From 6036cc8f79de5fe783da84880d10ec62502cfa83 Mon Sep 17 00:00:00 2001
From: Frodo Baggins <baggins31084@proton.me>
Date: Mon, 21 Oct 2024 16:41:02 -0700
Subject: [PATCH] add use tracking for Insts

---
 .../backend/spirv/emit_spirv.cpp              |  1 -
 src/shader_recompiler/ir/microinstruction.cpp | 30 +++++++++----------
 src/shader_recompiler/ir/value.h              | 20 +++++++++----
 3 files changed, 29 insertions(+), 22 deletions(-)

diff --git a/src/shader_recompiler/backend/spirv/emit_spirv.cpp b/src/shader_recompiler/backend/spirv/emit_spirv.cpp
index e84908a57..fefaea6a5 100644
--- a/src/shader_recompiler/backend/spirv/emit_spirv.cpp
+++ b/src/shader_recompiler/backend/spirv/emit_spirv.cpp
@@ -1,6 +1,5 @@
 // SPDX-FileCopyrightText: Copyright 2024 shadPS4 Emulator Project
 // SPDX-License-Identifier: GPL-2.0-or-later
-
 #include <span>
 #include <type_traits>
 #include <utility>
diff --git a/src/shader_recompiler/ir/microinstruction.cpp b/src/shader_recompiler/ir/microinstruction.cpp
index f0b4882b3..fae4b4a49 100644
--- a/src/shader_recompiler/ir/microinstruction.cpp
+++ b/src/shader_recompiler/ir/microinstruction.cpp
@@ -116,10 +116,10 @@ void Inst::SetArg(size_t index, Value value) {
     }
     const IR::Value arg{Arg(index)};
     if (!arg.IsImmediate()) {
-        UndoUse(arg);
+        UndoUse(arg.Inst());
     }
     if (!value.IsImmediate()) {
-        Use(value);
+        Use(value.Inst(), index);
     }
     if (op == Opcode::Phi) {
         phi_args[index].second = value;
@@ -140,12 +140,13 @@ Block* Inst::PhiBlock(size_t index) const {
 
 void Inst::AddPhiOperand(Block* predecessor, const Value& value) {
     if (!value.IsImmediate()) {
-        Use(value);
+        Use(value.Inst(), phi_args.size());
     }
     phi_args.emplace_back(predecessor, value);
 }
 
 void Inst::Invalidate() {
+    ASSERT(uses.empty());
     ClearArgs();
     ReplaceOpcode(Opcode::Void);
 }
@@ -155,14 +156,14 @@ void Inst::ClearArgs() {
         for (auto& pair : phi_args) {
             IR::Value& value{pair.second};
             if (!value.IsImmediate()) {
-                UndoUse(value);
+                UndoUse(value.Inst());
             }
         }
         phi_args.clear();
     } else {
         for (auto& value : args) {
             if (!value.IsImmediate()) {
-                UndoUse(value);
+                UndoUse(value.Inst());
             }
         }
         // Reset arguments to null
@@ -172,12 +173,13 @@ void Inst::ClearArgs() {
 }
 
 void Inst::ReplaceUsesWith(Value replacement) {
-    Invalidate();
-    ReplaceOpcode(Opcode::Identity);
     if (!replacement.IsImmediate()) {
-        Use(replacement);
+        for (auto& [user, operand] : uses) {
+            user->SetArg(operand, replacement);
+        }
     }
-    args[0] = replacement;
+    uses.clear();
+    Invalidate();
 }
 
 void Inst::ReplaceOpcode(IR::Opcode opcode) {
@@ -192,14 +194,12 @@ void Inst::ReplaceOpcode(IR::Opcode opcode) {
     op = opcode;
 }
 
-void Inst::Use(const Value& value) {
-    Inst* const inst{value.Inst()};
-    ++inst->use_count;
+void Inst::Use(Inst* used, u32 operand) {
+    used->uses.emplace_front(this, operand);
 }
 
-void Inst::UndoUse(const Value& value) {
-    Inst* const inst{value.Inst()};
-    --inst->use_count;
+void Inst::UndoUse(Inst* used) {
+    used->uses.remove_if([this](const IR::Use& use) { return use.user == this; });
 }
 
 } // namespace Shader::IR
diff --git a/src/shader_recompiler/ir/value.h b/src/shader_recompiler/ir/value.h
index a282b9168..a87db2f77 100644
--- a/src/shader_recompiler/ir/value.h
+++ b/src/shader_recompiler/ir/value.h
@@ -8,6 +8,7 @@
 #include <cstring>
 #include <type_traits>
 #include <utility>
+#include <boost/container/list.hpp>
 #include <boost/container/small_vector.hpp>
 #include <boost/intrusive/list.hpp>
 
@@ -15,6 +16,7 @@
 #include "shader_recompiler/exception.h"
 #include "shader_recompiler/ir/attribute.h"
 #include "shader_recompiler/ir/opcodes.h"
+#include "shader_recompiler/ir/patch.h"
 #include "shader_recompiler/ir/reg.h"
 #include "shader_recompiler/ir/type.h"
 
@@ -104,6 +106,11 @@ public:
     explicit TypedValue(IR::Inst* inst_) : TypedValue(Value(inst_)) {}
 };
 
+struct Use {
+    Inst* user;
+    u32 operand;
+};
+
 class Inst : public boost::intrusive::list_base_hook<> {
 public:
     explicit Inst(IR::Opcode op_, u32 flags_) noexcept;
@@ -117,12 +124,12 @@ public:
 
     /// Get the number of uses this instruction has.
     [[nodiscard]] int UseCount() const noexcept {
-        return use_count;
+        return uses.size();
     }
 
     /// Determines whether this instruction has uses or not.
     [[nodiscard]] bool HasUses() const noexcept {
-        return use_count > 0;
+        return uses.size() > 0;
     }
 
     /// Get the opcode this microinstruction represents.
@@ -199,11 +206,10 @@ private:
         NonTriviallyDummy() noexcept {}
     };
 
-    void Use(const Value& value);
-    void UndoUse(const Value& value);
+    void Use(Inst* used, u32 operand);
+    void UndoUse(Inst* used);
 
     IR::Opcode op{};
-    int use_count{};
     u32 flags{};
     u32 definition{};
     union {
@@ -211,8 +217,10 @@ private:
         boost::container::small_vector<std::pair<Block*, Value>, 2> phi_args;
         std::array<Value, 6> args;
     };
+
+    boost::container::list<IR::Use> uses;
 };
-static_assert(sizeof(Inst) <= 128, "Inst size unintentionally increased");
+static_assert(sizeof(Inst) <= 152, "Inst size unintentionally increased");
 
 using U1 = TypedValue<Type::U1>;
 using U8 = TypedValue<Type::U8>;