Bug: https://bugs.openjdk.java.net/browse/JDK-8151841 Webrev: http://cr.openjdk.java.net/~andrew/8151841/webrev.01/
A number of additional flags need to be passed to the C and C++ compiler for OpenJDK to compile with GCC 6: 1. The C++ standard needs to be explicitly lowered to the old default of gnu++98. With the new GCC default of C++14, the build fails, due to the way C++ is used in HotSpot and the JDK native code. Long term, it might be good to fix the code itself, in OpenJDK 9 or 10, but we need an interim solution to make OpenJDK buildable and one we can backport to existing supported version (6, 7 and 8). 2. A number of optimisations in GCC 6 lead to a broken JVM. We need to add -fno-delete-null-pointer-checks and -fno-lifetime-dse to get a working JVM. The webrev adds checks for these flags to configure and adds them if they are supported by GCC. It was necessary to split the macro FLAGS_COMPILER_CHECK_ARGUMENTS into FLAGS_C_COMPILER_CHECK_ARGUMENTS and FLAGS_CXX_COMPILER_CHECK_ARGUMENTS as the -std=g++98 argument is only applicable to the C++ compiler and will fail with the C compiler. With just the original macro, this would have meant that the argument never passed the test. I've built this locally on hs-rt/amd64 with GCC 5.3 successfully and I've also built a backport to 8u (nearly the same, but adjusted for macro placement and structural changes in 8u) on x86, amd64 and armv7hl with GCC 6 (Fedora rawhide) [0]. If this looks ok, let me know which tree to push it to; I'm not sure if it should go in as a general build change or a HotSpot change. [0] http://koji.fedoraproject.org/koji/taskinfo?taskID=13311585 Thanks. -- 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
