shader: Move recursive SSA rewrite to the heap
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		| @@ -119,6 +119,26 @@ IR::Opcode UndefOpcode(IndirectBranchVariable) noexcept { | ||||
|     return inst.Opcode() == IR::Opcode::Phi; | ||||
| } | ||||
|  | ||||
| enum class Status { | ||||
|     Start, | ||||
|     SetValue, | ||||
|     PreparePhiArgument, | ||||
|     PushPhiArgument, | ||||
| }; | ||||
|  | ||||
| template <typename Type> | ||||
| struct ReadState { | ||||
|     ReadState(IR::Block* block_) : block{block_} {} | ||||
|     ReadState() = default; | ||||
|  | ||||
|     IR::Block* block{}; | ||||
|     IR::Value result{}; | ||||
|     IR::Inst* phi{}; | ||||
|     IR::Block* const* pred_it{}; | ||||
|     IR::Block* const* pred_end{}; | ||||
|     Status pc{Status::Start}; | ||||
| }; | ||||
|  | ||||
| class Pass { | ||||
| public: | ||||
|     template <typename Type> | ||||
| @@ -127,12 +147,75 @@ public: | ||||
|     } | ||||
|  | ||||
|     template <typename Type> | ||||
|     IR::Value ReadVariable(Type variable, IR::Block* block) { | ||||
|     IR::Value ReadVariable(Type variable, IR::Block* root_block) { | ||||
|         boost::container::small_vector<ReadState<Type>, 64> stack{ | ||||
|             ReadState<Type>(nullptr), | ||||
|             ReadState<Type>(root_block), | ||||
|         }; | ||||
|         const auto prepare_phi_operand{[&] { | ||||
|             if (stack.back().pred_it == stack.back().pred_end) { | ||||
|                 IR::Inst* const phi{stack.back().phi}; | ||||
|                 IR::Block* const block{stack.back().block}; | ||||
|                 const IR::Value result{TryRemoveTrivialPhi(*phi, block, UndefOpcode(variable))}; | ||||
|                 stack.pop_back(); | ||||
|                 stack.back().result = result; | ||||
|                 WriteVariable(variable, block, result); | ||||
|             } else { | ||||
|                 IR::Block* const imm_pred{*stack.back().pred_it}; | ||||
|                 stack.back().pc = Status::PushPhiArgument; | ||||
|                 stack.emplace_back(imm_pred); | ||||
|             } | ||||
|         }}; | ||||
|         do { | ||||
|             IR::Block* const block{stack.back().block}; | ||||
|             switch (stack.back().pc) { | ||||
|             case Status::Start: { | ||||
|                 const ValueMap& def{current_def[variable]}; | ||||
|                 if (const auto it{def.find(block)}; it != def.end()) { | ||||
|             return it->second; | ||||
|                     stack.back().result = it->second; | ||||
|                 } else if (!sealed_blocks.contains(block)) { | ||||
|                     // Incomplete CFG | ||||
|                     IR::Inst* phi{&*block->PrependNewInst(block->begin(), IR::Opcode::Phi)}; | ||||
|                     incomplete_phis[block].insert_or_assign(variable, phi); | ||||
|                     stack.back().result = IR::Value{&*phi}; | ||||
|                 } else if (const std::span imm_preds{block->ImmediatePredecessors()}; | ||||
|                            imm_preds.size() == 1) { | ||||
|                     // Optimize the common case of one predecessor: no phi needed | ||||
|                     stack.back().pc = Status::SetValue; | ||||
|                     stack.emplace_back(imm_preds.front()); | ||||
|                     break; | ||||
|                 } else { | ||||
|                     // Break potential cycles with operandless phi | ||||
|                     IR::Inst* const phi{&*block->PrependNewInst(block->begin(), IR::Opcode::Phi)}; | ||||
|                     WriteVariable(variable, block, IR::Value{phi}); | ||||
|  | ||||
|                     stack.back().phi = phi; | ||||
|                     stack.back().pred_it = imm_preds.data(); | ||||
|                     stack.back().pred_end = imm_preds.data() + imm_preds.size(); | ||||
|                     prepare_phi_operand(); | ||||
|                     break; | ||||
|                 } | ||||
|         return ReadVariableRecursive(variable, block); | ||||
|             } | ||||
|                 [[fallthrough]]; | ||||
|             case Status::SetValue: { | ||||
|                 const IR::Value result{stack.back().result}; | ||||
|                 WriteVariable(variable, block, result); | ||||
|                 stack.pop_back(); | ||||
|                 stack.back().result = result; | ||||
|                 break; | ||||
|             } | ||||
|             case Status::PushPhiArgument: { | ||||
|                 IR::Inst* const phi{stack.back().phi}; | ||||
|                 phi->AddPhiOperand(*stack.back().pred_it, stack.back().result); | ||||
|                 ++stack.back().pred_it; | ||||
|             } | ||||
|                 [[fallthrough]]; | ||||
|             case Status::PreparePhiArgument: | ||||
|                 prepare_phi_operand(); | ||||
|                 break; | ||||
|             } | ||||
|         } while (stack.size() > 1); | ||||
|         return stack.back().result; | ||||
|     } | ||||
|  | ||||
|     void SealBlock(IR::Block* block) { | ||||
| @@ -146,29 +229,6 @@ public: | ||||
|     } | ||||
|  | ||||
| private: | ||||
|     template <typename Type> | ||||
|     IR::Value ReadVariableRecursive(Type variable, IR::Block* block) { | ||||
|         IR::Value val; | ||||
|         if (!sealed_blocks.contains(block)) { | ||||
|             // Incomplete CFG | ||||
|             IR::Inst* phi{&*block->PrependNewInst(block->begin(), IR::Opcode::Phi)}; | ||||
|             incomplete_phis[block].insert_or_assign(variable, phi); | ||||
|             val = IR::Value{&*phi}; | ||||
|         } else if (const std::span imm_preds{block->ImmediatePredecessors()}; | ||||
|                    imm_preds.size() == 1) { | ||||
|             // Optimize the common case of one predecessor: no phi needed | ||||
|             val = ReadVariable(variable, imm_preds.front()); | ||||
|         } else { | ||||
|             // Break potential cycles with operandless phi | ||||
|             IR::Inst& phi_inst{*block->PrependNewInst(block->begin(), IR::Opcode::Phi)}; | ||||
|             val = IR::Value{&phi_inst}; | ||||
|             WriteVariable(variable, block, val); | ||||
|             val = AddPhiOperands(variable, phi_inst, block); | ||||
|         } | ||||
|         WriteVariable(variable, block, val); | ||||
|         return val; | ||||
|     } | ||||
|  | ||||
|     template <typename Type> | ||||
|     IR::Value AddPhiOperands(Type variable, IR::Inst& phi, IR::Block* block) { | ||||
|         for (IR::Block* const imm_pred : block->ImmediatePredecessors()) { | ||||
|   | ||||
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