There are many linker input files in LLVM debug build with huge string
sections. All these string sections can be treated as read-only. But
linker copies all of them into memory which consumes huge amount of
memory and slows down linker significantly.
Add _bfd_mmap_readonly_persistent and _bfd_mmap_readonly_temporary to
mmap in reado-only sections with size >= 4 * page size.
NB: All string sections in valid ELF inputs must be null terminated.
There is no need to terminate it again and string sections are mmapped
as read-only.
* bfd.c (bfd_mmapped_entry): New.
(bfd_mmapped): Likewise.
(bfd): Add mmapped.
* bfdwin.c (bfd_get_file_window): Use _bfd_pagesize.
* cache.c (cache_bmmap): Remove pagesize_m1 and use pagesize_m1
instead.
* elf.c (bfd_elf_get_str_section): Call
_bfd_mmap_readonly_persistent instead of _bfd_alloc_and_read.
Don't terminate the string section again.
(get_hash_table_data): Call _bfd_mmap_readonly_temporary and
_bfd_munmap_readonly_temporary instead of _bfd_malloc_and_read
and free.
(_bfd_elf_get_dynamic_symbols): Call _bfd_mmap_readonly_persistent
instead of _bfd_alloc_and_read. Don't terminate the string
section again. Call _bfd_mmap_readonly_temporary and
_bfd_munmap_readonly_temporary instead of _bfd_malloc_and_read
and free.
(_bfd_elf_slurp_version_tables): Call _bfd_mmap_readonly_temporary
and _bfd_munmap_readonly_temporary instead of _bfd_malloc_and_read
and free.
* elflink.c (bfd_elf_link_record_dynamic_symbol): Use bfd_malloc
to get the unversioned symbol.
* libbfd-in.h (_bfd_pagesize): New.
(_bfd_pagesize_m1): Likewise.
(_bfd_minimum_mmap_size): Likewise.
(_bfd_mmap_readonly_persistent): Likewise.
(_bfd_mmap_readonly_temporary): Likewise.
(_bfd_munmap_readonly_temporary): Likewise.
* libbfd.c
(bfd_allocate_mmapped_page): New.
(_bfd_mmap_readonly_temporary): Likewise.
(_bfd_munmap_readonly_temporary): Likewise.
(_bfd_mmap_readonly_persistent): Likewise.
(_bfd_pagesize): Likewise.
(_bfd_pagesize_m1): Likewise.
(_bfd_minimum_mmap_size): Likewise.
(bfd_init_pagesize): Likewise.
* lynx-core.c (lynx_core_file_p): Use _bfd_pagesize.
* opncls.c (_bfd_delete_bfd): Munmap tracked mmapped memories.
* sysdep.h (MAP_ANONYMOUS): New. Define if undefined.
* bfd-in2.h: Regenerated.
* libbfd.h: Likewise.