https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109930
Bug ID: 109930
Summary: transform atomic exchange to unconditional store when
old value is unused?
Product: gcc
Version: 13.1.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: rtl-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: Simon.Richter at hogyros dot de
Target Milestone: ---
I'm not sure if that is a valid substitution, but...
I have a state machine that has a few transitions where I already know the old
state, so I can simply do an unconditional store, but I'd also like to have an
assertion on the old state in my debug version:
std::atomic<uint32_t> x;
/* ... */
auto old_value = x.exchange(5);
assert(old_value == 3);
with NDEBUG set, the assert is omitted, and no one is interested in the old
value, so the load-with-reserve can be omitted and the store-conditional
replaced with a regular store, and this should still be semantically
equivalent.
