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shader: Better constant folding

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This commit is contained in:
ReinUsesLisp 2021-02-06 04:47:53 -03:00 committed by ameerj
parent da8096e6e3
commit 6dafb08f52
2 changed files with 48 additions and 13 deletions
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2
src/shader_recompiler/frontend/ir/basic_block.cpp
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@ -87,7 +87,7 @@ static std::string ArgToIndex(const std::map<const Block*, size_t>& block_to_ind
}
switch (arg.Type()) {
case Type::U1:
return fmt::format("#{}", arg.U1() ? '1' : '0');
return fmt::format("#{}", arg.U1() ? "true" : "false");
case Type::U8:
return fmt::format("#{}", arg.U8());
case Type::U16:

59
src/shader_recompiler/ir_opt/constant_propagation_pass.cpp
View file

@ -3,6 +3,7 @@
// Refer to the license.txt file included.
#include <algorithm>
#include <tuple>
#include <type_traits>
#include "common/bit_cast.h"
@ -13,12 +14,17 @@
namespace Shader::Optimization {
namespace {
[[nodiscard]] u32 BitFieldUExtract(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 BitFieldUExtract({}, {}, {})", base, shift, count);
}
return (base >> shift) & ((1U << count) - 1);
}
// 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) {
@ -104,6 +110,14 @@ void FoldAdd(IR::Inst& inst) {
}
}
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;
@ -131,6 +145,21 @@ void FoldBitCast(IR::Inst& inst, IR::Opcode reverse) {
}
}
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:
@ -145,14 +174,20 @@ void ConstantPropagation(IR::Inst& inst) {
return FoldBitCast<u32, f32>(inst, IR::Opcode::BitCastF32U32);
case IR::Opcode::IAdd64:
return FoldAdd<u64>(inst);
case IR::Opcode::BitFieldUExtract:
if (inst.AreAllArgsImmediates() && !inst.HasAssociatedPseudoOperation()) {
inst.ReplaceUsesWith(IR::Value{
BitFieldUExtract(inst.Arg(0).U32(), inst.Arg(1).U32(), inst.Arg(2).U32())});
}
break;
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;
}