https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86320
--- Comment #4 from Jason Merrill <jason at gcc dot gnu.org> --- Author: jason Date: Wed Jun 27 02:59:44 2018 New Revision: 262173 URL: https://gcc.gnu.org/viewcvs?rev=262173&root=gcc&view=rev Log: PR c++/86320 - memory-hog with std::array of pair * typeck2.c (process_init_constructor_array): Only compute a constant initializer once. In this PR, we have a large std::array of pairs. Since the C array is wrapped in a class we don't go to build_vec_init, so we end up with digest_init wanting to build up the element initializer for each element of the array. In the more general case, like 80272, we have a data structure problem: we don't currently have a good way of expressing the same dynamic initialization of many elements within a CONSTRUCTOR. RANGE_EXPR probably ought to work, but will need more work at genericize or gimplify time. But in this case, the initialization for each element reduces to constant 0, so we don't even need to add anything to the CONSTRUCTOR. We just need to realize that if the initializer for one element is 0, the others will be as well, and we don't need to iterate over the whole array. For the trunk, I also use a RANGE_EXPR to handle constant initialization by a value other than 0. void foo () { std::array<std::pair<int, int>, 1024 * 1024> arr {}; } Modified: trunk/gcc/cp/ChangeLog trunk/gcc/cp/typeck2.c
