From 10f50ce4f71c4ed2bc7fb06ae726867e4bf7c3b8 Mon Sep 17 00:00:00 2001
From: Basilisk-Dev <basiliskdev@protonmail.com>
Date: Thu, 8 Jan 2026 10:37:43 -0500
Subject: [PATCH] MoonchildProductions/UXP#2897: Added a loongarch atomic-ops
 implementation

---
 js/src/jit/AtomicOperations.h                |   2 +
 js/src/jit/none/AtomicOperations-loongarch.h | 164 +++++++++++++++++++
 2 files changed, 166 insertions(+)
 create mode 100644 js/src/jit/none/AtomicOperations-loongarch.h

diff --git a/js/src/jit/AtomicOperations.h b/js/src/jit/AtomicOperations.h
index 3d19877694..35912a90de 100644
--- a/js/src/jit/AtomicOperations.h
+++ b/js/src/jit/AtomicOperations.h
@@ -325,6 +325,8 @@ AtomicOperations::isLockfree(int32_t size)
 # include "jit/arm64/AtomicOperations-arm64.h"
 #elif defined(JS_CODEGEN_MIPS32) || defined(JS_CODEGEN_MIPS64)
 # include "jit/mips-shared/AtomicOperations-mips-shared.h"
+#elif defined(__loongarch__) || defined(__loongarch64)
+# include "jit/none/AtomicOperations-loongarch.h"
 #elif defined(__ppc__) || defined(__PPC__) || defined(__powerpc__)
 # include "jit/none/AtomicOperations-ppc.h"
 #elif defined(__sparc__)
diff --git a/js/src/jit/none/AtomicOperations-loongarch.h b/js/src/jit/none/AtomicOperations-loongarch.h
new file mode 100644
index 0000000000..fddb0cbcc5
--- /dev/null
+++ b/js/src/jit/none/AtomicOperations-loongarch.h
@@ -0,0 +1,164 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* For documentation, see jit/AtomicOperations.h */
+
+#ifndef jit_loongarch_AtomicOperations_loongarch_h
+#define jit_loongarch_AtomicOperations_loongarch_h
+
+#include "mozilla/Assertions.h"
+#include "mozilla/Types.h"
+
+#if defined(__clang__) || defined(__GNUC__)
+
+inline bool
+js::jit::AtomicOperations::isLockfree8()
+{
+    MOZ_ASSERT(__atomic_always_lock_free(sizeof(int8_t), 0));
+    MOZ_ASSERT(__atomic_always_lock_free(sizeof(int16_t), 0));
+    MOZ_ASSERT(__atomic_always_lock_free(sizeof(int32_t), 0));
+#if defined(__loongarch64)
+    MOZ_ASSERT(__atomic_always_lock_free(sizeof(int64_t), 0));
+#endif
+    return true;
+}
+
+inline void
+js::jit::AtomicOperations::fenceSeqCst()
+{
+    __atomic_thread_fence(__ATOMIC_SEQ_CST);
+}
+
+template<typename T>
+inline T
+js::jit::AtomicOperations::loadSeqCst(T* addr)
+{
+    MOZ_ASSERT(sizeof(T) < 8 || isLockfree8());
+    T v;
+    __atomic_load(addr, &v, __ATOMIC_SEQ_CST);
+    return v;
+}
+
+template<typename T>
+inline void
+js::jit::AtomicOperations::storeSeqCst(T* addr, T val)
+{
+    MOZ_ASSERT(sizeof(T) < 8 || isLockfree8());
+    __atomic_store(addr, &val, __ATOMIC_SEQ_CST);
+}
+
+template<typename T>
+inline T
+js::jit::AtomicOperations::compareExchangeSeqCst(T* addr, T oldval, T newval)
+{
+    MOZ_ASSERT(sizeof(T) < 8 || isLockfree8());
+    __atomic_compare_exchange(addr, &oldval, &newval, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST);
+    return oldval;
+}
+
+template<typename T>
+inline T
+js::jit::AtomicOperations::fetchAddSeqCst(T* addr, T val)
+{
+    static_assert(sizeof(T) <= 4, "not available for 8-byte values yet");
+    return __atomic_fetch_add(addr, val, __ATOMIC_SEQ_CST);
+}
+
+template<typename T>
+inline T
+js::jit::AtomicOperations::fetchSubSeqCst(T* addr, T val)
+{
+    static_assert(sizeof(T) <= 4, "not available for 8-byte values yet");
+    return __atomic_fetch_sub(addr, val, __ATOMIC_SEQ_CST);
+}
+
+template<typename T>
+inline T
+js::jit::AtomicOperations::fetchAndSeqCst(T* addr, T val)
+{
+    static_assert(sizeof(T) <= 4, "not available for 8-byte values yet");
+    return __atomic_fetch_and(addr, val, __ATOMIC_SEQ_CST);
+}
+
+template<typename T>
+inline T
+js::jit::AtomicOperations::fetchOrSeqCst(T* addr, T val)
+{
+    static_assert(sizeof(T) <= 4, "not available for 8-byte values yet");
+    return __atomic_fetch_or(addr, val, __ATOMIC_SEQ_CST);
+}
+
+template<typename T>
+inline T
+js::jit::AtomicOperations::fetchXorSeqCst(T* addr, T val)
+{
+    static_assert(sizeof(T) <= 4, "not available for 8-byte values yet");
+    return __atomic_fetch_xor(addr, val, __ATOMIC_SEQ_CST);
+}
+
+template<typename T>
+inline T
+js::jit::AtomicOperations::loadSafeWhenRacy(T* addr)
+{
+    return *addr;               // FIXME (1208663): not yet safe
+}
+
+template<typename T>
+inline void
+js::jit::AtomicOperations::storeSafeWhenRacy(T* addr, T val)
+{
+    *addr = val;                // FIXME (1208663): not yet safe
+}
+
+inline void
+js::jit::AtomicOperations::memcpySafeWhenRacy(void* dest, const void* src, size_t nbytes)
+{
+    ::memcpy(dest, src, nbytes); // FIXME (1208663): not yet safe
+}
+
+inline void
+js::jit::AtomicOperations::memmoveSafeWhenRacy(void* dest, const void* src, size_t nbytes)
+{
+    ::memmove(dest, src, nbytes); // FIXME (1208663): not yet safe
+}
+
+template<typename T>
+inline T
+js::jit::AtomicOperations::exchangeSeqCst(T* addr, T val)
+{
+    MOZ_ASSERT(sizeof(T) < 8 || isLockfree8());
+    T v;
+    __atomic_exchange(addr, &val, &v, __ATOMIC_SEQ_CST);
+    return v;
+}
+
+template<size_t nbytes>
+inline void
+js::jit::RegionLock::acquire(void* addr)
+{
+    uint32_t zero = 0;
+    uint32_t one = 1;
+    while (!__atomic_compare_exchange(&spinlock, &zero, &one, false, __ATOMIC_ACQUIRE, __ATOMIC_ACQUIRE)) {
+        zero = 0;
+        continue;
+    }
+}
+
+template<size_t nbytes>
+inline void
+js::jit::RegionLock::release(void* addr)
+{
+    MOZ_ASSERT(AtomicOperations::loadSeqCst(&spinlock) == 1, "releasing unlocked region lock");
+    uint32_t zero = 0;
+    __atomic_store(&spinlock, &zero, __ATOMIC_SEQ_CST);
+}
+
+#elif defined(ENABLE_SHARED_ARRAY_BUFFER)
+
+# error "Either disable JS shared memory, use GCC or Clang, or add code here"
+
+#endif
+
+#endif // jit_loongarch_AtomicOperations_loongarch_h