From 2d48a7b4d0666ad16d03a22d85712617a0849046 Mon Sep 17 00:00:00 2001
From: ReinUsesLisp <reinuseslisp@airmail.cc>
Date: Sat, 9 Jan 2021 03:30:07 -0300
Subject: shader: Initial recompiler work
---
src/shader_recompiler/frontend/maxwell/decode.cpp | 149 ++++++++++++++++++++++
1 file changed, 149 insertions(+)
create mode 100644 src/shader_recompiler/frontend/maxwell/decode.cpp
(limited to 'src/shader_recompiler/frontend/maxwell/decode.cpp')
diff --git a/src/shader_recompiler/frontend/maxwell/decode.cpp b/src/shader_recompiler/frontend/maxwell/decode.cpp
new file mode 100644
index 0000000000..ab1cc6c8d3
--- /dev/null
+++ b/src/shader_recompiler/frontend/maxwell/decode.cpp
@@ -0,0 +1,149 @@
+// Copyright 2021 yuzu Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#include <algorithm>
+#include <array>
+#include <bit>
+#include <memory>
+#include <string_view>
+
+#include "common/common_types.h"
+#include "shader_recompiler/exception.h"
+#include "shader_recompiler/frontend/maxwell/decode.h"
+#include "shader_recompiler/frontend/maxwell/opcode.h"
+
+namespace Shader::Maxwell {
+namespace {
+struct MaskValue {
+ u64 mask;
+ u64 value;
+};
+
+constexpr MaskValue MaskValueFromEncoding(const char* encoding) {
+ u64 mask{};
+ u64 value{};
+ u64 bit{u64(1) << 63};
+ while (*encoding) {
+ switch (*encoding) {
+ case '0':
+ mask |= bit;
+ break;
+ case '1':
+ mask |= bit;
+ value |= bit;
+ break;
+ case '-':
+ break;
+ case ' ':
+ break;
+ default:
+ throw LogicError("Invalid encoding character '{}'", *encoding);
+ }
+ ++encoding;
+ if (*encoding != ' ') {
+ bit >>= 1;
+ }
+ }
+ return MaskValue{.mask{mask}, .value{value}};
+}
+
+struct InstEncoding {
+ MaskValue mask_value;
+ Opcode opcode;
+};
+constexpr std::array UNORDERED_ENCODINGS{
+#define INST(name, cute, encode) \
+ InstEncoding{ \
+ .mask_value{MaskValueFromEncoding(encode)}, \
+ .opcode{Opcode::name}, \
+ },
+#include "maxwell.inc"
+#undef INST
+};
+
+constexpr auto SortedEncodings() {
+ std::array encodings{UNORDERED_ENCODINGS};
+ std::ranges::sort(encodings, [](const InstEncoding& lhs, const InstEncoding& rhs) {
+ return std::popcount(lhs.mask_value.mask) > std::popcount(rhs.mask_value.mask);
+ });
+ return encodings;
+}
+constexpr auto ENCODINGS{SortedEncodings()};
+
+constexpr int WidestLeftBits() {
+ int bits{64};
+ for (const InstEncoding& encoding : ENCODINGS) {
+ bits = std::min(bits, std::countr_zero(encoding.mask_value.mask));
+ }
+ return 64 - bits;
+}
+constexpr int WIDEST_LEFT_BITS{WidestLeftBits()};
+constexpr int MASK_SHIFT{64 - WIDEST_LEFT_BITS};
+
+constexpr size_t ToFastLookupIndex(u64 value) {
+ return static_cast<size_t>(value >> MASK_SHIFT);
+}
+
+constexpr size_t FastLookupSize() {
+ size_t max_width{};
+ for (const InstEncoding& encoding : ENCODINGS) {
+ max_width = std::max(max_width, ToFastLookupIndex(encoding.mask_value.mask));
+ }
+ return max_width + 1;
+}
+constexpr size_t FAST_LOOKUP_SIZE{FastLookupSize()};
+
+struct InstInfo {
+ [[nodiscard]] u64 Mask() const noexcept {
+ return static_cast<u64>(high_mask) << MASK_SHIFT;
+ }
+
+ [[nodiscard]] u64 Value() const noexcept {
+ return static_cast<u64>(high_value) << MASK_SHIFT;
+ }
+
+ u16 high_mask;
+ u16 high_value;
+ Opcode opcode;
+};
+
+constexpr auto MakeFastLookupTableIndex(size_t index) {
+ std::array<InstInfo, 2> encodings{};
+ size_t element{};
+ for (const auto& encoding : ENCODINGS) {
+ const size_t mask{ToFastLookupIndex(encoding.mask_value.mask)};
+ const size_t value{ToFastLookupIndex(encoding.mask_value.value)};
+ if ((index & mask) == value) {
+ encodings.at(element) = InstInfo{
+ .high_mask{static_cast<u16>(encoding.mask_value.mask >> MASK_SHIFT)},
+ .high_value{static_cast<u16>(encoding.mask_value.value >> MASK_SHIFT)},
+ .opcode{encoding.opcode},
+ };
+ ++element;
+ }
+ }
+ return encodings;
+}
+
+/*constexpr*/ auto MakeFastLookupTable() {
+ auto encodings{std::make_unique<std::array<std::array<InstInfo, 2>, FAST_LOOKUP_SIZE>>()};
+ for (size_t index = 0; index < FAST_LOOKUP_SIZE; ++index) {
+ (*encodings)[index] = MakeFastLookupTableIndex(index);
+ }
+ return encodings;
+}
+const auto FAST_LOOKUP_TABLE{MakeFastLookupTable()};
+} // Anonymous namespace
+
+Opcode Decode(u64 insn) {
+ const auto& table{(*FAST_LOOKUP_TABLE)[ToFastLookupIndex(insn)]};
+ const auto it{std::ranges::find_if(
+ table, [insn](const InstInfo& info) { return (insn & info.Mask()) == info.Value(); })};
+ if (it == table.end()) {
+ throw NotImplementedException("Instruction 0x{:016x} is unknown / unimplemented", insn);
+ }
+ return it->opcode;
+}
+
+} // namespace Shader::Maxwell
--
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