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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 21:50:50 +00:00
parent 9cd94383e0
commit 781b5f4ceb
2 changed files with 49 additions and 1 deletions
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46
configure vendored
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@@ -2633,6 +2633,52 @@ cat >conftest.$ac_ext <<_ACEOF
#line $LINENO "configure"
#include "confdefs.h"
#ifdef F77_DUMMY_MAIN
# ifdef __cplusplus
extern "C"
# endif
int F77_DUMMY_MAIN() { return 1; }
#endif
int
main ()
{
;
return 0;
}
_ACEOF
rm -f conftest.$ac_objext
if { (eval echo "$as_me:$LINENO: \"$ac_compile\"") >&5
(eval $ac_compile) 2>&5
ac_status=$?
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 "$as_me: failed program was:" >&5
cat conftest.$ac_ext >&5
CFLAGS="$pgac_save_CFLAGS"
echo "$as_me:$LINENO: result: no" >&5
echo "${ECHO_T}no" >&6
fi
rm -f 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
#line $LINENO "configure"
#include "confdefs.h"
#ifdef F77_DUMMY_MAIN
# ifdef __cplusplus
extern "C"