RFR (S) 8249137: Remove CollectedHeap::obj_size

[Aleksey Shipilev]

Okay, thanks.

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

-Aleksey

On 7/9/20 3:34 PM, Daniel D. Daugherty wrote:
> Adding serviceability-dev at ... 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)
>>
> 


-- 
Thanks,
-Aleksey

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