RFR: JDK-8301072: Replace NULL with nullptr in share/oops/

[Stefan Karlsson]

On Wed, 25 Jan 2023 11:46:23 GMT, Johan Sjölen <jsjolen at openjdk.org> wrote:

> Hi, this PR changes all occurrences of NULL to nullptr for the subdirectory share/oops/. Unfortunately the script that does the change isn't perfect, and so we
> need to comb through these manually to make sure nothing has gone wrong. I also review these changes but things slip past my eyes sometimes.
> 
> Here are some typical things to look out for:
> 
> 1. No changes but copyright header changed (probably because I reverted some changes but forgot the copyright).
> 2. Macros having their NULL changed to nullptr, these are added to the script when I find them. They should be NULL.
> 3. nullptr in comments and logs. We try to use lower case "null" in these cases as it reads better. An exception is made when code expressions are in a comment.
> 
> An example of this:
> 
> ```c++
> // This function returns null
> void* ret_null();
> // This function returns true if *x == nullptr
> bool is_nullptr(void** x);
> 
> 
> Note how `nullptr` participates in a code expression here, we really are talking about the specific value `nullptr`.
> 
> Thanks!

Changes requested by stefank (Reviewer).

src/hotspot/share/oops/compressedOops.inline.hpp line 63:

> 61: 
> 62: inline oop CompressedOops::decode(narrowOop v) {
> 63:   return is_null(v) ? (oop)nullptr : decode_not_null(v);

Seems like we should be able to remove the `(oop)` cast after this change.

src/hotspot/share/oops/compressedOops.inline.hpp line 140:

> 138: 
> 139: inline Klass* CompressedKlassPointers::decode(narrowKlass v) {
> 140:   return is_null(v) ? (Klass*)nullptr : decode_not_null(v);

Seems like we should be able to remove the `(Klass*)` cast after this change.

src/hotspot/share/oops/constantPool.hpp line 189:

> 187:   Symbol* generic_signature() const {
> 188:     return (_generic_signature_index == 0) ?
> 189:       (Symbol*)nullptr : symbol_at(_generic_signature_index);

Remove cast?

src/hotspot/share/oops/constantPool.hpp line 197:

> 195:   Symbol* source_file_name() const {
> 196:     return (_source_file_name_index == 0) ?
> 197:       (Symbol*)nullptr : symbol_at(_source_file_name_index);

Remove cast?

src/hotspot/share/oops/generateOopMap.cpp line 677:

> 675: #define ALLOC_RESOURCE_ARRAY(var, type, count) \
> 676:   var = NEW_RESOURCE_ARRAY_RETURN_NULL(type, count);              \
> 677:   if (var == nullptr) {                                              \

Could you fix the alignment of the backslashes?

src/hotspot/share/oops/instanceKlass.cpp line 2166:

> 2164:   if (jmeths == nullptr ||   // no cache yet
> 2165:       length <= idnum ||  // cache is too short
> 2166:       id == nullptr) {       // cache doesn't contain entry

Comments seems to be misaligned now.

src/hotspot/share/oops/instanceKlass.cpp line 2259:

> 2257: 
> 2258:   if (jmeths == nullptr ||                         // no cache yet
> 2259:       (length = (size_t)jmeths[0]) <= idnum) {  // cache is too short

Alignment of comments

src/hotspot/share/oops/instanceKlass.cpp line 2318:

> 2316:   if (jmeths != NULL &&                         // If there is a cache
> 2317:       (length = (size_t)jmeths[0]) > idnum) {   // and if it is long enough,
> 2318:     id = jmeths[idnum+1];                       // Look up the id (may be NULL)

Alignment of comments

src/hotspot/share/oops/klass.cpp line 433:

> 431:   if (super == NULL) return;        // special case: class Object
> 432:   assert((!super->is_interface()    // interfaces cannot be supers
> 433:           && (super->superklass() == NULL || !is_interface())),

Alignment of comments

src/hotspot/share/oops/method.hpp line 167:

> 165: 
> 166:   // generics support
> 167:   Symbol* generic_signature() const              { int idx = generic_signature_index(); return ((idx != 0) ? constants()->symbol_at(idx) : (Symbol*)nullptr); }

Remove cast?

src/hotspot/share/oops/oopHandle.inline.hpp line 34:

> 32: 
> 33: inline oop OopHandle::resolve() const {
> 34:   return (_obj == nullptr) ? (oop)nullptr : NativeAccess<>::oop_load(_obj);

Remove cast?

src/hotspot/share/oops/oopHandle.inline.hpp line 38:

> 36: 
> 37: inline oop OopHandle::peek() const {
> 38:   return (_obj == nullptr) ? (oop)nullptr : NativeAccess<AS_NO_KEEPALIVE>::oop_load(_obj);

Remove cast?

src/hotspot/share/oops/oopHandle.inline.hpp line 53:

> 51:   if (_obj != nullptr) {
> 52:     // Clear the OopHandle first
> 53:     NativeAccess<>::oop_store(_obj, (oop)nullptr);

Remove cast?

src/hotspot/share/oops/weakHandle.cpp line 54:

> 52:     // Clear the WeakHandle.  For race in creating ClassLoaderData, we can release this
> 53:     // WeakHandle before it is cleared by GC.
> 54:     NativeAccess<ON_PHANTOM_OOP_REF>::oop_store(_obj, (oop)nullptr);

Remove cast?

-------------

PR: https://git.openjdk.org/jdk/pull/12186