Reduce move ops to a construct-in-place when possible
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15e34deba3
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508c48ce10
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@ -3207,6 +3207,25 @@ fn trans_callee(cx: @block_ctxt, e: @ast::expr) -> lval_maybe_callee {
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}
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}
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fn expr_is_lval(tcx: ty::ctxt, e: @ast::expr) -> bool {
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alt e.node {
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ast::expr_path(_) | ast::expr_index(_, _) |
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ast::expr_unary(ast::deref., _) { true }
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ast::expr_field(base, ident) {
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let basety = ty::type_autoderef(tcx, ty::expr_ty(tcx, base));
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alt ty::struct(tcx, basety) {
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ty::ty_obj(_) { false }
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ty::ty_rec(_) { true }
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}
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}
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ast::expr_call(f, _) {
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let fty = ty::expr_ty(tcx, f);
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ast_util::ret_by_ref(ty::ty_fn_ret_style(tcx, fty))
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}
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_ { false }
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}
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}
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// The additional bool returned indicates whether it's mem (that is
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// represented as an alloca or heap, hence needs a 'load' to be used as an
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// immediate).
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@ -4149,20 +4168,6 @@ fn trans_expr(cx: @block_ctxt, e: @ast::expr) -> result {
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add_clean_temp(bcx, r.val, e_ty);
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ret r;
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}
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ast::expr_move(dst, src) {
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let lhs_res = trans_lval(cx, dst);
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assert (lhs_res.is_mem);
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// FIXME Fill in lhs_res.bcx.sp
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let rhs_res = trans_lval(lhs_res.bcx, src);
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let t = ty::expr_ty(bcx_tcx(cx), src);
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// FIXME: calculate copy init-ness in typestate.
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let bcx =
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move_val(rhs_res.bcx, DROP_EXISTING, lhs_res.val, rhs_res,
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t);
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ret rslt(bcx, C_nil());
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}
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ast::expr_bind(f, args) { ret trans_bind(cx, f, args, e.id); }
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ast::expr_cast(val, _) { ret trans_cast(cx, val, e.id); }
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ast::expr_anon_obj(anon_obj) {
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@ -4325,6 +4330,19 @@ fn trans_expr_dps(bcx: @block_ctxt, e: @ast::expr, dest: dest)
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assert is_mem;
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ret trans_expr_save_in(bcx, src, lhs_addr, DROP_EXISTING);
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}
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ast::expr_move(dst, src) {
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assert dest == ignore;
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let {bcx, val: addr, is_mem} = trans_lval(bcx, dst);
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assert is_mem;
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// FIXME: calculate copy init-ness in typestate.
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if expr_is_lval(bcx_tcx(bcx), src) {
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ret trans_expr_save_in(bcx, src, addr, DROP_EXISTING);
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} else {
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let srclv = trans_lval(bcx, src);
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let t = ty::expr_ty(bcx_tcx(bcx), src);
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ret move_val(srclv.bcx, DROP_EXISTING, addr, srclv, t);
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}
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}
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ast::expr_swap(dst, src) {
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assert dest == ignore;
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let lhs_res = trans_lval(bcx, dst);
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@ -4665,15 +4683,12 @@ fn init_local(bcx: @block_ctxt, local: @ast::local) -> @block_ctxt {
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alt local.node.init {
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some(init) {
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alt init.op {
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ast::init_assign. {
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if init.op == ast::init_assign ||
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!expr_is_lval(bcx_tcx(bcx), init.expr) {
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bcx = trans_expr_save_in(bcx, init.expr, llptr, INIT);
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}
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// FIXME[DPS] do a save_in when expr isn't lval
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ast::init_move. {
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} else { // This is a move from an lval, must perform an actual move
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let sub = trans_lval(bcx, init.expr);
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bcx = move_val(sub.bcx, INIT, llptr, sub, ty);
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}
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}
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}
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_ { bcx = zero_alloca(bcx, llptr, ty); }
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