dynarmic/src/backend_x64/reg_alloc.cpp

299 lines
11 KiB
C++

/* This file is part of the dynarmic project.
* Copyright (c) 2016 MerryMage
* This software may be used and distributed according to the terms of the GNU
* General Public License version 2 or any later version.
*/
#include <algorithm>
#include <map>
#include "backend_x64/reg_alloc.h"
#include "common/assert.h"
#include "common/x64/emitter.h"
namespace Dynarmic {
namespace BackendX64 {
// TODO: Just turn this into a function that indexes a std::array.
const static std::map<HostLoc, Gen::X64Reg> hostloc_to_x64 = {
{ HostLoc::RAX, Gen::RAX },
{ HostLoc::RBX, Gen::RBX },
{ HostLoc::RCX, Gen::RCX },
{ HostLoc::RDX, Gen::RDX },
{ HostLoc::RSI, Gen::RSI },
{ HostLoc::RDI, Gen::RDI },
{ HostLoc::RBP, Gen::RBP },
{ HostLoc::RSP, Gen::RSP },
{ HostLoc::R8, Gen::R8 },
{ HostLoc::R9, Gen::R9 },
{ HostLoc::R10, Gen::R10 },
{ HostLoc::R11, Gen::R11 },
{ HostLoc::R12, Gen::R12 },
{ HostLoc::R13, Gen::R13 },
{ HostLoc::R14, Gen::R14 },
};
static Gen::OpArg SpillToOpArg(HostLoc loc) {
ASSERT(HostLocIsSpill(loc));
size_t i = static_cast<size_t>(loc) - static_cast<size_t>(HostLoc::FirstSpill);
return Gen::MDisp(Gen::R15, static_cast<int>(offsetof(JitState, Spill) + i * sizeof(u32)));
}
Gen::X64Reg RegAlloc::DefRegister(IR::Value* def_value, std::initializer_list<HostLoc> desired_locations) {
ASSERT(std::all_of(desired_locations.begin(), desired_locations.end(), HostLocIsRegister));
ASSERT_MSG(remaining_uses.find(def_value) == remaining_uses.end(), "def_value has already been defined");
ASSERT_MSG(ValueLocations(def_value).empty(), "def_value has already been defined");
HostLoc location = SelectARegister(desired_locations);
if (IsRegisterOccupied(location)) {
SpillRegister(location);
}
// Update state
hostloc_state[location] = HostLocState::Def;
hostloc_to_value[location] = def_value;
remaining_uses[def_value] = def_value->NumUses();
return hostloc_to_x64.at(location);
}
Gen::X64Reg RegAlloc::UseDefRegister(IR::Value* use_value, IR::Value* def_value, std::initializer_list<HostLoc> desired_locations) {
ASSERT(std::all_of(desired_locations.begin(), desired_locations.end(), HostLocIsRegister));
ASSERT_MSG(remaining_uses.find(def_value) == remaining_uses.end(), "def_value has already been defined");
ASSERT_MSG(ValueLocations(def_value).empty(), "def_value has already been defined");
ASSERT_MSG(remaining_uses.find(use_value) != remaining_uses.end(), "use_value has not been defined");
ASSERT_MSG(!ValueLocations(use_value).empty(), "use_value has not been defined");
// TODO: Optimize the case when this is the last use_value use.
Gen::X64Reg use_reg = UseRegister(use_value);
Gen::X64Reg def_reg = DefRegister(def_value, desired_locations);
code->MOV(32, Gen::R(def_reg), Gen::R(use_reg));
return def_reg;
}
Gen::X64Reg RegAlloc::UseRegister(IR::Value* use_value, std::initializer_list<HostLoc> desired_locations) {
ASSERT(std::all_of(desired_locations.begin(), desired_locations.end(), HostLocIsRegister));
ASSERT_MSG(remaining_uses.find(use_value) != remaining_uses.end(), "use_value has not been defined");
ASSERT_MSG(!ValueLocations(use_value).empty(), "use_value has not been defined");
ASSERT_MSG(remaining_uses[use_value] != 0, "use_value ran out of uses. (Use-d an IR::Value* too many times)");
HostLoc current_location = ValueLocations(use_value).front();
auto iter = std::find(desired_locations.begin(), desired_locations.end(), current_location);
if (iter != desired_locations.end()) {
ASSERT(hostloc_state[current_location] == HostLocState::Idle || hostloc_state[current_location] == HostLocState::Use);
// Update state
hostloc_state[current_location] = HostLocState::Use;
remaining_uses[use_value]--;
return hostloc_to_x64.at(current_location);
}
HostLoc new_location = SelectARegister(desired_locations);
if (HostLocIsSpill(current_location)) {
if (IsRegisterOccupied(new_location)) {
SpillRegister(new_location);
}
code->MOV(32, Gen::R(hostloc_to_x64.at(new_location)), SpillToOpArg(current_location));
hostloc_state[new_location] = HostLocState::Use;
std::swap(hostloc_to_value[new_location], hostloc_to_value[current_location]);
remaining_uses[use_value]--;
} else if (HostLocIsRegister(current_location)) {
ASSERT(hostloc_state[current_location] == HostLocState::Idle);
code->XCHG(32, Gen::R(hostloc_to_x64.at(new_location)), Gen::R(hostloc_to_x64.at(current_location)));
hostloc_state[new_location] = HostLocState::Use;
std::swap(hostloc_to_value[new_location], hostloc_to_value[current_location]);
remaining_uses[use_value]--;
} else {
ASSERT_MSG(0, "Invalid current_location");
}
return hostloc_to_x64.at(new_location);
}
Gen::X64Reg RegAlloc::UseScratchRegister(IR::Value* use_value, std::initializer_list<HostLoc> desired_locations) {
ASSERT(std::all_of(desired_locations.begin(), desired_locations.end(), HostLocIsRegister));
ASSERT_MSG(remaining_uses.find(use_value) != remaining_uses.end(), "use_value has not been defined");
ASSERT_MSG(!ValueLocations(use_value).empty(), "use_value has not been defined");
ASSERT_MSG(remaining_uses[use_value] != 0, "use_value ran out of uses. (Use-d an IR::Value* too many times)");
HostLoc current_location = ValueLocations(use_value).front();
HostLoc new_location = SelectARegister(desired_locations);
if (HostLocIsSpill(current_location)) {
if (IsRegisterOccupied(new_location)) {
SpillRegister(new_location);
}
code->MOV(32, Gen::R(hostloc_to_x64.at(new_location)), SpillToOpArg(current_location));
hostloc_state[new_location] = HostLocState::Scratch;
remaining_uses[use_value]--;
} else if (HostLocIsRegister(current_location)) {
ASSERT(hostloc_state[current_location] == HostLocState::Idle);
if (IsRegisterOccupied(new_location)) {
SpillRegister(new_location);
if (current_location != new_location) {
code->MOV(32, Gen::R(hostloc_to_x64.at(new_location)), Gen::R(hostloc_to_x64.at(current_location)));
}
} else {
code->MOV(32, Gen::R(hostloc_to_x64.at(new_location)), Gen::R(hostloc_to_x64.at(current_location)));
}
hostloc_state[new_location] = HostLocState::Scratch;
remaining_uses[use_value]--;
} else {
ASSERT_MSG(0, "Invalid current_location");
}
return hostloc_to_x64.at(new_location);
}
Gen::X64Reg RegAlloc::ScratchRegister(std::initializer_list<HostLoc> desired_locations) {
ASSERT(std::all_of(desired_locations.begin(), desired_locations.end(), HostLocIsRegister));
HostLoc location = SelectARegister(desired_locations);
if (IsRegisterOccupied(location)) {
SpillRegister(location);
}
// Update state
hostloc_state[location] = HostLocState::Scratch;
return hostloc_to_x64.at(location);
}
void RegAlloc::HostCall(IR::Value* result_def, IR::Value* arg0_use, IR::Value* arg1_use, IR::Value* arg2_use, IR::Value* arg3_use) {
constexpr HostLoc AbiReturn = HostLoc::RAX;
#ifdef _WIN32
constexpr std::array<HostLoc, 4> AbiArgs = { HostLoc::RCX, HostLoc::RDX, HostLoc::R8, HostLoc::R9 };
/// Caller-saved registers other than AbiReturn or AbiArgs
constexpr std::array<HostLoc, 2> OtherCallerSave = { HostLoc::R10, HostLoc::R11 };
#else
constexpr std::array<HostLoc, 4> AbiArgs = { HostLoc::RDI, HostLoc::RSI, HostLoc::RDX, HostLoc::RCX };
/// Caller-saved registers other than AbiReturn or AbiArgs
constexpr std::array<HostLoc, 4> OtherCallerSave = { HostLoc::R8, HostLoc::R9, HostLoc::R10, HostLoc::R11 };
#endif
const std::array<IR::Value*, 4> args = {arg0_use, arg1_use, arg2_use, arg3_use};
// TODO: This works but almost certainly leads to suboptimal generated code.
for (HostLoc caller_save : OtherCallerSave) {
ScratchRegister({caller_save});
}
if (result_def) {
DefRegister(result_def, {AbiReturn});
} else {
ScratchRegister({AbiReturn});
}
for (size_t i = 0; i < AbiArgs.size(); i++) {
if (args[i]) {
UseScratchRegister(args[i], {AbiArgs[i]});
} else {
ScratchRegister({AbiArgs[i]});
}
}
ScratchRegister({HostLoc::RSP});
code->MOV(64, Gen::R(Gen::RSP), Gen::MDisp(Gen::R15, offsetof(JitState, save_host_RSP)));
}
HostLoc RegAlloc::SelectARegister(std::initializer_list<HostLoc> desired_locations) const {
std::vector<HostLoc> candidates = desired_locations;
// Find all locations that have not been allocated..
auto allocated_locs = std::partition(candidates.begin(), candidates.end(), [this](auto loc){
return !this->IsRegisterAllocated(loc);
});
candidates.erase(allocated_locs, candidates.end());
ASSERT_MSG(!candidates.empty(), "All candidate registers have already been allocated");
// Selects the best location out of the available locations.
// TODO: Actually do LRU or something. Currently we just try to pick something without a value if possible.
std::partition(candidates.begin(), candidates.end(), [this](auto loc){
return !this->IsRegisterOccupied(loc);
});
return candidates.front();
}
std::vector<HostLoc> RegAlloc::ValueLocations(IR::Value* value) const {
std::vector<HostLoc> locations;
for (const auto& iter : hostloc_to_value)
if (iter.second == value)
locations.emplace_back(iter.first);
return locations;
}
bool RegAlloc::IsRegisterOccupied(HostLoc loc) const {
return hostloc_to_value.find(loc) != hostloc_to_value.end() && hostloc_to_value.at(loc) != nullptr;
}
bool RegAlloc::IsRegisterAllocated(HostLoc loc) const {
return hostloc_state.find(loc) != hostloc_state.end() && hostloc_state.at(loc) != HostLocState::Idle;
}
void RegAlloc::SpillRegister(HostLoc loc) {
ASSERT_MSG(HostLocIsRegister(loc), "Only registers can be spilled");
ASSERT_MSG(hostloc_state[loc] == HostLocState::Idle, "Allocated registers cannot be spilled");
ASSERT_MSG(IsRegisterOccupied(loc), "There is no need to spill unoccupied registers");
ASSERT_MSG(!IsRegisterAllocated(loc), "Registers that have been allocated must not be spilt");
HostLoc new_loc = FindFreeSpill();
code->MOV(32, SpillToOpArg(new_loc), Gen::R(hostloc_to_x64.at(loc)));
hostloc_to_value[new_loc] = hostloc_to_value[loc];
hostloc_to_value[loc] = nullptr;
}
HostLoc RegAlloc::FindFreeSpill() const {
for (size_t i = 0; i < SpillCount; i++)
if (!IsRegisterOccupied(HostLocSpill(i)))
return HostLocSpill(i);
ASSERT_MSG(0, "All spill locations are full");
}
void RegAlloc::EndOfAllocScope() {
hostloc_state.clear();
for (auto& iter : hostloc_to_value)
if (iter.second && remaining_uses[iter.second] == 0)
iter.second = nullptr;
}
void RegAlloc::DecrementRemainingUses(IR::Value* value) {
ASSERT_MSG(remaining_uses.find(value) != remaining_uses.end(), "value does not exist");
ASSERT_MSG(remaining_uses[value] > 0, "value doesn't have any remaining uses");
remaining_uses[value]--;
}
void RegAlloc::AssertNoMoreUses() {
ASSERT(std::all_of(hostloc_to_value.begin(), hostloc_to_value.end(), [](const auto& pair){ return !pair.second; }));
}
void RegAlloc::Reset() {
hostloc_to_value.clear();
hostloc_state.clear();
remaining_uses.clear();
}
} // namespace BackendX64
} // namespace Dynarmic