early-access version 1255

externals/dynarmic/src/backend/x64/devirtualize.h

@@ -0,0 +1,81 @@
+/* This file is part of the dynarmic project.
+ * Copyright (c) 2018 MerryMage
+ * SPDX-License-Identifier: 0BSD
+ */
+
+#pragma once
+
+#include <cstring>
+#include <utility>
+
+#include <mp/traits/function_info.h>
+
+#include "backend/x64/callback.h"
+#include "common/cast_util.h"
+#include "common/common_types.h"
+
+namespace Dynarmic {
+namespace Backend::X64 {
+
+namespace impl {
+
+template <typename FunctionType, FunctionType mfp>
+struct ThunkBuilder;
+
+template <typename C, typename R, typename... Args, R(C::*mfp)(Args...)>
+struct ThunkBuilder<R(C::*)(Args...), mfp> {
+    static R Thunk(C* this_, Args... args) {
+        return (this_->*mfp)(std::forward<Args>(args)...);
+    }
+};
+
+} // namespace impl
+
+template<auto mfp>
+ArgCallback DevirtualizeGeneric(mp::class_type<decltype(mfp)>* this_) {
+    return ArgCallback{&impl::ThunkBuilder<decltype(mfp), mfp>::Thunk, reinterpret_cast<u64>(this_)};
+}
+
+template<auto mfp>
+ArgCallback DevirtualizeWindows(mp::class_type<decltype(mfp)>* this_) {
+    static_assert(sizeof(mfp) == 8);
+    return ArgCallback{Common::BitCast<u64>(mfp), reinterpret_cast<u64>(this_)};
+}
+
+template<auto mfp>
+ArgCallback DevirtualizeItanium(mp::class_type<decltype(mfp)>* this_) {
+    struct MemberFunctionPointer {
+        /// For a non-virtual function, this is a simple function pointer.
+        /// For a virtual function, it is (1 + virtual table offset in bytes).
+        u64 ptr;
+        /// The required adjustment to `this`, prior to the call.
+        u64 adj;
+    } mfp_struct = Common::BitCast<MemberFunctionPointer>(mfp);
+
+    static_assert(sizeof(MemberFunctionPointer) == 16);
+    static_assert(sizeof(MemberFunctionPointer) == sizeof(mfp));
+
+    u64 fn_ptr = mfp_struct.ptr;
+    u64 this_ptr = reinterpret_cast<u64>(this_) + mfp_struct.adj;
+    if (mfp_struct.ptr & 1) {
+        u64 vtable = Common::BitCastPointee<u64>(this_ptr);
+        fn_ptr = Common::BitCastPointee<u64>(vtable + fn_ptr - 1);
+    }
+    return ArgCallback{fn_ptr, this_ptr};
+}
+
+template<auto mfp>
+ArgCallback Devirtualize(mp::class_type<decltype(mfp)>* this_) {
+#if defined(__APPLE__) || defined(linux) || defined(__linux) || defined(__linux__)
+    return DevirtualizeItanium<mfp>(this_);
+#elif defined(__MINGW64__)
+    return DevirtualizeItanium<mfp>(this_);
+#elif defined(_WIN32)
+    return DevirtualizeWindows<mfp>(this_);
+#else
+    return DevirtualizeGeneric<mfp>(this_);
+#endif
+}
+
+} // namespace Backend::X64
+} // namespace Dynarmic