RFR[XS] 8214686 [lworld][c1] Crash when invoking methods on value array

[Ioi Lam]

It seems like ciValueArrayKlass::exact_klass() is never called by C2.

However, C1 does call it when invoking vt_array.clone(), so I 
implemented this function.

My question is -- will this change be a potential problem for C2? Is the 
ShouldNotCallThis() there to catch problems in C2, or was it just never 
implemented because it's not needed?

Thanks
- Ioi

diff -r f19715f86b32 src/hotspot/share/ci/ciValueArrayKlass.cpp
--- a/src/hotspot/share/ci/ciValueArrayKlass.cpp    Sun Dec 02 20:00:41 
2018 -0800
+++ b/src/hotspot/share/ci/ciValueArrayKlass.cpp    Sun Dec 02 20:17:50 
2018 -0800
@@ -25,6 +25,7 @@
  #include "precompiled.hpp"
  #include "ci/ciInstanceKlass.hpp"
  #include "ci/ciValueArrayKlass.hpp"
+#include "ci/ciValueKlass.hpp"
  #include "ci/ciSymbol.hpp"
  #include "ci/ciUtilities.hpp"
  #include "ci/ciUtilities.inline.hpp"
@@ -161,6 +162,13 @@
  }

  ciKlass* ciValueArrayKlass::exact_klass() {
-  ShouldNotCallThis();
+  assert(element_klass()->is_valuetype(), "element type must be value 
type");
+  if (element_klass()->is_loaded()) {
+ assert(element_klass()->as_value_klass()->exact_klass() != NULL, "must 
be");
+    return this;
+  }
+
+  // TODO handle this
+  guarantee(false, "klass not loaded");
    return NULL;
  }