Disable excessive FP optimization by recent versions of gcc.

Suggested solution from Tom Lane. Problem discovered, probably not
for the first time, while testing the mingw-w64 32 bit compiler.

Backpatched to all live branches.

2 files changed, 56 insertions, 0 deletions

diff --git a/configure b/configure
index cf5424c8ba2..d850ee33c90 100755
--- a/configure
+++ b/configure
@@ -3140,6 +3140,60 @@ echo "${ECHO_T}no" >&6
 fi
 rm -f conftest.err conftest.$ac_objext conftest.$ac_ext
 
+  # Disable FP optimizations that cause various errors on gcc 4.5+ or maybe 4.6+
+  echo "$as_me:$LINENO: checking if $CC supports -fexcess-precision=standard" >&5
+echo $ECHO_N "checking if $CC supports -fexcess-precision=standard... $ECHO_C" >&6
+pgac_save_CFLAGS=$CFLAGS
+CFLAGS="$pgac_save_CFLAGS -fexcess-precision=standard"
+cat >conftest.$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
+fi
+rm -f conftest.err conftest.$ac_objext conftest.$ac_ext
+
 elif test x"${CC}" = x"xlc"; then
   # AIX xlc has to have strict aliasing turned off too
   echo "$as_me:$LINENO: checking if $CC supports -qnoansialias" >&5
diff --git a/configure.in b/configure.in
index 581f2e47a0c..ce106094956 100644
--- a/configure.in
+++ b/configure.in
@@ -292,6 +292,8 @@ choke me
   PGAC_PROG_CC_CFLAGS_OPT([-fno-strict-aliasing])
   # Disable optimizations that assume no overflow; needed for gcc 4.3+
   PGAC_PROG_CC_CFLAGS_OPT([-fwrapv])
+  # Disable FP optimizations that cause various errors on gcc 4.5+ or maybe 4.6+
+  PGAC_PROG_CC_CFLAGS_OPT([-fexcess-precision=standard])
 elif test x"${CC}" = x"xlc"; then
   # AIX xlc has to have strict aliasing turned off too
   PGAC_PROG_CC_CFLAGS_OPT([-qnoansialias])