From 18989b3c5642e2ba533e02737797dcf06134229b Mon Sep 17 00:00:00 2001 From: Andrew Burgess Date: Mon, 13 Apr 2015 16:31:21 +0100 Subject: [PATCH] gdb: New maintenance command to disable bfd sharing. In some rare maintainer cases it is desirable to be able to disable bfd sharing. This patch adds new commands maintenance set/show commands for bfd-sharing, allowing gdb's bfd cache to be turned off. gdb/ChangeLog: * gdb_bfd.c (bfd_sharing): New variable. (show_bfd_sharing): New function. (gdb_bfd_open): Check bfd_sharing variable. (_initialize_gdb_bfd): Add new set/show command. * NEWS: Mention new command. gdb/doc/ChangeLog: * gdb.texinfo (Maintenance Commands): Move documentation of "main info bfds" to... (File Caching): A New section. Outline bfd caching, and add new description for "main set/show bfd-sharing". --- gdb/ChangeLog | 8 ++++++++ gdb/NEWS | 4 ++++ gdb/doc/ChangeLog | 7 +++++++ gdb/doc/gdb.texinfo | 35 ++++++++++++++++++++++++++++++----- gdb/gdb_bfd.c | 34 ++++++++++++++++++++++++++++++---- 5 files changed, 79 insertions(+), 9 deletions(-) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 8967bc571a..b2860488e2 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,11 @@ +2015-08-18 Andrew Burgess + + * gdb_bfd.c (bfd_sharing): New variable. + (show_bfd_sharing): New function. + (gdb_bfd_open): Check bfd_sharing variable. + (_initialize_gdb_bfd): Add new set/show command. + * NEWS: Mention new command. + 2015-08-18 Andrew Burgess * gdb_bfd.c (struct gdb_bfd_data): Add size, inode, and device id diff --git a/gdb/NEWS b/gdb/NEWS index 174924f119..7a24e23442 100644 --- a/gdb/NEWS +++ b/gdb/NEWS @@ -20,6 +20,10 @@ maint show target-non-stop "set non-stop" is "off". The default is "auto", meaning non-stop mode is enabled if supported by the target. +maint set bfd-sharing +maint show bfd-sharing + Control the reuse of bfd objects. + * The "disassemble" command accepts a new modifier: /s. It prints mixed source+disassembly like /m with two differences: - disassembled instructions are now printed in program order, and diff --git a/gdb/doc/ChangeLog b/gdb/doc/ChangeLog index 806dac4b4f..7716917d7d 100644 --- a/gdb/doc/ChangeLog +++ b/gdb/doc/ChangeLog @@ -1,3 +1,10 @@ +2015-08-18 Andrew Burgess + + * gdb.texinfo (Maintenance Commands): Move documentation of "main + info bfds" to... + (File Caching): A New section. Outline bfd caching, and add new + description for "main set/show bfd-sharing". + 2015-08-14 Doug Evans * gdb.texinfo (Machine Code): Update docs for mixed source/assembly diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo index c876ed6266..bd6b8e4a42 100644 --- a/gdb/doc/gdb.texinfo +++ b/gdb/doc/gdb.texinfo @@ -18343,6 +18343,36 @@ Set whether a source file may have multiple base names. Show whether a source file may have multiple base names. @end table +@node File Caching +@section File Caching +@cindex caching of opened files +@cindex caching of bfd objects + +To speed up file loading, and reduce memory usage, @value{GDBN} will +reuse the @code{bfd} objects used to track open files. @xref{Top, , +BFD, bfd, The Binary File Descriptor Library}. The following commands +allow visibility and control of the caching behavior. + +@table @code +@kindex maint info bfds +@item maint info bfds +This prints information about each @code{bfd} object that is known to +@value{GDBN}. + +@kindex maint set bfd-sharing +@kindex maint show bfd-sharing +@kindex bfd caching +@item maint set bfd-sharing +@item maint show bfd-sharing +Control whether @code{bfd} objects can be shared. When sharing is +enabled @value{GDBN} reuses already open @code{bfd} objects rather +than reopening the same file. Turning sharing off does not cause +already shared @code{bfd} objects to be unshared, but all future files +that are opened will create a new @code{bfd} object. Similarly, +re-enabling sharing does not cause multiple existing @code{bfd} +objects to be collapsed into a single shared @code{bfd} object. +@end table + @node Separate Debug Files @section Debugging Information in Separate Files @cindex separate debugging information files @@ -34162,11 +34192,6 @@ Shared library events. @end table -@kindex maint info bfds -@item maint info bfds -This prints information about each @code{bfd} object that is known to -@value{GDBN}. @xref{Top, , BFD, bfd, The Binary File Descriptor Library}. - @kindex maint info btrace @item maint info btrace Pint information about raw branch tracing data. diff --git a/gdb/gdb_bfd.c b/gdb/gdb_bfd.c index ee2953117b..847177524c 100644 --- a/gdb/gdb_bfd.c +++ b/gdb/gdb_bfd.c @@ -111,6 +111,17 @@ DEFINE_REGISTRY (bfd, GDB_BFD_DATA_ACCESSOR) static htab_t gdb_bfd_cache; +/* When true gdb will reuse an existing bfd object if the filename, + modification time, and file size all match. */ + +static int bfd_sharing = 1; +static void +show_bfd_sharing (struct ui_file *file, int from_tty, + struct cmd_list_element *c, const char *value) +{ + fprintf_filtered (file, _("BFD sharing is %s.\n"), value); +} + /* The type of an object being looked up in gdb_bfd_cache. We use htab's capability of storing one kind of object (BFD in this case) and using a different sort of object for searching. */ @@ -394,7 +405,7 @@ gdb_bfd_open (const char *name, const char *target, int fd) opening the BFD may fail; and this would violate hashtab invariants. */ abfd = htab_find_with_hash (gdb_bfd_cache, &search, hash); - if (abfd != NULL) + if (bfd_sharing && abfd != NULL) { close (fd); gdb_bfd_ref (abfd); @@ -405,9 +416,12 @@ gdb_bfd_open (const char *name, const char *target, int fd) if (abfd == NULL) return NULL; - slot = htab_find_slot_with_hash (gdb_bfd_cache, &search, hash, INSERT); - gdb_assert (!*slot); - *slot = abfd; + if (bfd_sharing) + { + slot = htab_find_slot_with_hash (gdb_bfd_cache, &search, hash, INSERT); + gdb_assert (!*slot); + *slot = abfd; + } gdb_bfd_ref (abfd); return abfd; @@ -942,4 +956,16 @@ _initialize_gdb_bfd (void) add_cmd ("bfds", class_maintenance, maintenance_info_bfds, _("\ List the BFDs that are currently open."), &maintenanceinfolist); + + add_setshow_boolean_cmd ("bfd-sharing", no_class, + &bfd_sharing, _("\ +Set whether gdb will share bfds that appear to be the same file."), _("\ +Show whether gdb will share bfds that appear to be the same file."), _("\ +When enabled gdb will reuse existing bfds rather than reopening the\n\ +same file. To decide if two files are the same then gdb compares the\n\ +filename, file size, file modification time, and file inode."), + NULL, + &show_bfd_sharing, + &maintenance_set_cmdlist, + &maintenance_show_cmdlist); } -- 2.34.1