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Clean up copy bookkeeping in alias.rs

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This commit is contained in:
Marijn Haverbeke 2011-09-13 13:09:58 +02:00
parent 2f402343c9
commit 45bdff01b2
1 changed files with 33 additions and 35 deletions
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68
src/comp/middle/alias.rs
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@ -13,18 +13,17 @@ import std::option::{some, none, is_none};
// whether aliases are used in a safe way.
tag valid { valid; overwritten(span, ast::path); val_taken(span, ast::path); }
tag copied { not_allowed; copied; not_copied; }
type restrict =
@{root_var: option::t<node_id>,
node_id: node_id,
ty: ty::t,
span: span,
local_id: uint,
bindings: [node_id],
unsafe_tys: [ty::t],
depends_on: [uint],
mutable ok: valid,
mutable given_up: bool};
type restrict = @{root_var: option::t<node_id>,
node_id: node_id,
span: span,
local_id: uint,
binding: option::t<node_id>,
unsafe_tys: [ty::t],
depends_on: [uint],
mutable ok: valid,
mutable copied: copied};
type scope = @[restrict];
@ -143,19 +142,19 @@ fn visit_decl(cx: @ctx, d: @ast::decl, sc: scope, v: vt<scope>) {
}
fn cant_copy(cx: ctx, r: restrict) -> bool {
if r.given_up { ret false; }
// FIXME alt contexts copying not supported yet
if r.node_id == 0 { ret true; }
// FIXME warn when copy is expensive
if ty::type_allows_implicit_copy(cx.tcx, r.ty) {
r.given_up = true;
alt r.copied {
not_allowed. { ret true; }
copied. { ret false; }
not_copied. {}
}
let ty = ty::node_id_to_type(cx.tcx, r.node_id);
if ty::type_allows_implicit_copy(cx.tcx, ty) {
r.copied = copied;
cx.copy_map.insert(r.node_id, ());
if copy_is_expensive(cx.tcx, r.ty) {
// FIXME better message
if copy_is_expensive(cx.tcx, ty) {
cx.tcx.sess.span_warn(r.span,
"inserting an implicit copy for type " +
util::ppaux::ty_to_str(cx.tcx, r.ty));
util::ppaux::ty_to_str(cx.tcx, ty));
}
ret false;
} else { ret true; }
@ -182,16 +181,18 @@ fn check_call(cx: ctx, f: @ast::expr, args: [@ast::expr], sc: scope) ->
}
let root_var = path_def_id(cx, root.ex);
restricts += [@{root_var: root_var,
// FIXME kludge
node_id: arg_t.mode == ast::by_mut_ref ? 0 : arg.id,
ty: arg_t.ty,
node_id: arg.id,
span: arg.span,
local_id: cx.next_local,
bindings: [arg.id],
binding: none::<node_id>,
unsafe_tys: inner_mut(root.ds),
depends_on: deps(sc, root_var),
mutable ok: valid,
mutable given_up: arg_t.mode == ast::by_move}];
mutable copied: alt arg_t.mode {
ast::by_move. { copied }
ast::by_ref. { not_copied }
ast::by_mut_ref. { not_allowed }
}}];
i += 1u;
}
let f_may_close =
@ -261,7 +262,6 @@ fn check_alt(cx: ctx, input: @ast::expr, arms: [ast::arm], sc: scope,
v.visit_expr(input, sc, v);
let root = expr_root(cx.tcx, input, true);
for a: ast::arm in arms {
// FIXME handle other | patterns
let new_sc = *sc;
let root_var = path_def_id(cx, root.ex);
let pat_id_map = ast_util::pat_id_map(a.pats[0]);
@ -286,14 +286,13 @@ fn check_alt(cx: ctx, input: @ast::expr, arms: [ast::arm], sc: scope,
for info in binding_info {
new_sc += [@{root_var: root_var,
node_id: info.id,
ty: ty::node_id_to_type(cx.tcx, info.id),
span: info.span,
local_id: cx.next_local,
bindings: [info.id],
binding: some(info.id),
unsafe_tys: info.unsafe,
depends_on: deps(sc, root_var),
mutable ok: valid,
mutable given_up: false}];
mutable copied: not_copied}];
}
register_locals(cx, a.pats[0]);
visit::visit_arm(a, @new_sc, v);
@ -333,14 +332,13 @@ fn check_for(cx: ctx, local: @ast::local, seq: @ast::expr, blk: ast::blk,
for proot in *pattern_roots(cx.tcx, ext_ds, local.node.pat) {
new_sc += [@{root_var: root_var,
node_id: proot.id,
ty: ty::node_id_to_type(cx.tcx, proot.id),
span: proot.span,
local_id: cx.next_local,
bindings: [proot.id],
binding: some(proot.id),
unsafe_tys: inner_mut(proot.ds),
depends_on: deps(sc, root_var),
mutable ok: valid,
mutable given_up: false}];
mutable copied: not_copied}];
}
register_locals(cx, local.node.pat);
visit::visit_block(blk, @new_sc, v);
@ -362,7 +360,7 @@ fn check_var(cx: ctx, ex: @ast::expr, p: ast::path, id: ast::node_id,
r.ok = val_taken(ex.span, p);
}
}
} else if vec::member(my_defnum, r.bindings) {
} else if r.binding == some(my_defnum) {
test_scope(cx, sc, r, p);
}
}
@ -417,7 +415,7 @@ fn deps(sc: scope, root: option::t<node_id>) -> [uint] {
some(dn) {
let i = 0u;
for r: restrict in *sc {
if vec::member(dn, r.bindings) { result += [i]; }
if r.binding == some(dn) { result += [i]; }
i += 1u;
}
}