RFR: JDK-8301498: Replace NULL with nullptr in cpu/x86

[Johan Sjölen]

On Tue, 31 Jan 2023 11:40:19 GMT, Johan Sjölen <jsjolen at openjdk.org> wrote:

> Hi, this PR changes all occurrences of NULL to nullptr for the subdirectory cpu/x86. 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!

Some things to fix

Builds and sent out for testing.

src/hotspot/cpu/x86/frame_x86.inline.hpp line 163:

> 161:   // value.
> 162:   // UPDATE: this constructor is only used by trace_method_handle_stub() now.
> 163:   // assert(_pc != null, "no pc?");

nullptr

src/hotspot/cpu/x86/gc/g1/g1BarrierSetAssembler_x86.cpp line 233:

> 231:   // Calling the runtime using the regular call_VM_leaf mechanism generates
> 232:   // code (generated by InterpreterMacroAssember::call_VM_leaf_base)
> 233:   // that checks that the *(ebp+frame::interpreter_frame_last_sp) == null.

nullptr

src/hotspot/cpu/x86/gc/shenandoah/shenandoahBarrierSetAssembler_x86.cpp line 267:

> 265:   // Calling the runtime using the regular call_VM_leaf mechanism generates
> 266:   // code (generated by InterpreterMacroAssember::call_VM_leaf_base)
> 267:   // that checks that the *(ebp+frame::interpreter_frame_last_sp) == null.

nullptr

src/hotspot/cpu/x86/icBuffer_x86.cpp line 60:

> 58:   // (1) the value is old (i.e., doesn't matter for scavenges)
> 59:   // (2) these ICStubs are removed *before* a GC happens, so the roots disappear
> 60:   // assert(cached_value == null || cached_oop->is_perm(), "must be perm oop");

nullptr

src/hotspot/cpu/x86/interp_masm_x86.cpp line 303:

> 301:     jcc(Assembler::equal, L);
> 302:     stop("InterpreterMacroAssembler::call_VM_base:"
> 303:          " last_sp != null");

nullptr

src/hotspot/cpu/x86/interp_masm_x86.cpp line 402:

> 400:     movptr(tmp, Address(rthread, JavaThread::jvmti_thread_state_offset()));
> 401:     testptr(tmp, tmp);
> 402:     jcc(Assembler::zero, L); // if (thread->jvmti_thread_state() == null) exit;

nullptr

src/hotspot/cpu/x86/interp_masm_x86.cpp line 1779:

> 1777: //   // main copy of decision tree, rooted at row[1]
> 1778: //   if (row[0].rec == rec) { row[0].incr(); goto done; }
> 1779: //   if (row[0].rec != null) {

nullptr

src/hotspot/cpu/x86/macroAssembler_x86.cpp line 2866:

> 2864:   } else {
> 2865:     // nothing to do, (later) access of M[reg + offset]
> 2866:     // will provoke OS null exception if reg = null

is not =

src/hotspot/cpu/x86/macroAssembler_x86.cpp line 4265:

> 4263:   }
> 4264: 
> 4265:   // for (scan = klass->itable(); scan->interface() != null; scan += scan_step) {

nullptr

src/hotspot/cpu/x86/stubGenerator_x86_32.cpp line 1553:

> 1551:     // one less register, because needed values are on the argument stack.
> 1552:     // __ check_klass_subtype_fast_path(sub_klass, *super_klass*, temp,
> 1553:     //                                  L_success, L_failure, null);

nullptr

src/hotspot/cpu/x86/stubGenerator_x86_32.cpp line 1924:

> 1922:     const Register length  = rcx;       // transfer count
> 1923: 
> 1924:     //  if (src == null) return -1;

nullptr

src/hotspot/cpu/x86/stubGenerator_x86_32.cpp line 1934:

> 1932:     __ jccb(Assembler::negative, L_failed_0);
> 1933: 
> 1934:     //  if (dst == null) return -1;

nullptr

src/hotspot/cpu/x86/stubGenerator_x86_32.cpp line 1956:

> 1954: 
> 1955: #ifdef ASSERT
> 1956:     //  assert(src->klass() != null);

nullptr

src/hotspot/cpu/x86/stubGenerator_x86_64_arraycopy.cpp line 2298:

> 2296:   //
> 2297: 
> 2298:   //  if (src == null) return -1;

nullptr

src/hotspot/cpu/x86/stubGenerator_x86_64_arraycopy.cpp line 2307:

> 2305:   __ jccb(Assembler::negative, L_failed_0);
> 2306: 
> 2307:   //  if (dst == null) return -1;

nullptr

src/hotspot/cpu/x86/stubGenerator_x86_64_arraycopy.cpp line 2335:

> 2333:   __ load_klass(r10_src_klass, src, rklass_tmp);
> 2334: #ifdef ASSERT
> 2335:   //  assert(src->klass() != null);

nullptr

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PR: https://git.openjdk.org/jdk/pull/12326