RFR: Unreachable assert in ShenandoahCodeRoots::acquire_lock

[Roman Kennke]

Oops. Good catch! Go!

Am 5. September 2018 10:41:37 MESZ schrieb Aleksey Shipilev <shade at redhat.com>:
>Static analysis says that assert is unreachable. Indeed it is, because
>the loop exits with return.
>Not only that, the assert itself is incorrect.
>
>diff -r b67a4350c0b0
>src/hotspot/share/gc/shenandoah/shenandoahCodeRoots.hpp
>--- a/src/hotspot/share/gc/shenandoah/shenandoahCodeRoots.hpp   Tue Sep
>04 12:47:36 2018 -0400
>+++ b/src/hotspot/share/gc/shenandoah/shenandoahCodeRoots.hpp   Wed Sep
>05 09:37:45 2018 +0200
>@@ -151,16 +151,16 @@
>       while (true) {
>         int cur = OrderAccess::load_acquire(loc);
>         if (cur >= 0) {
>           if (Atomic::cmpxchg(cur + 1, loc, cur) == cur) {
>             // Success!
>+            assert (*loc > 0, "acquired for read");
>             return;
>           }
>         }
>         SpinPause();
>       }
>-      assert (*loc > 1, "acquired for read");
>     }
>   }
>
>   static void release_lock(bool write) {
>     volatile int* loc = &ShenandoahCodeRoots::_recorded_nms_lock;
>
>
>Testing: tier3_gc_shenandoah
>
>Thanks,
>-Aleksey