geode/loader/include/Geode/meta/membercall.hpp

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9.4 KiB
C++

#ifndef GEODE_CORE_META_MEMBERCALL_HPP
#define GEODE_CORE_META_MEMBERCALL_HPP
#include "callconv.hpp"
#include "tuple.hpp"
#include "x86.hpp"
namespace geode::core::meta::x86 {
template <class T>
concept MembercallStructReturn = std::is_class_v<T> && sizeof(T) > 8;
template <class Ret, class... Args>
class Membercall {};
template <class Ret, class... Args>
requires (!MembercallStructReturn<Ret>)
class Membercall<Ret, Args...> : public CallConv<Ret, Args...> {
protected:
// Metaprogramming / typedefs we need for the rest of the class.
using MyConv = CallConv<Ret, Args...>;
public:
class Sequences {
private:
// These are required for proper reordering.
static constexpr size_t length = sizeof...(Args);
static constexpr size_t SSES = 3;
static constexpr bool is_sse[length] = { sse_passable<Args>... };
static constexpr bool is_gpr[length] = { gpr_passable<Args>... };
static constexpr auto reordered_arr = reorder_pack<Args...>();
// Setup call from our caller, to "foreign" function
static constexpr auto filter_to() {
/* The size of our output may be longer than the input.
* For the third time, annoyingly, we need to make a lambda for this.
*/
constexpr auto arr_size = []() -> size_t {
// Magic constant 5: XMM0, XMM4, XMM5, ECX, and EDX.
size_t size = length + SSES + 5;
// Check our only GPR.
if (0 < length && is_gpr[reordered_arr[0]]) {
--size;
}
/* We assume there are no SSES initially.
* Any SSES we encounter, we have to remove a "duplicate".
*/
for (size_t i = 1; i < SSES + 1; ++i) {
if (i < length && is_sse[reordered_arr[i]]) {
--size;
}
}
return size;
};
std::array<size_t, arr_size()> to = {};
/* These are the indices of the placeholder float and int, for clobbering SSEs and
* GPRs, respectively.
*/
constexpr size_t CLOBBER_SSE = length;
constexpr size_t CLOBBER_GPR = length + 1;
// Put the SSEs into the right XMM registers, if they exist.
for (size_t i = 1; i < SSES + 1; ++i) {
if (i < length && is_sse[reordered_arr[i]]) {
to[i] = reordered_arr[i];
}
else {
to[i] = CLOBBER_SSE;
}
}
// Clobber XMM0, XMM4, XMM5, and EDX.
to[0] = CLOBBER_SSE;
to[4] = CLOBBER_SSE;
to[5] = CLOBBER_SSE;
to[7] = CLOBBER_GPR;
// Handle our GPR and put it in ECX if we can.
if (length > 0 && is_gpr[reordered_arr[0]]) {
to[6] = reordered_arr[0];
}
else {
to[6] = CLOBBER_GPR;
}
for (size_t in = 1, out = SSES + 5; in < length; ++in) {
// Put all non SSEs and non GPRs in their places.
size_t current = reordered_arr[in];
if (!(is_sse[current] && in < SSES + 1)) {
to[out] = current;
++out;
}
}
return to;
}
// Setup call from "foreign" function, to one of ours.
static constexpr auto filter_from() {
std::array<size_t, length> from = {};
constexpr size_t CLOBBER_SSE = length;
constexpr size_t CLOBBER_GPR = length + 1;
if (length > 0 && is_gpr[reordered_arr[0]]) {
// SSES + 3 = ECX
from[reordered_arr[0]] = SSES + 3;
}
for (size_t i = 1, offset = 0; i < length; ++i) {
size_t current = reordered_arr[i];
if (is_sse[current] && i < SSES + 1) {
// If in SSE, retain index
from[current] = i;
}
else {
// If on stack, offset by 8 (6 SSE + 2 GPR registers available)
from[current] = offset + SSES + 5;
++offset;
}
}
return from;
}
// Annoyingly, unless we're using C++20, we can't eliminate these intermediates. (afaik)
static constexpr auto to_arr = filter_to();
static constexpr auto from_arr = filter_from();
public:
using to = typename MyConv::template arr_to_seq<to_arr>;
using from = typename MyConv::template arr_to_seq<from_arr>;
};
protected:
// Where all the logic is actually implemented.
template <class Class, class>
class Impl {
static_assert(
always_false<Class>,
"Please report a bug to the Geode developers! This should never be reached.\n"
"SFINAE didn't reach the right overload!"
);
};
template <size_t... to, size_t... from>
class Impl<std::index_sequence<to...>, std::index_sequence<from...>> {
public:
static Ret invoke(void* address, Tuple<Args..., float, int> const& all) {
return reinterpret_cast<Ret(__vectorcall*)(
typename Tuple<Args..., float, int>::template type_at<to>...
)>(address)(all.template at<to>()...);
}
template <Ret (*detour)(Args...)>
static Ret __vectorcall wrapper(
/* It's wrapped to stop MSVC from giving me error messages with internal compiler
* info. WTF.
*/
typename Tuple<Args..., float, int>::template type_at_wrap<to>... raw
) {
auto all = Tuple<>::make(raw...);
return detour(all.template at<from>()...);
}
};
protected:
// Putting it all together: instantiating Impl with our filters.
using MyImpl = Impl<typename Sequences::to, typename Sequences::from>;
public:
// Just wrapping MyImpl.
static Ret invoke(void* address, Args... all) {
/* The extra float and int here are so that we can grab placeholders.
* If we don't have anything in XMM0 - 5 or ECX / EDX, we will use
* these placeholders instead. The values are 314 to avoid unintentional
* bugs (since 0 may work coincidentally).
*/
return MyImpl::invoke(address, { all..., 314.0f, 314 });
}
template <Ret (*detour)(Args...)>
static auto get_wrapper() {
return reinterpret_cast<void*>(&MyImpl::template wrapper<detour>);
}
};
template <class Ret, class Class, class... Args>
requires (MembercallStructReturn<Ret>)
class Membercall<Ret, Class, Args...> {
protected:
using Sequences = typename Membercall<Ret*, Class, Ret*, Args...>::Sequences;
// Where all the logic is actually implemented.
template <class ImplClass, class>
class Impl {
static_assert(
always_false<ImplClass>,
"Please report a bug to the Geode developers! This should never be reached.\n"
"SFINAE didn't reach the right overload!"
);
};
template <size_t... to, size_t... from>
class Impl<std::index_sequence<to...>, std::index_sequence<from...>> {
public:
static Ret* invoke(void* address, Tuple<Class, Ret*, Args..., float, int> const& all) {
return reinterpret_cast<Ret*(__vectorcall*)(
typename Tuple<Class, Ret*, Args..., float, int>::template type_at<to>...
)>(address)(all.template at<to>()...);
}
template <Ret (*detour)(Class, Args...)>
static Ret* __vectorcall wrapper(
/* It's wrapped to stop MSVC from giving me error messages with internal compiler
* info. WTF.
*/
typename Tuple<Class, Ret*, Args..., float, int>::template type_at_wrap<to>... raw
) {
auto all = Tuple<>::make(raw...);
return reinterpret_cast<Ret*(*)(Class, Ret*, Args...)>(detour)(all.template at<from>()...);
}
};
protected:
// Putting it all together: instantiating Impl with our filters.
using MyImpl = Impl<typename Sequences::to, typename Sequences::from>;
public:
static Ret invoke(void* address, Class inst, Args... all) {
Ret ret;
(void)MyImpl::invoke(address, { inst, &ret, all..., 314.0f, 314 });
return ret;
}
template <Ret (*detour)(Class, Args...)>
static auto get_wrapper() {
return reinterpret_cast<void*>(&MyImpl::template wrapper<detour>);
}
};
}
#endif /* GEODE_CORE_META_MEMBERCALL_HPP */