JVMCI support

Author: mur47x111

src/hotspot/share/jvmci/jvmciCompilerToVM.hpp

@@ -39,6 +39,9 @@ class CompilerToVM {
     friend class JVMCIVMStructs;
 
    private:
+    static int oopDesc_klass_offset_in_bytes;
+    static int arrayOopDesc_length_offset_in_bytes;
+
     static int Klass_vtable_start_offset;
     static int Klass_vtable_length_offset;
 

src/hotspot/share/jvmci/jvmciCompilerToVMInit.cpp

@@ -56,6 +56,8 @@
 #include "runtime/stubRoutines.hpp"
 #include "utilities/resourceHash.hpp"
 
+int CompilerToVM::Data::oopDesc_klass_offset_in_bytes;
+int CompilerToVM::Data::arrayOopDesc_length_offset_in_bytes;
 
 int CompilerToVM::Data::Klass_vtable_start_offset;
 int CompilerToVM::Data::Klass_vtable_length_offset;
@@ -148,6 +150,9 @@ int CompilerToVM::Data::data_section_item_alignment;
 JVMTI_ONLY( int* CompilerToVM::Data::_should_notify_object_alloc; )
 
 void CompilerToVM::Data::initialize(JVMCI_TRAPS) {
+  oopDesc_klass_offset_in_bytes = oopDesc::klass_offset_in_bytes();
+  arrayOopDesc_length_offset_in_bytes = arrayOopDesc::length_offset_in_bytes();
+
   Klass_vtable_start_offset = in_bytes(Klass::vtable_start_offset());
   Klass_vtable_length_offset = in_bytes(Klass::vtable_length_offset());
 

src/hotspot/share/jvmci/vmStructs_jvmci.cpp

@@ -56,6 +56,9 @@
 #endif
 
 #define VM_STRUCTS(nonstatic_field, static_field, unchecked_nonstatic_field, volatile_nonstatic_field) \
+  static_field(CompilerToVM::Data,             oopDesc_klass_offset_in_bytes,          int)                                          \
+  static_field(CompilerToVM::Data,             arrayOopDesc_length_offset_in_bytes,    int)                                          \
+                                                                                                                                     \
   static_field(CompilerToVM::Data,             Klass_vtable_start_offset,              int)                                          \
   static_field(CompilerToVM::Data,             Klass_vtable_length_offset,             int)                                          \
                                                                                                                                      \
@@ -794,6 +797,7 @@
   declare_constant(InvocationCounter::count_increment)                    \
   declare_constant(InvocationCounter::count_shift)                        \
                                                                           \
+  declare_constant(markWord::klass_shift)                                 \
   declare_constant(markWord::hash_shift)                                  \
   declare_constant(markWord::monitor_value)                               \
                                                                           \

src/hotspot/share/oops/oop.hpp

@@ -331,12 +331,12 @@ class oopDesc {
   static int klass_offset_in_bytes()     {
 #ifdef _LP64
     if (UseCompactObjectHeaders) {
-      // NOTE: The only place where this is used with compact headers is
-      // the C2 compiler, and even there we don't use it to access the (narrow)Klass*
+      // NOTE: The only places where this is used with compact headers are the C2
+      // compiler and JVMCI, and even there we don't use it to access the (narrow)Klass*
       // directly. It is used only as a placeholder to identify the special memory slice
-      // of LoadNKlass instructions. This value could be any value that is not a valid
+      // containing Klass* info. This value could be any value that is not a valid
       // field offset. Use an offset halfway into the markWord, as the markWord is never
-      // partially loaded from C2.
+      // partially loaded from C2 and JVMCI.
       return mark_offset_in_bytes() + 4;
     } else
 #endif

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

@@ -69,7 +69,7 @@ String getHostArchitectureName() {
 
     final int objectAlignment = getFlag("ObjectAlignmentInBytes", Integer.class);
 
-    final int hubOffset = getFieldOffset("oopDesc::_metadata._klass", Integer.class, "Klass*");
+    final int klassOffsetInBytes = getFieldValue("CompilerToVM::Data::oopDesc_klass_offset_in_bytes", Integer.class, "int");
 
     final int subklassOffset = getFieldOffset("Klass::_subklass", Integer.class, "Klass*");
     final int superOffset = getFieldOffset("Klass::_super", Integer.class, "Klass*");

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

@@ -191,7 +191,11 @@ HotSpotResolvedObjectTypeImpl getType(HotSpotObjectConstantImpl object) {
             String name = theClass.getName().replace('.', '/');
             return (HotSpotResolvedObjectTypeImpl) runtime().compilerToVm.lookupType(theClass.getClassLoader(), name);
         }
-        return runtime().compilerToVm.getResolvedJavaType(object, runtime().getConfig().hubOffset, false);
+        // HotSpot tests if the offset is oopDesc::klass_offset_in_bytes() and returns
+        // the object type accordingly. When UseCompactClassPointers is enabled,
+        // oopDesc::klass_offset_in_bytes() will return an offset halfway into the
+        // object's markWord as a placeholder referring to the klass pointer.
+        return runtime().compilerToVm.getResolvedJavaType(object, runtime().getConfig().klassOffsetInBytes, false);
     }
 
     @Override