enhance and cleanup

DataDog · zhengyu123 · Jul 9, 2025 · Jun 30, 2025 · Jun 30, 2025 · Jun 30, 2025
commit 57e602282509eb253ca7a70d25a133f57d9cccc2
@@ -20,10 +20,16 @@
 SafeAccess::SafeFetch32 SafeAccess::_safeFetch32Func = nullptr;
 
 void SafeAccess::initSafeFetch(CodeCache* libjvm) {
+  // Hotspot JVM's safefetch implementation appears better, e.g. it actually returns errorValue,
+  // when the address is invalid. let's use it whenever possible.
   _safeFetch32Func = (SafeFetch32)libjvm->findSymbol("SafeFetch32_impl");
   if (_safeFetch32Func == nullptr && !WX_MEMORY) {
     // jdk11 stub implementation other than Macosx/aarch64
     void** entry = (void**)libjvm->findSymbol("_ZN12StubRoutines18_safefetch32_entryE");
     _safeFetch32Func = (SafeFetch32)*entry;
   }
+  // Fallback
+  if (_safeFetch32Func == nullptr) {
+    _safeFetch32Func = (SafeFetch32)load32;
+  }
 }
@@ -19,6 +19,7 @@
 
 #include "arch_dd.h"
 #include "codeCache.h"
+#include <cassert>
 #include <stdint.h>
 
 #ifdef __clang__
@@ -30,21 +31,19 @@
 
 class SafeAccess {
 private:
-   typedef int (*SafeFetch32)(int* ptr, int defaultValue);
+   typedef int (*SafeFetch32)(int* ptr, int errorValue);
    static SafeFetch32 _safeFetch32Func;
+
 public:
   static void initSafeFetch(CodeCache* libjvm);
 
   static bool hasSafeFetch() {
     return _safeFetch32Func != nullptr;
   }
 
-  static int safeFetch(int* ptr, int defaultValue) {
-    if (_safeFetch32Func != nullptr) {
-      return _safeFetch32Func(ptr, defaultValue);
-    } else {
-      return defaultValue;
-    }
+  static inline int safeFetch(int* ptr, int errorValue) {
+    assert(_safeFetch32Func != nullptr);
+    return _safeFetch32Func(ptr, errorValue);
   }
 
   NOINLINE NOADDRSANITIZE __attribute__((aligned(16))) static void *load(void **ptr) {