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configure.ac: Set aliasing_flags to -fno-strict-aliasing if...

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gcc/ChangeLog:

	* configure.ac: Set aliasing_flags to -fno-strict-aliasing if
	the host compiler is affected by placement new aliasing bug.
	* configure: Regenerate.
	* Makefile.in (ALIASING_FLAGS): New variable.
	(ALL_CXXFLAGS): Add $(ALIASING_FLAGS).

From-SVN: r226499
This commit is contained in:
Ulrich Weigand 2015-08-03 11:48:57 +00:00 committed by Ulrich Weigand
parent 1f71aee9c1
commit 4c0cca1801
4 changed files with 77 additions and 3 deletions
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8
gcc/ChangeLog
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@ -1,3 +1,11 @@
2015-08-03 Ulrich Weigand <Ulrich.Weigand@de.ibm.com>
* configure.ac: Set aliasing_flags to -fno-strict-aliasing if
the host compiler is affected by placement new aliasing bug.
* configure: Regenerate.
* Makefile.in (ALIASING_FLAGS): New variable.
(ALL_CXXFLAGS): Add $(ALIASING_FLAGS).
2015-08-03 Szabolcs Nagy <szabolcs.nagy@arm.com>
PR target/66731

5
gcc/Makefile.in
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@ -180,6 +180,8 @@ NOCOMMON_FLAG = @nocommon_flag@
NOEXCEPTION_FLAGS = @noexception_flags@
ALIASING_FLAGS = @aliasing_flags@
# This is set by --disable-maintainer-mode (default) to "#"
# FIXME: 'MAINT' will always be set to an empty string, no matter if
# --disable-maintainer-mode is used or not. This is because the
@ -986,7 +988,8 @@ ALL_CFLAGS = $(T_CFLAGS) $(CFLAGS-$@) \
# The C++ version.
ALL_CXXFLAGS = $(T_CFLAGS) $(CFLAGS-$@) $(CXXFLAGS) $(INTERNAL_CFLAGS) \
$(COVERAGE_FLAGS) $(NOEXCEPTION_FLAGS) $(WARN_CXXFLAGS) @DEFS@
$(COVERAGE_FLAGS) $(ALIASING_FLAGS) $(NOEXCEPTION_FLAGS) \
$(WARN_CXXFLAGS) @DEFS@
# Likewise. Put INCLUDES at the beginning: this way, if some autoconf macro
# puts -I options in CPPFLAGS, our include files in the srcdir will always

41
gcc/configure vendored
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@ -789,6 +789,7 @@ c_strict_warn
strict_warn
c_loose_warn
loose_warn
aliasing_flags
CPP
EGREP
GREP
@ -6526,6 +6527,42 @@ fi
rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
fi
# Check whether compiler is affected by placement new aliasing bug (PR 29286).
# If the host compiler is affected by the bug, and we build with optimization
# enabled (which happens e.g. when cross-compiling), the pool allocator may
# get miscompiled. Use -fno-strict-aliasing to work around this problem.
# Since there is no reliable feature check for the presence of this bug,
# we simply use a GCC version number check. (This should never trigger for
# stages 2 or 3 of a native bootstrap.)
aliasing_flags=
if test "$GCC" = yes; then
saved_CXXFLAGS="$CXXFLAGS"
# The following test compilation will succeed if and only if $CXX accepts
# -fno-strict-aliasing *and* is older than GCC 4.3.
CXXFLAGS="$CXXFLAGS -fno-strict-aliasing"
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX is affected by placement new aliasing bug" >&5
$as_echo_n "checking whether $CXX is affected by placement new aliasing bug... " >&6; }
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */
#if (__GNUC__ > 4) || (__GNUC__ == 4 && __GNUC_MINOR__ >= 3)
#error compiler not affected by placement new aliasing bug
#endif
_ACEOF
if ac_fn_cxx_try_compile "$LINENO"; then :
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
$as_echo "yes" >&6; }; aliasing_flags='-fno-strict-aliasing'
else
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
$as_echo "no" >&6; }
fi
rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
CXXFLAGS="$saved_CXXFLAGS"
fi
@ -18301,7 +18338,7 @@ else
lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
lt_status=$lt_dlunknown
cat > conftest.$ac_ext <<_LT_EOF
#line 18304 "configure"
#line 18341 "configure"
#include "confdefs.h"
#if HAVE_DLFCN_H
@ -18407,7 +18444,7 @@ else
lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
lt_status=$lt_dlunknown
cat > conftest.$ac_ext <<_LT_EOF
#line 18410 "configure"
#line 18447 "configure"
#include "confdefs.h"
#if HAVE_DLFCN_H

26
gcc/configure.ac
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@ -416,6 +416,32 @@ struct X<long long> { typedef long long t; };
]], [[X<int64_t>::t x;]])],[],[AC_MSG_ERROR([error verifying int64_t uses long long])])
fi
# Check whether compiler is affected by placement new aliasing bug (PR 29286).
# If the host compiler is affected by the bug, and we build with optimization
# enabled (which happens e.g. when cross-compiling), the pool allocator may
# get miscompiled. Use -fno-strict-aliasing to work around this problem.
# Since there is no reliable feature check for the presence of this bug,
# we simply use a GCC version number check. (This should never trigger for
# stages 2 or 3 of a native bootstrap.)
aliasing_flags=
if test "$GCC" = yes; then
saved_CXXFLAGS="$CXXFLAGS"
# The following test compilation will succeed if and only if $CXX accepts
# -fno-strict-aliasing *and* is older than GCC 4.3.
CXXFLAGS="$CXXFLAGS -fno-strict-aliasing"
AC_MSG_CHECKING([whether $CXX is affected by placement new aliasing bug])
AC_COMPILE_IFELSE([
#if (__GNUC__ > 4) || (__GNUC__ == 4 && __GNUC_MINOR__ >= 3)
#error compiler not affected by placement new aliasing bug
#endif
],
[AC_MSG_RESULT([yes]); aliasing_flags='-fno-strict-aliasing'],
[AC_MSG_RESULT([no])])
CXXFLAGS="$saved_CXXFLAGS"
fi
AC_SUBST(aliasing_flags)