Hi, please review this build-only workaround for a GCC bug [1]. The problem surfaced on ARM32 when new code [2] got inlined with old code. In GCC at RTL level there is no good distinction between pointer and int, which makes it hard for the aliasing code to correctly recognize base addresses for objects, which leads to incorrect aliasing. As a consequence one of the loads in this code was completely eliminated on ARM32 by DSE. All GCC versions I could reach are affected.
Thanks to the GCC community, the fix will appear in GCC 10 but before it becomes mainstream we need a workaround. The workaround is to disable -ftree-pre optimization on ARM32 which triggers the bug. The problem does not surface on x86 in this code. issue: https://bugs.openjdk.java.net/browse/JDK-8231612 webrev: http://cr.openjdk.java.net/~avoitylov/webrev.8231612.02/ Testing on ARM32: the problem described in 8231612 (100% CPU utilization in Service Thread) no longer appears, the load is not eliminated as observed by disassembly. Testing on x86_64: linux-x86_64-server-release builds OK after this change. Thanks, -Aleksei [1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92462 [2] https://bugs.openjdk.java.net/browse/JDK-8226366
