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Implement move semantics.

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This commit is contained in:
Michael Sullivan 2011-05-31 14:36:08 -07:00 • committed by Graydon Hoare
parent 5e7bba3d23
commit c232964301
1 changed files with 42 additions and 4 deletions
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46
src/comp/middle/trans.rs
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@ -3259,6 +3259,45 @@ fn copy_val(&@block_ctxt cx,
fail;
}
// This works like copy_val, except that it deinitializes the source.
// Since it needs to zero out the source, src also needs to be an lval.
// FIXME: We always zero out the source. Ideally we would detect the
// case where a variable is always deinitialized by block exit and thus
// doesn't need to be dropped.
fn move_val(&@block_ctxt cx,
copy_action action,
ValueRef dst,
ValueRef src,
&ty::t t) -> result {
if (ty::type_is_scalar(cx.fcx.lcx.ccx.tcx, t) ||
ty::type_is_native(cx.fcx.lcx.ccx.tcx, t)) {
ret res(cx, cx.build.Store(src, dst));
} else if (ty::type_is_nil(cx.fcx.lcx.ccx.tcx, t) ||
ty::type_is_bot(cx.fcx.lcx.ccx.tcx, t)) {
ret res(cx, C_nil());
} else if (ty::type_is_boxed(cx.fcx.lcx.ccx.tcx, t)) {
if (action == DROP_EXISTING) {
cx = drop_ty(cx, cx.build.Load(dst), t).bcx;
}
auto r = res(cx, cx.build.Store(cx.build.Load(src), dst));
ret zero_alloca(r.bcx, src, t);
} else if (ty::type_is_structural(cx.fcx.lcx.ccx.tcx, t) ||
ty::type_has_dynamic_size(cx.fcx.lcx.ccx.tcx, t)) {
if (action == DROP_EXISTING) {
cx = drop_ty(cx, dst, t).bcx;
}
auto r = memmove_ty(cx, dst, cx.build.Load(src), t);
ret zero_alloca(r.bcx, src, t);
}
cx.fcx.lcx.ccx.sess.bug("unexpected type in trans::move_val: " +
ty::ty_to_str(cx.fcx.lcx.ccx.tcx, t));
fail;
}
fn trans_lit(&@crate_ctxt cx, &ast::lit lit, &ast::ann ann) -> ValueRef {
alt (lit.node) {
case (ast::lit_int(?i)) {
@ -5504,12 +5543,11 @@ fn trans_expr_out(&@block_ctxt cx, &@ast::expr e, out_method output)
auto lhs_res = trans_lval(cx, dst);
assert (lhs_res.is_mem);
*(lhs_res.res.bcx) = rec(sp=src.span with *(lhs_res.res.bcx));
auto rhs_res = trans_expr(lhs_res.res.bcx, src);
auto rhs_res = trans_lval(lhs_res.res.bcx, src);
auto t = node_ann_type(cx.fcx.lcx.ccx, ann);
// FIXME: calculate copy init-ness in typestate.
// FIXME: do all of the special move stuff
ret copy_ty(rhs_res.bcx, DROP_EXISTING,
lhs_res.res.val, rhs_res.val, t);
ret move_val(rhs_res.res.bcx, DROP_EXISTING,
lhs_res.res.val, rhs_res.res.val, t);
}
case (ast::expr_assign(?dst, ?src, ?ann)) {