[Bug c++/58487] Missed return value optimization
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58487 Jason Merrill changed: What|Removed |Added CC||jason at gcc dot gnu.org Target Milestone|--- |14.0 Resolution|--- |FIXED Status|NEW |RESOLVED --- Comment #9 from Jason Merrill --- Fixed for GCC 14.
[Bug c++/58487] Missed return value optimization
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58487 --- Comment #8 from CVS Commits --- The trunk branch has been updated by Jason Merrill : https://gcc.gnu.org/g:953bbeaeff050f4d0b670568a587aa1ce82ed711 commit r14-1660-g953bbeaeff050f4d0b670568a587aa1ce82ed711 Author: Jason Merrill Date: Fri Jun 9 10:37:35 2023 -0400 c++: fix 32-bit spaceship failures [PR110185] Various spaceship tests failed after r14-1624. This turned out to be because the comparison category classes return in memory on 32-bit targets, and the synthesized operator<=> looks something like if (auto v = a.x <=> b.x, v == 0); else return v; if (auto v = a.y <=> b.y, v == 0); else return v; etc. so check_return_expr was trying to do NRVO for all the 'v' variables, and now on subsequent returns we check to see if the previous NRV is still in scope. But the NRVs didn't have names, so looking up name bindings crashed. Fixed both by giving 'v' a name so we can NRVO the first one, and fixing the test to give up if the old NRV has no name. PR c++/110185 PR c++/58487 gcc/cp/ChangeLog: * method.cc (build_comparison_op): Give retval a name. * typeck.cc (check_return_expr): Fix for nameless variables.
[Bug c++/58487] Missed return value optimization
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58487 --- Comment #7 from CVS Commits --- The trunk branch has been updated by Jason Merrill : https://gcc.gnu.org/g:28db36e2cfca1b7106adc8d371600fa3a325c4e2 commit r14-1624-g28db36e2cfca1b7106adc8d371600fa3a325c4e2 Author: Jason Merrill Date: Wed Jun 7 05:15:02 2023 -0400 c++: allow NRV and non-NRV returns [PR58487] Now that we support NRV from an inner block, we can also support non-NRV returns from other blocks, since once the NRV is out of scope a later return expression can't possibly alias it. This fixes 58487 and half-fixes 53637: now one of the returns is elided, but not the other. Fixing the remaining xfails in these testcases will require a very different approach, probably involving a full tree/block walk from finalize_nrv, and check_return_expr only adding to a list of potential return variables. PR c++/58487 PR c++/53637 gcc/cp/ChangeLog: * cp-tree.h (INIT_EXPR_NRV_P): New. * semantics.cc (finalize_nrv_r): Check it. * name-lookup.h (decl_in_scope_p): Declare. * name-lookup.cc (decl_in_scope_p): New. * typeck.cc (check_return_expr): Allow non-NRV returns if the NRV is no longer in scope. gcc/testsuite/ChangeLog: * g++.dg/opt/nrv26.C: New test. * g++.dg/opt/nrv26a.C: New test. * g++.dg/opt/nrv27.C: New test.
[Bug c++/58487] Missed return value optimization
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58487 --- Comment #6 from CVS Commits --- The trunk branch has been updated by Jason Merrill : https://gcc.gnu.org/g:2ae5384d457b9c67586de012816dfc71a6943164 commit r14-1594-g2ae5384d457b9c67586de012816dfc71a6943164 Author: Jason Merrill Date: Tue Jun 6 12:46:26 2023 -0400 c++: Add -Wnrvo While looking at PRs about cases where we don't perform the named return value optimization, it occurred to me that it might be useful to have a warning for that. This does not fix PR58487, but might be interesting to people watching it. PR c++/58487 gcc/c-family/ChangeLog: * c.opt: Add -Wnrvo. gcc/ChangeLog: * doc/invoke.texi: Document it. gcc/cp/ChangeLog: * typeck.cc (want_nrvo_p): New. (check_return_expr): Handle -Wnrvo. gcc/testsuite/ChangeLog: * g++.dg/opt/nrv25.C: New test.
[Bug c++/58487] Missed return value optimization
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58487 --- Comment #5 from Jason Merrill --- *** Bug 96004 has been marked as a duplicate of this bug. ***
[Bug c++/58487] Missed return value optimization
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58487 Óscar Fuentes changed: What|Removed |Added CC||gcc_bugzilla at axeitado dot com --- Comment #4 from Óscar Fuentes --- Isn't this PR a trivial variation of PR53637 ?
[Bug c++/58487] Missed return value optimization
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58487
Antony Polukhin changed:
What|Removed |Added
CC||antoshkka at gmail dot com
--- Comment #3 from Antony Polukhin ---
Minimized example, move constructor should not be called:
struct A {
A() = default;
A(A&&);
};
A test() {
if (true) {
A a;
return a;
} else {
return A{};
}
}
Godbolt playground: https://godbolt.org/z/4Pzq83WWY
[Bug c++/58487] Missed return value optimization
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58487 Andrew Pinski changed: What|Removed |Added Status|UNCONFIRMED |NEW Last reconfirmed||2016-08-14 Ever confirmed|0 |1 --- Comment #2 from Andrew Pinski --- Confirmed.
[Bug c++/58487] Missed return value optimization
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58487 Andrew Pinski changed: What|Removed |Added Severity|normal |enhancement
[Bug c++/58487] Missed return value optimization
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58487 Andrew Pinski changed: What|Removed |Added Severity|normal |enhancement
[Bug c++/58487] Missed return value optimization
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58487 Marc Glisse glisse at gcc dot gnu.org changed: What|Removed |Added Keywords||missed-optimization --- Comment #1 from Marc Glisse glisse at gcc dot gnu.org --- PR53637 or one of the other RVO PRs (see the meta PR 58055).
