Disable -faggressive-loop-optimizations in gcc 4.8+ for pre-9.2 branches.

alvherre · alvherre · commit 105f3ef492ab · 2015-01-20T12:26:20.000-03:00
With this optimization flag enabled, recent versions of gcc can generate incorrect code that assumes variable-length arrays (such as oidvector) are actually fixed-length because they're embedded in some larger struct. The known instance of this problem was fixed in 9.2 and up by commit 8137f2c and followon work, which hides actually-variable-length catalog fields from the compiler altogether. And we plan to gradually convert variable-length fields to official "flexible array member" notation over time, which should prevent this type of bug from reappearing as gcc gets smarter. We're not going to try to back-port those changes into older branches, though, so apply this band-aid instead. Andres Freund This is a backpatch of commit 649839d to unsupported branches REL8_2_STABLE and REL8_3_STABLE, so that they work with newer toolsets.
diff --git a/configure b/configure
@@ -3188,6 +3188,61 @@ 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 loop optimizations that get confused by variable-length struct
+  # declarations in gcc 4.8+
+  echo "$as_me:$LINENO: checking if $CC supports -fno-aggressive-loop-optimizations" >&5
+echo $ECHO_N "checking if $CC supports -fno-aggressive-loop-optimizations... $ECHO_C" >&6
+pgac_save_CFLAGS=$CFLAGS
+CFLAGS="$pgac_save_CFLAGS -fno-aggressive-loop-optimizations"
+cat >conftest.$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
diff --git a/configure.in b/configure.in
@@ -294,6 +294,9 @@ choke me
   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])
+  # Disable loop optimizations that get confused by variable-length struct
+  # declarations in gcc 4.8+
+  PGAC_PROG_CC_CFLAGS_OPT([-fno-aggressive-loop-optimizations])
 elif test x"${CC}" = x"xlc"; then
   # AIX xlc has to have strict aliasing turned off too
   PGAC_PROG_CC_CFLAGS_OPT([-qnoansialias])
