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Avoid unnecessary temporary on assignments

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We only need the temporary when the type needs to be dropped, for other
types, we can use trans_into to directly place the value into the
destination.
This commit is contained in:
Björn Steinbrink 2014-06-22 15:32:55 +02:00 committed by Alex Crichton
parent e4e3550ff6
commit a0ec902e23
1 changed files with 2 additions and 2 deletions
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4
src/librustc/middle/trans/expr.rs
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@ -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) {
@ -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) => {