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Default to hidden visibility for extension libraries where possible

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Until now postgres built extension libraries with global visibility, i.e.
exporting all symbols.  On the one platform where that behavior is not
natively available, namely windows, we emulate it by analyzing the input files
to the shared library and exporting all the symbols therein.

Not exporting all symbols is actually desirable, as it can improve loading
speed, reduces the likelihood of symbol conflicts and can improve intra
extension library function call performance. It also makes the non-windows
builds more similar to windows builds.

Additionally, with meson implementing the export-all-symbols behavior for
windows, turns out to be more verbose than desirable.

This patch adds support for hiding symbols by default and, to counteract that,
explicit symbol visibility annotation for compilers that support
__attribute__((visibility("default"))) and -fvisibility=hidden. That is
expected to be most, if not all, compilers except msvc (for which we already
support explicit symbol export annotations).

Now that extension library symbols are explicitly exported, we don't need to
export all symbols on windows anymore, hence remove that behavior from
src/tools/msvc. The supporting code can't be removed, as we still need to
export all symbols from the main postgres binary.

Author: Andres Freund <andres@anarazel.de>
Author: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/20211101020311.av6hphdl6xbjbuif@alap3.anarazel.de
This commit is contained in:
Andres Freund
2022-07-17 17:49:51 -07:00
parent fd4bad1655
commit 089480c077
9 changed files with 198 additions and 12 deletions
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152
configure vendored Executable file → Normal file
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@ -741,6 +741,8 @@ CPP
CFLAGS_SL
BITCODE_CXXFLAGS
BITCODE_CFLAGS
CXXFLAGS_SL_MODULE
CFLAGS_SL_MODULE
CFLAGS_VECTORIZE
CFLAGS_UNROLL_LOOPS
PERMIT_DECLARATION_AFTER_STATEMENT
@ -6302,6 +6304,154 @@ if test x"$pgac_cv_prog_CC_cflags__ftree_vectorize" = x"yes"; then
fi
#
# If the compiler knows how to hide symbols add the switch needed for that
# to CFLAGS_SL_MODULE and define HAVE_VISIBILITY_ATTRIBUTE.
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether ${CC} supports -fvisibility=hidden, for CFLAGS_SL_MODULE" >&5
$as_echo_n "checking whether ${CC} supports -fvisibility=hidden, for CFLAGS_SL_MODULE... " >&6; }
if ${pgac_cv_prog_CC_cflags__fvisibility_hidden+:} false; then :
$as_echo_n "(cached) " >&6
else
pgac_save_CFLAGS=$CFLAGS
pgac_save_CC=$CC
CC=${CC}
CFLAGS="${CFLAGS_SL_MODULE} -fvisibility=hidden"
ac_save_c_werror_flag=$ac_c_werror_flag
ac_c_werror_flag=yes
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */
int
main ()
{
;
return 0;
}
_ACEOF
if ac_fn_c_try_compile "$LINENO"; then :
pgac_cv_prog_CC_cflags__fvisibility_hidden=yes
else
pgac_cv_prog_CC_cflags__fvisibility_hidden=no
fi
rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
ac_c_werror_flag=$ac_save_c_werror_flag
CFLAGS="$pgac_save_CFLAGS"
CC="$pgac_save_CC"
fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv_prog_CC_cflags__fvisibility_hidden" >&5
$as_echo "$pgac_cv_prog_CC_cflags__fvisibility_hidden" >&6; }
if test x"$pgac_cv_prog_CC_cflags__fvisibility_hidden" = x"yes"; then
CFLAGS_SL_MODULE="${CFLAGS_SL_MODULE} -fvisibility=hidden"
fi
if test "$pgac_cv_prog_CC_cflags__fvisibility_hidden" = yes; then
$as_echo "#define HAVE_VISIBILITY_ATTRIBUTE 1" >>confdefs.h
fi
# For C++ we additionally want -fvisibility-inlines-hidden
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether ${CXX} supports -fvisibility=hidden, for CXXFLAGS_SL_MODULE" >&5
$as_echo_n "checking whether ${CXX} supports -fvisibility=hidden, for CXXFLAGS_SL_MODULE... " >&6; }
if ${pgac_cv_prog_CXX_cxxflags__fvisibility_hidden+:} false; then :
$as_echo_n "(cached) " >&6
else
pgac_save_CXXFLAGS=$CXXFLAGS
pgac_save_CXX=$CXX
CXX=${CXX}
CXXFLAGS="${CXXFLAGS_SL_MODULE} -fvisibility=hidden"
ac_save_cxx_werror_flag=$ac_cxx_werror_flag
ac_cxx_werror_flag=yes
ac_ext=cpp
ac_cpp='$CXXCPP $CPPFLAGS'
ac_compile='$CXX -c $CXXFLAGS $CPPFLAGS conftest.$ac_ext >&5'
ac_link='$CXX -o conftest$ac_exeext $CXXFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
ac_compiler_gnu=$ac_cv_cxx_compiler_gnu
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */
int
main ()
{
;
return 0;
}
_ACEOF
if ac_fn_cxx_try_compile "$LINENO"; then :
pgac_cv_prog_CXX_cxxflags__fvisibility_hidden=yes
else
pgac_cv_prog_CXX_cxxflags__fvisibility_hidden=no
fi
rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
ac_ext=c
ac_cpp='$CPP $CPPFLAGS'
ac_compile='$CC -c $CFLAGS $CPPFLAGS conftest.$ac_ext >&5'
ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
ac_compiler_gnu=$ac_cv_c_compiler_gnu
ac_cxx_werror_flag=$ac_save_cxx_werror_flag
CXXFLAGS="$pgac_save_CXXFLAGS"
CXX="$pgac_save_CXX"
fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv_prog_CXX_cxxflags__fvisibility_hidden" >&5
$as_echo "$pgac_cv_prog_CXX_cxxflags__fvisibility_hidden" >&6; }
if test x"$pgac_cv_prog_CXX_cxxflags__fvisibility_hidden" = x"yes"; then
CXXFLAGS_SL_MODULE="${CXXFLAGS_SL_MODULE} -fvisibility=hidden"
fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether ${CXX} supports -fvisibility-inlines-hidden, for CXXFLAGS_SL_MODULE" >&5
$as_echo_n "checking whether ${CXX} supports -fvisibility-inlines-hidden, for CXXFLAGS_SL_MODULE... " >&6; }
if ${pgac_cv_prog_CXX_cxxflags__fvisibility_inlines_hidden+:} false; then :
$as_echo_n "(cached) " >&6
else
pgac_save_CXXFLAGS=$CXXFLAGS
pgac_save_CXX=$CXX
CXX=${CXX}
CXXFLAGS="${CXXFLAGS_SL_MODULE} -fvisibility-inlines-hidden"
ac_save_cxx_werror_flag=$ac_cxx_werror_flag
ac_cxx_werror_flag=yes
ac_ext=cpp
ac_cpp='$CXXCPP $CPPFLAGS'
ac_compile='$CXX -c $CXXFLAGS $CPPFLAGS conftest.$ac_ext >&5'
ac_link='$CXX -o conftest$ac_exeext $CXXFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
ac_compiler_gnu=$ac_cv_cxx_compiler_gnu
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */
int
main ()
{
;
return 0;
}
_ACEOF
if ac_fn_cxx_try_compile "$LINENO"; then :
pgac_cv_prog_CXX_cxxflags__fvisibility_inlines_hidden=yes
else
pgac_cv_prog_CXX_cxxflags__fvisibility_inlines_hidden=no
fi
rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
ac_ext=c
ac_cpp='$CPP $CPPFLAGS'
ac_compile='$CC -c $CFLAGS $CPPFLAGS conftest.$ac_ext >&5'
ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
ac_compiler_gnu=$ac_cv_c_compiler_gnu
ac_cxx_werror_flag=$ac_save_cxx_werror_flag
CXXFLAGS="$pgac_save_CXXFLAGS"
CXX="$pgac_save_CXX"
fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv_prog_CXX_cxxflags__fvisibility_inlines_hidden" >&5
$as_echo "$pgac_cv_prog_CXX_cxxflags__fvisibility_inlines_hidden" >&6; }
if test x"$pgac_cv_prog_CXX_cxxflags__fvisibility_inlines_hidden" = x"yes"; then
CXXFLAGS_SL_MODULE="${CXXFLAGS_SL_MODULE} -fvisibility-inlines-hidden"
fi
#
# The following tests want to suppress various unhelpful warnings by adding
# -Wno-foo switches. But gcc won't complain about unrecognized -Wno-foo
@ -6860,6 +7010,8 @@ fi
# Determine flags used to emit bitcode for JIT inlining.
# 1. We must duplicate any behaviour-changing compiler flags used above,
# to keep compatibility with the compiler used for normal Postgres code.