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Use -fwrapv in CFLAGS if we are using a version of gcc that accepts this flag.

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This prevents compiler optimizations that assume overflow won't occur, which
breaks numerous overflow tests that we need to have working.  It is known
that gcc 4.3 causes problems and possible that 4.1 does.  Per my proposal
of some time ago and a recent report from Kris Jurka.

Backpatch as far as 8.0, which is as far as the patch conveniently goes.
7.x was pretty short of overflow tests anyway, so it may not matter there,
even assuming that anyone cares whether 7.x builds on recent gcc.
This commit is contained in:
Tom Lane 2008-03-10 21:50:23 +00:00
parent d19d35431b
commit 899b9c3e04
2 changed files with 57 additions and 1 deletions
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54
configure vendored
View File

@ -3058,6 +3058,60 @@ else
echo "$as_me: failed program was:" >&5
sed 's/^/| /' conftest.$ac_ext >&5
CFLAGS="$pgac_save_CFLAGS"
echo "$as_me:$LINENO: result: no" >&5
echo "${ECHO_T}no" >&6
fi
rm -f conftest.err conftest.$ac_objext conftest.$ac_ext
# Disable optimizations that assume no overflow; needed for gcc 4.3+
echo "$as_me:$LINENO: checking if $CC supports -fwrapv" >&5
echo $ECHO_N "checking if $CC supports -fwrapv... $ECHO_C" >&6
pgac_save_CFLAGS=$CFLAGS
CFLAGS="$pgac_save_CFLAGS -fwrapv"
cat >conftest.$ac_ext <<_ACEOF
/* confdefs.h. */
_ACEOF
cat confdefs.h >>conftest.$ac_ext
cat >>conftest.$ac_ext <<_ACEOF
/* end confdefs.h. */
int
main ()
{
;
return 0;
}
_ACEOF
rm -f conftest.$ac_objext
if { (eval echo "$as_me:$LINENO: \"$ac_compile\"") >&5
(eval $ac_compile) 2>conftest.er1
ac_status=$?
grep -v '^ *+' conftest.er1 >conftest.err
rm -f conftest.er1
cat conftest.err >&5
echo "$as_me:$LINENO: \$? = $ac_status" >&5
(exit $ac_status); } &&
{ ac_try='test -z "$ac_c_werror_flag"
|| test ! -s conftest.err'
{ (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
(eval $ac_try) 2>&5
ac_status=$?
echo "$as_me:$LINENO: \$? = $ac_status" >&5
(exit $ac_status); }; } &&
{ ac_try='test -s conftest.$ac_objext'
{ (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
(eval $ac_try) 2>&5
ac_status=$?
echo "$as_me:$LINENO: \$? = $ac_status" >&5
(exit $ac_status); }; }; then
echo "$as_me:$LINENO: result: yes" >&5
echo "${ECHO_T}yes" >&6
else
echo "$as_me: failed program was:" >&5
sed 's/^/| /' conftest.$ac_ext >&5
CFLAGS="$pgac_save_CFLAGS"
echo "$as_me:$LINENO: result: no" >&5
echo "${ECHO_T}no" >&6

4
configure.in
View File

@ -1,5 +1,5 @@
dnl Process this file with autoconf to produce a configure script.
dnl $PostgreSQL: pgsql/configure.in,v 1.546.2.1 2008/02/24 05:22:03 tgl Exp $
dnl $PostgreSQL: pgsql/configure.in,v 1.546.2.2 2008/03/10 21:50:23 tgl Exp $
dnl
dnl Developers, please strive to achieve this order:
dnl
@ -290,6 +290,8 @@ if test "$GCC" = yes -a "$ICC" = no; then
PGAC_PROG_CC_CFLAGS_OPT([-Wendif-labels])
# Disable strict-aliasing rules; needed for gcc 3.3+
PGAC_PROG_CC_CFLAGS_OPT([-fno-strict-aliasing])
# Disable optimizations that assume no overflow; needed for gcc 4.3+
PGAC_PROG_CC_CFLAGS_OPT([-fwrapv])
elif test "$ICC" = yes; then
# Intel's compiler has a bug/misoptimization in checking for
# division by NAN (NaN == 0), -mp1 fixes it, so add it to the CFLAGS.