Use SafeAccess for signal-handler memory reads in vmStructs.h

Protect methods called from signal handlers against partially
initialized thread structures during GC worker thread creation.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: jbachorik

ddprof-lib/src/main/cpp/vmStructs.h

@@ -11,6 +11,7 @@
 #include <string.h>
 #include <type_traits>
 #include "codeCache.h"
+#include "safeAccess.h"
 
 
 class VMStructs {
@@ -311,23 +312,23 @@ class JavaFrameAnchor : VMStructs {
 
   public:
     static JavaFrameAnchor* fromEntryFrame(uintptr_t fp) {
-        const char* call_wrapper = *(const char**)(fp + _entry_frame_call_wrapper_offset);
+        const char* call_wrapper = (const char*) SafeAccess::loadPtr((void**)(fp + _entry_frame_call_wrapper_offset), nullptr);
         if (!goodPtr(call_wrapper) || (uintptr_t)call_wrapper - fp > MAX_CALL_WRAPPER_DISTANCE) {
             return NULL;
         }
         return (JavaFrameAnchor*)(call_wrapper + _call_wrapper_anchor_offset);
     }
 
     uintptr_t lastJavaSP() {
-        return *(uintptr_t*) at(_anchor_sp_offset);
+        return (uintptr_t) SafeAccess::loadPtr((void**) at(_anchor_sp_offset), nullptr);
     }
 
     uintptr_t lastJavaFP() {
-        return *(uintptr_t*) at(_anchor_fp_offset);
+        return (uintptr_t) SafeAccess::loadPtr((void**) at(_anchor_fp_offset), nullptr);
     }
 
     const void* lastJavaPC() {
-        return *(const void**) at(_anchor_pc_offset);
+        return SafeAccess::loadPtr((void**) at(_anchor_pc_offset), nullptr);
     }
 
     void setLastJavaPC(const void* pc) {
@@ -382,15 +383,15 @@ class VMThread : VMStructs {
     }
 
     int state() {
-        return _thread_state_offset >= 0 ? *(int*) at(_thread_state_offset) : 0;
+        return _thread_state_offset >= 0 ? SafeAccess::load32((int32_t*) at(_thread_state_offset), 0) : 0;
     }
 
     bool inJava() {
         return state() == 8;
     }
 
     bool inDeopt() {
-        return *(void**) at(_thread_vframe_offset) != NULL;
+        return SafeAccess::loadPtr((void**) at(_thread_vframe_offset), nullptr) != NULL;
     }
 
     void*& exception() {