shader_recompiler: Add use tracking for Insts

src/shader_recompiler/ir/microinstruction.cpp

@@ -2,6 +2,7 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
 
 #include <algorithm>
+#include <any>
 #include <memory>
 
 #include "shader_recompiler/exception.h"
@@ -119,10 +120,10 @@ void Inst::SetArg(size_t index, Value value) {
     }
     const IR::Value arg{Arg(index)};
     if (!arg.IsImmediate()) {
-        UndoUse(arg);
+        UndoUse(arg.Inst(), index);
     }
     if (!value.IsImmediate()) {
-        Use(value);
+        Use(value.Inst(), index);
     }
     if (op == Opcode::Phi) {
         phi_args[index].second = value;
@@ -143,29 +144,32 @@ 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);
 }
 
 void Inst::ClearArgs() {
     if (op == Opcode::Phi) {
-        for (auto& pair : phi_args) {
+        for (auto i = 0; i < phi_args.size(); i++) {
+            auto& pair = phi_args[i];
             IR::Value& value{pair.second};
             if (!value.IsImmediate()) {
-                UndoUse(value);
+                UndoUse(value.Inst(), i);
             }
         }
         phi_args.clear();
     } else {
-        for (auto& value : args) {
+        for (auto i = 0; i < args.size(); i++) {
+            auto& value = args[i];
             if (!value.IsImmediate()) {
-                UndoUse(value);
+                UndoUse(value.Inst(), i);
             }
         }
         // Reset arguments to null
@@ -174,13 +178,21 @@ void Inst::ClearArgs() {
     }
 }
 
-void Inst::ReplaceUsesWith(Value replacement) {
-    Invalidate();
-    ReplaceOpcode(Opcode::Identity);
-    if (!replacement.IsImmediate()) {
-        Use(replacement);
+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);
+    }
+    Invalidate();
+    if (preserve) {
+        // Still useful to have Identity for indirection.
+        // SSA pass would be more complicated without it
+        ReplaceOpcode(Opcode::Identity);
+        SetArg(0, replacement);
     }
-    args[0] = replacement;
 }
 
 void Inst::ReplaceOpcode(IR::Opcode opcode) {
@@ -195,14 +207,15 @@ 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) {
+    DEBUG_ASSERT(0 == std::count(used->uses.begin(), used->uses.end(), IR::Use(this, 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, u32 operand) {
+    IR::Use use(this, operand);
+    DEBUG_ASSERT(1 == std::count(used->uses.begin(), used->uses.end(), use));
+    used->uses.remove(use);
 }
 
 } // namespace Shader::IR

src/shader_recompiler/ir/passes/constant_propagation_pass.cpp

@@ -43,7 +43,7 @@ bool FoldCommutative(IR::Inst& inst, ImmFn&& imm_fn) {
 
     if (is_lhs_immediate && is_rhs_immediate) {
         const auto result{imm_fn(Arg<T>(lhs), Arg<T>(rhs))};
-        inst.ReplaceUsesWith(IR::Value{result});
+        inst.ReplaceUsesWithAndRemove(IR::Value{result});
         return false;
     }
     if (is_lhs_immediate && !is_rhs_immediate) {
@@ -75,7 +75,7 @@ bool FoldWhenAllImmediates(IR::Inst& inst, Func&& func) {
         return false;
     }
     using Indices = std::make_index_sequence<Common::LambdaTraits<decltype(func)>::NUM_ARGS>;
-    inst.ReplaceUsesWith(EvalImmediates(inst, func, Indices{}));
+    inst.ReplaceUsesWithAndRemove(EvalImmediates(inst, func, Indices{}));
     return true;
 }
 
@@ -83,12 +83,12 @@ template <IR::Opcode op, 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{std::bit_cast<Dest>(Arg<Source>(value))});
+        inst.ReplaceUsesWithAndRemove(IR::Value{std::bit_cast<Dest>(Arg<Source>(value))});
         return;
     }
     IR::Inst* const arg_inst{value.InstRecursive()};
     if (arg_inst->GetOpcode() == reverse) {
-        inst.ReplaceUsesWith(arg_inst->Arg(0));
+        inst.ReplaceUsesWithAndRemove(arg_inst->Arg(0));
         return;
     }
 }
@@ -131,7 +131,7 @@ void FoldCompositeExtract(IR::Inst& inst, IR::Opcode construct, IR::Opcode inser
     if (!result) {
         return;
     }
-    inst.ReplaceUsesWith(*result);
+    inst.ReplaceUsesWithAndRemove(*result);
 }
 
 void FoldConvert(IR::Inst& inst, IR::Opcode opposite) {
@@ -141,7 +141,7 @@ void FoldConvert(IR::Inst& inst, IR::Opcode opposite) {
     }
     IR::Inst* const producer{value.InstRecursive()};
     if (producer->GetOpcode() == opposite) {
-        inst.ReplaceUsesWith(producer->Arg(0));
+        inst.ReplaceUsesWithAndRemove(producer->Arg(0));
     }
 }
 
@@ -152,9 +152,9 @@ void FoldLogicalAnd(IR::Inst& inst) {
     const IR::Value rhs{inst.Arg(1)};
     if (rhs.IsImmediate()) {
         if (rhs.U1()) {
-            inst.ReplaceUsesWith(inst.Arg(0));
+            inst.ReplaceUsesWithAndRemove(inst.Arg(0));
         } else {
-            inst.ReplaceUsesWith(IR::Value{false});
+            inst.ReplaceUsesWithAndRemove(IR::Value{false});
         }
     }
 }
@@ -162,7 +162,7 @@ void FoldLogicalAnd(IR::Inst& inst) {
 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));
+        inst.ReplaceUsesWithAndRemove(cond.U1() ? inst.Arg(1) : inst.Arg(2));
     }
 }
 
@@ -173,9 +173,9 @@ void FoldLogicalOr(IR::Inst& inst) {
     const IR::Value rhs{inst.Arg(1)};
     if (rhs.IsImmediate()) {
         if (rhs.U1()) {
-            inst.ReplaceUsesWith(IR::Value{true});
+            inst.ReplaceUsesWithAndRemove(IR::Value{true});
         } else {
-            inst.ReplaceUsesWith(inst.Arg(0));
+            inst.ReplaceUsesWithAndRemove(inst.Arg(0));
         }
     }
 }
@@ -183,12 +183,12 @@ void FoldLogicalOr(IR::Inst& inst) {
 void FoldLogicalNot(IR::Inst& inst) {
     const IR::U1 value{inst.Arg(0)};
     if (value.IsImmediate()) {
-        inst.ReplaceUsesWith(IR::Value{!value.U1()});
+        inst.ReplaceUsesWithAndRemove(IR::Value{!value.U1()});
         return;
     }
     IR::Inst* const arg{value.InstRecursive()};
     if (arg->GetOpcode() == IR::Opcode::LogicalNot) {
-        inst.ReplaceUsesWith(arg->Arg(0));
+        inst.ReplaceUsesWithAndRemove(arg->Arg(0));
     }
 }
 
@@ -199,7 +199,7 @@ void FoldInverseFunc(IR::Inst& inst, IR::Opcode reverse) {
     }
     IR::Inst* const arg_inst{value.InstRecursive()};
     if (arg_inst->GetOpcode() == reverse) {
-        inst.ReplaceUsesWith(arg_inst->Arg(0));
+        inst.ReplaceUsesWithAndRemove(arg_inst->Arg(0));
         return;
     }
 }
@@ -211,7 +211,7 @@ void FoldAdd(IR::Block& block, IR::Inst& inst) {
     }
     const IR::Value rhs{inst.Arg(1)};
     if (rhs.IsImmediate() && Arg<T>(rhs) == 0) {
-        inst.ReplaceUsesWith(inst.Arg(0));
+        inst.ReplaceUsesWithAndRemove(inst.Arg(0));
         return;
     }
 }
@@ -226,7 +226,8 @@ void FoldCmpClass(IR::Block& block, IR::Inst& inst) {
     } else if ((class_mask & IR::FloatClassFunc::Finite) == IR::FloatClassFunc::Finite) {
         IR::IREmitter ir{block, IR::Block::InstructionList::s_iterator_to(inst)};
         const IR::F32 value = IR::F32{inst.Arg(0)};
-        inst.ReplaceUsesWith(ir.LogicalNot(ir.LogicalOr(ir.FPIsInf(value), ir.FPIsInf(value))));
+        inst.ReplaceUsesWithAndRemove(
+            ir.LogicalNot(ir.LogicalOr(ir.FPIsInf(value), ir.FPIsInf(value))));
     } else {
         UNREACHABLE();
     }
@@ -237,7 +238,7 @@ void FoldReadLane(IR::Inst& inst) {
     IR::Inst* prod = inst.Arg(0).InstRecursive();
     while (prod->GetOpcode() == IR::Opcode::WriteLane) {
         if (prod->Arg(2).U32() == lane) {
-            inst.ReplaceUsesWith(prod->Arg(1));
+            inst.ReplaceUsesWithAndRemove(prod->Arg(1));
             return;
         }
         prod = prod->Arg(0).InstRecursive();

src/shader_recompiler/ir/passes/lower_shared_mem_to_registers.cpp

@@ -25,7 +25,7 @@ void LowerSharedMemToRegisters(IR::Program& program) {
                 });
                 ASSERT(it != ds_writes.end());
                 // Replace data read with value written.
-                inst.ReplaceUsesWith((*it)->Arg(1));
+                inst.ReplaceUsesWithAndRemove((*it)->Arg(1));
             }
         }
     }

src/shader_recompiler/ir/passes/resource_tracking_pass.cpp

@@ -596,7 +596,7 @@ void PatchImageSampleInstruction(IR::Block& block, IR::Inst& inst, Info& info,
         }
         return ir.ImageSampleImplicitLod(handle, coords, bias, offset, inst_info);
     }();
-    inst.ReplaceUsesWith(new_inst);
+    inst.ReplaceUsesWithAndRemove(new_inst);
 }
 
 void PatchImageInstruction(IR::Block& block, IR::Inst& inst, Info& info, Descriptors& descriptors) {

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>
 
@@ -107,6 +108,16 @@ public:
     explicit TypedValue(IR::Inst* inst_) : TypedValue(Value(inst_)) {}
 };
 
+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 Inst : public boost::intrusive::list_base_hook<> {
 public:
     explicit Inst(IR::Opcode op_, u32 flags_) noexcept;
@@ -120,12 +131,12 @@ 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.
@@ -167,7 +178,13 @@ public:
     void Invalidate();
     void ClearArgs();
 
-    void ReplaceUsesWith(Value replacement);
+    void ReplaceUsesWithAndRemove(Value replacement) {
+        ReplaceUsesWith(replacement, false);
+    }
+
+    void ReplaceUsesWith(Value replacement) {
+        ReplaceUsesWith(replacement, true);
+    }
 
     void ReplaceOpcode(IR::Opcode opcode);
 
@@ -202,11 +219,11 @@ private:
         NonTriviallyDummy() noexcept {}
     };
 
-    void Use(const Value& value);
-    void UndoUse(const Value& value);
+    void Use(Inst* used, u32 operand);
+    void UndoUse(Inst* used, u32 operand);
+    void ReplaceUsesWith(Value replacement, bool preserve);
 
     IR::Opcode op{};
-    int use_count{};
     u32 flags{};
     u32 definition{};
     union {
@@ -214,8 +231,10 @@ 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>;