WIP: Reduce jmethodID

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

@@ -22,6 +22,7 @@
 #include "frame.h"
 #include "jfrMetadata.h"
 #include "log.h"
+#include "methodInfo.h"
 #include "mutex.h"
 #include "objectSampler.h"
 #include "threadFilter.h"
@@ -55,92 +56,6 @@ struct CpuTimes {
   CpuTime proc;
   CpuTime total;
 };
-
-class SharedLineNumberTable {
-public:
-  int _size;
-  void *_ptr;
-
-  SharedLineNumberTable(int size, void *ptr) : _size(size), _ptr(ptr) {}
-  ~SharedLineNumberTable();
-};
-
-class MethodInfo {
-public:
-  MethodInfo()
-      : _mark(false), _is_entry(false), _referenced(false), _age(0), _key(0), _class(0),
-        _name(0), _sig(0), _modifiers(0), _line_number_table(nullptr), _type() {}
-
-  bool _mark;
-  bool _is_entry;
-  bool _referenced;  // Tracked during writeStackTraces() for cleanup
-  int _age;          // Consecutive chunks without reference (0 = recently used)
-  u32 _key;
-  u32 _class;
-  u32 _name;
-  u32 _sig;
-  jint _modifiers;
-  std::shared_ptr<SharedLineNumberTable> _line_number_table;
-  FrameTypeId _type;
-
-  jint getLineNumber(jint bci) {
-    // if the shared pointer is not pointing to the line number table, consider
-    // size 0
-    if (!_line_number_table || _line_number_table->_size == 0) {
-      return 0;
-    }
-
-    int i = 1;
-    while (i < _line_number_table->_size &&
-           bci >= ((jvmtiLineNumberEntry *)_line_number_table->_ptr)[i]
-                      .start_location) {
-      i++;
-    }
-    return ((jvmtiLineNumberEntry *)_line_number_table->_ptr)[i - 1]
-        .line_number;
-  }
-
-  bool isHidden() {
-    // 0x1400 = ACC_SYNTHETIC(0x1000) | ACC_BRIDGE(0x0040)
-    return _modifiers == 0 || (_modifiers & 0x1040);
-  }
-};
-
-// MethodMap's key can be derived from 3 sources:
-// 1) jmethodID for Java methods
-// 2) void* address for native method names
-// 3) Encoded RemoteFrameInfo
-// The values of the keys are potentially overlapping, so we use 
-// the highest 2 bits to distinguish them.
-// 00 - jmethodID
-// 10 - void* address
-// 01 - RemoteFrameInfo
-class MethodMap : public std::map<unsigned long, MethodInfo> {
-public:
-  static constexpr unsigned long ADDRESS_MARK = 0x8000000000000000ULL;
-  static constexpr unsigned long REMOTE_FRAME_MARK = 0x4000000000000000ULL;
-  static constexpr unsigned long KEY_TYPE_MASK = ADDRESS_MARK | REMOTE_FRAME_MARK;
-
-  MethodMap() {}
-
-  static unsigned long makeKey(jmethodID method) {
-    unsigned long key = (unsigned long)method;
-    assert((key & KEY_TYPE_MASK) == 0);
-    return key;
-  }
-
-  static unsigned long makeKey(const char* addr) {
-    unsigned long key = (unsigned long)addr;
-    assert((key & KEY_TYPE_MASK) == 0);
-    return (key | ADDRESS_MARK);
-  }
-
-  static unsigned long makeKey(unsigned long packed_remote_frame) {
-    unsigned long key = packed_remote_frame;
-    assert((key & KEY_TYPE_MASK) == 0);
-    return (key | REMOTE_FRAME_MARK);}
-};
-
 class Recording {
   friend ObjectSampler;
   friend Profiler;
@@ -297,35 +212,6 @@ class Recording {
 private:
   void cleanupUnreferencedMethods();
 };
-
-class Lookup {
-public:
-  Recording *_rec;
-  MethodMap *_method_map;
-  Dictionary *_classes;
-  Dictionary _packages;
-  Dictionary _symbols;
-
-private:
-  void fillNativeMethodInfo(MethodInfo *mi, const char *name,
-                            const char *lib_name);
-  void fillRemoteFrameInfo(MethodInfo *mi, const RemoteFrameInfo *rfi);
-  void cutArguments(char *func);
-  void fillJavaMethodInfo(MethodInfo *mi, jmethodID method, bool first_time);
-  bool has_prefix(const char *str, const char *prefix) const {
-    return strncmp(str, prefix, strlen(prefix)) == 0;
-  }
-
-public:
-  Lookup(Recording *rec, MethodMap *method_map, Dictionary *classes)
-      : _rec(rec), _method_map(method_map), _classes(classes), _packages(),
-        _symbols() {}
-
-  MethodInfo *resolveMethod(ASGCT_CallFrame &frame);
-  u32 getPackage(const char *class_name);
-  u32 getSymbol(const char *name);
-};
-
 class FlightRecorder {
   friend Profiler;
 

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

@@ -1,6 +1,9 @@
 #ifndef _FRAME_H
 #define _FRAME_H
 
+#include <cassert>
+#include "vmEntry.h"
+
 enum FrameTypeId {
   FRAME_INTERPRETED = 0,
   FRAME_JIT_COMPILED = 1,
@@ -10,12 +13,14 @@ enum FrameTypeId {
   FRAME_KERNEL = 5,
   FRAME_C1_COMPILED = 6,
   FRAME_NATIVE_REMOTE = 7,  // Native frame with remote symbolication (build-id + pc-offset)
-  FRAME_TYPE_MAX = FRAME_NATIVE_REMOTE  // Maximum valid frame type
+  FRAME_INTERPRETED_METHOD = 8,
+  FRAME_TYPE_MAX = FRAME_INTERPRETED_METHOD  // Maximum valid frame type
 };
 
 class FrameType {
 public:
   static inline int encode(int type, int bci) {
+    assert((type != FRAME_INTERPRETED_METHOD || VM::isHotspot()) && "FRAME_INTERPRETED_METHOD is only valid for hotspot");
     return (1 << 24) | (type << 25) | (bci & 0xffffff);
   }
 

ddprof-lib/src/main/cpp/hotspot/classloader.h

@@ -0,0 +1,19 @@
+/*
+ * Copyright The async-profiler authors
+ * Copyright 2026, Datadog, Inc.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#ifndef _HOTSPOT_CLASSLOADER_H
+#define _HOTSPOT_CLASSLOADER_H
+
+#include "hotspot/vmStructs.h"
+
+class VMClassLoader {
+public:
+    // Is the method belongs to a class that is loaded by bootstrap class loader
+    static inline bool isLoadedByBootstrapClassLoader(const VMMethod* method);
+};
+
+#endif // _HOTSPOT_CLASSLOADER_H
+

ddprof-lib/src/main/cpp/hotspot/classloader.inline.h

@@ -0,0 +1,38 @@
+/*
+ * Copyright The async-profiler authors
+ * Copyright 2026, Datadog, Inc.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#ifndef _HOTSPOT_CLASSLOADER_INLINE_H
+#define _HOTSPOT_CLASSLOADER_INLINE_H
+
+#include "hotspot/classloader.h"
+
+#include <cassert>
+
+bool VMClassLoader::isLoadedByBootstrapClassLoader(const VMMethod* method) {
+    if (method == nullptr) {
+        return false;
+    }
+
+    VMKlass* method_klass = method->methodHolderSafe();
+    if (method_klass == nullptr) {
+        return false;
+    }
+
+    VMClassLoaderData* cld = method_klass->classLoaderDataSafe();
+    if (cld == nullptr) {
+        return false;
+    }
+
+    // java/lang/Object must be loaded by bootstrap class loader
+    VMKlass* obj_klass = VMClasses::obj_klass();
+    assert(obj_klass != nullptr && "VMClasses not yet initialized");
+    assert(obj_klass->classLoaderData() != nullptr && "Object class has no class loader data");
+
+    return cld == obj_klass->classLoaderData();
+}
+
+#endif // _HOTSPOT_CLASSLOADER_INLINE_H
+