From b67201b60f5aad98f6accd24ea454f2d3c27a2ef Mon Sep 17 00:00:00 2001
From: lijincheng <lijincheng13@huawei.com>
Date: Wed, 25 Jun 2025 15:54:36 +0800
Subject: [PATCH] Add fast random

1.change mt to xorshift64

Issue:https://gitee.com/openharmony/arkcompiler_runtime_core/issues/ICHQQB

Signed-off-by: lijincheng <lijincheng13@huawei.com>
---
 .../ets/runtime/intrinsics/std_math.cpp       | 30 +++++++++++++++++--
 static_core/runtime/include/thread.h          |  8 +++++
 static_core/runtime/thread.cpp                | 11 ++++++-
 3 files changed, 46 insertions(+), 3 deletions(-)

diff --git a/static_core/plugins/ets/runtime/intrinsics/std_math.cpp b/static_core/plugins/ets/runtime/intrinsics/std_math.cpp
index b560be1592..92d844a51f 100644
--- a/static_core/plugins/ets/runtime/intrinsics/std_math.cpp
+++ b/static_core/plugins/ets/runtime/intrinsics/std_math.cpp
@@ -30,6 +30,16 @@ namespace ark::ets::intrinsics {
 namespace {
 constexpr int INT_MAX_SIZE = 63;
 constexpr double ROUND_BIAS = 0.5;
+constexpr uint32_t RIGHT_12 = 12;
+constexpr uint32_t LEFT_25 = 25;
+constexpr uint32_t RIGHT_27 = 27;
+constexpr uint64_t RANDOM_MULTIPLY = 0x2545F4914F6CDD1D;
+constexpr uint64_t DOUBLE_MASK = 0x3FF0000000000000;
+
+union Uint64ToDouble {
+    double to;
+    uint64_t from;
+};
 
 int32_t ToInt32(double x)
 {
@@ -48,6 +58,16 @@ int32_t ToInt32(double x)
     return static_cast<int32_t>(static_cast<int64_t>(intPart));
 }
 
+uint64_t XorShift64(uint64_t *ptr)
+{
+    uint64_t val = *ptr;
+    val ^= val >> RIGHT_12;
+    val ^= val << LEFT_25;
+    val ^= val >> RIGHT_27;
+    *ptr = val;
+    return val * RANDOM_MULTIPLY;
+}
+
 uint32_t ToUint32(double x)
 {
     return static_cast<uint32_t>(ToInt32(x));
@@ -56,8 +76,14 @@ uint32_t ToUint32(double x)
 
 extern "C" double StdMathRandom()
 {
-    std::uniform_real_distribution<double> urd(0.0, 1.0);
-    return urd(EtsCoroutine::GetCurrent()->GetPandaVM()->GetRandomEngine());
+    uint64_t threadRandom = XorShift64(EtsCoroutine::GetCurrent()->GetThreadRandomState());
+    uint64_t random = (threadRandom >> RIGHT_12) | DOUBLE_MASK;
+    // The use of security functions 'memcpy_s' here will have a greater impact on performance
+    Uint64ToDouble data {};
+    // NOLINTNEXTLINE(cppcoreguidelines-pro-type-union-access)
+    data.from = random;
+    // NOLINTNEXTLINE(cppcoreguidelines-pro-type-union-access)
+    return data.to - 1;
 }
 
 extern "C" double StdMathAcos(double val)
diff --git a/static_core/runtime/include/thread.h b/static_core/runtime/include/thread.h
index 174784d303..bf35de19dc 100644
--- a/static_core/runtime/include/thread.h
+++ b/static_core/runtime/include/thread.h
@@ -15,6 +15,7 @@
 #ifndef PANDA_RUNTIME_THREAD_H_
 #define PANDA_RUNTIME_THREAD_H_
 
+#include <cstdint>
 #include <memory>
 #include <chrono>
 #include <limits>
@@ -316,8 +317,14 @@ public:
         return MEMBER_OFFSET(Thread, vm_);
     }
 
+    uint64_t *GetThreadRandomState()
+    {
+        return &threadRandomState_;
+    }
+
 private:
     void InitCardTableData(mem::GCBarrierSet *barrier);
+    void InitThreadRandomState();
 
 protected:
     // NOLINTBEGIN(misc-non-private-member-variables-in-classes)
@@ -346,6 +353,7 @@ protected:
 #ifndef NDEBUG
     uintptr_t runtimeCallEnabled_ {1};
 #endif
+    uint64_t threadRandomState_ {0};
     // NOLINTEND(misc-non-private-member-variables-in-classes)
 
 private:
diff --git a/static_core/runtime/thread.cpp b/static_core/runtime/thread.cpp
index bf404b6556..e3ea24a091 100644
--- a/static_core/runtime/thread.cpp
+++ b/static_core/runtime/thread.cpp
@@ -28,6 +28,7 @@
 #include "runtime/mem/object_helpers.h"
 #include "tooling/pt_thread_info.h"
 #include "runtime/mem/runslots_allocator-inl.h"
+#include <sys/time.h>
 
 namespace ark {
 using TaggedValue = coretypes::TaggedValue;
@@ -35,6 +36,7 @@ using TaggedType = coretypes::TaggedType;
 
 mem::TLAB *ManagedThread::zeroTlab_ = nullptr;
 static const int MIN_PRIORITY = os::thread::LOWEST_PRIORITY;
+static constexpr int MICROSEC_CONVERSION = 1000000;
 
 static mem::InternalAllocatorPtr GetInternalAllocator(Thread *thread)
 {
@@ -84,7 +86,7 @@ Thread::Thread(PandaVM *vm, ThreadType threadType) : ThreadProxy(vm->GetMutatorL
         InitCardTableData(barrierSet_);
     }
     InitializeThreadFlag();
-
+    InitThreadRandomState();
 #ifdef PANDA_USE_CUSTOM_SIGNAL_STACK
     mem::InternalAllocatorPtr allocator = Runtime::GetCurrent()->GetInternalAllocator();
     signalStack_.ss_sp = allocator->Alloc(SIGSTKSZ * 8U);
@@ -94,6 +96,13 @@ Thread::Thread(PandaVM *vm, ThreadType threadType) : ThreadProxy(vm->GetMutatorL
 #endif
 }
 
+void Thread::InitThreadRandomState()
+{
+    struct timeval tv = {0, 0};
+    gettimeofday(&tv, nullptr);
+    threadRandomState_ = static_cast<uint64_t>(tv.tv_sec * MICROSEC_CONVERSION + tv.tv_usec);
+}
+
 void Thread::InitCardTableData(mem::GCBarrierSet *barrier)
 {
     auto postBarrierType = barrier->GetPostType();
-- 
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