i386: Fail at configure time for i386 builds.

This change does two things:

* Treats a target i386-* as if it were i686.
* Fails configure if the user is generating code
  for i386.

We no longer support i386 code-generation because the i386
lacks the atomic operations we need in glibc.

You can still configure for i386-*, but you get i686 code.

You can't build with --march=i386, --mtune=i386 or a compiler
that defaults to i386 code-generation.

I've added two i386 entries in the master todo list to discuss
merging and renaming:
http://sourceware.org/glibc/wiki/Development_Todo/Master#i386

The failure modes are fail-safe here. You compile for i386,
get i686, and try to run on i386 and it fails. The configure
log has a warning saying we elided to i686. There is no situation
that I can see where we run into any serious problems.

The patch makes the current state better in that we get less
confused users and we build successfully in more default
configurations.

The next enhancement would be to add --march=i?86
as suggested in #c20 of BZ#10062 for any i?86-* builds, which
would solve the problem of a 32-bit compiler that defaults to
i386 code-gen and glibc configured for i686-* target. Which
previously failed at build time, and now will fail at configure
time (requires adding --march=i686).

Updated NEWS with BZ #10060 and #10062.

No regressions.

---

2013-04-06  Carlos O'Donell  <carlos@redhat.com>

	[BZ #10060, #10062]
	* aclocal.m4 (LIBC_COMPILER_BUILTIN_INLINED): New macro.
	* sysdeps/i386/configure.in: Use LIBC_COMPILER_BUILTIN_INLINED and
	fail configure if __sync_val_compare_and_swap is not inlined.
	* sysdeps/i386/configure: Regenerate.
	* configure.in: Build for i686 when configured for i386.
	* configure: Regenerate.
	* README: Remove i386 reference.
This commit is contained in:
Carlos O'Donell 2013-04-06 12:00:35 -04:00
parent b7a329a561
commit a01f19c8fb
8 changed files with 126 additions and 6 deletions

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@ -1,3 +1,14 @@
2013-04-06 Carlos O'Donell <carlos@redhat.com>
[BZ #10060, #10062]
* aclocal.m4 (LIBC_COMPILER_BUILTIN_INLINED): New macro.
* sysdeps/i386/configure.in: Use LIBC_COMPILER_BUILTIN_INLINED and
fail configure if __sync_val_compare_and_swap is not inlined.
* sysdeps/i386/configure: Regenerate.
* configure.in: Build for i686 when configured for i386.
* configure: Regenerate.
* README: Remove i386 reference.
2013-04-06 Carlos O'Donell <carlos@redhat.com>
* sysdeps/s390/s390-32/sysdep.h: Undefine PSEUDO before redefinition.

10
NEWS
View File

@ -9,11 +9,11 @@ Version 2.18
* The following bugs are resolved with this release:
10357, 11120, 11561, 12723, 13550, 13889, 13951, 14142, 14176, 14200,
14317, 14327, 14478, 14496, 14686, 14812, 14920, 14964, 14981, 14982,
14985, 14994, 14996, 15003, 15006, 15020, 15023, 15036, 15054, 15055,
15062, 15078, 15160, 15214, 15232, 15234, 15283, 15285, 15287, 15304,
15305, 15307, 15327, 15330, 15335, 15336, 15337, 15342.
10060, 10062, 10357, 11120, 11561, 12723, 13550, 13889, 13951, 14142,
14176, 14200, 14317, 14327, 14478, 14496, 14686, 14812, 14920, 14964,
14981, 14982, 14985, 14994, 14996, 15003, 15006, 15020, 15023, 15036,
15054, 15055, 15062, 15078, 15160, 15214, 15232, 15234, 15283, 15285,
15287, 15304, 15305, 15307, 15327, 15330, 15335, 15336, 15337, 15342.
* CVE-2013-0242 Buffer overrun in regexp matcher has been fixed (Bugzilla
#15078).

2
README
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@ -12,7 +12,7 @@ implement the operating system behavior seen by user applications.
In GNU/Hurd systems, it works with a microkernel and Hurd servers.
The GNU C Library implements much of the POSIX.1 functionality in the
GNU/Hurd system, using configurations i[34567]86-*-gnu. The current
GNU/Hurd system, using configurations i[4567]86-*-gnu. The current
GNU/Hurd support requires out-of-tree patches that will eventually be
incorporated into an official GNU C Library release.

33
aclocal.m4 vendored
View File

@ -248,3 +248,36 @@ dnl LIBC_CONFIG_VAR(make-variable, shell-value)
AC_DEFUN([LIBC_CONFIG_VAR],
[config_vars="$config_vars
$1 = $2"])
dnl Check that function FUNC was inlined as a builtin. The code fragment
dnl CODE is compiled with additional options CC_OPTION. If FUNC is
dnl not found in the assembly then it is assumed the compiler has support
dnl for this builtin and has inlined the call. If the compiler has the
dnl feature then ACTION-IF-TRUE is called, otherwise ACTION-IF-FALSE.
dnl It is up to the caller to provide a CC_OPTION that ensures the
dnl builtin is inlined if present.
dnl Warning: This may not work for some machines. For example on ARM the
dnl ABI dictates that some functions should not be inlined and instead
dnl should be provided by a compiler helper library e.g. __aeabi_memcpy.
dnl This is done to reduce code size.
dnl LIBC_COMPILER_BUILTIN([func], [code], [cc_option], [action-if-true], [action-if-false])
AC_DEFUN([LIBC_COMPILER_BUILTIN_INLINED],
[AC_MSG_CHECKING([for compiler support of inlined builtin function $1])
libc_compiler_builtin_inlined=no
cat > conftest.c <<EOF
int _start (void) { $2 return 0; }
EOF
if ! AC_TRY_COMMAND([${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS
$3 -nostdlib -nostartfiles
-S conftest.c -o - | fgrep "$1"
1>&AS_MESSAGE_LOG_FD])
then
libc_compiler_builtin_inlined=yes
fi
rm -f conftest*
if test $libc_compiler_builtin_inlined = yes; then
$4
else
$5
fi
AC_MSG_RESULT($libc_compiler_builtin_inlined)])

9
configure vendored
View File

@ -3741,6 +3741,15 @@ case "$machine-$host_os" in
;;
esac
# Configure for i686 if the user asks for i386. We don't support
# i386 any more but it continues to be common for users to configure
# 32-bit x86 as i386. We build for i686 instead.
if test "$machine" = i386; then
machine="i686"
echo "\
*** WARNING: Support for i386 is deprecated. Building for i686 instead."
fi
submachine=
# Check whether --with-cpu was given.

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@ -390,6 +390,15 @@ case "$machine-$host_os" in
;;
esac
# Configure for i686 if the user asks for i386. We don't support
# i386 any more but it continues to be common for users to configure
# 32-bit x86 as i386. We build for i686 instead.
if test "$machine" = i386; then
machine="i686"
echo "\
*** WARNING: Support for i386 is deprecated. Building for i686 instead."
fi
submachine=
AC_ARG_WITH([cpu],
AS_HELP_STRING([--with-cpu=CPU], [select code for CPU variant]),

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@ -32,6 +32,45 @@ $as_echo "$ac_res" >&6; }
# This file is generated from configure.in by Autoconf. DO NOT EDIT!
# Local configure fragment for sysdeps/i386.
# The GNU C Library can't be built for i386. There are several reasons for
# this restriction. The primary reason is that i386 lacks the atomic
# operations required to support the current NPTL implementation. While it is
# possible that such atomic operations could be emulated in the kernel to date
# no such work has been done to enable this. Even with NPTL disabled you still
# have no atomic.h implementation. Given the declining use of i386 we disable
# support for building with `-march=i386' or `-mcpu=i386.' We don't explicitly
# check for i386, instead we make sure the compiler has support for inlining
# the builtin __sync_val_compare_and_swap. If it does then we should have no
# problem building for i386.
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for compiler support of inlined builtin function __sync_val_compare_and_swap" >&5
$as_echo_n "checking for compiler support of inlined builtin function __sync_val_compare_and_swap... " >&6; }
libc_compiler_builtin_inlined=no
cat > conftest.c <<EOF
int _start (void) { int a, b, c; __sync_val_compare_and_swap (&a, b, c); return 0; }
EOF
if ! { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS
-O0 -nostdlib -nostartfiles
-S conftest.c -o - | fgrep "__sync_val_compare_and_swap"
1>&5'
{ { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
(eval $ac_try) 2>&5
ac_status=$?
$as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
test $ac_status = 0; }; }
then
libc_compiler_builtin_inlined=yes
fi
rm -f conftest*
if test $libc_compiler_builtin_inlined = yes; then
libc_cv_unsupported_i386=no
else
as_fn_error $? "
*** Building with -march=i386/-mcpu=i386 is not supported.
*** Please use host i786, i686, i586, or i486." "$LINENO" 5
fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_compiler_builtin_inlined" >&5
$as_echo "$libc_compiler_builtin_inlined" >&6; }
ac_fn_c_check_header_compile "$LINENO" "cpuid.h" "ac_cv_header_cpuid_h" "/* No default includes. */
"

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@ -1,6 +1,25 @@
GLIBC_PROVIDES dnl See aclocal.m4 in the top level source directory.
# Local configure fragment for sysdeps/i386.
# The GNU C Library can't be built for i386. There are several reasons for
# this restriction. The primary reason is that i386 lacks the atomic
# operations required to support the current NPTL implementation. While it is
# possible that such atomic operations could be emulated in the kernel to date
# no such work has been done to enable this. Even with NPTL disabled you still
# have no atomic.h implementation. Given the declining use of i386 we disable
# support for building with `-march=i386' or `-mcpu=i386.' We don't explicitly
# check for i386, instead we make sure the compiler has support for inlining
# the builtin __sync_val_compare_and_swap. If it does then we should have no
# problem building for i386.
LIBC_COMPILER_BUILTIN_INLINED(
[__sync_val_compare_and_swap],
[int a, b, c; __sync_val_compare_and_swap (&a, b, c);],
[-O0],
[libc_cv_unsupported_i386=no],
[AC_MSG_ERROR([
*** Building with -march=i386/-mcpu=i386 is not supported.
*** Please use host i786, i686, i586, or i486.])])
AC_CHECK_HEADER([cpuid.h], ,
[AC_MSG_ERROR([gcc must provide the <cpuid.h> header])],
[/* No default includes. */])