The JDK8u backport of 8034788 changed the variable name CXX_VERSION (in configure) to CXX_VERSION_NUMBER. Unfortunately this was not done consistently, and as a result the version number check for GCC is broken. As a result of that brokenness, HotSpot built on all GCC versions >=6 is unstable.
Intriguingly, the comments aroud te affected code are correct, and refer to CXX_VERSION_NUMBER, but the actual variable name is wrong. http://cr.openjdk.java.net/~aph/8210423/ OK? -- Andrew Haley Java Platform Lead Engineer Red Hat UK Ltd. <https://www.redhat.com> EAC8 43EB D3EF DB98 CC77 2FAD A5CD 6035 332F A671