PING: [8u112] Request for review & approval for CR8151841: Build needs additional flags to compile with GCC 6

[Andrew Hughes]

Ping?

----- Original Message -----
> ----- Original Message -----
> > Hello,
> > 
> > It looks like TOOLCHAIN_CXX_COMPILER_CHECK_ARGUMENTS is always returning
> > yes and TOOLCHAIN_C_COMPILER_CHECK_ARGUMENTS still does both the C and
> > C++ checks.
> > 
> 
> Ugh, merged a block in the wrong place by the looks of it.
> 
> Fixed in http://cr.openjdk.java.net/~andrew/8u/8151841/webrev.02/
> 
> configure:29739: checking if the C++ compiler supports "-std=gnu++98 "
> configure:29755: /usr/bin/g++ -c  -std=gnu++98   conftest.cpp >&5
> configure:29755: $? = 0
> configure:29769: result: yes
> configure:29815: checking if the C compiler supports
> "-fno-delete-null-pointer-checks -Werror"
> configure:29832: /usr/bin/gcc -c  -fno-delete-null-pointer-checks -Werror
> conftest.c >&5
> configure:29832: $? = 0
> configure:29846: result: yes
> configure:29855: checking if the C++ compiler supports
> "-fno-delete-null-pointer-checks -Werror"
> configure:29871: /usr/bin/g++ -c  -fno-delete-null-pointer-checks -Werror
> conftest.cpp >&5
> configure:29871: $? = 0
> configure:29885: result: yes
> configure:29894: checking if both compilers support
> "-fno-delete-null-pointer-checks -Werror"
> configure:29899: result: yes
> configure:29911: checking if the C compiler supports "-fno-lifetime-dse
> -Werror"
> configure:29927: /usr/bin/gcc -c  -fno-lifetime-dse -Werror  conftest.c >&5
> configure:29927: $? = 0
> configure:29941: result: yes
> configure:29950: checking if the C++ compiler supports "-fno-lifetime-dse
> -Werror"
> configure:29966: /usr/bin/g++ -c  -fno-lifetime-dse -Werror  conftest.cpp >&5
> configure:29966: $? = 0
> configure:29980: result: yes
> configure:29989: checking if both compilers support "-fno-lifetime-dse
> -Werror"
> configure:29994: result: yes
> 
> 
> > /Erik
> > 
> > On 2016-07-07 22:21, Andrew Hughes wrote:
> > > Webrev: http://cr.openjdk.java.net/~andrew/8u/8151841/webrev.01/
> > > Bug: https://bugs.openjdk.java.net/browse/JDK-8151841
> > >
> > > This is a backport of the original fix to support building OpenJDK
> > > with GCC 6. It was necessary to cherry-pick parts of a number of
> > > earlier fixes to make this work with the build system in 8:
> > >
> > > 8149647: Incremental enhancements from build-infra
> > > 8032045: Enable compiler and linker safety switches for debug builds
> > >
> > > and so I'm requesting a review of the 8 version of the patch here as well
> > > as approval for 8u.
> > >
> > > In brief, the patch makes OpenJDK build with GCC 6 by explicitly
> > > specifying
> > > the C++ standard to use (-std=gnu++98) and disabling two optimisations
> > > with
> > > -fno-lifetime-dse and -fno-delete-null-pointer-checks. Further
> > > information
> > > on the changes is available in the GCC 6 release notes [0]. GCC 6 uses
> > > a newer C++ standard, C++14, with which the OpenJDK codebase is not yet
> > > compliant. The simplest way to fix this, especially for existing
> > > releases,
> > > is to explicitly request the previous default, gnu++98. The deletion
> > > of null pointer checks and more aggressive lifetime dead store
> > > elimination
> > > in 6 lead to a crashing virtual machine being built, so we disable them
> > > if GCC >= 6 is used.
> > >
> > > To make the original patch work with 8u, a number of changes from other
> > > fixes had to also be brought over:
> > >
> > > * We need to check we are using GCC 6 or above, so we need to bring
> > > over the TOOLCHAIN_CHECK_COMPILER_VERSION and
> > > TOOLCHAIN_PREPARE_FOR_VERSION_COMPARISONS macros from 8149647.
> > > TOOLCHAIN_CHECK_COMPILER_VERSION is converted back to a traditional
> > > numbered rather than named argument macro so we don't need to backport
> > > BASIC_DEFUN_NAMED.
> > > * We bring over the introduction of COMMON_CCXXFLAGS_JDK from 8030245
> > > as we need to apply the -std option only to the C++ compiler, not the
> > > C compiler. If passed to the C compiler, it will produce a warning,
> > > and this is converted to an error at one point in the build
> > > (a -Werror in libsctp).
> > >
> > > Generally, we've kept things in toolchain.m4 (8034788 introduced
> > > flags.m4,
> > > separating out some code, and so many of these changes are in that file
> > > in 9) and avoid named argument macros. Otherwise, it's largely the
> > > same as the 9 version. We have adopted the longer name for
> > > the -fno-delete-null-pointer-checks flag variable as suggested in the
> > > review of the update to this patch for the new HotSpot build [1].
> > >
> > > [0] https://gcc.gnu.org/gcc-6/porting_to.html
> > > [1]
> > > http://mail.openjdk.java.net/pipermail/hotspot-dev/2016-July/023840.html
> > 
> > 
> 
> --
> Andrew :)
> 
> Senior Free Java Software Engineer
> Red Hat, Inc. (http://www.redhat.com)
> 
> PGP Key: ed25519/35964222 (hkp://keys.gnupg.net)
> Fingerprint = 5132 579D D154 0ED2 3E04  C5A0 CFDA 0F9B 3596 4222
> 
> 
> 

-- 
Andrew :)

Senior Free Java Software Engineer
Red Hat, Inc. (http://www.redhat.com)

PGP Key: ed25519/35964222 (hkp://keys.gnupg.net)
Fingerprint = 5132 579D D154 0ED2 3E04  C5A0 CFDA 0F9B 3596 4222