rust/src/librustc/middle/trans/callee.rs
2013-06-01 15:31:56 -07:00

801 lines
28 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.
//!
//
// Handles translation of callees as well as other call-related
// things. Callees are a superset of normal rust values and sometimes
// have different representations. In particular, top-level fn items
// and methods are represented as just a fn ptr and not a full
// closure.
use core::prelude::*;
use back::abi;
use driver::session;
use lib;
use lib::llvm::ValueRef;
use lib::llvm::llvm;
use metadata::csearch;
use middle::trans::base;
use middle::trans::base::*;
use middle::trans::build::*;
use middle::trans::callee;
use middle::trans::closure;
use middle::trans::common;
use middle::trans::common::*;
use middle::trans::datum::*;
use middle::trans::datum::Datum;
use middle::trans::expr;
use middle::trans::glue;
use middle::trans::inline;
use middle::trans::meth;
use middle::trans::monomorphize;
use middle::trans::type_of;
use middle::ty;
use middle::typeck;
use util::ppaux::Repr;
use core::vec;
use syntax::ast;
use syntax::ast_map;
use syntax::visit;
// Represents a (possibly monomorphized) top-level fn item or method
// item. Note that this is just the fn-ptr and is not a Rust closure
// value (which is a pair).
pub struct FnData {
llfn: ValueRef,
}
pub struct MethodData {
llfn: ValueRef,
llself: ValueRef,
self_ty: ty::t,
self_mode: ty::SelfMode,
}
pub enum CalleeData {
Closure(Datum),
Fn(FnData),
Method(MethodData)
}
pub struct Callee {
bcx: block,
data: CalleeData
}
pub fn trans(bcx: block, expr: @ast::expr) -> Callee {
let _icx = bcx.insn_ctxt("trans_callee");
debug!("callee::trans(expr=%s)", expr.repr(bcx.tcx()));
// pick out special kinds of expressions that can be called:
match expr.node {
ast::expr_path(_) => {
return trans_def(bcx, bcx.def(expr.id), expr);
}
_ => {}
}
// any other expressions are closures:
return datum_callee(bcx, expr);
fn datum_callee(bcx: block, expr: @ast::expr) -> Callee {
let DatumBlock {bcx, datum} = expr::trans_to_datum(bcx, expr);
match ty::get(datum.ty).sty {
ty::ty_bare_fn(*) => {
let llval = datum.to_appropriate_llval(bcx);
return Callee {bcx: bcx, data: Fn(FnData {llfn: llval})};
}
ty::ty_closure(*) => {
return Callee {bcx: bcx, data: Closure(datum)};
}
_ => {
bcx.tcx().sess.span_bug(
expr.span,
fmt!("Type of callee is neither bare-fn nor closure: %s",
bcx.ty_to_str(datum.ty)));
}
}
}
fn fn_callee(bcx: block, fd: FnData) -> Callee {
return Callee {bcx: bcx, data: Fn(fd)};
}
fn trans_def(bcx: block, def: ast::def, ref_expr: @ast::expr) -> Callee {
match def {
ast::def_fn(did, _) | ast::def_static_method(did, None, _) => {
fn_callee(bcx, trans_fn_ref(bcx, did, ref_expr.id))
}
ast::def_static_method(impl_did, Some(trait_did), _) => {
fn_callee(bcx, meth::trans_static_method_callee(bcx, impl_did,
trait_did,
ref_expr.id))
}
ast::def_variant(tid, vid) => {
// nullary variants are not callable
assert!(ty::enum_variant_with_id(bcx.tcx(),
tid,
vid).args.len() > 0u);
fn_callee(bcx, trans_fn_ref(bcx, vid, ref_expr.id))
}
ast::def_struct(def_id) => {
fn_callee(bcx, trans_fn_ref(bcx, def_id, ref_expr.id))
}
ast::def_arg(*) |
ast::def_local(*) |
ast::def_binding(*) |
ast::def_upvar(*) |
ast::def_self(*) => {
datum_callee(bcx, ref_expr)
}
ast::def_mod(*) | ast::def_foreign_mod(*) | ast::def_trait(*) |
ast::def_const(*) | ast::def_ty(*) | ast::def_prim_ty(*) |
ast::def_use(*) | ast::def_typaram_binder(*) |
ast::def_region(*) | ast::def_label(*) | ast::def_ty_param(*) |
ast::def_self_ty(*) => {
bcx.tcx().sess.span_bug(
ref_expr.span,
fmt!("Cannot translate def %? \
to a callable thing!", def));
}
}
}
}
pub fn trans_fn_ref_to_callee(bcx: block,
def_id: ast::def_id,
ref_id: ast::node_id) -> Callee {
Callee {bcx: bcx,
data: Fn(trans_fn_ref(bcx, def_id, ref_id))}
}
pub fn trans_fn_ref(bcx: block,
def_id: ast::def_id,
ref_id: ast::node_id) -> FnData {
/*!
*
* Translates a reference (with id `ref_id`) to the fn/method
* with id `def_id` into a function pointer. This may require
* monomorphization or inlining. */
let _icx = bcx.insn_ctxt("trans_fn_ref");
let type_params = node_id_type_params(bcx, ref_id);
let vtables = node_vtables(bcx, ref_id);
debug!("trans_fn_ref(def_id=%s, ref_id=%?, type_params=%s, vtables=%s)",
def_id.repr(bcx.tcx()), ref_id, type_params.repr(bcx.tcx()),
vtables.repr(bcx.tcx()));
trans_fn_ref_with_vtables(bcx, def_id, ref_id, type_params, vtables)
}
pub fn trans_fn_ref_with_vtables_to_callee(
bcx: block,
def_id: ast::def_id,
ref_id: ast::node_id,
type_params: &[ty::t],
vtables: Option<typeck::vtable_res>)
-> Callee {
Callee {bcx: bcx,
data: Fn(trans_fn_ref_with_vtables(bcx, def_id, ref_id,
type_params, vtables))}
}
pub fn trans_fn_ref_with_vtables(
bcx: block, //
def_id: ast::def_id, // def id of fn
ref_id: ast::node_id, // node id of use of fn; may be zero if N/A
type_params: &[ty::t], // values for fn's ty params
vtables: Option<typeck::vtable_res>)
-> FnData {
//!
//
// Translates a reference to a fn/method item, monomorphizing and
// inlining as it goes.
//
// # Parameters
//
// - `bcx`: the current block where the reference to the fn occurs
// - `def_id`: def id of the fn or method item being referenced
// - `ref_id`: node id of the reference to the fn/method, if applicable.
// This parameter may be zero; but, if so, the resulting value may not
// have the right type, so it must be cast before being used.
// - `type_params`: values for each of the fn/method's type parameters
// - `vtables`: values for each bound on each of the type parameters
let _icx = bcx.insn_ctxt("trans_fn_ref_with_vtables");
let ccx = bcx.ccx();
let tcx = ccx.tcx;
debug!("trans_fn_ref_with_vtables(bcx=%s, def_id=%s, ref_id=%?, \
type_params=%s, vtables=%s)",
bcx.to_str(),
def_id.repr(bcx.tcx()),
ref_id,
type_params.repr(bcx.tcx()),
vtables.repr(bcx.tcx()));
assert!(type_params.all(|t| !ty::type_needs_infer(*t)));
// Polytype of the function item (may have type params)
let fn_tpt = ty::lookup_item_type(tcx, def_id);
// Modify the def_id if this is a default method; we want to be
// monomorphizing the trait's code.
let (def_id, opt_impl_did) = match tcx.provided_method_sources.find(&def_id) {
None => (def_id, None),
Some(source) => (source.method_id, Some(source.impl_id))
};
// Check whether this fn has an inlined copy and, if so, redirect
// def_id to the local id of the inlined copy.
let def_id = {
if def_id.crate != ast::local_crate {
let may_translate = opt_impl_did.is_none();
inline::maybe_instantiate_inline(ccx, def_id, may_translate)
} else {
def_id
}
};
// We must monomorphise if the fn has type parameters, is a rust
// intrinsic, or is a default method. In particular, if we see an
// intrinsic that is inlined from a different crate, we want to reemit the
// intrinsic instead of trying to call it in the other crate.
let must_monomorphise;
if type_params.len() > 0 || opt_impl_did.is_some() {
must_monomorphise = true;
} else if def_id.crate == ast::local_crate {
let map_node = session::expect(
ccx.sess,
ccx.tcx.items.find(&def_id.node),
|| fmt!("local item should be in ast map"));
match *map_node {
ast_map::node_foreign_item(_, abis, _, _) => {
must_monomorphise = abis.is_intrinsic()
}
_ => {
must_monomorphise = false;
}
}
} else {
must_monomorphise = false;
}
// Create a monomorphic verison of generic functions
if must_monomorphise {
// Should be either intra-crate or inlined.
assert_eq!(def_id.crate, ast::local_crate);
let mut (val, must_cast) =
monomorphize::monomorphic_fn(ccx, def_id, type_params,
vtables, opt_impl_did, Some(ref_id));
if must_cast && ref_id != 0 {
// Monotype of the REFERENCE to the function (type params
// are subst'd)
let ref_ty = common::node_id_type(bcx, ref_id);
val = PointerCast(
bcx, val, T_ptr(type_of::type_of_fn_from_ty(ccx, ref_ty)));
}
return FnData {llfn: val};
}
// Find the actual function pointer.
let val = {
if def_id.crate == ast::local_crate {
// Internal reference.
get_item_val(ccx, def_id.node)
} else {
// External reference.
trans_external_path(ccx, def_id, fn_tpt.ty)
}
};
return FnData {llfn: val};
}
// ______________________________________________________________________
// Translating calls
pub fn trans_call(in_cx: block,
call_ex: @ast::expr,
f: @ast::expr,
args: CallArgs,
id: ast::node_id,
dest: expr::Dest)
-> block {
let _icx = in_cx.insn_ctxt("trans_call");
trans_call_inner(in_cx,
call_ex.info(),
expr_ty(in_cx, f),
node_id_type(in_cx, id),
|cx| trans(cx, f),
args,
dest,
DontAutorefArg)
}
pub fn trans_method_call(in_cx: block,
call_ex: @ast::expr,
callee_id: ast::node_id,
rcvr: @ast::expr,
args: CallArgs,
dest: expr::Dest)
-> block {
let _icx = in_cx.insn_ctxt("trans_method_call");
debug!("trans_method_call(call_ex=%s, rcvr=%s)",
call_ex.repr(in_cx.tcx()),
rcvr.repr(in_cx.tcx()));
trans_call_inner(
in_cx,
call_ex.info(),
node_id_type(in_cx, callee_id),
expr_ty(in_cx, call_ex),
|cx| {
match cx.ccx().maps.method_map.find_copy(&call_ex.id) {
Some(origin) => {
debug!("origin for %s: %s",
call_ex.repr(in_cx.tcx()),
origin.repr(in_cx.tcx()));
meth::trans_method_callee(cx,
callee_id,
rcvr,
origin)
}
None => {
cx.tcx().sess.span_bug(call_ex.span, "method call expr wasn't in method map")
}
}
},
args,
dest,
DontAutorefArg)
}
pub fn trans_lang_call(bcx: block,
did: ast::def_id,
args: &[ValueRef],
dest: expr::Dest)
-> block {
let fty = if did.crate == ast::local_crate {
ty::node_id_to_type(bcx.ccx().tcx, did.node)
} else {
csearch::get_type(bcx.ccx().tcx, did).ty
};
let rty = ty::ty_fn_ret(fty);
callee::trans_call_inner(bcx,
None,
fty,
rty,
|bcx| {
trans_fn_ref_with_vtables_to_callee(bcx,
did,
0,
[],
None)
},
ArgVals(args),
dest,
DontAutorefArg)
}
pub fn trans_lang_call_with_type_params(bcx: block,
did: ast::def_id,
args: &[ValueRef],
type_params: &[ty::t],
dest: expr::Dest)
-> block {
let fty;
if did.crate == ast::local_crate {
fty = ty::node_id_to_type(bcx.tcx(), did.node);
} else {
fty = csearch::get_type(bcx.tcx(), did).ty;
}
let rty = ty::ty_fn_ret(fty);
return callee::trans_call_inner(
bcx, None, fty, rty,
|bcx| {
let callee =
trans_fn_ref_with_vtables_to_callee(bcx, did, 0,
type_params,
None);
let new_llval;
match callee.data {
Fn(fn_data) => {
let substituted = ty::subst_tps(callee.bcx.tcx(),
type_params,
None,
fty);
let llfnty = type_of::type_of(callee.bcx.ccx(),
substituted);
new_llval = PointerCast(callee.bcx, fn_data.llfn, llfnty);
}
_ => fail!()
}
Callee { bcx: callee.bcx, data: Fn(FnData { llfn: new_llval }) }
},
ArgVals(args), dest, DontAutorefArg);
}
pub fn body_contains_ret(body: &ast::blk) -> bool {
let cx = @mut false;
visit::visit_block(body, cx, visit::mk_vt(@visit::Visitor {
visit_item: |_i, _cx, _v| { },
visit_expr: |e: @ast::expr, cx: @mut bool, v| {
if !*cx {
match e.node {
ast::expr_ret(_) => *cx = true,
_ => visit::visit_expr(e, cx, v),
}
}
},
..*visit::default_visitor()
}));
*cx
}
// See [Note-arg-mode]
pub fn trans_call_inner(in_cx: block,
call_info: Option<NodeInfo>,
fn_expr_ty: ty::t,
ret_ty: ty::t,
get_callee: &fn(block) -> Callee,
args: CallArgs,
dest: expr::Dest,
autoref_arg: AutorefArg)
-> block {
do base::with_scope(in_cx, call_info, "call") |cx| {
let ret_in_loop = match args {
ArgExprs(args) => {
args.len() > 0u && match vec::last(args).node {
ast::expr_loop_body(@ast::expr {
node: ast::expr_fn_block(_, ref body),
_
}) => body_contains_ret(body),
_ => false
}
}
_ => false
};
let callee = get_callee(cx);
let mut bcx = callee.bcx;
let ccx = cx.ccx();
let ret_flag = if ret_in_loop {
let flag = alloca(bcx, T_bool());
Store(bcx, C_bool(false), flag);
Some(flag)
} else {
None
};
let (llfn, llenv) = unsafe {
match callee.data {
Fn(d) => {
(d.llfn, llvm::LLVMGetUndef(T_opaque_box_ptr(ccx)))
}
Method(d) => {
// Weird but true: we pass self in the *environment* slot!
let llself = PointerCast(bcx,
d.llself,
T_opaque_box_ptr(ccx));
(d.llfn, llself)
}
Closure(d) => {
// Closures are represented as (llfn, llclosure) pair:
// load the requisite values out.
let pair = d.to_ref_llval(bcx);
let llfn = GEPi(bcx, pair, [0u, abi::fn_field_code]);
let llfn = Load(bcx, llfn);
let llenv = GEPi(bcx, pair, [0u, abi::fn_field_box]);
let llenv = Load(bcx, llenv);
(llfn, llenv)
}
}
};
let llretslot = trans_ret_slot(bcx, fn_expr_ty, dest);
let mut llargs = ~[];
if !ty::type_is_immediate(ret_ty) {
llargs.push(llretslot);
}
llargs.push(llenv);
bcx = trans_args(bcx, args, fn_expr_ty,
ret_flag, autoref_arg, &mut llargs);
// Now that the arguments have finished evaluating, we need to revoke
// the cleanup for the self argument, if it exists
match callee.data {
Method(d) if d.self_mode == ty::ByCopy => {
revoke_clean(bcx, d.llself);
}
_ => {}
}
// Uncomment this to debug calls.
/*
io::println(fmt!("calling: %s", bcx.val_str(llfn)));
for llargs.each |llarg| {
io::println(fmt!("arg: %s", bcx.val_str(*llarg)));
}
io::println("---");
*/
// If the block is terminated, then one or more of the args
// has type _|_. Since that means it diverges, the code for
// the call itself is unreachable.
let (llresult, new_bcx) = base::invoke(bcx, llfn, llargs);
bcx = new_bcx;
match dest {
expr::Ignore => {
// drop the value if it is not being saved.
unsafe {
if llvm::LLVMIsUndef(llretslot) != lib::llvm::True {
if ty::type_is_nil(ret_ty) {
// When implementing the for-loop sugar syntax, the
// type of the for-loop is nil, but the function
// it's invoking returns a bool. This is a special
// case to ignore instead of invoking the Store
// below into a scratch pointer of a mismatched
// type.
} else if ty::type_is_immediate(ret_ty) {
let llscratchptr = alloc_ty(bcx, ret_ty);
Store(bcx, llresult, llscratchptr);
bcx = glue::drop_ty(bcx, llscratchptr, ret_ty);
} else {
bcx = glue::drop_ty(bcx, llretslot, ret_ty);
}
}
}
}
expr::SaveIn(lldest) => {
// If this is an immediate, store into the result location.
// (If this was not an immediate, the result will already be
// directly written into the output slot.)
if ty::type_is_immediate(ret_ty) {
Store(bcx, llresult, lldest);
}
}
}
if ty::type_is_bot(ret_ty) {
Unreachable(bcx);
} else if ret_in_loop {
let ret_flag_result = bool_to_i1(bcx, Load(bcx, ret_flag.get()));
bcx = do with_cond(bcx, ret_flag_result) |bcx| {
for (copy bcx.fcx.loop_ret).each |&(flagptr, _)| {
Store(bcx, C_bool(true), flagptr);
Store(bcx, C_bool(false), bcx.fcx.llretptr.get());
}
base::cleanup_and_leave(bcx, None, Some(bcx.fcx.llreturn));
Unreachable(bcx);
bcx
}
}
bcx
}
}
pub enum CallArgs<'self> {
ArgExprs(&'self [@ast::expr]),
ArgVals(&'self [ValueRef])
}
pub fn trans_ret_slot(bcx: block, fn_ty: ty::t, dest: expr::Dest)
-> ValueRef {
let retty = ty::ty_fn_ret(fn_ty);
match dest {
expr::SaveIn(dst) => dst,
expr::Ignore => {
if ty::type_is_nil(retty) {
unsafe {
llvm::LLVMGetUndef(T_ptr(T_nil()))
}
} else {
alloc_ty(bcx, retty)
}
}
}
}
pub fn trans_args(cx: block,
args: CallArgs,
fn_ty: ty::t,
ret_flag: Option<ValueRef>,
autoref_arg: AutorefArg,
llargs: &mut ~[ValueRef]) -> block
{
let _icx = cx.insn_ctxt("trans_args");
let mut temp_cleanups = ~[];
let arg_tys = ty::ty_fn_args(fn_ty);
let mut bcx = cx;
// First we figure out the caller's view of the types of the arguments.
// This will be needed if this is a generic call, because the callee has
// to cast her view of the arguments to the caller's view.
match args {
ArgExprs(arg_exprs) => {
let last = arg_exprs.len() - 1u;
for arg_exprs.eachi |i, arg_expr| {
let arg_val = unpack_result!(bcx, {
trans_arg_expr(bcx,
arg_tys[i],
ty::ByCopy,
*arg_expr,
&mut temp_cleanups,
if i == last { ret_flag } else { None },
autoref_arg)
});
llargs.push(arg_val);
}
}
ArgVals(vs) => {
llargs.push_all(vs);
}
}
// now that all arguments have been successfully built, we can revoke any
// temporary cleanups, as they are only needed if argument construction
// should fail (for example, cleanup of copy mode args).
for vec::each(temp_cleanups) |c| {
revoke_clean(bcx, *c)
}
return bcx;
}
pub enum AutorefArg {
DontAutorefArg,
DoAutorefArg
}
// temp_cleanups: cleanups that should run only if failure occurs before the
// call takes place:
pub fn trans_arg_expr(bcx: block,
formal_arg_ty: ty::t,
self_mode: ty::SelfMode,
arg_expr: @ast::expr,
temp_cleanups: &mut ~[ValueRef],
ret_flag: Option<ValueRef>,
autoref_arg: AutorefArg) -> Result {
let _icx = bcx.insn_ctxt("trans_arg_expr");
let ccx = bcx.ccx();
debug!("trans_arg_expr(formal_arg_ty=(%s), self_mode=%?, arg_expr=%s, \
ret_flag=%?)",
formal_arg_ty.repr(bcx.tcx()),
self_mode,
arg_expr.repr(bcx.tcx()),
ret_flag.map(|v| bcx.val_str(*v)));
// translate the arg expr to a datum
let arg_datumblock = match ret_flag {
None => expr::trans_to_datum(bcx, arg_expr),
// If there is a ret_flag, this *must* be a loop body
Some(_) => {
match arg_expr.node {
ast::expr_loop_body(
blk @ @ast::expr {
node: ast::expr_fn_block(ref decl, ref body),
_
}) => {
let scratch_ty = expr_ty(bcx, arg_expr);
let scratch = alloc_ty(bcx, scratch_ty);
let arg_ty = expr_ty(bcx, arg_expr);
let sigil = ty::ty_closure_sigil(arg_ty);
let bcx = closure::trans_expr_fn(
bcx, sigil, decl, body, arg_expr.id,
blk.id, Some(ret_flag), expr::SaveIn(scratch));
DatumBlock {bcx: bcx,
datum: Datum {val: scratch,
ty: scratch_ty,
mode: ByRef(RevokeClean)}}
}
_ => {
bcx.sess().impossible_case(
arg_expr.span, "ret_flag with non-loop-body expr");
}
}
}
};
let arg_datum = arg_datumblock.datum;
let bcx = arg_datumblock.bcx;
debug!(" arg datum: %s", arg_datum.to_str(bcx.ccx()));
let mut val;
if ty::type_is_bot(arg_datum.ty) {
// For values of type _|_, we generate an
// "undef" value, as such a value should never
// be inspected. It's important for the value
// to have type lldestty (the callee's expected type).
let llformal_arg_ty = type_of::type_of(ccx, formal_arg_ty);
unsafe {
val = llvm::LLVMGetUndef(llformal_arg_ty);
}
} else {
// FIXME(#3548) use the adjustments table
match autoref_arg {
DoAutorefArg => {
assert!(!
bcx.ccx().maps.moves_map.contains(&arg_expr.id));
val = arg_datum.to_ref_llval(bcx);
}
DontAutorefArg => {
match self_mode {
ty::ByRef => {
// This assertion should really be valid, but because
// the explicit self code currently passes by-ref, it
// does not hold.
//
//assert !bcx.ccx().maps.moves_map.contains_key(
// &arg_expr.id);
debug!("by ref arg with type %s",
bcx.ty_to_str(arg_datum.ty));
val = arg_datum.to_ref_llval(bcx);
}
ty::ByCopy => {
debug!("by copy arg with type %s, storing to scratch",
bcx.ty_to_str(arg_datum.ty));
let scratch = scratch_datum(bcx, arg_datum.ty, false);
arg_datum.store_to_datum(bcx,
arg_expr.id,
INIT,
scratch);
// Technically, ownership of val passes to the callee.
// However, we must cleanup should we fail before the
// callee is actually invoked.
scratch.add_clean(bcx);
temp_cleanups.push(scratch.val);
match arg_datum.appropriate_mode() {
ByValue => val = Load(bcx, scratch.val),
ByRef(_) => val = scratch.val,
}
}
}
}
}
if formal_arg_ty != arg_datum.ty {
// this could happen due to e.g. subtyping
let llformal_arg_ty = type_of::type_of_explicit_arg(ccx, &formal_arg_ty);
let llformal_arg_ty = match self_mode {
ty::ByRef => T_ptr(llformal_arg_ty),
ty::ByCopy => llformal_arg_ty,
};
debug!("casting actual type (%s) to match formal (%s)",
bcx.val_str(val), bcx.llty_str(llformal_arg_ty));
val = PointerCast(bcx, val, llformal_arg_ty);
}
}
debug!("--- trans_arg_expr passing %s", val_str(bcx.ccx().tn, val));
return rslt(bcx, val);
}