Review comments

Author: tkrodriguez

src/hotspot/share/jvmci/jvmciCompilerToVM.cpp

@@ -409,6 +409,7 @@ C2V_VMENTRY_NULL(jobject, getResolvedJavaType0, (JNIEnv* env, jobject, jobject b
     JVMCI_THROW_MSG_NULL(NullPointerException, "base object is null");
   }
 
+  const char* base_desc = nullptr;
   JVMCIKlassHandle klass(THREAD);
   if (offset == oopDesc::klass_offset_in_bytes()) {
     if (JVMCIENV->isa_HotSpotObjectConstantImpl(base_object)) {
@@ -423,6 +424,7 @@ C2V_VMENTRY_NULL(jobject, getResolvedJavaType0, (JNIEnv* env, jobject, jobject b
       if (offset == ConstantPool::pool_holder_offset_in_bytes()) {
         klass = cp->pool_holder();
       } else {
+        base_desc = FormatBufferResource("[constant pool for %s]", cp->pool_holder()->signature_name());
         goto unexpected;
       }
     } else if (JVMCIENV->isa_HotSpotResolvedObjectTypeImpl(base_object)) {
@@ -442,6 +444,7 @@ C2V_VMENTRY_NULL(jobject, getResolvedJavaType0, (JNIEnv* env, jobject, jobject b
         int index = (offset - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
         klass = base_klass->primary_super_of_depth(index);
       } else {
+        base_desc = FormatBufferResource("[%s]", base_klass->signature_name());
         goto unexpected;
       }
     } else if (JVMCIENV->isa_HotSpotObjectConstantImpl(base_object)) {
@@ -452,9 +455,13 @@ C2V_VMENTRY_NULL(jobject, getResolvedJavaType0, (JNIEnv* env, jobject, jobject b
         } else if (offset == java_lang_Class::array_klass_offset()) {
           klass = java_lang_Class::array_klass_acquire(base_oop());
         } else {
+          base_desc = FormatBufferResource("[Class=%s]", java_lang_Class::as_Klass(base_oop())->signature_name());
           goto unexpected;
         }
       } else {
+        if (!base_oop.is_null()) {
+          base_desc = FormatBufferResource("[%s]", base_oop()->klass()->signature_name());
+        }
         goto unexpected;
       }
     } else if (JVMCIENV->isa_HotSpotMethodData(base_object)) {
@@ -481,8 +488,8 @@ C2V_VMENTRY_NULL(jobject, getResolvedJavaType0, (JNIEnv* env, jobject, jobject b
 
 unexpected:
   JVMCI_THROW_MSG_NULL(IllegalArgumentException,
-                       err_msg("Unexpected arguments: %s " JLONG_FORMAT " %s",
-                               base_object.is_non_null() ? JVMCIENV->klass_name(base_object) : "null",
+                       err_msg("Unexpected arguments: %s%s " JLONG_FORMAT " %s",
+                               JVMCIENV->klass_name(base_object), base_desc == nullptr ? "" : base_desc,
                                offset, compressed ? "true" : "false"));
 }
 

src/jdk.internal.vm.ci/share/classes/jdk/vm/ci/hotspot/CompilerToVM.java

@@ -868,19 +868,21 @@ HotSpotConstantPool getConstantPool(MetaspaceObject object) {
 
     /**
      * Read a {@code Klass*} value from the memory location described by {@code base} plus
-     * {@code displacement} and return the {@link HotSpotResolvedObjectTypeImpl} wrapping it. This
-     * method does no checking that the memory location actually contains a valid pointer and may
-     * crash the VM if an invalid location is provided. If the {@code base} is null then
-     * {@code displacement} is used by itself. If {@code base} is a
-     * {@link HotSpotResolvedJavaMethodImpl}, {@link HotSpotConstantPool} or
-     * {@link HotSpotResolvedObjectTypeImpl} then the metaspace pointer is fetched from that object
-     * and added to {@code displacement}. Any other non-null object type causes an
-     * {@link IllegalArgumentException} to be thrown.
+     * {@code displacement} and return the {@link HotSpotResolvedObjectTypeImpl} wrapping it. This method
+     * only performs the read if the memory location is known to contain a valid Klass*.  If
+     * {@code base} is a {@link HotSpotConstantPool}, {@link HotSpotMethodData}, {@link HotSpotObjectConstantImpl},
+     * or {@link HotSpotResolvedObjectTypeImpl} then the field
+     * corresopnding to {@code displacement} is fetched using the appropriate HotSpot accessor. Any
+     * other object type or an unexpected displacement causes an {@link IllegalArgumentException} to
+     * be thrown.  The set of fields which can be read in this fashion corresponds to the {@link VMField}
+     * with type {@code Klass*} that are described in the {@link HotSpotVMConfigStore#getFields()}.
+     * Additionally several injected fields in {@link Class} are also handled.
      *
-     * @param base an object to read from or null
+     * @param base an object to read from
      * @param displacement
      * @param compressed true if the location contains a compressed Klass*
      * @return null or the resolved method for this location
+     * @throws NullPointerException if {@code base == null}
      */
     private native HotSpotResolvedObjectTypeImpl getResolvedJavaType0(Object base, long displacement, boolean compressed);