8337523: Fix -Wzero-as-null-pointer-constant warnings in jvmci code

Reviewed-by: chagedorn, shade

Author: Kim Barrett

src/hotspot/share/jvmci/jvmciCodeInstaller.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2011, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2011, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -664,7 +664,7 @@ JVMCI::CodeInstallResult CodeInstaller::install_runtime_stub(CodeBlob*& cb,
   GrowableArray<RuntimeStub*> *stubs_to_free = nullptr;
 #ifdef ASSERT
   const char* val = Arguments::PropertyList_get_value(Arguments::system_properties(), "test.jvmci.forceRuntimeStubAllocFail");
-  if (val != nullptr && strstr(name , val) != 0) {
+  if (val != nullptr && strstr(name , val) != nullptr) {
     stubs_to_free = new GrowableArray<RuntimeStub*>();
     JVMCI_event_1("forcing allocation of %s in code cache to fail", name);
   }

src/hotspot/share/jvmci/jvmciCompilerToVM.cpp

@@ -424,7 +424,7 @@ C2V_VMENTRY_NULL(jobject, getResolvedJavaMethod, (JNIEnv* env, jobject, jobject
 
 C2V_VMENTRY_NULL(jobject, getConstantPool, (JNIEnv* env, jobject, ARGUMENT_PAIR(klass_or_method), jboolean is_klass))
   ConstantPool* cp = nullptr;
-  if (UNPACK_PAIR(address, klass_or_method) == 0) {
+  if (UNPACK_PAIR(address, klass_or_method) == nullptr) {
     JVMCI_THROW_NULL(NullPointerException);
   }
   if (!is_klass) {
@@ -1098,7 +1098,7 @@ C2V_END
 
 C2V_VMENTRY_0(jlong, getMaxCallTargetOffset, (JNIEnv* env, jobject, jlong addr))
   address target_addr = (address) addr;
-  if (target_addr != 0x0) {
+  if (target_addr != nullptr) {
     int64_t off_low = (int64_t)target_addr - ((int64_t)CodeCache::low_bound() + sizeof(int));
     int64_t off_high = (int64_t)target_addr - ((int64_t)CodeCache::high_bound() + sizeof(int));
     return MAX2(ABS(off_low), ABS(off_high));

src/hotspot/share/jvmci/jvmciCompilerToVMInit.cpp

@@ -240,7 +240,7 @@ void CompilerToVM::Data::initialize(JVMCI_TRAPS) {
     cardtable_shift = CardTable::card_shift();
   } else {
     // No card mark barriers
-    cardtable_start_address = 0;
+    cardtable_start_address = nullptr;
     cardtable_shift = 0;
   }
 

src/hotspot/share/jvmci/jvmciRuntime.cpp

@@ -628,7 +628,7 @@ JRT_LEAF(oopDesc*, JVMCIRuntime::load_and_clear_exception(JavaThread* thread))
   oop exception = thread->exception_oop();
   assert(exception != nullptr, "npe");
   thread->set_exception_oop(nullptr);
-  thread->set_exception_pc(0);
+  thread->set_exception_pc(nullptr);
   return exception;
 JRT_END