rust/src/librustc/middle/trans/meth.rs

578 lines
21 KiB
Rust

// Copyright 2012 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.
use back::abi;
use lib::llvm::llvm;
use lib::llvm::ValueRef;
use lib;
use metadata::csearch;
use middle::subst;
use middle::trans::base::*;
use middle::trans::build::*;
use middle::trans::callee::*;
use middle::trans::callee;
use middle::trans::cleanup;
use middle::trans::common::*;
use middle::trans::datum::*;
use middle::trans::expr::{SaveIn, Ignore};
use middle::trans::expr;
use middle::trans::glue;
use middle::trans::monomorphize;
use middle::trans::type_::Type;
use middle::trans::type_of::*;
use middle::ty;
use middle::typeck;
use middle::typeck::MethodCall;
use util::common::indenter;
use util::ppaux::Repr;
use std::c_str::ToCStr;
use syntax::abi::Rust;
use syntax::parse::token;
use syntax::{ast, ast_map, visit};
/**
The main "translation" pass for methods. Generates code
for non-monomorphized methods only. Other methods will
be generated once they are invoked with specific type parameters,
see `trans::base::lval_static_fn()` or `trans::base::monomorphic_fn()`.
*/
pub fn trans_impl(ccx: &CrateContext,
name: ast::Ident,
methods: &[@ast::Method],
generics: &ast::Generics,
id: ast::NodeId) {
let _icx = push_ctxt("meth::trans_impl");
let tcx = ccx.tcx();
debug!("trans_impl(name={}, id={:?})", name.repr(tcx), id);
// Both here and below with generic methods, be sure to recurse and look for
// items that we need to translate.
if !generics.ty_params.is_empty() {
let mut v = TransItemVisitor{ ccx: ccx };
for method in methods.iter() {
visit::walk_method_helper(&mut v, *method, ());
}
return;
}
for method in methods.iter() {
if method.generics.ty_params.len() == 0u {
let llfn = get_item_val(ccx, method.id);
trans_fn(ccx, method.decl, method.body,
llfn, None, method.id, []);
} else {
let mut v = TransItemVisitor{ ccx: ccx };
visit::walk_method_helper(&mut v, *method, ());
}
}
}
pub fn trans_method_callee<'a>(
bcx: &'a Block<'a>,
method_call: MethodCall,
self_expr: Option<&ast::Expr>,
arg_cleanup_scope: cleanup::ScopeId)
-> Callee<'a> {
let _icx = push_ctxt("meth::trans_method_callee");
let (origin, method_ty) = match bcx.tcx().method_map
.borrow().find(&method_call) {
Some(method) => {
debug!("trans_method_callee({:?}, method={})",
method_call, method.repr(bcx.tcx()));
(method.origin, method.ty)
}
None => {
bcx.sess().span_bug(bcx.tcx().map.span(method_call.expr_id),
"method call expr wasn't in method map")
}
};
match origin {
typeck::MethodStatic(did) => {
Callee {
bcx: bcx,
data: Fn(callee::trans_fn_ref(bcx, did, MethodCall(method_call)))
}
}
typeck::MethodParam(typeck::MethodParam {
trait_id: trait_id,
method_num: off,
param_num: p,
bound_num: b
}) => {
match bcx.fcx.param_substs {
Some(substs) => {
ty::populate_implementations_for_trait_if_necessary(
bcx.tcx(),
trait_id);
let vtbl = find_vtable(bcx.tcx(), substs, p, b);
trans_monomorphized_callee(bcx, method_call,
trait_id, off, vtbl)
}
// how to get rid of this?
None => fail!("trans_method_callee: missing param_substs")
}
}
typeck::MethodObject(ref mt) => {
let self_expr = match self_expr {
Some(self_expr) => self_expr,
None => {
bcx.sess().span_bug(bcx.tcx().map.span(method_call.expr_id),
"self expr wasn't provided for trait object \
callee (trying to call overloaded op?)")
}
};
trans_trait_callee(bcx,
monomorphize_type(bcx, method_ty),
mt.real_index,
self_expr,
arg_cleanup_scope)
}
}
}
pub fn trans_static_method_callee(bcx: &Block,
method_id: ast::DefId,
trait_id: ast::DefId,
expr_id: ast::NodeId)
-> ValueRef {
let _icx = push_ctxt("meth::trans_static_method_callee");
let ccx = bcx.ccx();
debug!("trans_static_method_callee(method_id={:?}, trait_id={}, \
expr_id={:?})",
method_id,
ty::item_path_str(bcx.tcx(), trait_id),
expr_id);
let _indenter = indenter();
ty::populate_implementations_for_trait_if_necessary(bcx.tcx(), trait_id);
// When we translate a static fn defined in a trait like:
//
// trait<T1...Tn> Trait {
// fn foo<M1...Mn>(...) {...}
// }
//
// this winds up being translated as something like:
//
// fn foo<T1...Tn,self: Trait<T1...Tn>,M1...Mn>(...) {...}
//
// So when we see a call to this function foo, we have to figure
// out which impl the `Trait<T1...Tn>` bound on the type `self` was
// bound to.
let bound_index = ty::lookup_trait_def(bcx.tcx(), trait_id).
generics.type_param_defs().len();
let mname = if method_id.krate == ast::LOCAL_CRATE {
match bcx.tcx().map.get(method_id.node) {
ast_map::NodeTraitMethod(method) => {
let ident = match *method {
ast::Required(ref m) => m.ident,
ast::Provided(ref m) => m.ident
};
ident.name
}
_ => fail!("callee is not a trait method")
}
} else {
csearch::get_item_path(bcx.tcx(), method_id).last().unwrap().name()
};
debug!("trans_static_method_callee: method_id={:?}, expr_id={:?}, \
name={}", method_id, expr_id, token::get_name(mname));
let vtable_key = MethodCall::expr(expr_id);
let vtbls = resolve_vtables_in_fn_ctxt(bcx.fcx, ccx.tcx.vtable_map.borrow()
.get(&vtable_key).as_slice());
match vtbls.move_iter().nth(bound_index).unwrap().move_iter().nth(0).unwrap() {
typeck::vtable_static(impl_did, rcvr_substs, rcvr_origins) => {
assert!(rcvr_substs.tps.iter().all(|t| !ty::type_needs_infer(*t)));
let mth_id = method_with_name(ccx, impl_did, mname);
let (callee_substs, callee_origins) =
combine_impl_and_methods_tps(
bcx, mth_id, ExprId(expr_id),
rcvr_substs, rcvr_origins);
let llfn = trans_fn_ref_with_vtables(bcx, mth_id, ExprId(expr_id),
callee_substs,
Some(callee_origins));
let callee_ty = node_id_type(bcx, expr_id);
let llty = type_of_fn_from_ty(ccx, callee_ty).ptr_to();
PointerCast(bcx, llfn, llty)
}
_ => {
fail!("vtable_param left in monomorphized \
function's vtable substs");
}
}
}
fn method_with_name(ccx: &CrateContext,
impl_id: ast::DefId,
name: ast::Name) -> ast::DefId {
match ccx.impl_method_cache.borrow().find_copy(&(impl_id, name)) {
Some(m) => return m,
None => {}
}
let methods = ccx.tcx.impl_methods.borrow();
let methods = methods.find(&impl_id)
.expect("could not find impl while translating");
let meth_did = methods.iter().find(|&did| ty::method(&ccx.tcx, *did).ident.name == name)
.expect("could not find method while translating");
ccx.impl_method_cache.borrow_mut().insert((impl_id, name), *meth_did);
*meth_did
}
fn trans_monomorphized_callee<'a>(bcx: &'a Block<'a>,
method_call: MethodCall,
trait_id: ast::DefId,
n_method: uint,
vtbl: typeck::vtable_origin)
-> Callee<'a> {
let _icx = push_ctxt("meth::trans_monomorphized_callee");
match vtbl {
typeck::vtable_static(impl_did, rcvr_substs, rcvr_origins) => {
let ccx = bcx.ccx();
let mname = ty::trait_method(ccx.tcx(), trait_id, n_method).ident;
let mth_id = method_with_name(bcx.ccx(), impl_did, mname.name);
// create a concatenated set of substitutions which includes
// those from the impl and those from the method:
let (callee_substs, callee_origins) =
combine_impl_and_methods_tps(
bcx, mth_id, MethodCall(method_call),
rcvr_substs, rcvr_origins);
// translate the function
let llfn = trans_fn_ref_with_vtables(bcx,
mth_id,
MethodCall(method_call),
callee_substs,
Some(callee_origins));
Callee { bcx: bcx, data: Fn(llfn) }
}
typeck::vtable_param(..) => {
fail!("vtable_param left in monomorphized function's vtable substs");
}
}
}
fn combine_impl_and_methods_tps(bcx: &Block,
mth_did: ast::DefId,
node: ExprOrMethodCall,
rcvr_substs: subst::Substs,
rcvr_origins: typeck::vtable_res)
-> (subst::Substs, typeck::vtable_res)
{
/*!
* Creates a concatenated set of substitutions which includes
* those from the impl and those from the method. This are
* some subtle complications here. Statically, we have a list
* of type parameters like `[T0, T1, T2, M1, M2, M3]` where
* `Tn` are type parameters that appear on the receiver. For
* example, if the receiver is a method parameter `A` with a
* bound like `trait<B,C,D>` then `Tn` would be `[B,C,D]`.
*
* The weird part is that the type `A` might now be bound to
* any other type, such as `foo<X>`. In that case, the vector
* we want is: `[X, M1, M2, M3]`. Therefore, what we do now is
* to slice off the method type parameters and append them to
* the type parameters from the type that the receiver is
* mapped to.
*/
let ccx = bcx.ccx();
let method = ty::method(ccx.tcx(), mth_did);
let n_m_tps = method.generics.type_param_defs().len();
let node_substs = node_id_substs(bcx, node);
debug!("rcvr_substs={:?}", rcvr_substs.repr(ccx.tcx()));
debug!("node_substs={:?}", node_substs.repr(ccx.tcx()));
let rcvr_self_ty = rcvr_substs.self_ty;
let mut tps = rcvr_substs.tps;
{
let start = node_substs.tps.len() - n_m_tps;
tps.extend(node_substs.tps.move_iter().skip(start));
}
debug!("n_m_tps={:?}", n_m_tps);
debug!("tps={}", tps.repr(ccx.tcx()));
// Now, do the same work for the vtables. The vtables might not
// exist, in which case we need to make them.
let vtable_key = match node {
ExprId(id) => MethodCall::expr(id),
MethodCall(method_call) => method_call
};
let mut vtables = rcvr_origins;
match node_vtables(bcx, vtable_key) {
Some(vt) => {
let start = vt.len() - n_m_tps;
vtables.extend(vt.move_iter().skip(start));
}
None => {
vtables.extend(range(0, n_m_tps).map(
|_| -> typeck::vtable_param_res {
Vec::new()
}
));
}
}
let ty_substs = subst::Substs {
tps: tps,
regions: subst::ErasedRegions,
self_ty: rcvr_self_ty
};
(ty_substs, vtables)
}
fn trans_trait_callee<'a>(bcx: &'a Block<'a>,
method_ty: ty::t,
n_method: uint,
self_expr: &ast::Expr,
arg_cleanup_scope: cleanup::ScopeId)
-> Callee<'a> {
/*!
* Create a method callee where the method is coming from a trait
* object (e.g., Box<Trait> type). In this case, we must pull the fn
* pointer out of the vtable that is packaged up with the object.
* Objects are represented as a pair, so we first evaluate the self
* expression and then extract the self data and vtable out of the
* pair.
*/
let _icx = push_ctxt("meth::trans_trait_callee");
let mut bcx = bcx;
// Translate self_datum and take ownership of the value by
// converting to an rvalue.
let self_datum = unpack_datum!(
bcx, expr::trans(bcx, self_expr));
let llval = if ty::type_needs_drop(bcx.tcx(), self_datum.ty) {
let self_datum = unpack_datum!(
bcx, self_datum.to_rvalue_datum(bcx, "trait_callee"));
// Convert to by-ref since `trans_trait_callee_from_llval` wants it
// that way.
let self_datum = unpack_datum!(
bcx, self_datum.to_ref_datum(bcx));
// Arrange cleanup in case something should go wrong before the
// actual call occurs.
self_datum.add_clean(bcx.fcx, arg_cleanup_scope)
} else {
// We don't have to do anything about cleanups for &Trait and &mut Trait.
assert!(self_datum.kind.is_by_ref());
self_datum.val
};
trans_trait_callee_from_llval(bcx, method_ty, n_method, llval)
}
pub fn trans_trait_callee_from_llval<'a>(bcx: &'a Block<'a>,
callee_ty: ty::t,
n_method: uint,
llpair: ValueRef)
-> Callee<'a> {
/*!
* Same as `trans_trait_callee()` above, except that it is given
* a by-ref pointer to the object pair.
*/
let _icx = push_ctxt("meth::trans_trait_callee");
let ccx = bcx.ccx();
// Load the data pointer from the object.
debug!("(translating trait callee) loading second index from pair");
let llboxptr = GEPi(bcx, llpair, [0u, abi::trt_field_box]);
let llbox = Load(bcx, llboxptr);
let llself = PointerCast(bcx, llbox, Type::i8p(ccx));
// Load the function from the vtable and cast it to the expected type.
debug!("(translating trait callee) loading method");
// Replace the self type (&Self or Box<Self>) with an opaque pointer.
let llcallee_ty = match ty::get(callee_ty).sty {
ty::ty_bare_fn(ref f) if f.abi == Rust => {
type_of_rust_fn(ccx, true, f.sig.inputs.slice_from(1), f.sig.output)
}
_ => {
ccx.sess().bug("meth::trans_trait_callee given non-bare-rust-fn");
}
};
let llvtable = Load(bcx,
PointerCast(bcx,
GEPi(bcx, llpair,
[0u, abi::trt_field_vtable]),
Type::vtable(ccx).ptr_to().ptr_to()));
let mptr = Load(bcx, GEPi(bcx, llvtable, [0u, n_method + 1]));
let mptr = PointerCast(bcx, mptr, llcallee_ty.ptr_to());
return Callee {
bcx: bcx,
data: TraitMethod(MethodData {
llfn: mptr,
llself: llself,
})
};
}
/// Creates a returns a dynamic vtable for the given type and vtable origin.
/// This is used only for objects.
fn get_vtable(bcx: &Block,
self_ty: ty::t,
origins: typeck::vtable_param_res)
-> ValueRef {
let ccx = bcx.ccx();
let _icx = push_ctxt("meth::get_vtable");
// Check the cache.
let hash_id = (self_ty, monomorphize::make_vtable_id(ccx, origins.get(0)));
match ccx.vtables.borrow().find(&hash_id) {
Some(&val) => { return val }
None => { }
}
// Not in the cache. Actually build it.
let methods = origins.move_iter().flat_map(|origin| {
match origin {
typeck::vtable_static(id, substs, sub_vtables) => {
emit_vtable_methods(bcx, id, substs, sub_vtables).move_iter()
}
_ => ccx.sess().bug("get_vtable: expected a static origin"),
}
});
// Generate a destructor for the vtable.
let drop_glue = glue::get_drop_glue(ccx, self_ty);
let vtable = make_vtable(ccx, drop_glue, methods);
ccx.vtables.borrow_mut().insert(hash_id, vtable);
vtable
}
/// Helper function to declare and initialize the vtable.
pub fn make_vtable<I: Iterator<ValueRef>>(ccx: &CrateContext,
drop_glue: ValueRef,
ptrs: I)
-> ValueRef {
let _icx = push_ctxt("meth::make_vtable");
let components: Vec<_> = Some(drop_glue).move_iter().chain(ptrs).collect();
unsafe {
let tbl = C_struct(ccx, components.as_slice(), false);
let sym = token::gensym("vtable");
let vt_gvar = format!("vtable{}", sym).with_c_str(|buf| {
llvm::LLVMAddGlobal(ccx.llmod, val_ty(tbl).to_ref(), buf)
});
llvm::LLVMSetInitializer(vt_gvar, tbl);
llvm::LLVMSetGlobalConstant(vt_gvar, lib::llvm::True);
lib::llvm::SetLinkage(vt_gvar, lib::llvm::InternalLinkage);
vt_gvar
}
}
fn emit_vtable_methods(bcx: &Block,
impl_id: ast::DefId,
substs: subst::Substs,
vtables: typeck::vtable_res)
-> Vec<ValueRef> {
let ccx = bcx.ccx();
let tcx = ccx.tcx();
let trt_id = match ty::impl_trait_ref(tcx, impl_id) {
Some(t_id) => t_id.def_id,
None => ccx.sess().bug("make_impl_vtable: don't know how to \
make a vtable for a type impl!")
};
ty::populate_implementations_for_trait_if_necessary(bcx.tcx(), trt_id);
let trait_method_def_ids = ty::trait_method_def_ids(tcx, trt_id);
trait_method_def_ids.iter().map(|method_def_id| {
let ident = ty::method(tcx, *method_def_id).ident;
// The substitutions we have are on the impl, so we grab
// the method type from the impl to substitute into.
let m_id = method_with_name(ccx, impl_id, ident.name);
let m = ty::method(tcx, m_id);
debug!("(making impl vtable) emitting method {} at subst {}",
m.repr(tcx),
substs.repr(tcx));
if m.generics.has_type_params() ||
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(), Some(vtables.clone()))
}
}).collect()
}
pub fn trans_trait_cast<'a>(bcx: &'a Block<'a>,
datum: Datum<Expr>,
id: ast::NodeId,
dest: expr::Dest)
-> &'a Block<'a> {
/*!
* Generates the code to convert from a pointer (`Box<T>`, `&T`, etc)
* into an object (`Box<Trait>`, `&Trait`, etc). This means creating a
* pair where the first word is the vtable and the second word is
* the pointer.
*/
let mut bcx = bcx;
let _icx = push_ctxt("meth::trans_cast");
let lldest = match dest {
Ignore => {
return datum.clean(bcx, "trait_cast", id);
}
SaveIn(dest) => dest
};
let ccx = bcx.ccx();
let v_ty = datum.ty;
let llbox_ty = type_of(bcx.ccx(), datum.ty);
// Store the pointer into the first half of pair.
let mut llboxdest = GEPi(bcx, lldest, [0u, abi::trt_field_box]);
llboxdest = PointerCast(bcx, llboxdest, llbox_ty.ptr_to());
bcx = datum.store_to(bcx, llboxdest);
// Store the vtable into the second half of pair.
let origins = {
let vtable_map = ccx.tcx.vtable_map.borrow();
resolve_param_vtables_under_param_substs(ccx.tcx(),
bcx.fcx.param_substs,
vtable_map.get(&MethodCall::expr(id)).get(0).as_slice())
};
let vtable = get_vtable(bcx, v_ty, origins);
let llvtabledest = GEPi(bcx, lldest, [0u, abi::trt_field_vtable]);
let llvtabledest = PointerCast(bcx, llvtabledest, val_ty(vtable).ptr_to());
Store(bcx, vtable, llvtabledest);
bcx
}