Re: RFR (S) 8249137: Remove CollectedHeap::obj_size

[Chris Plummer]

Looks good to me.

Chris

On 7/10/20 8:07 AM, Daniel D. Daugherty wrote:

On 7/10/20 4:37 AM, Aleksey Shipilev wrote:

Okay, thanks.

I already have 2 reviewers (rkennke, tschatzl), do I need more specifically from serviceability-dev@?

Since you're touching the Serviceability team's code, it would be
polite to wait for a review...

Dan

-Aleksey

On 7/9/20 3:34 PM, Daniel D. Daugherty wrote:

Adding serviceability-dev@... since a couple of JVM/TI files are changed

in this RFR. Also, I moved the bug from hotspot/runtime -> hotspot/gc.

Dan


On 7/9/20 2:36 AM, Aleksey Shipilev wrote:

RFE:
    https://bugs.openjdk.java.net/browse/JDK-8249137

It was added by JDK-8211270 to support old-style Shenandoah that needed a separate fwdptr slot. After JDK-8224584 it does not need this anymore. Additionally, CH::obj_size may disagree with other code that pokes at layout helper directly, for example GraphKit::new_instance.

This also avoids a virtual call on some paths, although those paths are not very performance-sensitive.

The patch is a simple series of few-liners:

diff -r 9cc348ebdc82 src/hotspot/share/gc/shared/collectedHeap.cpp

--- a/src/hotspot/share/gc/shared/collectedHeap.cpp     Thu Jul 09 04:32:30 2020 +0200 +++ b/src/hotspot/share/gc/shared/collectedHeap.cpp     Thu Jul 09 08:05:46 2020 +0200

@@ -578,6 +578,2 @@

-size_t CollectedHeap::obj_size(oop obj) const {
-  return obj->size();
-}
-
   uint32_t CollectedHeap::hash_oop(oop obj) const {
diff -r 9cc348ebdc82 src/hotspot/share/gc/shared/collectedHeap.hpp

--- a/src/hotspot/share/gc/shared/collectedHeap.hpp     Thu Jul 09 04:32:30 2020 +0200 +++ b/src/hotspot/share/gc/shared/collectedHeap.hpp     Thu Jul 09 08:05:46 2020 +0200

@@ -495,4 +495,2 @@

-  virtual size_t obj_size(oop obj) const;
-
     // Non product verification and debugging.
diff -r 9cc348ebdc82 src/hotspot/share/prims/jvmtiEnv.cpp

--- a/src/hotspot/share/prims/jvmtiEnv.cpp      Thu Jul 09 04:32:30 2020 +0200 +++ b/src/hotspot/share/prims/jvmtiEnv.cpp      Thu Jul 09 08:05:46 2020 +0200

@@ -488,3 +488,3 @@
     NULL_CHECK(mirror, JVMTI_ERROR_INVALID_OBJECT);
-  *size_ptr = (jlong)Universe::heap()->obj_size(mirror) * wordSize;
+  *size_ptr = (jlong)mirror->size() * wordSize;
     return JVMTI_ERROR_NONE;
diff -r 9cc348ebdc82 src/hotspot/share/prims/jvmtiExport.cpp

--- a/src/hotspot/share/prims/jvmtiExport.cpp   Thu Jul 09 04:32:30 2020 +0200 +++ b/src/hotspot/share/prims/jvmtiExport.cpp   Thu Jul 09 08:05:46 2020 +0200

@@ -1067,3 +1067,3 @@
        _jobj = (jobject)to_jobject(obj);
-     _size = Universe::heap()->obj_size(obj) * wordSize;
+     _size = obj->size() * wordSize;
      };
diff -r 9cc348ebdc82 src/hotspot/share/prims/whitebox.cpp

--- a/src/hotspot/share/prims/whitebox.cpp      Thu Jul 09 04:32:30 2020 +0200 +++ b/src/hotspot/share/prims/whitebox.cpp      Thu Jul 09 08:05:46 2020 +0200

@@ -389,3 +389,3 @@
     oop p = JNIHandles::resolve(obj);
-  return Universe::heap()->obj_size(p) * HeapWordSize;
+  return p->size() * HeapWordSize;
   WB_END

Testing: tier{1,2}; jdk-submit (running)