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Tom de Vries 0dce428051 [gdb] Don't set initial language if set manually
Initially, gdb sets the language to auto/c:
...
$ gdb -q
(gdb) show language
The current source language is "auto; currently c".
...

And after loading a c++ executable, that changes to auto/c++:
...
(gdb) file a.out
Reading symbols from a.out...
(gdb) show language
The current source language is "auto; currently c++".
...

Now consider setting the language manually to c:
...
$ gdb -q
(gdb) show language
The current source language is "auto; currently c".
(gdb) set language c
(gdb) show language
The current source language is "c".
...
The resulting language is manual/c.

Surprisingly, a subsequent load of the c++ executable:
...
(gdb) file a.out
Reading symbols from a.out...
(gdb) show language
The current source language is "c++".
...
gets us language manual/c++.

Loading the file should get us either:
- auto/c++, or
- manual/c.
That is, either the manual setting should be reset by loading, or the manual
setting should persist.

Fix this in the manual/c fashion. [ Though we could make some gdb setting to
choose one or the other. ]

Build and reg-tested on x86_64-linux.

[ Note: In PR23710 comment 1 a cc1 binary is attached for which gdb is slow when
loading and settting a breakpoint on do_rpo_vn:
...
$ time.sh gdb cc1 -batch -ex "b do_rpo_vn"
Breakpoint 1 at 0xd40e30: do_rpo_vn. (2 locations)
maxmem: 1463496
real: 8.88
user: 8.59
system: 0.35
...

This fix enables a speedup by manually setting the language before
loading, reducing executing time with ~17%, due to not having to load the full
symtab containing main:
...
$ time.sh gdb -iex "set language c++" cc1 -batch -ex "b do_rpo_vn"
Breakpoint 1 at 0xd40e30: do_rpo_vn. (2 locations)
maxmem: 1067308
real: 7.36
user: 7.14
system: 0.28
... ]

gdb/ChangeLog:

2020-02-26  Tom de Vries  <tdevries@suse.de>

	PR gdb/25603
	* symfile.c (set_initial_language): Exit-early if
	language_mode == language_mode_manual.

gdb/testsuite/ChangeLog:

2020-02-26  Tom de Vries  <tdevries@suse.de>

	PR gdb/25603
	* gdb.base/persistent-lang.cc: New test.
	* gdb.base/persistent-lang.exp: New file.
2020-02-26 14:52:00 +01:00
bfd Archive sanity checks 2020-02-26 20:51:33 +10:30
binutils Indent labels 2020-02-26 10:37:25 +10:30
config Merge changes from GCC for the config/ directory 2020-02-19 17:51:24 +00:00
contrib
cpu ubsan: m32c: left shift of negative value 2020-02-03 15:59:08 +10:30
elfcpp Add markers for 2.34 branch to the NEWS files and ChangeLogs. 2020-01-18 13:50:25 +00:00
etc
gas gas gettext warning 2020-02-26 13:04:54 +10:30
gdb [gdb] Don't set initial language if set manually 2020-02-26 14:52:00 +01:00
gdbserver Add a mostlyclean target to gdbserver 2020-02-21 18:30:10 -07:00
gdbsupport Merge changes from GCC for the config/ directory 2020-02-19 17:51:24 +00:00
gnulib gdb: update gnulib import 2020-02-22 20:37:18 -05:00
gold Updated translations for some of the binutils sub-directories. 2020-02-24 14:52:34 +00:00
gprof Updated translations for some of the binutils sub-directories. 2020-02-24 14:52:34 +00:00
include Merge upstream GCC changes for include/ and libiberty/ directories 2020-02-25 17:04:42 +00:00
intl Regen with blessed automake-1.15.1 2020-02-20 13:02:24 +10:30
ld ld: Add PR ld/25593 tests 2020-02-26 03:58:47 -08:00
libctf Add markers for 2.34 branch to the NEWS files and ChangeLogs. 2020-01-18 13:50:25 +00:00
libdecnumber
libiberty Merge upstream GCC changes for include/ and libiberty/ directories 2020-02-25 17:04:42 +00:00
opcodes Indent labels 2020-02-26 10:37:25 +10:30
readline
sim sim/aarch64: Fix register ordering bug in blr (PR sim/25318) 2020-02-06 22:50:26 +00:00
texinfo
zlib Merge changes from GCC for the config/ directory 2020-02-19 17:51:24 +00:00
.cvsignore
.gitattributes
.gitignore
ar-lib
ChangeLog Fix gdbserver-without-gdb build 2020-02-17 10:03:15 -07:00
compile
config-ml.in
config.guess Update top level config files with copies from the official repository. 2020-01-18 13:43:19 +00:00
config.rpath
config.sub Update top level config files with copies from the official repository. 2020-01-18 13:43:19 +00:00
configure Fix gdbserver-without-gdb build 2020-02-17 10:03:15 -07:00
configure.ac Fix gdbserver-without-gdb build 2020-02-17 10:03:15 -07:00
COPYING
COPYING3
COPYING3.LIB
COPYING.LIB
COPYING.LIBGLOSS
COPYING.NEWLIB
depcomp
djunpack.bat
install-sh
libtool.m4
lt~obsolete.m4
ltgcc.m4
ltmain.sh
ltoptions.m4
ltsugar.m4
ltversion.m4
MAINTAINERS Move gdbserver to top level 2020-02-07 08:42:25 -07:00
Makefile.def Change gdbserver to use existing gnulib and libiberty 2020-02-14 14:34:20 -07:00
Makefile.in Change gdbserver to use existing gnulib and libiberty 2020-02-14 14:34:20 -07:00
Makefile.tpl
makefile.vms
missing
mkdep
mkinstalldirs
move-if-change
multilib.am
README
README-maintainer-mode
setup.com
src-release.sh Move gdbserver to top level 2020-02-07 08:42:25 -07:00
symlink-tree
test-driver
ylwrap

		   README for GNU development tools

This directory contains various GNU compilers, assemblers, linkers, 
debuggers, etc., plus their support routines, definitions, and documentation.

If you are receiving this as part of a GDB release, see the file gdb/README.
If with a binutils release, see binutils/README;  if with a libg++ release,
see libg++/README, etc.  That'll give you info about this
package -- supported targets, how to use it, how to report bugs, etc.

It is now possible to automatically configure and build a variety of
tools with one command.  To build all of the tools contained herein,
run the ``configure'' script here, e.g.:

	./configure 
	make

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then do:
	make install

(If the configure script can't determine your type of computer, give it
the name as an argument, for instance ``./configure sun4''.  You can
use the script ``config.sub'' to test whether a name is recognized; if
it is, config.sub translates it to a triplet specifying CPU, vendor,
and OS.)

If you have more than one compiler on your system, it is often best to
explicitly set CC in the environment before running configure, and to
also set CC when running make.  For example (assuming sh/bash/ksh):

	CC=gcc ./configure
	make

A similar example using csh:

	setenv CC gcc
	./configure
	make

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the Free Software Foundation, Inc.  See the file COPYING or
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on where and how to report problems.