On Wed, Aug 21, 2024 at 4:25 PM H.J. Lu <hjl.to...@gmail.com> wrote:
>
> This hook allows the BFD linker plugin to distinguish calls to
> claim_file_handler that know the object is being used by the linker
> (from ldmain.c:add_archive_element), from calls that don't know it's
> being used by the linker (from elf_link_is_defined_archive_symbol); in
> the latter case, the plugin should avoid including the unused LTO archive
> members in link output. To get the proper support for archives with LTO
> common symbols, the linker fix
OK.
Thanks,
Richard.
> commit a6f8fe0a9e9cbe871652e46ba7c22d5e9fb86208
> Author: H.J. Lu <hjl.to...@gmail.com>
> Date: Wed Aug 14 20:50:02 2024 -0700
>
> lto: Don't include unused LTO archive members in output
>
> is required.
>
> PR lto/116361
> * lto-plugin.c (claim_file_handler_v2): Rename claimed to
> can_be_claimed. Include the LTO object only if it is known to
> be included in link output.
>
> Signed-off-by: H.J. Lu <hjl.to...@gmail.com>
> ---
> lto-plugin/lto-plugin.c | 53 ++++++++++++++++++++++++-----------------
> 1 file changed, 31 insertions(+), 22 deletions(-)
>
> diff --git a/lto-plugin/lto-plugin.c b/lto-plugin/lto-plugin.c
> index 152648338b9..61b0de62f52 100644
> --- a/lto-plugin/lto-plugin.c
> +++ b/lto-plugin/lto-plugin.c
> @@ -1191,16 +1191,19 @@ process_offload_section (void *data, const char
> *name, off_t offset, off_t len)
> return 1;
> }
>
> -/* Callback used by a linker to check if the plugin will claim FILE. Writes
> - the result in CLAIMED. If KNOWN_USED, the object is known by the linker
> - to be used, or an older API version is in use that does not provide that
> - information; otherwise, the linker is only determining whether this is
> - a plugin object and it should not be registered as having offload data if
> - not claimed by the plugin. */
> +/* Callback used by a linker to check if the plugin can claim FILE.
> + Writes the result in CAN_BE_CLAIMED. If KNOWN_USED != 0, the object
> + is known by the linker to be included in link output, or an older API
> + version is in use that does not provide that information. Otherwise,
> + the linker is only determining whether this is a plugin object and
> + only the symbol table is needed by the linker. In this case, the
> + object should not be included in link output and this function will
> + be called by the linker again with KNOWN_USED != 0 after the linker
> + decides the object should be included in link output. */
>
> static enum ld_plugin_status
> -claim_file_handler_v2 (const struct ld_plugin_input_file *file, int *claimed,
> - int known_used)
> +claim_file_handler_v2 (const struct ld_plugin_input_file *file,
> + int *can_be_claimed, int known_used)
> {
> enum ld_plugin_status status;
> struct plugin_objfile obj;
> @@ -1229,7 +1232,7 @@ claim_file_handler_v2 (const struct
> ld_plugin_input_file *file, int *claimed,
> }
> lto_file.handle = file->handle;
>
> - *claimed = 0;
> + *can_be_claimed = 0;
> obj.file = file;
> obj.found = 0;
> obj.offload = false;
> @@ -1286,15 +1289,19 @@ claim_file_handler_v2 (const struct
> ld_plugin_input_file *file, int *claimed,
> lto_file.symtab.syms);
> check (status == LDPS_OK, LDPL_FATAL, "could not add symbols");
>
> - LOCK_SECTION;
> - num_claimed_files++;
> - claimed_files =
> - xrealloc (claimed_files,
> - num_claimed_files * sizeof (struct plugin_file_info));
> - claimed_files[num_claimed_files - 1] = lto_file;
> - UNLOCK_SECTION;
> + /* Include it only if it is known to be used for link output. */
> + if (known_used)
> + {
> + LOCK_SECTION;
> + num_claimed_files++;
> + claimed_files =
> + xrealloc (claimed_files,
> + num_claimed_files * sizeof (struct plugin_file_info));
> + claimed_files[num_claimed_files - 1] = lto_file;
> + UNLOCK_SECTION;
> + }
>
> - *claimed = 1;
> + *can_be_claimed = 1;
> }
>
> LOCK_SECTION;
> @@ -1310,10 +1317,10 @@ claim_file_handler_v2 (const struct
> ld_plugin_input_file *file, int *claimed,
> /* If this is an LTO file without offload, and it is the first LTO file,
> save
> the pointer to the last offload file in the list. Further offload LTO
> files will be inserted after it, if any. */
> - if (*claimed && !obj.offload && offload_files_last_lto == NULL)
> + if (*can_be_claimed && !obj.offload && offload_files_last_lto == NULL)
> offload_files_last_lto = offload_files_last;
>
> - if (obj.offload && (known_used || obj.found > 0))
> + if (obj.offload && known_used && obj.found > 0)
> {
> /* Add file to the list. The order must be exactly the same as the
> final
> order after recompilation and linking, otherwise host and target
> tables
> @@ -1324,7 +1331,9 @@ claim_file_handler_v2 (const struct
> ld_plugin_input_file *file, int *claimed,
> ofld->name = lto_file.name;
> ofld->next = NULL;
>
> - if (*claimed && offload_files_last_lto == NULL && file->offset != 0
> + if (*can_be_claimed
> + && offload_files_last_lto == NULL
> + && file->offset != 0
> && gold_version == -1)
> {
> /* ld only: insert first LTO file from the archive after the last
> real
> @@ -1341,7 +1350,7 @@ claim_file_handler_v2 (const struct
> ld_plugin_input_file *file, int *claimed,
> offload_files->next = ofld;
> }
> }
> - else if (*claimed && offload_files_last_lto != NULL)
> + else if (*can_be_claimed && offload_files_last_lto != NULL)
> {
> /* Insert LTO file after the last LTO file in the list. */
> ofld->next = offload_files_last_lto->next;
> @@ -1356,7 +1365,7 @@ claim_file_handler_v2 (const struct
> ld_plugin_input_file *file, int *claimed,
> offload_files_last = ofld;
> if (file->offset == 0)
> offload_files_last_obj = ofld;
> - if (*claimed)
> + if (*can_be_claimed)
> offload_files_last_lto = ofld;
> num_offload_files++;
> }
> --
> 2.46.0
>
