On 1.3.2016 12:06, Lukas Slebodnik wrote: > On (25/02/16 15:57), Petr Spacek wrote: >> On 19.2.2016 13:55, Petr Spacek wrote: >>> Hello, >>> >>> Fix build with GCC 4.9+. >>> >>> GCC 4.9+ is too aggressive when optimizing functions with nonnull >>> attributes. This removes most of asserts() in the plugin. >>> GCC 6 adds warnings for these cases. >>> >>> We are disabling the unwanted condition pruning by adding >>> -fno-delete-null-pointer-checks argument. >>> BIND 9 did the same in its commit 603a78708343f063b44affb882ef93bb19a5142a. >>> >>> Additionally we silence warnings to prevent build failures when -Werror >>> is used. >>> >>> https://bugzilla.redhat.com/show_bug.cgi?id=1307346 >> >> Updated version is attached. It contains less autotools magic because it >> enables attribute nonnull only under Clang static analyzer and Coverity - as >> a >> result we do not have to silence GCC warnings from -Wnonnull. >> >> Please review so I can fix build in Fedora 24. >> >> Thank you. >> >> -- >> Petr^2 Spacek > >>From 4732fe9f4e525c44b46e7ed0734ccaec94fba49e Mon Sep 17 00:00:00 2001 >> From: Petr Spacek <pspa...@redhat.com> >> Date: Fri, 19 Feb 2016 13:39:27 +0100 >> Subject: [PATCH] Fix build with GCC 4.9+. >> >> GCC 4.9+ is too aggressive when optimizing functions with nonnull >> attributes. This removes most of asserts() in the plugin. >> GCC 6 adds warnings for these cases. >> >> We are disabling the unwanted condition pruning by adding >> -fno-delete-null-pointer-checks argument. >> BIND 9 did the same in its commit 603a78708343f063b44affb882ef93bb19a5142a. >> >> Additionally we enable nonnull attribute only when the build is running under >> Clang static analyzer or Coverity. >> >> https://bugzilla.redhat.com/show_bug.cgi?id=1307346 >> --- >> configure.ac | 13 +++++++++++++ >> src/util.h | 8 ++++++-- >> 2 files changed, 19 insertions(+), 2 deletions(-) >> >> diff --git a/configure.ac b/configure.ac >> index >> a06708b1a5ee64bb64c80272c10ed1a35670c8d0..a0123ac0a62b5acd5238f028d8c42e83af4060db >> 100644 >> --- a/configure.ac >> +++ b/configure.ac >> @@ -39,6 +39,19 @@ AC_TRY_COMPILE([ >> [CFLAGS="$SAVED_CFLAGS" >> AC_MSG_RESULT([no])]) >> >> +# Check if build chain supports -fno-delete-null-pointer-checks >> +# this flag avoids too agressive optimizations which would remove some >> asserts >> +# BIND 9 did the same in its commit 603a78708343f063b44affb882ef93bb19a5142a >> +AC_MSG_CHECKING([for -fno-delete-null-pointer-checks compiler flag]) >> +SAVED_CFLAGS="$CFLAGS" >> +CFLAGS="$CFLAGS -fno-delete-null-pointer-checks" >> +AC_TRY_COMPILE([ >> + extern int fdef(void); >> +],[], >> +[AC_MSG_RESULT([yes])], >> +[CFLAGS="$SAVED_CFLAGS" >> + AC_MSG_RESULT([no])]) >> + > NACK. > > It failes with clang. > > configure:12982: checking for -fno-delete-null-pointer-checks compiler flag > configure:12999: clang -c -O2 -g -pipe -Wall -Werror=format-security > -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong > --param=ssp-buffer-size=4 -grecord-gcc-switches > -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -m64 -mtune=generic > -fvisibility=hidden -fno-delete-null-pointer-checks conftest.c >&5 > clang-3.8: warning: optimization flag '-fno-delete-null-pointer-checks' is > not supported > clang-3.8: warning: argument unused during compilation: > '-specs=/usr/lib/rpm/redhat/redhat-hardened-cc1' > configure:12999: $? = 0 > configure:13000: result: yes > > Reproducer: > autoreconf -if && CC=clang ./configure && make
Thanks! I was testing this only with Clang static analyzer ... Here is updated patch. -- Petr^2 Spacek
From 6b2ac51fe4ff75c9f59499cbaa4306f70db46425 Mon Sep 17 00:00:00 2001 From: Petr Spacek <pspa...@redhat.com> Date: Fri, 19 Feb 2016 13:39:27 +0100 Subject: [PATCH] Fix build with GCC 4.9+. GCC 4.9+ is too aggressive when optimizing functions with nonnull attributes. This removes most of asserts() in the plugin. GCC 6 adds warnings for these cases. We are disabling the unwanted condition pruning by adding -fno-delete-null-pointer-checks argument. BIND 9 did the same in its commit 603a78708343f063b44affb882ef93bb19a5142a. Additionally we enable nonnull attribute only when the build is running under Clang static analyzer or Coverity. https://bugzilla.redhat.com/show_bug.cgi?id=1307346 --- configure.ac | 14 ++++++++++++++ src/util.h | 8 ++++++-- 2 files changed, 20 insertions(+), 2 deletions(-) diff --git a/configure.ac b/configure.ac index a06708b1a5ee64bb64c80272c10ed1a35670c8d0..48f5cb63c3bb5535fe1da56abe7583e15d4b5f92 100644 --- a/configure.ac +++ b/configure.ac @@ -39,6 +39,20 @@ AC_TRY_COMPILE([ [CFLAGS="$SAVED_CFLAGS" AC_MSG_RESULT([no])]) +# Check if build chain supports -fno-delete-null-pointer-checks +# this flag avoids too agressive optimizations which would remove some asserts +# BIND 9 did the same in its commit 603a78708343f063b44affb882ef93bb19a5142a +AC_MSG_CHECKING([for -fno-delete-null-pointer-checks compiler flag]) +SAVED_CFLAGS="$CFLAGS" +CFLAGS="-fno-delete-null-pointer-checks -Werror" +AC_TRY_COMPILE([ + extern int fdef(void); +],[], +[AC_MSG_RESULT([yes]) + CFLAGS="$SAVED_CFLAGS -fno-delete-null-pointer-checks"], +[CFLAGS="$SAVED_CFLAGS" + AC_MSG_RESULT([no])]) + # Get CFLAGS from isc-config.sh AC_ARG_VAR([BIND9_CFLAGS], [C compiler flags for bind9, overriding isc-config.sh]) diff --git a/src/util.h b/src/util.h index 9849ff9b6c38ec1c6dd143440d5b5e584b2ecd51..402503c339a5ab6ca5273cae420e743b9fc252ab 100644 --- a/src/util.h +++ b/src/util.h @@ -103,11 +103,15 @@ extern isc_boolean_t verbose_checks; /* from settings.c */ /* If no argument index list is given to the nonnull attribute, * all pointer arguments are marked as non-null. */ #define ATTR_NONNULLS ATTR_NONNULL() -#ifdef __GNUC__ +#if defined(__COVERITY__) || defined(__clang_analyzer__) #define ATTR_NONNULL(...) __attribute__((nonnull(__VA_ARGS__))) -#define ATTR_CHECKRESULT __attribute__((warn_unused_result)) #else #define ATTR_NONNULL(...) +#endif + +#if defined(__GNUC__) +#define ATTR_CHECKRESULT __attribute__((warn_unused_result)) +#else #define ATTR_CHECKRESULT #endif -- 2.5.0
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