From 0bb35fa2306a66f1f0baf118619b5c1640ed9c01 Mon Sep 17 00:00:00 2001 From: Richard-Qin-X Date: Wed, 12 Aug 2026 21:56:37 +0800 Subject: [GlobalISel] Split the generic pipeline components --- .../lib/CodeGen/GlobalISel/InstructionSelect.cpp | 351 +++++++++++++++++++++ 1 file changed, 351 insertions(+) create mode 100644 backend/lib/CodeGen/GlobalISel/InstructionSelect.cpp (limited to 'backend/lib/CodeGen/GlobalISel/InstructionSelect.cpp') diff --git a/backend/lib/CodeGen/GlobalISel/InstructionSelect.cpp b/backend/lib/CodeGen/GlobalISel/InstructionSelect.cpp new file mode 100644 index 0000000..8937fd8 --- /dev/null +++ b/backend/lib/CodeGen/GlobalISel/InstructionSelect.cpp @@ -0,0 +1,351 @@ +// SPDX-License-Identifier: GPL-3.0-or-later + +#include "rcc/CodeGen/GlobalISel/InstructionSelect.h" + +#include "rcc/CodeGen/MachineBasicBlock.h" +#include "rcc/CodeGen/MachineFunction.h" +#include "rcc/CodeGen/MachineFunctionCloner.h" +#include "rcc/CodeGen/MachineInstr.h" +#include "rcc/CodeGen/MachineLiveness.h" +#include "rcc/CodeGen/MachineRegisterInfo.h" +#include "rcc/CodeGen/TargetDescription.h" + +#include +#include +#include +#include +#include +#include +#include + +namespace rcc { +namespace { + +[[nodiscard]] const MachinePassContract &instructionSelectContract() { + static const MachinePassContract Contract{ + .Name = "instruction-select", + .Requires = {MachineFunctionProperty::Legalized, MachineFunctionProperty::RegBankSelected}, + .Sets = {MachineFunctionProperty::Selected}, + .Clears = {}, + .RequiredAnalyses = {}, + .VerificationStage = PipelineStage::Selected, + }; + return Contract; +} + +struct OpcodeState final { + MachineInstrStableID Instruction; + Opcode OpcodeValue; + std::uint64_t OperandFingerprint = 0; + + friend bool operator==(const OpcodeState &Left, const OpcodeState &Right) noexcept = default; +}; + +struct OpcodeStateHash final { + [[nodiscard]] std::size_t operator()(const OpcodeState &State) const noexcept { + return std::hash{}(State.Instruction.value()) ^ + (std::hash{}(State.OpcodeValue.value()) << 1U) ^ + (std::hash{}(State.OperandFingerprint) << 2U); + } +}; + +void combineFingerprint(std::uint64_t &State, std::uint64_t Value) noexcept { + State ^= Value + 0x9e3779b97f4a7c15ULL + (State << 6U) + (State >> 2U); +} + +[[nodiscard]] std::uint64_t operandFingerprint(const MachineInstr &Instruction) noexcept { + std::uint64_t Result = 0xcbf29ce484222325ULL; + combineFingerprint(Result, Instruction.flags().rawValue()); + combineFingerprint(Result, Instruction.operandCount()); + for (const MachineOperand &Operand : Instruction.operands()) { + combineFingerprint(Result, static_cast(Operand.kind())); + combineFingerprint(Result, Operand.targetFlags()); + combineFingerprint(Result, Operand.registerFlags().rawValue()); + combineFingerprint(Result, Operand.subReg().value()); + if (const Register *Reg = Operand.getIf()) + combineFingerprint(Result, Reg->opaqueValue()); + else if (const std::int64_t *Immediate = Operand.getIf()) + combineFingerprint(Result, static_cast(*Immediate)); + else if (const auto *Integer = Operand.getIf()) + combineFingerprint(Result, Integer->Value.bitWidth()); + else if (const auto *Floating = Operand.getIf()) + combineFingerprint(Result, static_cast(Floating->Bits.semantics())); + else if (const auto *Block = Operand.getIf()) + combineFingerprint(Result, Block->Block == nullptr ? 0 : Block->Block->stableID().value()); + } + return Result; +} + +[[nodiscard]] OpcodeState stateOf(const MachineInstr &Instruction) noexcept { + return {Instruction.stableID(), Instruction.opcode(), operandFingerprint(Instruction)}; +} + +[[nodiscard]] std::vector layoutInstructions(MachineFunction &Function) { + std::vector Result; + for (MachineBasicBlock *Block = Function.firstBlock(); Block != nullptr; Block = Block->next()) + for (MachineInstr *Instruction = Block->firstInstruction(); Instruction != nullptr; + Instruction = Instruction->next()) + Result.push_back(Instruction); + return Result; +} + +[[nodiscard]] std::vector stableCFGPostOrder(MachineFunction &Function) { + std::vector Roots; + for (MachineBasicBlock *Block = Function.firstBlock(); Block != nullptr; Block = Block->next()) + Roots.push_back(Block); + std::ranges::sort(Roots, {}, + [](const MachineBasicBlock *Block) { return Block->stableID().value(); }); + if (MachineBasicBlock *Entry = Function.firstBlock(); Entry != nullptr) { + const auto Position = std::ranges::find(Roots, Entry); + if (Position != Roots.end()) + std::rotate(Roots.begin(), Position, std::next(Position)); + } + + struct TraversalFrame final { + MachineBasicBlock *Block = nullptr; + std::vector Successors; + std::size_t NextSuccessor = 0; + }; + const auto MakeFrame = [](MachineBasicBlock &Block) { + TraversalFrame Frame; + Frame.Block = &Block; + for (const MachineSuccessor &Successor : Block.successors()) { + if (Successor.Block != nullptr) + Frame.Successors.push_back(Successor.Block); + } + std::ranges::sort(Frame.Successors, {}, [](const MachineBasicBlock *Successor) { + return Successor->stableID().value(); + }); + return Frame; + }; + + std::vector Result; + std::unordered_set Visited; + std::vector Stack; + for (MachineBasicBlock *Root : Roots) { + if (!Visited.insert(Root).second) + continue; + Stack.push_back(MakeFrame(*Root)); + while (!Stack.empty()) { + TraversalFrame &Frame = Stack.back(); + if (Frame.NextSuccessor < Frame.Successors.size()) { + MachineBasicBlock *Successor = Frame.Successors[Frame.NextSuccessor++]; + if (Visited.insert(Successor).second) + Stack.push_back(MakeFrame(*Successor)); + continue; + } + Result.push_back(Frame.Block); + Stack.pop_back(); + } + } + return Result; +} + +[[nodiscard]] std::vector bottomUpInstructions(MachineFunction &Function) { + std::vector Result; + for (MachineBasicBlock *Block : stableCFGPostOrder(Function)) { + for (MachineInstr *Instruction = Block->lastInstruction(); Instruction != nullptr; + Instruction = Instruction->previous()) + Result.push_back(Instruction); + } + return Result; +} + +[[nodiscard]] Expected requireProperties(const MachineFunction &Function, + const MachinePassContract &Contract) { + const MachineFunctionProperties Missing = Contract.Requires.missingFrom(Function.properties()); + if (!Missing.empty()) { + return makeUnexpected(ErrorCode::VerificationError, + "pass '" + Contract.Name + + "' requires properties: " + Missing.toString()); + } + return {}; +} + +[[nodiscard]] Error passFailure(std::string Message, + ErrorCode Code = ErrorCode::VerificationError) { + return Error(Code, std::move(Message)); +} + +[[nodiscard]] Error prefixedError(const Error &Source, std::string Prefix) { + Prefix.append(Source.message()); + return Error(Source.code(), std::move(Prefix)); +} + +[[nodiscard]] Expected repairTrackedLiveness(MachineFunction &Function, + const TargetDescription &Target, + MachinePassResult &Result) { + if (!Result.Changed || !Function.properties().has(MachineFunctionProperty::TracksLiveness)) { + return {}; + } + auto Rebuilt = rebuildMachineLiveness(Function, Target); + if (!Rebuilt) + return std::unexpected(Rebuilt.error()); + if (*Rebuilt) + Result.Changes.add(MachinePassChange::Operands); + return {}; +} + +} // namespace + +const MachinePassContract &InstructionSelect::contract() const noexcept { + return instructionSelectContract(); +} + +Expected InstructionSelect::run(MachineFunction &Function, + const TargetDescription &Target, + MachineAnalysisManager &Analyses) { + if (Info == nullptr) + return std::unexpected(passFailure("instruction select has no target behavior interface", + ErrorCode::InvalidArgument)); + auto Required = requireProperties(Function, contract()); + if (!Required) + return std::unexpected(Required.error()); + + auto Trial = cloneMachineFunction( + Function, Target, + MachineFunctionCloneOptions{.NewStableID = Function.stableID(), .NewName = std::nullopt}); + if (!Trial) { + return std::unexpected( + prefixedError(Trial.error(), "instruction-selection transaction setup failed: ")); + } + MachineActionReplay Actions(Analyses, Trial->InstructionStableIDs); + auto TrialResult = runImplementation(*Trial->ClonedFunction, Target, Actions); + if (!TrialResult) + return std::unexpected(TrialResult.error()); + Actions.beginReplay(); + auto Result = runImplementation(Function, Target, Actions); + if (!Result) { + return std::unexpected( + prefixedError(Result.error(), + "instruction selection diverged after a successful transaction preflight: ")); + } + auto Replayed = Actions.finishReplay(); + if (!Replayed) + return std::unexpected(Replayed.error()); + return Result; +} + +Expected InstructionSelect::runImplementation(MachineFunction &Function, + const TargetDescription &Target, + MachineActionReplay &Actions) { + + MachinePassResult Result; + std::vector Worklist; + std::unordered_set DiscoveredInstructions; + std::unordered_set SeenStates; + for (MachineInstr *Instruction : bottomUpInstructions(Function)) { + const InstructionDescriptor *Descriptor = Target.instructionDescriptor(Instruction->opcode()); + if (Descriptor == nullptr) + return std::unexpected( + passFailure("instruction selector encountered an unknown instruction descriptor")); + auto Validation = Target.validateInstruction(*Instruction, Function.registerInfo()); + if (!Validation) + return std::unexpected( + prefixedError(Validation.error(), "instruction selector input is invalid: ")); + if (!Descriptor->Flags.has(InstructionFlag::Generic)) + continue; + auto Match = Info->canSelect(*Instruction, Function, Target); + if (!Match) + return std::unexpected(Match.error()); + Worklist.push_back(Instruction); + DiscoveredInstructions.insert(Instruction->stableID()); + } + + for (std::size_t Index = 0; Index < Worklist.size(); ++Index) { + MachineInstr *Instruction = Worklist[Index]; + if (Instruction->parent() == nullptr) + return std::unexpected(passFailure("instruction selector lost its input instruction")); + const InstructionDescriptor *CurrentDescriptor = + Target.instructionDescriptor(Instruction->opcode()); + if (CurrentDescriptor == nullptr) + return std::unexpected( + passFailure("instruction selector encountered an unknown instruction descriptor")); + if (!CurrentDescriptor->Flags.has(InstructionFlag::Generic)) + continue; + const OpcodeState Before = stateOf(*Instruction); + if (!SeenStates.insert(Before).second) { + return std::unexpected(passFailure("instruction selector entered a repeated state for '" + + CurrentDescriptor->Name + "'", + ErrorCode::InternalError)); + } + auto Match = Info->canSelect(*Instruction, Function, Target); + if (!Match) + return std::unexpected(Match.error()); + std::string Rule = "select."; + Rule.append(CurrentDescriptor->Name); + auto Accepted = Actions.request(Rule, Function, Instruction->stableID()); + if (!Accepted) + return std::unexpected(Accepted.error()); + if (!*Accepted) { + return std::unexpected(passFailure("required selection action was rejected for '" + + CurrentDescriptor->Name + "'", + ErrorCode::VerificationError)); + } + auto Selection = Info->select(*Instruction, Function, Target); + if (!Selection) + return std::unexpected(Selection.error()); + const InstructionDescriptor *Selected = Target.instructionDescriptor(Instruction->opcode()); + if (Selected == nullptr) + return std::unexpected( + passFailure("instruction selector produced an unknown instruction descriptor")); + auto Constraint = Info->constrainSelectedInstruction(*Instruction, Function, Target); + if (!Constraint) { + return std::unexpected(prefixedError( + Constraint.error(), "instruction selector could not constrain selected registers: ")); + } + auto Validation = Target.validateInstruction(*Instruction, Function.registerInfo()); + if (!Validation) + return std::unexpected( + prefixedError(Validation.error(), "instruction selector produced invalid MachineIR: ")); + const OpcodeState After = stateOf(*Instruction); + if (After == Before) + return std::unexpected( + passFailure("instruction selector reported success without observable progress", + ErrorCode::InternalError)); + Result.Changed = true; + Result.Changes.add(MachinePassChange::Instructions); + if (Selected->Flags.has(InstructionFlag::Generic)) + Worklist.push_back(Instruction); + for (MachineInstr *Candidate : bottomUpInstructions(Function)) { + const InstructionDescriptor *CandidateDescriptor = + Target.instructionDescriptor(Candidate->opcode()); + if (CandidateDescriptor == nullptr) + return std::unexpected( + passFailure("instruction selector produced an unknown instruction descriptor")); + if (!CandidateDescriptor->Flags.has(InstructionFlag::Generic) || + !DiscoveredInstructions.insert(Candidate->stableID()).second) { + continue; + } + auto CandidateMatch = Info->canSelect(*Candidate, Function, Target); + if (!CandidateMatch) + return std::unexpected(CandidateMatch.error()); + Worklist.push_back(Candidate); + } + } + for (MachineInstr *Instruction : layoutInstructions(Function)) { + const InstructionDescriptor *Descriptor = Target.instructionDescriptor(Instruction->opcode()); + if (Descriptor == nullptr) + return std::unexpected( + passFailure("instruction selector produced an unknown instruction descriptor")); + auto Validation = Target.validateInstruction(*Instruction, Function.registerInfo()); + if (!Validation) + return std::unexpected( + prefixedError(Validation.error(), "instruction selector produced invalid MachineIR: ")); + if (Descriptor->Flags.has(InstructionFlag::Generic)) + return std::unexpected( + passFailure("instruction selector left a generic opcode in the function")); + } + auto RegisterValidation = Target.validateRegisterInfo(Function.registerInfo()); + if (!RegisterValidation) + return std::unexpected(prefixedError(RegisterValidation.error(), + "instruction selection produced invalid registers: ")); + auto Liveness = repairTrackedLiveness(Function, Target, Result); + if (!Liveness) { + return std::unexpected( + prefixedError(Liveness.error(), "instruction-selection liveness repair failed: ")); + } + Result.Preserved = Result.Changed ? PreservedAnalyses::none() : PreservedAnalyses::all(); + return Result; +} +} // namespace rcc -- cgit v1.2.3