https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119179
Bug ID: 119179
Summary: Allow the [[gnu:::uninitialized]] attribute on classes
/ non-static data members
Product: gcc
Version: 15.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: dangelog at gmail dot com
Target Milestone: ---
When building under -ftrivial-auto-var-init, certain classes that contain
buffers (e.g. for SBO) and/or are used as "buffers" on the stack are now
automatically filled with byte patterns. This may cause a performance hit in
sensitive code paths.
The [[gnu::uninitialized]] attribute can be used to prevent such a hit, but
that requires annotating all use sites. That's extremely invasive and
error-prone.
It would be much more ergonomic if one could annotate with the attribute the
class itself and/or certain non-static data members, so that every usage will
automatically avoid the byte filling.
