backend/a64: Devirtualize functions for a64

src/backend/A64/devirtualize.h

@@ -0,0 +1,98 @@
+/* This file is part of the dynarmic project.
+ * Copyright (c) 2018 MerryMage
+ * This software may be used and distributed according to the terms of the GNU
+ * General Public License version 2 or any later version.
+ */
+
+#pragma once
+
+#include <cstring>
+#include <memory>
+
+#include "backend/A64/callback.h"
+#include "common/assert.h"
+#include "common/cast_util.h"
+#include "common/common_types.h"
+#include "common/mp/function_info.h"
+
+namespace Dynarmic::BackendA64 {
+
+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(Common::mp::class_type_t<decltype(mfp)>* this_) {
+    return ArgCallback{&impl::ThunkBuilder<decltype(mfp), mfp>::Thunk, reinterpret_cast<u64>(this_)};
+}
+
+template<auto mfp>
+ArgCallback DevirtualizeWindows(Common::mp::class_type_t<decltype(mfp)>* this_) {
+    static_assert(sizeof(mfp) == 8);
+    return ArgCallback{Common::BitCast<u64>(mfp), reinterpret_cast<u64>(this_)};
+}
+
+template<auto mfp>
+ArgCallback DevirtualizeItanium(Common::mp::class_type_t<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 DevirtualizeAarch64(Common::mp::class_type_t<decltype(mfp)>* this_) {
+    struct MemberFunctionPointer {
+        /// For a non-virtual function, this is a simple function pointer.
+        /// For a virtual function, it is virtual table offset in bytes.
+        u64 ptr;
+        /// Twice the required adjustment to `this`, plus 1 if the member function is virtual.
+        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 / 2;
+    if (mfp_struct.adj & 1) {
+        u64 vtable = Common::BitCastPointee<u64>(this_ptr);
+        fn_ptr = Common::BitCastPointee<u64>(vtable + fn_ptr);
+    }
+    return ArgCallback{fn_ptr, this_ptr};
+}
+
+template<auto mfp>
+ArgCallback Devirtualize(Common::mp::class_type_t<decltype(mfp)>* this_) {
+#if defined(linux) || defined(__linux) || defined(__linux__)
+    return DevirtualizeAarch64<mfp>(this_);
+#else
+    return DevirtualizeGeneric<mfp>(this_);
+#endif
+}
+
+} // namespace Dynarmic::BackendA64