8000 Disable -faggressive-loop-optimizations in gcc 4.8+ for pre-9.2 branc… · percona/postgres@105f3ef · GitHub
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alvherrealvherre
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Disable -faggressive-loop-optimizations in gcc 4.8+ for pre-9.2 branches.
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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‎configure

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@@ -3188,6 +3188,61 @@ else
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echo "$as_me: failed program was:" >&5
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sed 's/^/| /' conftest.$ac_ext >&5
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CFLAGS="$pgac_save_CFLAGS"
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echo "$as_me:$LINENO: result: no" >&5
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echo "${ECHO_T}no" >&6
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fi
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rm -f conftest.err conftest.$ac_objext conftest.$ac_ext
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# Disable loop optimizations that get confused by variable-length struct
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# declarations in gcc 4.8+
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echo "$as_me:$LINENO: checking if $CC supports -fno-aggressive-loop-optimizations" >&5
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echo $ECHO_N "checking if $CC supports -fno-aggressive-loop-optimizations... $ECHO_C" >&6
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pgac_save_CFLAGS=$CFLAGS
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CFLAGS="$pgac_save_CFLAGS -fno-aggressive-loop-optimizations"
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cat >conftest.$ac_ext <<_ACEOF
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/* confdefs.h. */
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_ACEOF
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cat confdefs.h >>conftest.$ac_ext
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cat >>conftest.$ac_ext <<_ACEOF
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/* end confdefs.h. */
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int
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main ()
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{
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;
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return 0;
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}
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_ACEOF
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rm -f conftest.$ac_objext
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if { (eval echo "$as_me:$LINENO: \"$ac_compile\"") >&5
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(eval $ac_compile) 2>conftest.er1
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ac_status=$?
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grep -v '^ *+' conftest.er1 >conftest.err
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rm -f conftest.er1
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cat conftest.err >&5
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echo "$as_me:$LINENO: \$? = $ac_status" >&5
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(exit $ac_status); } &&
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{ ac_try='test -z "$ac_c_werror_flag"
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|| test ! -s conftest.err'
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{ (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
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(eval $ac_try) 2>&5
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ac_status=$?
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echo "$as_me:$LINENO: \$? = $ac_status" >&5
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(exit $ac_status); }; } &&
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{ ac_try='test -s conftest.$ac_objext'
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{ (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
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(eval $ac_try) 2>&5
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ac_status=$?
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echo "$as_me:$LINENO: \$? = $ac_status" >&5
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(exit $ac_status); }; }; then
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echo "$as_me:$LINENO: result: yes" >&5
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echo "${ECHO_T}yes" >&6
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else
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echo "$as_me: failed program was:" >&5
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sed 's/^/| /' conftest.$ac_ext >&5
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CFLAGS="$pgac_save_CFLAGS"
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echo "$as_me:$LINENO: result: no" >&5
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echo "${ECHO_T}no" >&6

‎configure.in

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@@ -294,6 +294,9 @@ choke me
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PGAC_PROG_CC_CFLAGS_OPT([-fwrapv])
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# Disable FP optimizations that cause various errors on gcc 4.5+ or maybe 4.6+
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PGAC_PROG_CC_CFLAGS_OPT([-fexcess-precision=standard])
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# Disable loop optimizations that get confused by variable-length struct
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# declarations in gcc 4.8+
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PGAC_PROG_CC_CFLAGS_OPT([-fno-aggressive-loop-optimizations])
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elif test x"${CC}" = x"xlc"; then
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# AIX xlc has to have strict aliasing turned off too
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PGAC_PROG_CC_CFLAGS_OPT([-qnoansialias])

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