https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116416
--- Comment #13 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Patrick Palka <ppa...@gcc.gnu.org>: https://gcc.gnu.org/g:e7bccec33beece4a46bc1b20ed375e803e97aa88 commit r15-9400-ge7bccec33beece4a46bc1b20ed375e803e97aa88 Author: Patrick Palka <ppa...@redhat.com> Date: Sat Apr 12 14:06:56 2025 -0400 c++: improve constexpr prvalue folding [PR116416] This patch improves upon r15-6052-g12de1942a0a673 by performing prvalue folding with mce_false rather than mce_unknown when it's safe to do so (i.e. ff_mce_false is set), so that we can also fold temporary initializers that call is_constant_evaluated etc. In passing I noticed constexpr-prvalue1.C could more precisely verify the optimization happened by inspecting what the front end spits out instead of inspecting the optimized assembly -- that there's no constructor call doesn't necessarily imply the constructor has been completely folded away, only that its body has been inlined. PR c++/116416 gcc/cp/ChangeLog: * constexpr.cc (maybe_constant_init_1): Generalize type of of manifestly_const_eval parameter from bool to mce_value. (maybe_constant_init): Define 3-parameter version taking a manifestly_const_eval instead of bool parameter. (cxx_constant_init): Adjust. * cp-gimplify.cc (cp_fold_r) <case TARGET_EXPR>: Pass mce_false to maybe_constant_init during prvalue folding if ff_mce_false is set. * cp-tree.h (maybe_constant_init): Declare new overload. gcc/testsuite/ChangeLog: * g++.dg/cpp1y/constexpr-prvalue1.C: Adjust to instead inspect the 'original' dump. * g++.dg/cpp1y/constexpr-prvalue1a.C: New test. Reviewed-by: Jason Merrill <ja...@redhat.com>
