Store users as list. Use iterator facade for uses

src/shader_recompiler/ir/microinstruction.cpp

@@ -147,7 +147,7 @@ void Inst::AddPhiOperand(Block* predecessor, const Value& value) {
 }
 
 void Inst::Invalidate() {
-    ASSERT(uses.empty());
+    ASSERT(users.list.empty());
     ClearArgs();
     ReplaceOpcode(Opcode::Void);
 }
@@ -175,13 +175,52 @@ void Inst::ClearArgs() {
     }
 }
 
+UseIterator Inst::UserList::UseBegin() {
+    return UseIterator(list.begin(), list.end());
+}
+
+UseIterator Inst::UserList::UseEnd() {
+    return UseIterator(list.end(), list.end());
+}
+
+boost::iterator_range<UseIterator> Inst::UserList::Uses() {
+    return boost::make_iterator_range(UseBegin(), UseEnd());
+}
+
+void Inst::UserList::AddUse(IR::Inst* user, u32 operand) {
+    DEBUG_ASSERT(operand < 31);
+    auto it = std::find_if(list.begin(), list.end(),
+                           [&](const UserNode& user_node) { return user_node.user == user; });
+    u32 operand_pos = 1 << operand;
+    if (it == list.end()) {
+        list.emplace_front(user, operand_pos);
+    } else {
+        DEBUG_ASSERT((it->operand_mask & operand_pos) == 0);
+        it->operand_mask |= operand_pos;
+    }
+    ++num_uses;
+}
+
+void Inst::UserList::RemoveUse(IR::Inst* user, u32 operand) {
+    auto it = std::find_if(list.begin(), list.end(),
+                           [&](const UserNode& user_node) { return user_node.user == user; });
+    DEBUG_ASSERT(it != list.end());
+    u32 operand_pos = 1 << operand;
+    DEBUG_ASSERT((it->operand_mask & operand_pos) != 0);
+    it->operand_mask &= ~operand_pos;
+    if (it->operand_mask == 0) {
+        list.erase(it);
+    }
+    --num_uses;
+}
+
 void Inst::ReplaceUsesWith(Value replacement, bool preserve) {
     // Copy since user->SetArg will mutate this->uses
     // Could also do temp_uses = std::move(uses) but more readable
-    boost::container::list<IR::Use> temp_uses = uses;
-    for (auto& [user, operand] : temp_uses) {
-        DEBUG_ASSERT(user->Arg(operand).Inst() == this);
-        user->SetArg(operand, replacement);
+    UserList temp_users = users;
+    for (IR::Use use : temp_users.Uses()) {
+        DEBUG_ASSERT(use.user->Arg(use.operand).Inst() == this);
+        use.user->SetArg(use.operand, replacement);
     }
     Invalidate();
     if (preserve) {
@@ -205,14 +244,23 @@ void Inst::ReplaceOpcode(IR::Opcode opcode) {
 }
 
 void Inst::Use(Inst* used, u32 operand) {
-    DEBUG_ASSERT(0 == std::count(used->uses.begin(), used->uses.end(), IR::Use(this, operand)));
-    used->uses.emplace_front(this, operand);
+    used->users.AddUse(this, operand);
 }
 
 void Inst::UndoUse(Inst* used, u32 operand) {
-    IR::Use use(this, operand);
-    DEBUG_ASSERT(1 == std::count(used->uses.begin(), used->uses.end(), use));
-    used->uses.remove(use);
+    used->users.RemoveUse(this, operand);
+}
+
+UseIterator Inst::UseBegin() {
+    return users.UseBegin();
+}
+
+UseIterator Inst::UseEnd() {
+    return users.UseEnd();
+}
+
+boost::iterator_range<UseIterator> Inst::Uses() {
+    return boost::make_iterator_range(UseBegin(), UseEnd());
 }
 
 } // namespace Shader::IR

src/shader_recompiler/ir/value.h

@@ -110,13 +110,10 @@ public:
 struct Use {
     Inst* user;
     u32 operand;
-
-    Use() = default;
-    Use(Inst* user_, u32 operand_) : user(user_), operand(operand_) {}
-    Use(const Use&) = default;
-    bool operator==(const Use&) const noexcept = default;
 };
 
+class UseIterator;
+
 class Inst : public boost::intrusive::list_base_hook<> {
 public:
     explicit Inst(IR::Opcode op_, u32 flags_) noexcept;
@@ -130,12 +127,12 @@ public:
 
     /// Get the number of uses this instruction has.
     [[nodiscard]] int UseCount() const noexcept {
-        return uses.size();
+        return users.num_uses;
     }
 
     /// Determines whether this instruction has uses or not.
     [[nodiscard]] bool HasUses() const noexcept {
-        return uses.size() > 0;
+        return users.num_uses > 0;
     }
 
     /// Get the opcode this microinstruction represents.
@@ -213,20 +210,22 @@ public:
         return std::bit_cast<DefinitionType>(definition);
     }
 
-    auto users() {
+    auto Users() {
+        return boost::adaptors::transform(users.list,
+                                          [](UserList::UserNode& user) { return user.user; });
+    }
+
+    const auto Users() const {
         return boost::adaptors::transform(
-            boost::unique(uses,
-                          [](const IR::Use& a, const IR::Use& b) { return a.user == b.user; }),
-            [](const IR::Use& use) { return use.user; });
+            users.list,
+            [](const UserList::UserNode& user) -> const IR::Inst* { return user.user; });
     }
 
-    auto user_begin() {
-        return users().begin();
-    }
+    UseIterator UseBegin();
+    UseIterator UseEnd();
 
-    auto user_end() {
-        return users().end();
-    }
+    boost::iterator_range<UseIterator> Uses();
+    const boost::iterator_range<const UseIterator> Uses() const;
 
 private:
     struct NonTriviallyDummy {
@@ -246,9 +245,73 @@ private:
         std::array<Value, 6> args;
     };
 
-    boost::container::list<IR::Use> uses;
+    struct UserList {
+        struct UserNode {
+            IR::Inst* user;
+            u32 operand_mask;
+        };
+
+        boost::container::list<UserNode> list;
+        using UserIterator = boost::container::list<UserNode>::iterator;
+        u32 num_uses{};
+
+        void AddUse(IR::Inst* user, u32 operand);
+        void RemoveUse(IR::Inst* user, u32 operand);
+
+        UseIterator UseBegin();
+        UseIterator UseEnd();
+        boost::iterator_range<UseIterator> Uses();
+    } users;
+
+    friend class UseIterator;
 };
-static_assert(sizeof(Inst) <= 152, "Inst size unintentionally increased");
+static_assert(sizeof(Inst) <= 160, "Inst size unintentionally increased");
+
+class UseIterator
+    : public boost::iterator_facade<UseIterator, IR::Use, boost::forward_traversal_tag, IR::Use> {
+public:
+    UseIterator() : user_it(), user_end(), bitmask_pos(0) {};
+
+    explicit UseIterator(IR::Inst::UserList::UserIterator user_begin_,
+                         IR::Inst::UserList::UserIterator user_end_)
+        : user_it(user_begin_), user_end(user_end_), bitmask_pos(0) {
+        if (user_it != user_end) {
+            bitmask_pos = std::countr_zero(user_it->operand_mask);
+            DEBUG_ASSERT(user_it->operand_mask != 0);
+        }
+    };
+
+private:
+    friend class boost::iterator_core_access;
+
+    void increment() {
+        // Assumes inst has less than 31 operands
+        u32 mask = 1 << (bitmask_pos + 1);
+        u32 use_mask = user_it->operand_mask & ~(mask - 1);
+        if (use_mask == 0) {
+            ++user_it;
+            if (user_it == user_end) {
+                bitmask_pos = 0;
+                return;
+            }
+            use_mask = user_it->operand_mask;
+            ASSERT(use_mask != 0);
+        }
+        bitmask_pos = std::countr_zero(use_mask);
+    };
+
+    bool equal(UseIterator const& other) const {
+        return user_it == other.user_it && bitmask_pos == other.bitmask_pos;
+    };
+
+    IR::Use dereference() const {
+        return IR::Use(user_it->user, bitmask_pos);
+    };
+
+    IR::Inst::UserList::UserIterator user_it;
+    IR::Inst::UserList::UserIterator user_end;
+    u32 bitmask_pos;
+}; // class UseIterator
 
 using U1 = TypedValue<Type::U1>;
 using U8 = TypedValue<Type::U8>;