RFR: Remove ShenandoahCompileCheck

[Aleksey Shipilev]

This increases our upstream exposure. I asked if upstream wants to have it generically:
  http://mail.openjdk.java.net/pipermail/hotspot-compiler-dev/2018-October/030912.html

...but there is no need to have it in upstreamable Shenandoah:

diff -r 429af28fcb53 src/hotspot/share/compiler/compileBroker.cpp
--- a/src/hotspot/share/compiler/compileBroker.cpp      Thu Oct 11 09:40:48 2018 -0400
+++ b/src/hotspot/share/compiler/compileBroker.cpp      Thu Oct 11 18:47:55 2018 +0200
@@ -2089,8 +2089,4 @@
     ciMethod* target = ci_env.get_method_from_handle(target_handle);

-#if INCLUDE_SHENANDOAHGC
-    bool target_compilable = target->can_be_parsed() && target->can_be_compiled();
-#endif
-
     TraceTime t1("compilation", &time);
     EventCompilation event;
@@ -2124,11 +2120,4 @@
     }

-#if INCLUDE_SHENANDOAHGC
-    guarantee(!UseShenandoahGC || !ShenandoahCompileCheck || !target_compilable || (compilable !=
ciEnv::MethodCompilable_not_at_tier),
-              "Not compilable on level %d due to: %s", task_level, failure_reason);
-    guarantee(!UseShenandoahGC || !ShenandoahCompileCheck || !target_compilable ||(compilable !=
ciEnv::MethodCompilable_never || !target_compilable),
-              "Never compilable due to: %s", failure_reason);
-#endif
-
     post_compile(thread, task, !ci_env.failing(), &ci_env);
     if (event.should_commit()) {
diff -r 429af28fcb53 src/hotspot/share/gc/shenandoah/shenandoah_globals.hpp
--- a/src/hotspot/share/gc/shenandoah/shenandoah_globals.hpp    Thu Oct 11 09:40:48 2018 -0400
+++ b/src/hotspot/share/gc/shenandoah/shenandoah_globals.hpp    Thu Oct 11 18:47:55 2018 +0200
@@ -420,7 +420,4 @@
           "Use Elastic TLABs with Shenandoah")                              \
                                                                             \
-  diagnostic(bool, ShenandoahCompileCheck, false,                           \
-          "Assert that methods are successfully compilable")                \
-                                                                            \
   experimental(bool, ShenandoahAlwaysClearSoftRefs, false,                  \
           "Clear soft references unconditionally")                          \

Testing: tier3_gc_shenandoah

Thanks,
-Aleksey