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When CTF linking is done, the linker has to track the association between types in the inputs and types in the outputs. The deduplicator does this via the cd_output_emission_hashes, which maps from hashes of types (valid in both the input and output) to the IDs of types in the specific dict in which the cd_emission_hashes is held. However, the nondeduplicating linker and ctf_add_type used a different mechanism, a dedicated hashtab stored in the ctf_link_type_mapping, populated via ctf_add_type_mapping and queried via the ctf_type_mapping function. To allow the same functions to be used for variable and symbol population in both the deduplicating and nondeduplicating linker, the deduplicator carefully transferred all its input->output mappings into this hashtab before returning. This is *expensive*. The number of entries in this hashtab scales as the number of input types, and unlike the hashing machinery the type mapping machinery (the only other thing which scales that way) has not been much optimized. Now the nondeduplicating linker is gone, we can throw this out, move the existing type mapping machinery to ctf-create.c and dedicate it to ctf_add_type alone, and add a new function ctf_dedup_type_mapping which uses the deduplicator's built-in knowledge of type mappings directly, without requiring an expensive repopulation phase. This speeds up a test link of nouveau.ko (a good worst-case candidate with a lot of types in each of a lot of input files) from 9.11s to 7.15s in my testing, a speedup of over 20%. libctf/ChangeLog 2021-03-02 Nick Alcock <nick.alcock@oracle.com> * ctf-impl.h (ctf_dict_t) <ctf_link_type_mapping>: No longer used by the nondeduplicating linker. (ctf_add_type_mapping): Removed, now static. (ctf_type_mapping): Likewise. (ctf_dedup_type_mapping): New. (ctf_dedup_t) <cd_input_nums>: New. * ctf-dedup.c (ctf_dedup_init): Populate it. (ctf_dedup_fini): Free it again. Emphasise that this has to be the last thing called. (ctf_dedup): Populate it. (ctf_dedup_populate_type_mapping): Removed. (ctf_dedup_populate_type_mappings): Likewise. (ctf_dedup_emit): No longer call it. No longer call ctf_dedup_fini either. (ctf_dedup_type_mapping): New. * ctf-link.c (ctf_unnamed_cuname): New. (ctf_create_per_cu): Arguments must be non-null now. (ctf_in_member_cb_arg): Removed. (ctf_link): No longer populate it. No longer discard the mapping table. (ctf_link_deduplicating_one_symtypetab): Use ctf_dedup_type_mapping, not ctf_type_mapping. Use ctf_unnamed_cuname. (ctf_link_one_variable): Likewise. Pass in args individually: no longer a ctf_variable_iter callback. (empty_link_type_mapping): Removed. (ctf_link_deduplicating_variables): Use ctf_variable_next, not ctf_variable_iter. No longer pack arguments to ctf_link_one_variable into a struct. (ctf_link_deduplicating_per_cu): Call ctf_dedup_fini once all link phases are done. (ctf_link_deduplicating): Likewise. (ctf_link_intern_extern_string): Improve comment. (ctf_add_type_mapping): Migrate... (ctf_type_mapping): ... these functions... * ctf-create.c (ctf_add_type_mapping): ... here... (ctf_type_mapping): ... and make static, for the sole use of ctf_add_type. |
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| .. | ||
| testsuite | ||
| .gitignore | ||
| aclocal.m4 | ||
| ChangeLog | ||
| ChangeLog-2020 | ||
| config.h.in | ||
| configure | ||
| configure.ac | ||
| ctf-archive.c | ||
| ctf-create.c | ||
| ctf-decl.c | ||
| ctf-decls.h | ||
| ctf-dedup.c | ||
| ctf-dump.c | ||
| ctf-endian.h | ||
| ctf-error.c | ||
| ctf-hash.c | ||
| ctf-impl.h | ||
| ctf-inlines.h | ||
| ctf-intl.h | ||
| ctf-labels.c | ||
| ctf-link.c | ||
| ctf-lookup.c | ||
| ctf-open-bfd.c | ||
| ctf-open.c | ||
| ctf-qsort_r.c | ||
| ctf-sha1.c | ||
| ctf-sha1.h | ||
| ctf-string.c | ||
| ctf-subr.c | ||
| ctf-types.c | ||
| ctf-util.c | ||
| elf.h | ||
| libctf.ver | ||
| Makefile.am | ||
| Makefile.in | ||
| NEWS | ||
| swap.h | ||