gcc/libstdc++-v3
Nathan C. Myers ca566e4c07 Avoid multi-processor bus contention on increment/decrement-and- test of the reference count in the empty-string object...
2003-06-13  Nathan C. Myers <ncm-nospam@cantrip.org>

	Avoid multi-processor bus contention on increment/decrement-and-
	test of the reference count in the empty-string object, by comparing
        addresses first, and never touching the reference count of the empty-
        string object.
	* include/bits/basic_string.h:
	(_S_empty_rep_storage): Move into basic_string<>::_Rep for use by its
	members.
	(_Rep::_S_empty_rep()): New accessor.
	(_Rep::_M_length, _Rep::_M_capacity, _Rep::_M_references): Move to
	a base class _Rep_base.
	(_Rep::_M_dispose, _Rep::_M_refcopy): Check for the empty string.
	(basic_string()): Change to use _M_refdata() in place of _M_refcopy(),
	since no longer must increment its refcount.
	* include/bits/basic_string.tcc:
	(_Rep::_M_destroy, _M_leak_hard): Check for the empty string and
        return immediately.  The former might be unnecessary.  The latter
        prevents begin() and end() from cloning it unnecessarily.
	(_S_construct(_InIterator, _InIterator, const _Alloc&,
	input_iterator_tag), _S_construct(_InIterator, _InIterator,
	const _Alloc&, forward_iterator_tag), _S_construct(size_type, _CharT,
	const _Alloc&)): Change to use _M_refdata() in place of _M_refcopy().
	(_M_mutate): Check for the empty string and treat it as shared.
        This is necessary here because _M_mutate is sometimes called with
        all-zero arguments; in all other uses of _M_is_shared, the test comes
        out right anyhow.

From-SVN: r67912
2003-06-13 20:59:42 +00:00
..
config allocator-inst.cc: Explicitly instantiate. 2003-06-13 05:45:57 +00:00
docs acinclude.m4 (GLIBCPP_ENABLE_CSTDIO): Simplify. 2003-06-12 03:24:16 +00:00
include Avoid multi-processor bus contention on increment/decrement-and- test of the reference count in the empty-string object... 2003-06-13 20:59:42 +00:00
libmath acinclude.m4 (GLIBCPP_ENABLE_CSTDIO): Simplify. 2003-06-12 03:24:16 +00:00
libsupc++ acinclude.m4 (GLIBCPP_ENABLE_CSTDIO): Simplify. 2003-06-12 03:24:16 +00:00
po acinclude.m4 (GLIBCPP_ENABLE_CSTDIO): Simplify. 2003-06-12 03:24:16 +00:00
src allocator-inst.cc: Explicitly instantiate. 2003-06-13 05:45:57 +00:00
testsuite acinclude.m4 (GLIBCPP_ENABLE_CSTDIO): Simplify. 2003-06-12 03:24:16 +00:00
ChangeLog Avoid multi-processor bus contention on increment/decrement-and- test of the reference count in the empty-string object... 2003-06-13 20:59:42 +00:00
ChangeLog-2000 ChangeLog, [...]: Fix spelling errors. 2001-11-23 16:29:02 +00:00
ChangeLog-2001 c_locale_gnu.cc: Same errno fixes as generic. 2002-01-31 02:05:17 +00:00
ChangeLog-2002 tables.html: Finished now. 2003-01-12 02:56:50 +00:00
Makefile.am acinclude.m4 (GLIBCPP_ENABLE_CSTDIO): Simplify. 2003-06-12 03:24:16 +00:00
Makefile.in acinclude.m4 (GLIBCPP_ENABLE_CSTDIO): Simplify. 2003-06-12 03:24:16 +00:00
README 002-03-05 Benjamin Kosnik <bkoz@redhat.com> 2002-03-05 21:14:20 +00:00
acconfig.h acconfig.h (_GLIBCPP_USE_NLS): New symbol. 2003-05-02 02:53:28 +00:00
acinclude.m4 acinclude.m4 (GLIBCPP_ENABLE_CSTDIO): Simplify. 2003-06-12 03:24:16 +00:00
aclocal.m4 acinclude.m4 (GLIBCPP_ENABLE_CSTDIO): Simplify. 2003-06-12 03:24:16 +00:00
config.h.in acinclude.m4 (GLIBCPP_ENABLE_CSTDIO): Simplify. 2003-06-12 03:24:16 +00:00
configure acinclude.m4 (GLIBCPP_ENABLE_CSTDIO): Simplify. 2003-06-12 03:24:16 +00:00
configure.host re PR libstdc++/3066 (configure.in generates bad arguments for cross compiling libraries) 2003-05-23 02:31:07 +00:00
configure.in acinclude.m4 (GLIBCPP_ENABLE_CSTDIO): Simplify. 2003-06-12 03:24:16 +00:00
mkcheck.in [multiple changes] 2003-03-15 04:53:52 +00:00
testsuite_flags.in acinclude.m4 (GLIBCPP_CHECK_PCH): Only set glibcpp_PCHFLAGS if .gch compilation works. 2003-06-05 22:22:12 +00:00

README

file: libstdc++-v3/README

New users may wish to point their web browsers to the file
documentation.html in the 'docs/html' subdirectory.  It contains brief
building instructions and notes on how to configure the library in
interesting ways.

Instructions for configuring and building appear in
docs/html/install.html.

This directory contains the files needed to create an ISO Standard C++
Library.

It has subdirectories:

  docs
    Files in HTML and text format that document usage, quirks of the
    implementation, and contributor checklists.

  include
    All header files for the C++ library are within this directory,
    modulo specific runtime-related files that are in the libsupc++
    directory.

    include/std
      Files meant to be found by #include <name> directives in
      standard-conforming user programs.  

    include/c
      Headers intended to directly include standard C headers. 
      [NB: this can be enabled via --enable-cheaders=c]

    include/c_std
      Headers intended to include standard C headers, and put select
      names into the std:: namespace.
      [NB: this is the default, and is the same as --enable-cheaders=c_std]

    include/c_shadow
      Headers intended to shadow standard C headers provided by an
      underlying OS or C library, and other headers depended on directly
      by C++ headers (e.g. unistd.h).  These are meant to wrap the names
      defined there into the _C_legacy namespace.
      [NB: this can be enabled via --enable-cheaders=c_shadow]

    include/bits
      Files included by standard headers and by other files in
      the bits directory. 

    include/backward
      Headers provided for backward compatibility, such as <iostream.h>.
      They are not used in this library.

    include/ext
      Headers that define extensions to the standard library.  No
      standard header refers to any of them.

  src
    Files that are used in constructing the library, but are not
    installed.

  testsuites/[thread, 17_* to 27_*]
    Test programs are here, and may be used to begin to exercise the 
    library.  Support for "make check" and "make check-install" is
    complete, and runs through all the subdirectories here when this
    command is issued from the build directory.  Please note that
    "make check" requires DejaGNU 1.4 or later to be installed.  Please
    note that "make check-script" calls the script mkcheck, which
    requires bash, and which may need the paths to bash adjusted to
    work properly, as /bin/bash is assumed.

Other subdirectories contain variant versions of certain files
that are meant to be copied or linked by the configure script.
Currently these are:

  config/cpu
  config/os
  config/io
  config/locale

In addition, three subdirectories are convenience libraries:

  libio
    Contains the subset of the GNU libio library needed for
    C++. Currently not used.

  libmath
    Support routines needed for C++ math. Only needed if the
    underlying "C" implementation is non-existent, in particular
    required or optimal long double, long long, and C99 functionality.

  libsupc++
    Contains the runtime library for C++, including exception
    handling and memory allocation and deallocation, RTTI, terminate
    handlers, etc.

Note that glibc also has a bits/ subdirectory.  We will either
need to be careful not to collide with names in its bits/
directory; or rename bits to (e.g.) cppbits/.

In files throughout the system, lines marked with an "XXX" indicate
a bug or incompletely-implemented feature.  Lines marked "XXX MT"
indicate a place that may require attention for multi-thread safety.