// Copyright 2021 yuzu Emulator Project
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.
#include <algorithm>
#include <tuple>
#include <type_traits>
#include "common/bit_cast.h"
#include "common/bit_util.h"
#include "shader_recompiler/exception.h"
#include "shader_recompiler/frontend/ir/microinstruction.h"
#include "shader_recompiler/ir_opt/passes.h"
namespace Shader::Optimization {
namespace {
// Metaprogramming stuff to get arguments information out of a lambda
template <typename Func>
struct LambdaTraits : LambdaTraits<decltype(&std::remove_reference_t<Func>::operator())> {};
template <typename ReturnType, typename LambdaType, typename... Args>
struct LambdaTraits<ReturnType (LambdaType::*)(Args...) const> {
template <size_t I>
using ArgType = std::tuple_element_t<I, std::tuple<Args...>>;
static constexpr size_t NUM_ARGS{sizeof...(Args)};
};
template <typename T>
[[nodiscard]] T Arg(const IR::Value& value) {
if constexpr (std::is_same_v<T, bool>) {
return value.U1();
} else if constexpr (std::is_same_v<T, u32>) {
return value.U32();
} else if constexpr (std::is_same_v<T, f32>) {
return value.F32();
} else if constexpr (std::is_same_v<T, u64>) {
return value.U64();
}
}
template <typename ImmFn>
bool FoldCommutative(IR::Inst& inst, ImmFn&& imm_fn) {
const auto arg = [](const IR::Value& value) {
if constexpr (std::is_invocable_r_v<bool, ImmFn, bool, bool>) {
return value.U1();
} else if constexpr (std::is_invocable_r_v<u32, ImmFn, u32, u32>) {
return value.U32();
} else if constexpr (std::is_invocable_r_v<u64, ImmFn, u64, u64>) {
return value.U64();
}
};
const IR::Value lhs{inst.Arg(0)};
const IR::Value rhs{inst.Arg(1)};
const bool is_lhs_immediate{lhs.IsImmediate()};
const bool is_rhs_immediate{rhs.IsImmediate()};
if (is_lhs_immediate && is_rhs_immediate) {
const auto result{imm_fn(arg(lhs), arg(rhs))};
inst.ReplaceUsesWith(IR::Value{result});
return false;
}
if (is_lhs_immediate && !is_rhs_immediate) {
IR::Inst* const rhs_inst{rhs.InstRecursive()};
if (rhs_inst->Opcode() == inst.Opcode() && rhs_inst->Arg(1).IsImmediate()) {
const auto combined{imm_fn(arg(lhs), arg(rhs_inst->Arg(1)))};
inst.SetArg(0, rhs_inst->Arg(0));
inst.SetArg(1, IR::Value{combined});
} else {
// Normalize
inst.SetArg(0, rhs);
inst.SetArg(1, lhs);
}
}
if (!is_lhs_immediate && is_rhs_immediate) {
const IR::Inst* const lhs_inst{lhs.InstRecursive()};
if (lhs_inst->Opcode() == inst.Opcode() && lhs_inst->Arg(1).IsImmediate()) {
const auto combined{imm_fn(arg(rhs), arg(lhs_inst->Arg(1)))};
inst.SetArg(0, lhs_inst->Arg(0));
inst.SetArg(1, IR::Value{combined});
}
}
return true;
}
void FoldGetRegister(IR::Inst& inst) {
if (inst.Arg(0).Reg() == IR::Reg::RZ) {
inst.ReplaceUsesWith(IR::Value{u32{0}});
}
}
void FoldGetPred(IR::Inst& inst) {
if (inst.Arg(0).Pred() == IR::Pred::PT) {
inst.ReplaceUsesWith(IR::Value{true});
}
}
template <typename T>
void FoldAdd(IR::Inst& inst) {
if (inst.HasAssociatedPseudoOperation()) {
return;
}
if (!FoldCommutative(inst, [](T a, T b) { return a + b; })) {
return;
}
const IR::Value rhs{inst.Arg(1)};
if (rhs.IsImmediate() && Arg<T>(rhs) == 0) {
inst.ReplaceUsesWith(inst.Arg(0));
}
}
template <typename T>
void FoldSelect(IR::Inst& inst) {
const IR::Value cond{inst.Arg(0)};
if (cond.IsImmediate()) {
inst.ReplaceUsesWith(cond.U1() ? inst.Arg(1) : inst.Arg(2));
}
}
void FoldLogicalAnd(IR::Inst& inst) {
if (!FoldCommutative(inst, [](bool a, bool b) { return a && b; })) {
return;
}
const IR::Value rhs{inst.Arg(1)};
if (rhs.IsImmediate()) {
if (rhs.U1()) {
inst.ReplaceUsesWith(inst.Arg(0));
} else {
inst.ReplaceUsesWith(IR::Value{false});
}
}
}
template <typename Dest, typename Source>
void FoldBitCast(IR::Inst& inst, IR::Opcode reverse) {
const IR::Value value{inst.Arg(0)};
if (value.IsImmediate()) {
inst.ReplaceUsesWith(IR::Value{Common::BitCast<Dest>(Arg<Source>(value))});
return;
}
IR::Inst* const arg_inst{value.InstRecursive()};
if (value.InstRecursive()->Opcode() == reverse) {
inst.ReplaceUsesWith(arg_inst->Arg(0));
}
}
template <typename Func, size_t... I>
IR::Value EvalImmediates(const IR::Inst& inst, Func&& func, std::index_sequence<I...>) {
using Traits = LambdaTraits<decltype(func)>;
return IR::Value{func(Arg<Traits::ArgType<I>>(inst.Arg(I))...)};
}
template <typename Func>
void FoldWhenAllImmediates(IR::Inst& inst, Func&& func) {
if (!inst.AreAllArgsImmediates() || inst.HasAssociatedPseudoOperation()) {
return;
}
using Indices = std::make_index_sequence<LambdaTraits<decltype(func)>::NUM_ARGS>;
inst.ReplaceUsesWith(EvalImmediates(inst, func, Indices{}));
}
void ConstantPropagation(IR::Inst& inst) {
switch (inst.Opcode()) {
case IR::Opcode::GetRegister:
return FoldGetRegister(inst);
case IR::Opcode::GetPred:
return FoldGetPred(inst);
case IR::Opcode::IAdd32:
return FoldAdd<u32>(inst);
case IR::Opcode::BitCastF32U32:
return FoldBitCast<f32, u32>(inst, IR::Opcode::BitCastU32F32);
case IR::Opcode::BitCastU32F32:
return FoldBitCast<u32, f32>(inst, IR::Opcode::BitCastF32U32);
case IR::Opcode::IAdd64:
return FoldAdd<u64>(inst);
case IR::Opcode::Select32:
return FoldSelect<u32>(inst);
case IR::Opcode::LogicalAnd:
return FoldLogicalAnd(inst);
case IR::Opcode::ULessThan:
return FoldWhenAllImmediates(inst, [](u32 a, u32 b) { return a < b; });
case IR::Opcode::BitFieldUExtract:
return FoldWhenAllImmediates(inst, [](u32 base, u32 shift, u32 count) {
if (static_cast<size_t>(shift) + static_cast<size_t>(count) > Common::BitSize<u32>()) {
throw LogicError("Undefined result in {}({}, {}, {})", IR::Opcode::BitFieldUExtract,
base, shift, count);
}
return (base >> shift) & ((1U << count) - 1);
});
default:
break;
}
}
} // Anonymous namespace
void ConstantPropagationPass(IR::Block& block) {
std::ranges::for_each(block, ConstantPropagation);
}
} // namespace Shader::Optimization
