(bcx: &Block,
m.repr(tcx),
substs.repr(tcx));
if m.generics.has_type_params(subst::FnSpace) ||
ty::type_has_self(ty::mk_bare_fn(tcx, m.fty.clone()))
{
ty::type_has_self(ty::mk_bare_fn(tcx, m.fty.clone())) {
debug!("(making impl vtable) method has self or type params: {}",
token::get_ident(ident));
C_null(Type::nil(ccx).ptr_to())
} else {
trans_fn_ref_with_vtables(bcx, m_id, ExprId(0),
substs.clone(), vtables.clone())
let mut fn_ref = trans_fn_ref_with_vtables(bcx,
m_id,
ExprId(0),
substs.clone(),
vtables.clone());
if m.explicit_self == ast::SelfValue {
fn_ref = trans_unboxing_shim(bcx,
fn_ref,
&*m,
m_id,
substs.clone());
}
fn_ref
}
}).collect()
}

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@ -271,7 +271,9 @@ fn construct_transformed_self_ty_for_object(
tcx.sess.span_bug(span, "static method for object type receiver");
}
ast::SelfValue => {
ty::mk_err() // error reported in `enforce_object_limitations()`
let tr = ty::mk_trait(tcx, trait_def_id, obj_substs,
ty::empty_builtin_bounds());
ty::mk_uniq(tcx, tr)
}
ast::SelfRegion(..) | ast::SelfUniq => {
let transformed_self_ty = *method_ty.fty.sig.inputs.get(0);
@ -1225,14 +1227,7 @@ impl<'a> LookupContext<'a> {
through an object");
}
ast::SelfValue => { // reason (a) above
self.tcx().sess.span_err(
self.span,
"cannot call a method with a by-value receiver \
through an object");
}
ast::SelfRegion(..) | ast::SelfUniq => {}
ast::SelfValue | ast::SelfRegion(..) | ast::SelfUniq => {}
}
// reason (a) above
@ -1302,7 +1297,26 @@ impl<'a> LookupContext<'a> {
}
SelfValue => {
rcvr_matches_ty(self.fcx, rcvr_ty, candidate)
debug!("(is relevant?) explicit self is by-value");
match ty::get(rcvr_ty).sty {
ty::ty_uniq(typ) => {
match ty::get(typ).sty {
ty::ty_trait(box ty::TyTrait {
def_id: self_did,
..
}) => {
rcvr_matches_object(self_did, candidate) ||
rcvr_matches_ty(self.fcx,
rcvr_ty,
candidate)
}
_ => {
rcvr_matches_ty(self.fcx, rcvr_ty, candidate)
}
}
}
_ => rcvr_matches_ty(self.fcx, rcvr_ty, candidate)
}
}
SelfRegion(_, m) => {

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@ -0,0 +1,51 @@
// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
// error-pattern:explicit failure
trait Foo {
fn foo(self, x: int);
}
struct S {
x: int,
y: int,
z: int,
s: String,
}
impl Foo for S {
fn foo(self, x: int) {
fail!()
}
}
impl Drop for S {
fn drop(&mut self) {
println!("bye 1!");
}
}
fn f() {
let s = S {
x: 2,
y: 3,
z: 4,
s: "hello".to_string(),
};
let st = box s as Box<Foo>;
st.foo(5);
}
fn main() {
f();
}

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@ -0,0 +1,77 @@
// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
static mut destructor_count: uint = 0;
trait Foo {
fn foo(self, x: int);
}
struct S {
x: int,
y: int,
z: int,
s: String,
}
impl Foo for S {
fn foo(self, x: int) {
assert!(self.x == 2);
assert!(self.y == 3);
assert!(self.z == 4);
assert!(self.s.as_slice() == "hello");
assert!(x == 5);
}
}
impl Drop for S {
fn drop(&mut self) {
println!("bye 1!");
unsafe {
destructor_count += 1;
}
}
}
impl Foo for int {
fn foo(self, x: int) {
println!("{}", x * x);
}
}
fn f() {
let s = S {
x: 2,
y: 3,
z: 4,
s: "hello".to_string(),
};
let st = box s as Box<Foo>;
st.foo(5);
println!("bye 2!");
}
fn g() {
let s = 2i;
let st = box s as Box<Foo>;
st.foo(3);
println!("bye 3!");
}
fn main() {
f();
unsafe {
assert!(destructor_count == 1);
}
g();
}