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gcc: Add support for building libstdc++ with alternate libc

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This adds another mode to do_gcc_core_backend that builds libstdc++
against an alternate libc implementation.

Signed-off-by: Keith Packard <keithp@keithp.com>
This commit is contained in:
Keith Packard 2021-01-07 17:25:32 -08:00
parent 74949b1d35
commit 43f5079382
3 changed files with 353 additions and 8 deletions
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2
config/cc/gcc.in
View File

@ -1,6 +1,6 @@
# GCC options
## select CC_SUPPORT_CXX if !LIBC_NONE
## select CC_SUPPORT_CXX
## select CC_SUPPORT_FORTRAN
## select CC_SUPPORT_JAVA if !GCC_7_or_later && OBSOLETE
## select CC_SUPPORT_ADA

275
packages/gcc/10.2.0/0019-libstdcxx-pure-stdio.patch vendored Normal file
View File

@ -0,0 +1,275 @@
From ce06ad6901b1d24abb90d6baba5fe01c750ffb4e Mon Sep 17 00:00:00 2001
From: Keith Packard <keithp@keithp.com>
Date: Tue, 15 Dec 2020 17:39:24 +0000
Subject: [PATCH] libstdc++: Support libc with stdio-only I/O in libstdc++
The current libstdc++ basic_file_stdio.cc code assumes a POSIX API
underneath the stdio implementation provided by the host libc. This
means that the host must provide a fairly broad POSIX file API,
including read, write, open, close, lseek and ioctl.
This patch changes basic_file_stdio.cc to only use basic ANSI-C stdio
functions, allowing it to be used with libc implementations like
picolibc which may not have a POSIX operating system underneath.
This is enabled by a new --enable-cstdio=stdio_pure configure option.
Aided-by: Jonathan Wakely <jwakely@redhat.com>
Signed-off-by: Keith Packard <keithp@keithp.com>
libstdc++-v3/ChangeLog:
* acinclude.m4 (GLIBCXX_ENABLE_CSTDIO): Allow "stdio_pure"
option and define _GLIBCXX_USE_PURE_STDIO when it is used. Also
add "stdio_posix" option as an alias for "stdio".
* config/io/basic_file_stdio.cc [_GLIBCXX_USE_PURE_STDIO]: Only
use defined stdio entry points for all I/O operations, without
direct calls to underlying POSIX functions.
* config.h.in: Regenerate.
* configure: Regenerate.
---
libstdc++-v3/acinclude.m4 | 20 ++++++----
libstdc++-v3/config.h.in | 3 ++
libstdc++-v3/config/io/basic_file_stdio.cc | 46 +++++++++++++++++++---
libstdc++-v3/configure | 17 +++++---
4 files changed, 69 insertions(+), 17 deletions(-)
diff --git a/libstdc++-v3/acinclude.m4 b/libstdc++-v3/acinclude.m4
index ee5e0336f2c..9604533c306 100644
--- a/libstdc++-v3/acinclude.m4
+++ b/libstdc++-v3/acinclude.m4
@@ -2826,24 +2826,30 @@ AC_DEFUN([GLIBCXX_ENABLE_PARALLEL], [
dnl
-dnl Check for which I/O library to use: stdio, or something specific.
+dnl Check for which I/O library to use: stdio and POSIX, or pure stdio.
dnl
-dnl Default is stdio.
+dnl Default is stdio_posix.
dnl
AC_DEFUN([GLIBCXX_ENABLE_CSTDIO], [
AC_MSG_CHECKING([for underlying I/O to use])
GLIBCXX_ENABLE(cstdio,stdio,[[[=PACKAGE]]],
- [use target-specific I/O package], [permit stdio])
+ [use target-specific I/O package], [permit stdio|stdio_posix|stdio_pure])
- # Now that libio has been removed, you can have any color you want as long
- # as it's black. This is one big no-op until other packages are added, but
- # showing the framework never hurts.
+ # The only available I/O model is based on stdio, via basic_file_stdio.
+ # The default "stdio" is actually "stdio + POSIX" because it uses fdopen(3)
+ # to get a file descriptor and then uses read(3) and write(3) with it.
+ # The "stdio_pure" model doesn't use fdopen and only uses FILE* for I/O.
case ${enable_cstdio} in
- stdio)
+ stdio*)
CSTDIO_H=config/io/c_io_stdio.h
BASIC_FILE_H=config/io/basic_file_stdio.h
BASIC_FILE_CC=config/io/basic_file_stdio.cc
AC_MSG_RESULT(stdio)
+
+ if test "x$enable_cstdio" = "xstdio_pure" ; then
+ AC_DEFINE(_GLIBCXX_USE_STDIO_PURE, 1,
+ [Define to restrict std::__basic_file<> to stdio APIs.])
+ fi
;;
esac
diff --git a/libstdc++-v3/config.h.in b/libstdc++-v3/config.h.in
index 8940e0c7acd..eabcf18b52b 100644
--- a/libstdc++-v3/config.h.in
+++ b/libstdc++-v3/config.h.in
@@ -1031,6 +1031,9 @@
/* Define if sendfile is available in <sys/sendfile.h>. */
#undef _GLIBCXX_USE_SENDFILE
+/* Define to restrict std::__basic_file<> to stdio APIs. */
+#undef _GLIBCXX_USE_STDIO_PURE
+
/* Define if struct stat has timespec members. */
#undef _GLIBCXX_USE_ST_MTIM
diff --git a/libstdc++-v3/config/io/basic_file_stdio.cc b/libstdc++-v3/config/io/basic_file_stdio.cc
index ba830fb9e97..eedffb017b6 100644
--- a/libstdc++-v3/config/io/basic_file_stdio.cc
+++ b/libstdc++-v3/config/io/basic_file_stdio.cc
@@ -111,13 +111,21 @@ namespace
// Wrapper handling partial write.
static std::streamsize
+#ifdef _GLIBCXX_USE_STDIO_PURE
+ xwrite(FILE *__file, const char* __s, std::streamsize __n)
+#else
xwrite(int __fd, const char* __s, std::streamsize __n)
+#endif
{
std::streamsize __nleft = __n;
for (;;)
{
+#ifdef _GLIBCXX_USE_STDIO_PURE
+ const std::streamsize __ret = fwrite(__file, 1, __nleft, __file);
+#else
const std::streamsize __ret = write(__fd, __s, __nleft);
+#endif
if (__ret == -1L && errno == EINTR)
continue;
if (__ret == -1L)
@@ -133,7 +141,7 @@ namespace
return __n - __nleft;
}
-#ifdef _GLIBCXX_HAVE_WRITEV
+#if defined(_GLIBCXX_HAVE_WRITEV) && !defined(_GLIBCXX_USE_STDIO_PURE)
// Wrapper handling partial writev.
static std::streamsize
xwritev(int __fd, const char* __s1, std::streamsize __n1,
@@ -286,9 +294,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
__basic_file<char>::is_open() const throw ()
{ return _M_cfile != 0; }
+#ifndef _GLIBCCXX_USE_STDIO_PURE
int
__basic_file<char>::fd() throw ()
{ return fileno(_M_cfile); }
+#endif
__c_file*
__basic_file<char>::file() throw ()
@@ -315,28 +325,46 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{
streamsize __ret;
do
+#ifdef _GLIBCXX_USE_STDIO_PURE
+ __ret = fread(__s, 1, __n, this->file());
+#else
__ret = read(this->fd(), __s, __n);
+#endif
while (__ret == -1L && errno == EINTR);
return __ret;
}
streamsize
__basic_file<char>::xsputn(const char* __s, streamsize __n)
- { return xwrite(this->fd(), __s, __n); }
+ {
+#ifdef _GLIBCXX_USE_STDIO_PURE
+ return xwrite(this->file(), __s, __n);
+#else
+ return xwrite(this->fd(), __s, __n);
+#endif
+ }
streamsize
__basic_file<char>::xsputn_2(const char* __s1, streamsize __n1,
const char* __s2, streamsize __n2)
{
streamsize __ret = 0;
-#ifdef _GLIBCXX_HAVE_WRITEV
+#if defined(_GLIBCXX_HAVE_WRITEV) && !defined(_GLIBCXX_USE_STDIO_PURE)
__ret = xwritev(this->fd(), __s1, __n1, __s2, __n2);
#else
if (__n1)
+#ifdef _GLIBCXX_USE_STDIO_PURE
+ __ret = xwrite(this->file(), __s1, __n1);
+#else
__ret = xwrite(this->fd(), __s1, __n1);
+#endif
if (__ret == __n1)
+#ifdef _GLIBCXX_USE_STDIO_PURE
+ __ret += xwrite(this->file(), __s2, __n2);
+#else
__ret += xwrite(this->fd(), __s2, __n2);
+#endif
#endif
return __ret;
}
@@ -350,7 +378,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
if (__off > numeric_limits<off_t>::max()
|| __off < numeric_limits<off_t>::min())
return -1L;
+#ifdef _GLIBCXX_USE_STDIO_PURE
+ return fseek(this->file(), __off, __way);
+#else
return lseek(this->fd(), __off, __way);
+#endif
#endif
}
@@ -361,7 +393,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
streamsize
__basic_file<char>::showmanyc()
{
-#ifndef _GLIBCXX_NO_IOCTL
+#if !defined(_GLIBCXX_NO_IOCTL) && !defined(_GLIBCXX_USE_STDIO_PURE)
#ifdef FIONREAD
// Pipes and sockets.
int __num = 0;
@@ -371,7 +403,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
#endif
#endif
-#ifdef _GLIBCXX_HAVE_POLL
+#if defined(_GLIBCXX_HAVE_POLL) && !defined(_GLIBCXX_USE_STDIO_PURE)
// Cheap test.
struct pollfd __pfd[1];
__pfd[0].fd = this->fd();
@@ -395,8 +427,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
struct stat __buffer;
const int __err = fstat(this->fd(), &__buffer);
if (!__err && _GLIBCXX_ISREG(__buffer.st_mode))
+#ifdef _GLIBCXX_USE_STDIO_PURE
+ return __buffer.st_size - fseek(this->file(), 0, ios_base::cur);
+#else
return __buffer.st_size - lseek(this->fd(), 0, ios_base::cur);
#endif
+#endif
#endif
return 0;
}
diff --git a/libstdc++-v3/configure b/libstdc++-v3/configure
index 9f9c5a2419a..50c8f00a41c 100755
--- a/libstdc++-v3/configure
+++ b/libstdc++-v3/configure
@@ -16299,7 +16299,7 @@ $as_echo_n "checking for underlying I/O to use... " >&6; }
if test "${enable_cstdio+set}" = set; then :
enableval=$enable_cstdio;
case "$enableval" in
- stdio) ;;
+ stdio|stdio_posix|stdio_pure) ;;
*) as_fn_error $? "Unknown argument to enable/disable cstdio" "$LINENO" 5 ;;
esac
@@ -16309,16 +16309,23 @@ fi
- # Now that libio has been removed, you can have any color you want as long
- # as it's black. This is one big no-op until other packages are added, but
- # showing the framework never hurts.
+ # The only available I/O model is based on stdio, via basic_file_stdio.
+ # The default "stdio" is actually "stdio + POSIX" because it uses fdopen(3)
+ # to get a file descriptor and then uses read(3) and write(3) with it.
+ # The "stdio_pure" model doesn't use fdopen and only uses FILE* for I/O.
case ${enable_cstdio} in
- stdio)
+ stdio*)
CSTDIO_H=config/io/c_io_stdio.h
BASIC_FILE_H=config/io/basic_file_stdio.h
BASIC_FILE_CC=config/io/basic_file_stdio.cc
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: stdio" >&5
$as_echo "stdio" >&6; }
+
+ if test "x$enable_cstdio" = "xstdio_pure" ; then
+
+$as_echo "#define _GLIBCXX_USE_STDIO_PURE 1" >>confdefs.h
+
+ fi
;;
esac
--
2.29.2

84
scripts/build/cc/gcc.sh
View File

@ -279,7 +279,8 @@ do_cc_core_pass_2() {
# build_manuals : whether to build manuals or not : bool : no
# cflags : cflags to use : string : (empty)
# ldflags : ldflags to use : string : (empty)
# build_step : build step 'core1', 'core2', 'gcc_build'
# build_step : build step 'core1', 'core2', 'gcc_build',
# 'libstdcxx'
# or 'gcc_host' : string : (none)
# Usage: do_gcc_core_backend mode=[static|shared|baremetal] build_libgcc=[yes|no] build_staticlinked=[yes|no]
do_gcc_core_backend() {
@ -291,6 +292,7 @@ do_gcc_core_backend() {
local build_manuals=no
local host
local prefix
local enable_optspace
local complibs
local lang_list
local cflags cflags_for_build cflags_for_target
@ -298,6 +300,9 @@ do_gcc_core_backend() {
local build_step
local log_txt
local tmp
local exec_prefix
local header_dir
local libstdcxx_name
local -a host_libstdcxx_flags
local -a extra_config
local -a core_LDFLAGS
@ -327,11 +332,30 @@ do_gcc_core_backend() {
# to inhibit the libiberty and libgcc tricks later on
build_libgcc=no
;;
libstdcxx)
CT_DoLog EXTRA "Configuring libstdc++ for ${libstdcxx_name}"
if [ "${header_dir}" = "" ]; then
header_dir="${CT_PREFIX_DIR}/${libstdcxx_name}/include"
fi
if [ "${exec_prefix}" = "" ]; then
exec_prefix="${CT_PREFIX_DIR}/${libstdcxx_name}"
fi
extra_config+=( "${CT_CC_SYSROOT_ARG[@]}" )
extra_config+=( "--with-headers=${header_dir}" )
extra_user_config=( "${CT_CC_GCC_EXTRA_CONFIG_ARRAY[@]}" )
log_txt="libstdc++ ${libstdcxx_name} library"
# to inhibit the libiberty and libgcc tricks later on
build_libgcc=no
;;
*)
CT_Abort "Internal Error: 'build_step' must be one of: 'core1', 'core2', 'gcc_build' or 'gcc_host', not '${build_step:-(empty)}'"
CT_Abort "Internal Error: 'build_step' must be one of: 'core1', 'core2', 'gcc_build', 'gcc_host' or 'libstdcxx', not '${build_step:-(empty)}'"
;;
esac
if [ "${exec_prefix}" = "" ]; then
exec_prefix="${prefix}"
fi
case "${mode}" in
static)
extra_config+=("--with-newlib")
@ -389,6 +413,10 @@ do_gcc_core_backend() {
extra_config+=(--disable-libquadmath-support)
fi
if [ "${build_libstdcxx}" = "no" ]; then
extra_config+=(--disable-libstdcxx)
fi
core_LDFLAGS+=("${ldflags}")
# *** WARNING ! ***
@ -447,7 +475,8 @@ do_gcc_core_backend() {
extra_config+=("--with-host-libstdcxx=${host_libstdcxx_flags[*]}")
fi
if [ "${CT_CC_GCC_ENABLE_TARGET_OPTSPACE}" = "y" ]; then
if [ "${CT_CC_GCC_ENABLE_TARGET_OPTSPACE}" = "y" ] || \
[ "${enable_optspace}" = "yes" ]; then
extra_config+=("--enable-target-optspace")
fi
if [ "${CT_CC_GCC_DISABLE_PCH}" = "y" ]; then
@ -595,6 +624,7 @@ do_gcc_core_backend() {
--host=${host} \
--target=${CT_TARGET} \
--prefix="${prefix}" \
--exec_prefix="${exec_prefix}" \
--with-local-prefix="${CT_SYSROOT_DIR}" \
"${extra_config[@]}" \
--enable-languages="${lang_list}" \
@ -678,6 +708,11 @@ do_gcc_core_backend() {
core_targets_all=all
core_targets_install=install
;;
libstdcxx)
core_targets=( target-libstdc++-v3 )
core_targets_all="${core_targets[@]/#/all-}"
core_targets_install="${core_targets[@]/#/install-}"
;;
esac
CT_DoLog EXTRA "Building ${log_txt}"
@ -754,7 +789,9 @@ do_cc_for_build() {
# lack of such a compiler, but better safe than sorry...
build_final_opts+=( "mode=baremetal" )
build_final_opts+=( "build_libgcc=yes" )
build_final_opts+=( "build_libstdcxx=yes" )
if [ "${CT_LIBC_NONE}" != "y" ]; then
build_final_opts+=( "build_libstdcxx=yes" )
fi
build_final_opts+=( "build_libgfortran=yes" )
if [ "${CT_STATIC_TOOLCHAIN}" = "y" ]; then
build_final_opts+=( "build_staticlinked=yes" )
@ -843,7 +880,9 @@ do_cc_for_host() {
if [ "${CT_BARE_METAL}" = "y" ]; then
final_opts+=( "mode=baremetal" )
final_opts+=( "build_libgcc=yes" )
final_opts+=( "build_libstdcxx=yes" )
if [ "${CT_LIBC_NONE}" != "y" ]; then
final_opts+=( "build_libstdcxx=yes" )
fi
final_opts+=( "build_libgfortran=yes" )
if [ "${CT_STATIC_TOOLCHAIN}" = "y" ]; then
final_opts+=( "build_staticlinked=yes" )
@ -876,20 +915,27 @@ do_cc_for_host() {
# Parameter : Definition : Type : Default
# host : the host we run onto : tuple : (none)
# prefix : the runtime prefix : dir : (none)
# exec_prefix : prefix for executables : dir : (none)
# complibs : the companion libraries prefix : dir : (none)
# cflags : cflags to use : string : (empty)
# ldflags : ldflags to use : string : (empty)
# lang_list : the list of languages to build : string : (empty)
# build_manuals : whether to build manuals or not : bool : no
# build_step : build step 'gcc_build', 'gcc_host'
# or 'libstdcxx' : string : (none)
do_gcc_backend() {
local host
local prefix
local exec_prefix
local complibs
local lang_list
local cflags
local cflags_for_build
local ldflags
local build_manuals
local exec_prefix
local header_dir
local libstdcxx_name
local -a host_libstdcxx_flags
local -a extra_config
local -a final_LDFLAGS
@ -900,7 +946,24 @@ do_gcc_backend() {
eval "${arg// /\\ }"
done
CT_DoLog EXTRA "Configuring final gcc compiler"
if [ "${exec_prefix}" = "" ]; then
exec_prefix="${prefix}"
fi
# This function gets called for final gcc and libstdcxx.
case "${build_step}" in
gcc_build|gcc_host)
log_txt="final gcc compiler"
;;
libstdcxx)
log_txt="libstdc++ library for ${libstdcxx_name}"
;;
*)
CT_Abort "Internal Error: 'build_step' must be one of: 'gcc_build', 'gcc_host' or 'libstdcxx', not '${build_step:-(empty)}'"
;;
esac
CT_DoLog EXTRA "Configuring ${log_txt}"
# Enable selected languages
extra_config+=("--enable-languages=${lang_list}")
@ -974,6 +1037,10 @@ do_gcc_backend() {
fi
fi
if [ "${build_libstdcxx}" = "no" ]; then
extra_config+=(--disable-libstdcxx)
fi
final_LDFLAGS+=("${ldflags}")
# *** WARNING ! ***
@ -1043,9 +1110,11 @@ do_gcc_backend() {
fi
fi
if [ "${CT_CC_GCC_ENABLE_TARGET_OPTSPACE}" = "y" ]; then
if [ "${CT_CC_GCC_ENABLE_TARGET_OPTSPACE}" = "y" ] || \
[ "${enable_optspace}" = "yes" ]; then
extra_config+=("--enable-target-optspace")
fi
if [ "${CT_CC_GCC_DISABLE_PCH}" = "y" ]; then
extra_config+=("--disable-libstdcxx-pch")
fi
@ -1161,6 +1230,7 @@ do_gcc_backend() {
--host=${host} \
--target=${CT_TARGET} \
--prefix="${prefix}" \
--exec_prefix="${exec_prefix}" \
${CT_CC_SYSROOT_ARG} \
"${extra_config[@]}" \
--with-local-prefix="${CT_SYSROOT_DIR}" \