changeset 12533:fbb492c97959

8163880: Constant pool caching of fields inhibited/delayed unnecessarily Summary: Delay/inhibit constant pool caching of fields only if necessary Reviewed-by: kvn
author zmajo
date Mon, 29 Aug 2016 07:32:37 +0200
parents 8dcab338ec58
children 64840dbba932
files src/share/vm/interpreter/interpreterRuntime.cpp
diffstat 1 files changed, 21 insertions(+), 9 deletions(-) [+]
line wrap: on
line diff
--- a/src/share/vm/interpreter/interpreterRuntime.cpp	Fri Aug 26 14:47:52 2016 -0700
+++ b/src/share/vm/interpreter/interpreterRuntime.cpp	Mon Aug 29 07:32:37 2016 +0200
@@ -576,27 +576,39 @@
   // compute auxiliary field attributes
   TosState state  = as_TosState(info.field_type());
 
-  // Put instructions on final fields are not resolved. This is required so we throw
-  // exceptions at the correct place (when the instruction is actually invoked).
+  // Resolution of put instructions on final fields is delayed. That is required so that
+  // exceptions are thrown at the correct place (when the instruction is actually invoked).
   // If we do not resolve an instruction in the current pass, leaving the put_code
   // set to zero will cause the next put instruction to the same field to reresolve.
+
+  // Resolution of put instructions to final instance fields with invalid updates (i.e.,
+  // to final instance fields with updates originating from a method different than <init>)
+  // is inhibited. A putfield instruction targeting an instance final field must throw
+  // an IllegalAccessError if the instruction is not in an instance
+  // initializer method <init>. If resolution were not inhibited, a putfield
+  // in an initializer method could be resolved in the initializer. Subsequent
+  // putfield instructions to the same field would then use cached information.
+  // As a result, those instructions would not pass through the VM. That is,
+  // checks in resolve_field_access() would not be executed for those instructions
+  // and the required IllegalAccessError would not be thrown.
   //
   // Also, we need to delay resolving getstatic and putstatic instructions until the
   // class is initialized.  This is required so that access to the static
   // field will call the initialization function every time until the class
   // is completely initialized ala. in 2.17.5 in JVM Specification.
   InstanceKlass* klass = InstanceKlass::cast(info.field_holder());
-  bool uninitialized_static = ((bytecode == Bytecodes::_getstatic || bytecode == Bytecodes::_putstatic) &&
-                               !klass->is_initialized());
-
-  Bytecodes::Code put_code = (Bytecodes::Code)0;
-  if (is_put && !info.access_flags().is_final() && !uninitialized_static) {
-    put_code = ((is_static) ? Bytecodes::_putstatic : Bytecodes::_putfield);
-  }
+  bool uninitialized_static = is_static && !klass->is_initialized();
+  bool has_initialized_final_update = info.field_holder()->major_version() >= 53 &&
+                                      info.has_initialized_final_update();
+  assert(!(has_initialized_final_update && !info.access_flags().is_final()), "Fields with initialized final updates must be final");
 
   Bytecodes::Code get_code = (Bytecodes::Code)0;
+  Bytecodes::Code put_code = (Bytecodes::Code)0;
   if (!uninitialized_static) {
     get_code = ((is_static) ? Bytecodes::_getstatic : Bytecodes::_getfield);
+    if ((is_put && !has_initialized_final_update) || !info.access_flags().is_final()) {
+      put_code = ((is_static) ? Bytecodes::_putstatic : Bytecodes::_putfield);
+    }
   }
 
   cp_cache_entry->set_field(