fix System.loadLibrary for OpenJDK tails=true build

src/avian/machine.h

@@ -1583,6 +1583,10 @@ class Classpath {
   virtual int64_t
   getDirectBufferCapacity(Thread* t, object buffer) = 0;
 
+  virtual bool
+  canTailCall(Thread* t, object caller, object calleeClassName,
+              object calleeMethodName, object calleeMethodSpec) = 0;
+
   virtual void
   dispose() = 0;
 };

src/classpath-android.cpp

@@ -439,6 +439,12 @@ class MyClasspath : public Classpath {
     return fieldAtOffset<int32_t>(b, fieldOffset(t, field));
   }
 
+  virtual bool
+  canTailCall(Thread*, object, object, object, object)
+  {
+    return true;
+  }
+
   virtual void
   dispose()
   {

src/classpath-avian.cpp

@@ -174,6 +174,12 @@ class MyClasspath : public Classpath {
     return fieldAtOffset<int32_t>(b, fieldOffset(t, field));
   }
 
+  virtual bool
+  canTailCall(Thread*, object, object, object, object)
+  {
+    return true;
+  }
+
   virtual void
   dispose()
   {

src/classpath-openjdk.cpp

@@ -842,6 +842,30 @@ class MyClasspath : public Classpath {
     return fieldAtOffset<int32_t>(b, fieldOffset(t, field));
   }
 
+  virtual bool
+  canTailCall(Thread* t, object, object calleeClassName,
+              object calleeMethodName, object)
+  {
+    // we can't tail call System.loadLibrary or Runtime.loadLibrary
+    // due to their use of System.getCallerClass, which gets confused
+    // if we elide stack frames.
+
+    return (strcmp("loadLibrary", reinterpret_cast<char*>
+                  (&byteArrayBody(t, calleeMethodName, 0)))
+            or (strcmp("java/lang/System", reinterpret_cast<char*>
+                       (&byteArrayBody(t, calleeClassName, 0)))
+                and strcmp("java/lang/Runtime", reinterpret_cast<char*>
+                           (&byteArrayBody(t, calleeClassName, 0)))))
+
+      // and we can't tail call Reflection.getCallerClass because the
+      // number of stack frames will be wrong
+
+      and (strcmp("getCallerClass", reinterpret_cast<char*>
+                  (&byteArrayBody(t, calleeMethodName, 0)))
+           or strcmp("sun/reflect/Reflection", reinterpret_cast<char*>
+                     (&byteArrayBody(t, calleeClassName, 0))));
+  }
+
   virtual void
   dispose()
   { 

src/compile.cpp

@@ -3730,7 +3730,8 @@ returnsNext(MyThread* t, object code, unsigned ip)
 
 bool
 isTailCall(MyThread* t, object code, unsigned ip, object caller,
-           int calleeReturnCode)
+           int calleeReturnCode, object calleeClassName,
+           object calleeMethodName, object calleeMethodSpec)
 {
   return avian::codegen::TailCalls
     and ((methodFlags(t, caller) & ACC_SYNCHRONIZED) == 0)
@@ -3738,21 +3739,32 @@ isTailCall(MyThread* t, object code, unsigned ip, object caller,
     and (not needsReturnBarrier(t, caller))
     and (methodReturnCode(t, caller) == VoidField
          or methodReturnCode(t, caller) == calleeReturnCode)
-    and returnsNext(t, code, ip);
+    and returnsNext(t, code, ip)
+    and t->m->classpath->canTailCall
+    (t, caller, calleeClassName, calleeMethodName, calleeMethodSpec);
 }
 
 bool
 isTailCall(MyThread* t, object code, unsigned ip, object caller, object callee)
 {
-  return isTailCall(t, code, ip, caller, methodReturnCode(t, callee));
+  return isTailCall
+    (t, code, ip, caller, methodReturnCode(t, callee),
+     className(t, methodClass(t, callee)), methodName(t, callee),
+     methodSpec(t, callee));
 }
 
 bool
 isReferenceTailCall(MyThread* t, object code, unsigned ip, object caller,
                     object calleeReference)
 {
+  object c = referenceClass(t, calleeReference);
+  if (objectClass(t, c) == type(t, Machine::ClassType)) {
+    c = className(t, c);
+  }
+
   return isTailCall
-    (t, code, ip, caller, methodReferenceReturnCode(t, calleeReference));
+    (t, code, ip, caller, methodReferenceReturnCode(t, calleeReference),
+     c, referenceName(t, calleeReference), referenceSpec(t, calleeReference));
 }
 
 bool