On Thu, May 23, 2024 at 04:04:13PM -0400, Jason Merrill wrote: > On 5/23/24 10:41, Marek Polacek wrote: > > Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk? > > > > -- >8 -- > > Coming back to our discussion in > > <https://gcc.gnu.org/pipermail/gcc-patches/2024-April/649426.html>: > > TARGET_EXPRs that initialize a function argument are not marked > > TARGET_EXPR_ELIDING_P even though gimplify_arg drops such TARGET_EXPRs > > on the floor. > > But only if TREE_TYPE (TARGET_EXPR_INITIAL is non-void, I think we should > check that here too to be parallel.
Ah yes, definitely. > Perhaps most/all affected TARGET_EXPRs will have been handled earlier in the > function under the TREE_ADDRESSABLE check, but I wouldn't rely on that > without an assert. So like this or you want an assert somewhere too? dg.exp passed. -- >8 -- Coming back to our discussion in <https://gcc.gnu.org/pipermail/gcc-patches/2024-April/649426.html>: TARGET_EXPRs that initialize a function argument are not marked TARGET_EXPR_ELIDING_P even though gimplify_arg drops such TARGET_EXPRs on the floor. To work around it, I added a pset to replace_placeholders_for_class_temp_r, but it would be best to just rely on TARGET_EXPR_ELIDING_P. PR c++/114707 gcc/cp/ChangeLog: * call.cc (convert_for_arg_passing): Call set_target_expr_eliding. * typeck2.cc (replace_placeholders_for_class_temp_r): Don't use pset. (digest_nsdmi_init): Call cp_walk_tree_without_duplicates instead of cp_walk_tree. --- gcc/cp/call.cc | 6 ++++++ gcc/cp/typeck2.cc | 20 ++++---------------- 2 files changed, 10 insertions(+), 16 deletions(-) diff --git a/gcc/cp/call.cc b/gcc/cp/call.cc index ed68eb3c568..35c024f2c7c 100644 --- a/gcc/cp/call.cc +++ b/gcc/cp/call.cc @@ -9437,6 +9437,12 @@ convert_for_arg_passing (tree type, tree val, tsubst_flags_t complain) if (complain & tf_warning) warn_for_address_of_packed_member (type, val); + /* gimplify_arg elides TARGET_EXPRs that initialize a function argument. */ + if (TREE_CODE (val) == TARGET_EXPR) + if (tree init = TARGET_EXPR_INITIAL (val)) + if (!VOID_TYPE_P (TREE_TYPE (init))) + set_target_expr_eliding (val); + return val; } diff --git a/gcc/cp/typeck2.cc b/gcc/cp/typeck2.cc index 06bad4d3303..7782f38da43 100644 --- a/gcc/cp/typeck2.cc +++ b/gcc/cp/typeck2.cc @@ -1409,16 +1409,14 @@ digest_init_flags (tree type, tree init, int flags, tsubst_flags_t complain) in the context of guaranteed copy elision). */ static tree -replace_placeholders_for_class_temp_r (tree *tp, int *, void *data) +replace_placeholders_for_class_temp_r (tree *tp, int *, void *) { tree t = *tp; - auto pset = static_cast<hash_set<tree> *>(data); /* We're looking for a TARGET_EXPR nested in the whole expression. */ if (TREE_CODE (t) == TARGET_EXPR /* That serves as temporary materialization, not an initializer. */ - && !TARGET_EXPR_ELIDING_P (t) - && !pset->add (t)) + && !TARGET_EXPR_ELIDING_P (t)) { tree init = TARGET_EXPR_INITIAL (t); while (TREE_CODE (init) == COMPOUND_EXPR) @@ -1433,16 +1431,6 @@ replace_placeholders_for_class_temp_r (tree *tp, int *, void *data) gcc_checking_assert (!find_placeholders (init)); } } - /* TARGET_EXPRs initializing function arguments are not marked as eliding, - even though gimplify_arg drops them on the floor. Don't go replacing - placeholders in them. */ - else if (TREE_CODE (t) == CALL_EXPR || TREE_CODE (t) == AGGR_INIT_EXPR) - for (int i = 0; i < call_expr_nargs (t); ++i) - { - tree arg = get_nth_callarg (t, i); - if (TREE_CODE (arg) == TARGET_EXPR && !TARGET_EXPR_ELIDING_P (arg)) - pset->add (arg); - } return NULL_TREE; } @@ -1490,8 +1478,8 @@ digest_nsdmi_init (tree decl, tree init, tsubst_flags_t complain) temporary materialization does not occur when initializing an object from a prvalue of the same type, therefore we must not replace the placeholder with a temporary object so that it can be elided. */ - hash_set<tree> pset; - cp_walk_tree (&init, replace_placeholders_for_class_temp_r, &pset, nullptr); + cp_walk_tree_without_duplicates (&init, replace_placeholders_for_class_temp_r, + nullptr); return init; } base-commit: ee492101c2e51b58e926307448d35f539aec0b2c -- 2.45.1
