8355896: Lossy narrowing cast of JVMCINMethodData::size

Reviewed-by: kvn, dnsimon

Author: Boris Ulasevich

src/hotspot/share/code/nmethod.cpp

@@ -1323,8 +1323,9 @@ nmethod::nmethod(
     _unwind_handler_offset   = 0;
 
     CHECKED_CAST(_oops_size, uint16_t, align_up(code_buffer->total_oop_size(), oopSize));
-    int metadata_size = align_up(code_buffer->total_metadata_size(), wordSize);
-    JVMCI_ONLY( _jvmci_data_size = 0; )
+    uint16_t metadata_size;
+    CHECKED_CAST(metadata_size, uint16_t, align_up(code_buffer->total_metadata_size(), wordSize));
+    JVMCI_ONLY( _metadata_size = metadata_size; )
     assert(_mutable_data_size == _relocation_size + metadata_size,
            "wrong mutable data size: %d != %d + %d",
            _mutable_data_size, _relocation_size, metadata_size);
@@ -1497,9 +1498,10 @@ nmethod::nmethod(
     }
 
     CHECKED_CAST(_oops_size, uint16_t, align_up(code_buffer->total_oop_size(), oopSize));
-    uint16_t metadata_size = (uint16_t)align_up(code_buffer->total_metadata_size(), wordSize);
-    JVMCI_ONLY(CHECKED_CAST(_jvmci_data_size, uint16_t, align_up(compiler->is_jvmci() ? jvmci_data->size() : 0, oopSize)));
-    int jvmci_data_size = 0 JVMCI_ONLY(+ _jvmci_data_size);
+    uint16_t metadata_size;
+    CHECKED_CAST(metadata_size, uint16_t, align_up(code_buffer->total_metadata_size(), wordSize));
+    JVMCI_ONLY( _metadata_size = metadata_size; )
+    int jvmci_data_size = 0 JVMCI_ONLY( + align_up(compiler->is_jvmci() ? jvmci_data->size() : 0, oopSize));
     assert(_mutable_data_size == _relocation_size + metadata_size + jvmci_data_size,
            "wrong mutable data size: %d != %d + %d + %d",
            _mutable_data_size, _relocation_size, metadata_size, jvmci_data_size);

src/hotspot/share/code/nmethod.hpp

@@ -237,7 +237,9 @@ class nmethod : public CodeBlob {
 
   uint16_t _oops_size;
 #if INCLUDE_JVMCI
-  uint16_t _jvmci_data_size;
+  // _metadata_size is not specific to JVMCI. In the non-JVMCI case, it can be derived as:
+  // _metadata_size = mutable_data_size - relocation_size
+  uint16_t _metadata_size;
 #endif
 
   // Offset in immutable data section
@@ -537,8 +539,8 @@ class nmethod : public CodeBlob {
   // mutable data
   Metadata** metadata_begin     () const { return (Metadata**) (mutable_data_begin() + _relocation_size); }
 #if INCLUDE_JVMCI
-  Metadata** metadata_end       () const { return (Metadata**) (mutable_data_end() - _jvmci_data_size); }
-  address jvmci_data_begin      () const { return               mutable_data_end() - _jvmci_data_size; }
+  Metadata** metadata_end       () const { return (Metadata**) (mutable_data_begin() + _relocation_size + _metadata_size); }
+  address jvmci_data_begin      () const { return               mutable_data_begin() + _relocation_size + _metadata_size; }
   address jvmci_data_end        () const { return               mutable_data_end(); }
 #else
   Metadata** metadata_end       () const { return (Metadata**)  mutable_data_end(); }