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librustc: Don't create scratch for the base expr in function record update.

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This commit is contained in:
Luqman Aden 2014-08-14 22:16:35 -04:00
parent f8e0ede921
commit 7e30ba8fc9
1 changed files with 35 additions and 30 deletions
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65
src/librustc/middle/trans/expr.rs
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@ -746,12 +746,12 @@ fn trans_rvalue_dps_unadjusted<'a>(bcx: &'a Block<'a>,
controlflow::trans_block(bcx, &**blk, dest)
}
ast::ExprStruct(_, ref fields, base) => {
trans_rec_or_struct(bcx,
fields.as_slice(),
base,
expr.span,
expr.id,
dest)
trans_struct(bcx,
fields.as_slice(),
base,
expr.span,
expr.id,
dest)
}
ast::ExprTup(ref args) => {
let repr = adt::represent_type(bcx.ccx(), expr_ty(bcx, expr));
@ -1042,16 +1042,13 @@ pub fn with_field_tys<R>(tcx: &ty::ctxt,
}
}
fn trans_rec_or_struct<'a>(
bcx: &'a Block<'a>,
fields: &[ast::Field],
base: Option<Gc<ast::Expr>>,
expr_span: codemap::Span,
id: ast::NodeId,
dest: Dest)
-> &'a Block<'a> {
fn trans_struct<'a>(bcx: &'a Block<'a>,
fields: &[ast::Field],
base: Option<Gc<ast::Expr>>,
expr_span: codemap::Span,
id: ast::NodeId,
dest: Dest) -> &'a Block<'a> {
let _icx = push_ctxt("trans_rec");
let bcx = bcx;
let ty = node_id_type(bcx, id);
let tcx = bcx.tcx();
@ -1121,7 +1118,7 @@ pub struct StructBaseInfo {
* - `optbase` contains information on the base struct (if any) from
* which remaining fields are copied; see comments on `StructBaseInfo`.
*/
pub fn trans_adt<'a>(bcx: &'a Block<'a>,
pub fn trans_adt<'a>(mut bcx: &'a Block<'a>,
repr: &adt::Repr,
discr: ty::Disr,
fields: &[(uint, Gc<ast::Expr>)],
@ -1129,7 +1126,6 @@ pub fn trans_adt<'a>(bcx: &'a Block<'a>,
dest: Dest) -> &'a Block<'a> {
let _icx = push_ctxt("trans_adt");
let fcx = bcx.fcx;
let mut bcx = bcx;
let addr = match dest {
Ignore => {
for &(_i, ref e) in fields.iter() {
@ -1148,6 +1144,28 @@ pub fn trans_adt<'a>(bcx: &'a Block<'a>,
// failure occur before the ADT as a whole is ready.
let custom_cleanup_scope = fcx.push_custom_cleanup_scope();
// First we trans the base, if we have one, to the dest
for base in optbase.iter() {
assert_eq!(discr, 0);
match ty::expr_kind(bcx.tcx(), &*base.expr) {
ty::LvalueExpr => {
let base_datum = unpack_datum!(bcx, trans_to_lvalue(bcx, &*base.expr, "base"));
for &(i, t) in base.fields.iter() {
let datum = base_datum.get_element(
t, |srcval| adt::trans_field_ptr(bcx, repr, srcval, discr, i));
let dest = adt::trans_field_ptr(bcx, repr, addr, discr, i);
bcx = datum.store_to(bcx, dest);
}
},
ty::RvalueDpsExpr | ty::RvalueDatumExpr => {
bcx = trans_into(bcx, &*base.expr, SaveIn(addr));
},
ty::RvalueStmtExpr => bcx.tcx().sess.bug("unexpected expr kind for struct base expr")
}
}
// Now, we just overwrite the fields we've explicity specified
for &(i, ref e) in fields.iter() {
let dest = adt::trans_field_ptr(bcx, repr, addr, discr, i);
let e_ty = expr_ty_adjusted(bcx, &**e);
@ -1157,19 +1175,6 @@ pub fn trans_adt<'a>(bcx: &'a Block<'a>,
fcx.schedule_drop_mem(scope, dest, e_ty);
}
for base in optbase.iter() {
// FIXME #6573: is it sound to use the destination's repr on the base?
// And, would it ever be reasonable to be here with discr != 0?
let base_datum = unpack_datum!(bcx, trans_to_lvalue(bcx, &*base.expr, "base"));
for &(i, t) in base.fields.iter() {
let datum = base_datum.get_element(
t,
|srcval| adt::trans_field_ptr(bcx, repr, srcval, discr, i));
let dest = adt::trans_field_ptr(bcx, repr, addr, discr, i);
bcx = datum.store_to(bcx, dest);
}
}
adt::trans_set_discr(bcx, repr, addr, discr);
fcx.pop_custom_cleanup_scope(custom_cleanup_scope);