https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121831
--- Comment #17 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The releases/gcc-15 branch has been updated by Jakub Jelinek <[email protected]>: https://gcc.gnu.org/g:761efd0e18417cf386ace300af2f9f9b5d39d07c commit r15-10363-g761efd0e18417cf386ace300af2f9f9b5d39d07c Author: Jakub Jelinek <[email protected]> Date: Wed Sep 10 12:33:14 2025 +0200 expr: Handle RAW_DATA_CST in store_constructor [PR121831] I thought this wouldn't be necessary because RAW_DATA_CST can only appear inside of (array) CONSTRUCTORs within DECL_INITIAL of TREE_STATIC vars, so there shouldn't be a need to expand it. Except that we have an optimization when reading ARRAY_REF from such a CONSTRUCTOR which will try to expand the constructor if it either can be stored by pieces (I think that is just fine) or if it is mostly zeros (which is at least 75% of the initializer zeros). Now the second case is I think in some cases desirable (say 256MB initializer and just 20 elements out of that non-zero, so clear everything and store 20 elements must be fastest and short), but could be really bad as well (say 40GB initializer with 10GB non-zero in it, especially if it doesn't result in the original variable being optimized away). Maybe it would help if expand_constructor and store_constructor* etc. had some optional argument with addresses into the original VAR_DECL so that it could be copying larger amounts of data like larger RAW_DATA_CSTs from there instead of pushing those into new .rodata again. And another problem is that we apparently expand the initializes twice, expand_constructor in store_constructor can expand the stores one and if expand_constructor returns non-NULL, we then expand_expr the CONSTRUCTOR again. to the same location. This patch doesn't address either of those issues, just adds RAW_DATA_CST support to store_constructor for now. For the can_store_by_pieces cases it stores those by pieces using a new callback very similar to string_cst_read_str, for the rest (unfortunately) forces it into a memory and copies from there. 2025-09-10 Jakub Jelinek <[email protected]> PR middle-end/121831 * expr.cc (raw_data_cst_read_str): New function. (store_constructor) <case ARRAY_TYPE>: Handle RAW_DATA_CST. * g++.dg/lto/pr121831_0.C: New test. * g++.dg/lto/pr121831_1.C: New test. (cherry picked from commit 225d13c01d4e231bfabfda1c1c9135e36f55946a)
