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Avoid unnecessary temporary on assignments #15145

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Avoid unnecessary temporary on assignments #15145

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4 changes: 2 additions & 2 deletions src/librustc/middle/trans/expr.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -610,7 +610,6 @@ fn trans_rvalue_stmt_unadjusted<'a>(bcx: &'a Block<'a>,
controlflow::trans_loop(bcx, expr.id, &**body)
}
ast::ExprAssign(ref dst, ref src) => {
let src_datum = unpack_datum!(bcx, trans(bcx, &**src));
let dst_datum = unpack_datum!(bcx, trans_to_lvalue(bcx, &**dst, "assign"));

if ty::type_needs_drop(bcx.tcx(), dst_datum.ty) {
Expand All @@ -630,12 +629,13 @@ fn trans_rvalue_stmt_unadjusted<'a>(bcx: &'a Block<'a>,
//
// We could avoid this intermediary with some analysis
// to determine whether `dst` may possibly own `src`.
let src_datum = unpack_datum!(bcx, trans(bcx, &**src));
let src_datum = unpack_datum!(
bcx, src_datum.to_rvalue_datum(bcx, "ExprAssign"));
bcx = glue::drop_ty(bcx, dst_datum.val, dst_datum.ty);
src_datum.store_to(bcx, dst_datum.val)
} else {
src_datum.store_to(bcx, dst_datum.val)
trans_into(bcx, &**src, SaveIn(dst_datum.to_llref()))
}
}
ast::ExprAssignOp(op, ref dst, ref src) => {
Expand Down