https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107635
--- Comment #3 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Andre Vehreschild <ve...@gcc.gnu.org>: https://gcc.gnu.org/g:586477d67bf2e320e8ec41f82b194259c1dcc43a commit r15-6415-g586477d67bf2e320e8ec41f82b194259c1dcc43a Author: Andre Vehreschild <ve...@gcc.gnu.org> Date: Fri Dec 6 08:57:34 2024 +0100 Fortran: Replace getting of coarray data with accessor-based version. [PR107635] Getting coarray data from remote images was slow, inefficient and did not work for object files that where not compiled with coarray support for derived types with allocatable/pointer components. The old approach emulated accessing data through a whole structure ref, which was error prone for corner cases. Furthermore was did it have a runtime complexity of O(N), where N is the number of allocatable/pointer components and descriptors involved. Each of those needed communication twice. The new approach creates a routine for each access into a coarray object putting all required operations there. Looking a tree-dump one will see those small routines. But this time it is just compiled fortran with all the knowledge of the compiler of bounds and so on. New paradigms will be available out of the box. Furthermore is the complexity of the communication reduced to be O(1). E.g. the mpi implementation sends one message for the parameters of the access and one message back with the results without caring about the number of allocatable/pointer/descriptor components in the access. Identification of access routines is done be adding them to a hash map, where the hash is the same on all images. Translating the hash to an index, which is the same on all images again, allows for fast calls of the access routines. Resolving the hash to an index is cached at runtime, preventing additional hash map lookups. A hashmap was use because not all processor OS combinations may use the same address for the access routine. gcc/fortran/ChangeLog: PR fortran/107635 * gfortran.h (gfc_add_caf_accessor): New function. * gfortran.texi: Document new API routines. * resolve.cc (get_arrayspec_from_expr): Synthesize the arrayspec resulting from an expression, i.e. not only the rank, but also the bounds. (remove_coarray_from_derived_type): Remove coarray ref from a derived type to access it in access routine. (convert_coarray_class_to_derived_type): Same but for classes. The result is a derived type. (split_expr_at_caf_ref): Split an expression at the coarray reference to move the reference after the coarray ref into the access routine. (check_add_new_component): Helper to add variables as components to derived type transfered to the access routine. (create_get_parameter_type): Create the derived type to transfer addressing data to the access routine. (create_get_callback): Create the access routine. (add_caf_get_intrinsic): Use access routine instead of old caf_get. * trans-decl.cc (gfc_build_builtin_function_decls): Register new API routines. (gfc_create_module_variable): Use renamed flag. (gfc_emit_parameter_debug_info): (struct caf_accessor): Linked list of hash-access routine pairs. (gfc_add_caf_accessor): Add a hash-access routine pair to above linked list. (create_caf_accessor_register): Add all registered hash-access routine pairs to the current caf_init. (generate_coarray_init): Use routine above. (gfc_generate_module_vars): Use renamed flag. (generate_local_decl): Same. (gfc_generate_function_code): Same. (gfc_process_block_locals): Same. * trans-intrinsic.cc (conv_shape_to_cst): Build the product of a shape. (gfc_conv_intrinsic_caf_get): Create call to access routine. (conv_caf_send): Adapt to caf_get using less arguments. (gfc_conv_intrinsic_function): Same. * trans.cc (gfc_trans_force_lval): Helper to ensure that an expression can be used as an lvalue-ref. * trans.h (gfc_trans_force_lval): See above. libgfortran/ChangeLog: * caf/libcaf.h (_gfortran_caf_register_accessor): New function to register access routines at runtime. (_gfortran_caf_register_accessors_finish): New function to finish registration of access routine and sort hash map. (_gfortran_caf_get_remote_function_index): New function to convert an hash to an index. (_gfortran_caf_get_by_ct): New function to get data from a remote image using the access routine given by an index. * caf/single.c (struct accessor_hash_t): Hashmap type. (_gfortran_caf_send): Fixed formatting. (_gfortran_caf_register_accessor): Register a hash accessor routine. (hash_compare): Compare two hashes for sort() and bsearch(). (_gfortran_caf_register_accessors_finish): Sort the hashmap to allow bsearch()'s quick lookup. (_gfortran_caf_get_remote_function_index): Map a hash to an index. (_gfortran_caf_get_by_ct): Get data from a remote image using the index provided by get_remote_function_index(). gcc/testsuite/ChangeLog: * gfortran.dg/coarray_atomic_5.f90: Adapted to look for get_by_ct. * gfortran.dg/coarray_lib_comm_1.f90: Same. * gfortran.dg/coarray_stat_function.f90: Same.
