RFR (S) 8249137: Remove CollectedHeap::obj_size

[Roman Kennke]

Looks good to me!

Thanks,
Roman

> > 
> 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)
>