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Reduce move ops to a construct-in-place when possible

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This commit is contained in:
Marijn Haverbeke 2011-09-28 15:15:29 +02:00
parent 15e34deba3
commit 508c48ce10
1 changed files with 35 additions and 20 deletions
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55
src/comp/middle/trans.rs
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@ -3207,6 +3207,25 @@ fn trans_callee(cx: @block_ctxt, e: @ast::expr) -> lval_maybe_callee {
}
}
fn expr_is_lval(tcx: ty::ctxt, e: @ast::expr) -> bool {
alt e.node {
ast::expr_path(_) | ast::expr_index(_, _) |
ast::expr_unary(ast::deref., _) { true }
ast::expr_field(base, ident) {
let basety = ty::type_autoderef(tcx, ty::expr_ty(tcx, base));
alt ty::struct(tcx, basety) {
ty::ty_obj(_) { false }
ty::ty_rec(_) { true }
}
}
ast::expr_call(f, _) {
let fty = ty::expr_ty(tcx, f);
ast_util::ret_by_ref(ty::ty_fn_ret_style(tcx, fty))
}
_ { false }
}
}
// The additional bool returned indicates whether it's mem (that is
// represented as an alloca or heap, hence needs a 'load' to be used as an
// immediate).
@ -4149,20 +4168,6 @@ fn trans_expr(cx: @block_ctxt, e: @ast::expr) -> result {
add_clean_temp(bcx, r.val, e_ty);
ret r;
}
ast::expr_move(dst, src) {
let lhs_res = trans_lval(cx, dst);
assert (lhs_res.is_mem);
// FIXME Fill in lhs_res.bcx.sp
let rhs_res = trans_lval(lhs_res.bcx, src);
let t = ty::expr_ty(bcx_tcx(cx), src);
// FIXME: calculate copy init-ness in typestate.
let bcx =
move_val(rhs_res.bcx, DROP_EXISTING, lhs_res.val, rhs_res,
t);
ret rslt(bcx, C_nil());
}
ast::expr_bind(f, args) { ret trans_bind(cx, f, args, e.id); }
ast::expr_cast(val, _) { ret trans_cast(cx, val, e.id); }
ast::expr_anon_obj(anon_obj) {
@ -4325,6 +4330,19 @@ fn trans_expr_dps(bcx: @block_ctxt, e: @ast::expr, dest: dest)
assert is_mem;
ret trans_expr_save_in(bcx, src, lhs_addr, DROP_EXISTING);
}
ast::expr_move(dst, src) {
assert dest == ignore;
let {bcx, val: addr, is_mem} = trans_lval(bcx, dst);
assert is_mem;
// FIXME: calculate copy init-ness in typestate.
if expr_is_lval(bcx_tcx(bcx), src) {
ret trans_expr_save_in(bcx, src, addr, DROP_EXISTING);
} else {
let srclv = trans_lval(bcx, src);
let t = ty::expr_ty(bcx_tcx(bcx), src);
ret move_val(srclv.bcx, DROP_EXISTING, addr, srclv, t);
}
}
ast::expr_swap(dst, src) {
assert dest == ignore;
let lhs_res = trans_lval(bcx, dst);
@ -4665,15 +4683,12 @@ fn init_local(bcx: @block_ctxt, local: @ast::local) -> @block_ctxt {
alt local.node.init {
some(init) {
alt init.op {
ast::init_assign. {
if init.op == ast::init_assign ||
!expr_is_lval(bcx_tcx(bcx), init.expr) {
bcx = trans_expr_save_in(bcx, init.expr, llptr, INIT);
}
// FIXME[DPS] do a save_in when expr isn't lval
ast::init_move. {
} else { // This is a move from an lval, must perform an actual move
let sub = trans_lval(bcx, init.expr);
bcx = move_val(sub.bcx, INIT, llptr, sub, ty);
}
}
}
_ { bcx = zero_alloca(bcx, llptr, ty); }