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Disable -faggressive-loop-optimizations in gcc 4.8+ for pre-9.2 branc…

…hes.

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.
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1 parent 91a1e14 commit 105f3ef492abd22985321b64e8f40e58f3a15a83 @alvherre alvherre committed Jan 20, 2015
Showing with 58 additions and 0 deletions.
  1. +55 −0 configure
  2. +3 −0 configure.in
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@@ -3194,6 +3194,61 @@ 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
+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 $CC supports -qnoansialias" >&5
View
@@ -294,6 +294,9 @@ choke me
PGAC_PROG_CC_CFLAGS_OPT([-fwrapv])
# Disable FP optimizations that cause various errors on gcc 4.5+ or maybe 4.6+
PGAC_PROG_CC_CFLAGS_OPT([-fexcess-precision=standard])
+ # Disable loop optimizations that get confused by variable-length struct
+ # declarations in gcc 4.8+
+ PGAC_PROG_CC_CFLAGS_OPT([-fno-aggressive-loop-optimizations])
elif test x"${CC}" = x"xlc"; then
# AIX xlc has to have strict aliasing turned off too
PGAC_PROG_CC_CFLAGS_OPT([-qnoansialias])

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