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diff --git a/third_party/jpeg-xl/lib/jxl/base/profiler.h b/third_party/jpeg-xl/lib/jxl/base/profiler.h
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+// Copyright (c) the JPEG XL Project Authors. All rights reserved.
+//
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#ifndef LIB_JXL_BASE_PROFILER_H_
+#define LIB_JXL_BASE_PROFILER_H_
+
+// High precision, low overhead time measurements. Returns exact call counts and
+// total elapsed time for user-defined 'zones' (code regions, i.e. C++ scopes).
+//
+// To use the profiler you must set the JPEGXL_ENABLE_PROFILER CMake flag, which
+// defines JXL_PROFILER_ENABLED.
+//
+// Usage: instrument regions of interest: { PROFILER_ZONE("name"); /*code*/ } or
+// void FuncToMeasure() { PROFILER_FUNC; /*code*/ }.
+// After all threads have exited any zones, invoke PROFILER_PRINT_RESULTS() to
+// print call counts and average durations [CPU cycles] to stdout, sorted in
+// descending order of total duration.
+
+// If zero, this file has no effect and no measurements will be recorded.
+#ifndef JXL_PROFILER_ENABLED
+#define JXL_PROFILER_ENABLED 0
+#endif
+#if JXL_PROFILER_ENABLED
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include <hwy/aligned_allocator.h>
+#include <hwy/base.h>
+
+#include "lib/jxl/base/tsc_timer.h"
+
+#if HWY_COMPILER_MSVC
+#define PROFILER_PUBLIC
+#else
+#define PROFILER_PUBLIC __attribute__((visibility("default")))
+#endif
+
+namespace jxl {
+namespace profiler {
+
+// Represents zone entry/exit events. POD.
+#pragma pack(push, 1)
+struct Packet {
+  // Computing a hash or string table is likely too expensive, and offsets
+  // from other libraries' string literals can be too large to combine them and
+  // a full-resolution timestamp into 64 bits.
+  uint64_t timestamp;
+  const char* name;  // nullptr for exit packets
+#if UINTPTR_MAX <= 0xFFFFFFFFu
+  uint32_t padding;
+#endif
+};
+#pragma pack(pop)
+static_assert(sizeof(Packet) == 16, "Wrong Packet size");
+
+class Results;  // pImpl
+
+// Per-thread packet storage, dynamically allocated and aligned.
+class ThreadSpecific {
+  static constexpr size_t kBufferCapacity = 64 / sizeof(Packet);
+
+ public:
+  PROFILER_PUBLIC explicit ThreadSpecific();
+  PROFILER_PUBLIC ~ThreadSpecific();
+
+  // Depends on Zone => defined out of line.
+  PROFILER_PUBLIC void ComputeOverhead();
+
+  HWY_INLINE void WriteEntry(const char* name) { Write(name, TicksBefore()); }
+  HWY_INLINE void WriteExit() { Write(nullptr, TicksAfter()); }
+
+  PROFILER_PUBLIC void AnalyzeRemainingPackets();
+
+  // Accessors instead of public member for well-defined data layout.
+  void SetNext(ThreadSpecific* next) { next_ = next; }
+  ThreadSpecific* GetNext() const { return next_; }
+
+  Results& GetResults() { return *results_; }
+
+ private:
+  PROFILER_PUBLIC void FlushBuffer();
+
+  // Write packet to buffer/storage, emptying them as needed.
+  void Write(const char* name, const uint64_t timestamp) {
+    if (buffer_size_ == kBufferCapacity) {  // Full
+      FlushBuffer();
+    }
+    buffer_[buffer_size_].name = name;
+    buffer_[buffer_size_].timestamp = timestamp;
+    ++buffer_size_;
+  }
+
+  // Write-combining buffer to avoid cache pollution. Must be the first
+  // non-static member to ensure cache-line alignment.
+  Packet buffer_[kBufferCapacity];
+  size_t buffer_size_ = 0;
+
+  // Contiguous storage for zone enter/exit packets.
+  const size_t max_packets_;
+  hwy::AlignedFreeUniquePtr<Packet[]> packets_;
+  size_t num_packets_;
+
+  // Linked list of all threads.
+  ThreadSpecific* next_ = nullptr;  // Owned, never released.
+
+  hwy::AlignedUniquePtr<Results> results_;
+};
+
+// RAII zone enter/exit recorder constructed by PROFILER_ZONE; also
+// responsible for initializing ThreadSpecific.
+class Zone {
+ public:
+  HWY_NOINLINE explicit Zone(const char* name) {
+    HWY_FENCE;
+    ThreadSpecific* HWY_RESTRICT thread_specific = GetThreadSpecific();
+    if (HWY_UNLIKELY(thread_specific == nullptr)) {
+      thread_specific = InitThreadSpecific();
+    }
+
+    thread_specific->WriteEntry(name);
+  }
+
+  HWY_NOINLINE ~Zone() { GetThreadSpecific()->WriteExit(); }
+
+  // Call exactly once after all threads have exited all zones.
+  PROFILER_PUBLIC static void PrintResults();
+
+ private:
+  // Returns reference to the thread's ThreadSpecific pointer (initially null).
+  // Function-local static avoids needing a separate definition.
+  static ThreadSpecific*& GetThreadSpecific() {
+    static thread_local ThreadSpecific* thread_specific;
+    return thread_specific;
+  }
+
+  // Non time-critical.
+  PROFILER_PUBLIC ThreadSpecific* InitThreadSpecific();
+};
+
+// Creates a zone starting from here until the end of the current scope.
+// Timestamps will be recorded when entering and exiting the zone.
+// To ensure the name pointer remains valid, we require it to be a string
+// literal (by merging with ""). We also compare strings by address.
+#define PROFILER_ZONE(name)                  \
+  HWY_FENCE;                                 \
+  const ::jxl::profiler::Zone zone("" name); \
+  HWY_FENCE
+
+// Creates a zone for an entire function (when placed at its beginning).
+// Shorter/more convenient than ZONE.
+#define PROFILER_FUNC                         \
+  HWY_FENCE;                                  \
+  const ::jxl::profiler::Zone zone(__func__); \
+  HWY_FENCE
+
+#define PROFILER_PRINT_RESULTS ::jxl::profiler::Zone::PrintResults
+
+}  // namespace profiler
+}  // namespace jxl
+
+#else  // !JXL_PROFILER_ENABLED
+#define PROFILER_ZONE(name)
+#define PROFILER_FUNC
+#define PROFILER_PRINT_RESULTS()
+#endif
+
+#endif  // LIB_JXL_BASE_PROFILER_H_