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[CPU/Backend] Refactor shared backend logic into CRTP base

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This commit is contained in:
Herman S.
2026-03-17 09:22:10 +09:00
parent b621e89c0b
commit b8912a4c79
4 changed files with 407 additions and 423 deletions
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src/xenia/cpu/backend/code_cache_base.h Normal file
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/**
******************************************************************************
* Xenia : Xbox 360 Emulator Research Project *
******************************************************************************
* Copyright 2026 Ben Vanik. All rights reserved. *
* Released under the BSD license - see LICENSE in the root for more details. *
******************************************************************************
*/
#ifndef XENIA_CPU_BACKEND_CODE_CACHE_BASE_H_
#define XENIA_CPU_BACKEND_CODE_CACHE_BASE_H_
#include <atomic>
#include <cstddef>
#include <cstdint>
#include <cstdlib>
#include <cstring>
#include <memory>
#include <string>
#include <utility>
#include <vector>
#include "third_party/fmt/include/fmt/format.h"
#include "xenia/base/assert.h"
#include "xenia/base/clock.h"
#include "xenia/base/literals.h"
#include "xenia/base/logging.h"
#include "xenia/base/math.h"
#include "xenia/base/memory.h"
#include "xenia/base/mutex.h"
#include "xenia/cpu/backend/code_cache.h"
#include "xenia/cpu/function.h"
namespace xe {
namespace cpu {
namespace backend {
struct EmitFunctionInfo {
struct _code_size {
size_t prolog;
size_t body;
size_t epilog;
size_t tail;
size_t total;
} code_size;
size_t prolog_stack_alloc_offset;
size_t stack_size;
};
// CRTP base class for JIT code caches. Contains all platform-independent
// logic for memory management, indirection tables, code placement, and
// function lookup. Derived classes provide architecture-specific hooks:
//
// void FillCode(void* address, size_t size)
// Fill unused code regions with trap instructions (0xCC / BRK).
//
// void FlushCodeRange(void* address, size_t size)
// Flush I-cache after writing code (no-op on x86, required on ARM64).
//
// UnwindReservation RequestUnwindReservation(uint8_t* entry_address)
// Reserve space for platform-specific unwind info.
//
// void PlaceCode(uint32_t guest_address, void* machine_code,
// const EmitFunctionInfo& func_info,
// void* code_execute_address,
// UnwindReservation unwind_reservation)
// Register unwind info and perform platform-specific post-placement.
//
// void OnCodePlaced(uint32_t guest_address, GuestFunction* function_info,
// void* code_execute_address, size_t code_size)
// Optional hook called after code is placed outside the critical section
// (used for VTune integration on x64). Default is no-op.
template <typename Derived>
class CodeCacheBase : public CodeCache {
public:
~CodeCacheBase() override {
if (indirection_table_base_) {
xe::memory::DeallocFixed(indirection_table_base_, kIndirectionTableSize,
xe::memory::DeallocationType::kRelease);
}
if (mapping_ != xe::memory::kFileMappingHandleInvalid) {
if (generated_code_write_base_ &&
generated_code_write_base_ != generated_code_execute_base_) {
xe::memory::UnmapFileView(mapping_, generated_code_write_base_,
kGeneratedCodeSize);
}
if (generated_code_execute_base_) {
xe::memory::UnmapFileView(mapping_, generated_code_execute_base_,
kGeneratedCodeSize);
}
xe::memory::CloseFileMappingHandle(mapping_, file_name_);
mapping_ = xe::memory::kFileMappingHandleInvalid;
}
}
const std::filesystem::path& file_name() const override { return file_name_; }
uintptr_t execute_base_address() const override {
return kGeneratedCodeExecuteBase;
}
size_t total_size() const override { return kGeneratedCodeSize; }
bool has_indirection_table() { return indirection_table_base_ != nullptr; }
void set_indirection_default(uint32_t default_value) {
indirection_default_value_ = default_value;
}
void AddIndirection(uint32_t guest_address, uint32_t host_address) {
if (!indirection_table_base_) {
return;
}
uint32_t* indirection_slot = reinterpret_cast<uint32_t*>(
indirection_table_base_ + (guest_address - kIndirectionTableBase));
*indirection_slot = host_address;
}
void CommitExecutableRange(uint32_t guest_low, uint32_t guest_high) {
if (!indirection_table_base_) {
return;
}
xe::memory::AllocFixed(
indirection_table_base_ + (guest_low - kIndirectionTableBase),
guest_high - guest_low, xe::memory::AllocationType::kCommit,
xe::memory::PageAccess::kReadWrite);
uint32_t* p = reinterpret_cast<uint32_t*>(indirection_table_base_);
for (uint32_t address = guest_low; address < guest_high; ++address) {
p[(address - kIndirectionTableBase) / 4] = indirection_default_value_;
}
}
void PlaceHostCode(uint32_t guest_address, void* machine_code,
const EmitFunctionInfo& func_info,
void*& code_execute_address_out,
void*& code_write_address_out) {
PlaceGuestCode(guest_address, machine_code, func_info, nullptr,
code_execute_address_out, code_write_address_out);
}
void PlaceGuestCode(uint32_t guest_address, void* machine_code,
const EmitFunctionInfo& func_info,
GuestFunction* function_info,
void*& code_execute_address_out,
void*& code_write_address_out) {
using namespace xe::literals;
uint8_t* code_execute_address;
{
auto global_lock = global_critical_region_.Acquire();
code_execute_address =
generated_code_execute_base_ + generated_code_offset_;
code_execute_address_out = code_execute_address;
uint8_t* code_write_address =
generated_code_write_base_ + generated_code_offset_;
code_write_address_out = code_write_address;
generated_code_offset_ += xe::round_up(func_info.code_size.total, 16);
auto tail_write_address =
generated_code_write_base_ + generated_code_offset_;
auto unwind_reservation = self().RequestUnwindReservation(
generated_code_write_base_ + generated_code_offset_);
generated_code_offset_ += xe::round_up(unwind_reservation.data_size, 16);
auto end_write_address =
generated_code_write_base_ + generated_code_offset_;
size_t high_mark = generated_code_offset_;
generated_code_map_.emplace_back(
(uint64_t(code_execute_address - generated_code_execute_base_)
<< 32) |
generated_code_offset_,
function_info);
// Commit memory if needed.
EnsureCommitted(high_mark);
// Copy code.
std::memcpy(code_write_address, machine_code, func_info.code_size.total);
// Fill unused tail/unwind gap with arch-specific trap instructions.
self().FillCode(
tail_write_address,
static_cast<size_t>(end_write_address - tail_write_address));
// Flush I-cache for code and fill regions.
self().FlushCodeRange(code_write_address, func_info.code_size.total);
if (tail_write_address < end_write_address) {
self().FlushCodeRange(
tail_write_address,
static_cast<size_t>(end_write_address - tail_write_address));
}
// Platform-specific unwind registration.
self().PlaceCode(guest_address, machine_code, func_info,
code_execute_address, unwind_reservation);
}
// Post-placement hook (e.g. VTune notification).
self().OnCodePlaced(guest_address, function_info, code_execute_address,
func_info.code_size.total);
// Fix up indirection table.
if (guest_address && indirection_table_base_) {
uint32_t* indirection_slot = reinterpret_cast<uint32_t*>(
indirection_table_base_ + (guest_address - kIndirectionTableBase));
*indirection_slot =
uint32_t(reinterpret_cast<uint64_t>(code_execute_address));
}
}
uint32_t PlaceData(const void* data, size_t length) {
size_t high_mark;
uint8_t* data_address = nullptr;
{
auto global_lock = global_critical_region_.Acquire();
data_address = generated_code_write_base_ + generated_code_offset_;
generated_code_offset_ += xe::round_up(length, 16);
high_mark = generated_code_offset_;
}
EnsureCommitted(high_mark);
std::memcpy(data_address, data, length);
return uint32_t(uintptr_t(data_address));
}
GuestFunction* LookupFunction(uint64_t host_pc) override {
uint32_t key = uint32_t(host_pc - kGeneratedCodeExecuteBase);
void* fn_entry = std::bsearch(
&key, generated_code_map_.data(), generated_code_map_.size(),
sizeof(std::pair<uint32_t, Function*>),
[](const void* key_ptr, const void* element_ptr) {
auto key = *reinterpret_cast<const uint32_t*>(key_ptr);
auto element =
reinterpret_cast<const std::pair<uint64_t, GuestFunction*>*>(
element_ptr);
if (key < (element->first >> 32)) {
return -1;
} else if (key > uint32_t(element->first)) {
return 1;
} else {
return 0;
}
});
if (fn_entry) {
return reinterpret_cast<const std::pair<uint64_t, GuestFunction*>*>(
fn_entry)
->second;
} else {
return nullptr;
}
}
protected:
static constexpr size_t kIndirectionTableSize = 0x1FFFFFFF;
static constexpr uintptr_t kIndirectionTableBase = 0x80000000;
static constexpr size_t kGeneratedCodeSize = 0x0FFFFFFF;
static constexpr uintptr_t kGeneratedCodeExecuteBase = 0xA0000000;
static const uintptr_t kGeneratedCodeWriteBase =
kGeneratedCodeExecuteBase + kGeneratedCodeSize + 1;
static constexpr size_t kMaximumFunctionCount = 1000000;
struct UnwindReservation {
size_t data_size = 0;
size_t table_slot = 0;
uint8_t* entry_address = 0;
};
CodeCacheBase() = default;
bool Initialize() {
indirection_table_base_ = reinterpret_cast<uint8_t*>(xe::memory::AllocFixed(
reinterpret_cast<void*>(kIndirectionTableBase), kIndirectionTableSize,
xe::memory::AllocationType::kReserve,
xe::memory::PageAccess::kReadWrite));
if (!indirection_table_base_) {
XELOGE("Unable to allocate code cache indirection table");
XELOGE(
"This is likely because the {:X}-{:X} range is in use by some "
"other system DLL",
static_cast<uint64_t>(kIndirectionTableBase),
kIndirectionTableBase + kIndirectionTableSize);
}
file_name_ =
fmt::format("xenia_code_cache_{}", Clock::QueryHostTickCount());
mapping_ = xe::memory::CreateFileMappingHandle(
file_name_, kGeneratedCodeSize,
xe::memory::PageAccess::kExecuteReadWrite, false);
if (mapping_ == xe::memory::kFileMappingHandleInvalid) {
XELOGE("Unable to create code cache mmap");
return false;
}
if (xe::memory::IsWritableExecutableMemoryPreferred()) {
generated_code_execute_base_ =
reinterpret_cast<uint8_t*>(xe::memory::MapFileView(
mapping_, reinterpret_cast<void*>(kGeneratedCodeExecuteBase),
kGeneratedCodeSize, xe::memory::PageAccess::kExecuteReadWrite,
0));
generated_code_write_base_ = generated_code_execute_base_;
if (!generated_code_execute_base_ || !generated_code_write_base_) {
XELOGE("Unable to allocate code cache generated code storage");
XELOGE(
"This is likely because the {:X}-{:X} range is in use by some "
"other system DLL",
uint64_t(kGeneratedCodeExecuteBase),
uint64_t(kGeneratedCodeExecuteBase + kGeneratedCodeSize));
return false;
}
} else {
generated_code_execute_base_ =
reinterpret_cast<uint8_t*>(xe::memory::MapFileView(
mapping_, reinterpret_cast<void*>(kGeneratedCodeExecuteBase),
kGeneratedCodeSize, xe::memory::PageAccess::kExecuteReadOnly, 0));
generated_code_write_base_ =
reinterpret_cast<uint8_t*>(xe::memory::MapFileView(
mapping_, reinterpret_cast<void*>(kGeneratedCodeWriteBase),
kGeneratedCodeSize, xe::memory::PageAccess::kReadWrite, 0));
if (!generated_code_execute_base_ || !generated_code_write_base_) {
XELOGE("Unable to allocate code cache generated code storage");
XELOGE(
"This is likely because the {:X}-{:X} and {:X}-{:X} ranges are "
"in use by some other system DLL",
uint64_t(kGeneratedCodeExecuteBase),
uint64_t(kGeneratedCodeExecuteBase + kGeneratedCodeSize),
uint64_t(kGeneratedCodeWriteBase),
uint64_t(kGeneratedCodeWriteBase + kGeneratedCodeSize));
return false;
}
}
generated_code_map_.reserve(kMaximumFunctionCount);
return true;
}
// Default no-op for the OnCodePlaced hook.
void OnCodePlaced(uint32_t guest_address, GuestFunction* function_info,
void* code_execute_address, size_t code_size) {}
std::filesystem::path file_name_;
xe::memory::FileMappingHandle mapping_ =
xe::memory::kFileMappingHandleInvalid;
xe::global_critical_region global_critical_region_;
uint32_t indirection_default_value_ = 0xFEEDF00D;
uint8_t* indirection_table_base_ = nullptr;
uint8_t* generated_code_execute_base_ = nullptr;
uint8_t* generated_code_write_base_ = nullptr;
size_t generated_code_offset_ = 0;
std::atomic<size_t> generated_code_commit_mark_ = {0};
std::vector<std::pair<uint64_t, GuestFunction*>> generated_code_map_;
private:
Derived& self() { return static_cast<Derived&>(*this); }
void EnsureCommitted(size_t high_mark) {
using namespace xe::literals;
size_t old_commit_mark, new_commit_mark;
do {
old_commit_mark = generated_code_commit_mark_;
if (high_mark <= old_commit_mark) break;
new_commit_mark = old_commit_mark + 16_MiB;
if (generated_code_execute_base_ == generated_code_write_base_) {
xe::memory::AllocFixed(generated_code_execute_base_, new_commit_mark,
xe::memory::AllocationType::kCommit,
xe::memory::PageAccess::kExecuteReadWrite);
} else {
xe::memory::AllocFixed(generated_code_execute_base_, new_commit_mark,
xe::memory::AllocationType::kCommit,
xe::memory::PageAccess::kExecuteReadOnly);
xe::memory::AllocFixed(generated_code_write_base_, new_commit_mark,
xe::memory::AllocationType::kCommit,
xe::memory::PageAccess::kReadWrite);
}
} while (generated_code_commit_mark_.compare_exchange_weak(
old_commit_mark, new_commit_mark));
}
};
} // namespace backend
} // namespace cpu
} // namespace xe
#endif // XENIA_CPU_BACKEND_CODE_CACHE_BASE_H_