[dynarmic] add current code page cache (#3459)

should make JIT translation a bit faster - especially for non-fastmem
test if thumb still werks

previously:
we read 32-bits one by one, and do translation **for each u32 we read**

now:
one big read of 4096 bytes (aligned of course), only 1 VAddr translation

Signed-off-by: lizzie <lizzie@eden-emu.dev>

Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/3459
Reviewed-by: DraVee <dravee@eden-emu.dev>
Reviewed-by: CamilleLaVey <camillelavey99@gmail.com>
Co-authored-by: lizzie <lizzie@eden-emu.dev>
Co-committed-by: lizzie <lizzie@eden-emu.dev>

src/core/arm/dynarmic/arm_dynarmic_32.cpp

@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
+// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
 // SPDX-License-Identifier: GPL-3.0-or-later
 
 // SPDX-FileCopyrightText: Copyright 2020 yuzu Emulator Project
@@ -38,10 +38,16 @@ u64 DynarmicCallbacks32::MemoryRead64(u32 vaddr) {
     CheckMemoryAccess(vaddr, 8, Kernel::DebugWatchpointType::Read);
     return m_memory.Read64(vaddr);
 }
+
 std::optional<u32> DynarmicCallbacks32::MemoryReadCode(u32 vaddr) {
     if (!m_memory.IsValidVirtualAddressRange(vaddr, sizeof(u32)))
         return std::nullopt;
-    return m_memory.Read32(vaddr);
+    auto const aligned_vaddr = vaddr & ~Core::Memory::YUZU_PAGEMASK;
+    if (last_code_addr != aligned_vaddr) {
+        m_memory.ReadBlock(aligned_vaddr, &cached_code_page, sizeof(cached_code_page));
+        last_code_addr = aligned_vaddr;
+    }
+    return cached_code_page.inst[(vaddr & Core::Memory::YUZU_PAGEMASK) / sizeof(u32)];
 }
 
 void DynarmicCallbacks32::MemoryWrite8(u32 vaddr, u8 value) {

src/core/arm/dynarmic/arm_dynarmic_32.h

@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
+// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
 // SPDX-License-Identifier: GPL-3.0-or-later
 
 // SPDX-FileCopyrightText: Copyright 2020 yuzu Emulator Project
@@ -7,6 +7,7 @@
 #pragma once
 
 #include <dynarmic/interface/A32/a32.h>
+#include <dynarmic/interface/code_page.h>
 
 #include "core/arm/arm_interface.h"
 #include "core/arm/dynarmic/dynarmic_exclusive_monitor.h"
@@ -49,6 +50,9 @@ public:
     u64 GetTicksRemaining() override;
     bool CheckMemoryAccess(u64 addr, u64 size, Kernel::DebugWatchpointType type);
     void ReturnException(u32 pc, Dynarmic::HaltReason hr);
+    //
+    Dynarmic::CodePage cached_code_page;
+    u64 last_code_addr = 0;
     ArmDynarmic32& m_parent;
     Core::Memory::Memory& m_memory;
     Kernel::KProcess* m_process{};

src/core/arm/dynarmic/arm_dynarmic_64.cpp

@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
+// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
 // SPDX-License-Identifier: GPL-3.0-or-later
 
 // SPDX-FileCopyrightText: Copyright 2018 yuzu Emulator Project
@@ -41,10 +41,17 @@ Dynarmic::A64::Vector DynarmicCallbacks64::MemoryRead128(u64 vaddr) {
     CheckMemoryAccess(vaddr, 16, Kernel::DebugWatchpointType::Read);
     return {m_memory.Read64(vaddr), m_memory.Read64(vaddr + 8)};
 }
+
 std::optional<u32> DynarmicCallbacks64::MemoryReadCode(u64 vaddr) {
     if (!m_memory.IsValidVirtualAddressRange(vaddr, sizeof(u32)))
         return std::nullopt;
-    return m_memory.Read32(vaddr);
+//    return m_memory.Read32(vaddr);
+    auto const aligned_vaddr = vaddr & ~Core::Memory::YUZU_PAGEMASK;
+    if (last_code_addr != aligned_vaddr) {
+        m_memory.ReadBlock(aligned_vaddr, &cached_code_page, sizeof(cached_code_page));
+        last_code_addr = aligned_vaddr;
+    }
+    return cached_code_page.inst[(vaddr & Core::Memory::YUZU_PAGEMASK) / sizeof(u32)];
 }
 
 void DynarmicCallbacks64::MemoryWrite8(u64 vaddr, u8 value) {

src/core/arm/dynarmic/arm_dynarmic_64.h

@@ -11,6 +11,7 @@
 #include <ankerl/unordered_dense.h>
 
 #include <dynarmic/interface/A64/a64.h>
+#include <dynarmic/interface/code_page.h>
 #include "common/common_types.h"
 #include "common/hash.h"
 #include "core/arm/arm_interface.h"
@@ -61,6 +62,8 @@ public:
     bool CheckMemoryAccess(u64 addr, u64 size, Kernel::DebugWatchpointType type);
     void ReturnException(u64 pc, Dynarmic::HaltReason hr);
 
+    Dynarmic::CodePage cached_code_page;
+    u64 last_code_addr = 0;
     ArmDynarmic64& m_parent;
     Core::Memory::Memory& m_memory;
     u64 m_tpidrro_el0{};

src/core/hle/service/jit/jit_context.cpp

@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
+// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
 // SPDX-License-Identifier: GPL-3.0-or-later
 
 // SPDX-FileCopyrightText: Copyright 2022 yuzu Emulator Project
@@ -10,6 +10,7 @@
 #include <boost/icl/interval_set.hpp>
 #include <dynarmic/interface/A64/a64.h>
 #include <dynarmic/interface/A64/config.h>
+#include <dynarmic/interface/code_page.h>
 
 #include "common/alignment.h"
 #include "common/common_funcs.h"
@@ -46,6 +47,15 @@ public:
         : memory{memory_}, local_memory{local_memory_},
           mapped_ranges{mapped_ranges_}, parent{parent_} {}
 
+    std::optional<std::uint32_t> MemoryReadCode(VAddr vaddr) override {
+        static_assert(Core::Memory::YUZU_PAGESIZE == Dynarmic::CODE_PAGE_SIZE);
+        auto const aligned_vaddr = vaddr & ~Core::Memory::YUZU_PAGEMASK;
+        if (last_code_addr != aligned_vaddr) {
+            cached_code_page = ReadMemory<Dynarmic::CodePage>(aligned_vaddr);
+            last_code_addr = aligned_vaddr;
+        }
+        return cached_code_page.inst[(vaddr & Core::Memory::YUZU_PAGEMASK) / sizeof(u32)];
+    }
     u8 MemoryRead8(u64 vaddr) override {
         return ReadMemory<u8>(vaddr);
     }
@@ -116,8 +126,7 @@ public:
         return 0;
     }
 
-    template <class T>
-    T ReadMemory(u64 vaddr) {
+    template<typename T> T ReadMemory(u64 vaddr) {
         T ret{};
         if (boost::icl::contains(mapped_ranges, vaddr)) {
             memory.ReadBlock(vaddr, &ret, sizeof(T));
@@ -146,6 +155,9 @@ private:
     std::vector<u8>& local_memory;
     IntervalSet& mapped_ranges;
     JITContextImpl& parent;
+
+    Dynarmic::CodePage cached_code_page;
+    u64 last_code_addr = 0;
 };
 
 class JITContextImpl {

src/core/memory.cpp

@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
+// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
 // SPDX-License-Identifier: GPL-3.0-or-later
 
 // SPDX-FileCopyrightText: 2015 Citra Emulator Project
@@ -36,8 +36,7 @@
 
 namespace Core::Memory {
 
-static inline bool AddressSpaceContains(const Common::PageTable& table, const Common::ProcessAddress addr,
-                          const std::size_t size) {
+static inline bool AddressSpaceContains(const Common::PageTable& table, const Common::ProcessAddress addr, const std::size_t size) {
     const Common::ProcessAddress max_addr = 1ULL << table.GetAddressSpaceBits();
     return addr + size >= addr && addr + size <= max_addr;
 }

src/dynarmic/src/dynarmic/interface/code_page.h

@@ -0,0 +1,17 @@
+// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#pragma once
+
+#include <cstddef>
+#include <cstdint>
+
+namespace Dynarmic {
+
+/// @brief Smallest valid page (may change for Apple?)
+constexpr inline uint64_t CODE_PAGE_SIZE = 4096;
+struct CodePage {
+    uint32_t inst[CODE_PAGE_SIZE / sizeof(uint32_t)];
+};
+
+}