| //===-- llvm/CodeGen/Collector.h - Garbage collection -----------*- C++ -*-===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // Collector records sufficient information about a machine function to enable |
| // accurate garbage collectors. Specifically: |
| // |
| // - Safe points |
| // Garbage collection is only possible at certain points in code. Code |
| // generators should record points: |
| // |
| // - At and after any call to a subroutine |
| // - Before returning from the current function |
| // - Before backwards branches (loops) |
| // |
| // - Roots |
| // When a reference to a GC-allocated object exists on the stack, it must be |
| // stored in an alloca registered with llvm.gcoot. |
| // |
| // This generic information should used by ABI-specific passes to emit support |
| // tables for the runtime garbage collector. |
| // |
| // MachineCodeAnalysis identifies the GC safe points in the machine code. (Roots |
| // are identified in SelectionDAGISel.) |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #ifndef LLVM_CODEGEN_COLLECTOR_H |
| #define LLVM_CODEGEN_COLLECTOR_H |
| |
| #include "llvm/CodeGen/CollectorMetadata.h" |
| #include <iosfwd> |
| #include <string> |
| |
| namespace llvm { |
| |
| /// Collector describes a garbage collector's code generation requirements, |
| /// and provides overridable hooks for those needs which cannot be abstractly |
| /// described. |
| class Collector { |
| public: |
| typedef std::vector<CollectorMetadata*> list_type; |
| typedef list_type::iterator iterator; |
| |
| private: |
| friend class CollectorModuleMetadata; |
| const Module *M; |
| std::string Name; |
| |
| list_type Functions; |
| |
| protected: |
| unsigned NeededSafePoints; //< Bitmask of required safe points. |
| bool CustomReadBarriers; //< Default is to insert loads. |
| bool CustomWriteBarriers; //< Default is to insert stores. |
| bool CustomRoots; //< Default is to pass through to backend. |
| bool InitRoots; //< If set, roots are nulled during lowering. |
| |
| public: |
| Collector(); |
| |
| virtual ~Collector(); |
| |
| |
| /// getName - The name of the collector, for debugging. |
| /// |
| const std::string &getName() const { return Name; } |
| |
| /// getModule - The module upon which the collector is operating. |
| /// |
| const Module &getModule() const { return *M; } |
| |
| /// True if this collector requires safe points of any kind. By default, |
| /// none are recorded. |
| bool needsSafePoints() const { return NeededSafePoints != 0; } |
| |
| /// True if the collector requires the given kind of safe point. By default, |
| /// none are recorded. |
| bool needsSafePoint(GC::PointKind Kind) const { |
| return (NeededSafePoints & 1 << Kind) != 0; |
| } |
| |
| /// By default, write barriers are replaced with simple store instructions. |
| /// If true, then addPassesToCustomLowerIntrinsics must instead process |
| /// them. |
| bool customWriteBarrier() const { return CustomWriteBarriers; } |
| |
| /// By default, read barriers are replaced with simple load instructions. |
| /// If true, then addPassesToCustomLowerIntrinsics must instead process |
| /// them. |
| bool customReadBarrier() const { return CustomReadBarriers; } |
| |
| /// By default, roots are left for the code generator. If Custom, then |
| /// addPassesToCustomLowerIntrinsics must add passes to delete them. |
| bool customRoots() const { return CustomRoots; } |
| |
| /// If set, gcroot intrinsics should initialize their allocas to null. This |
| /// is necessary for most collectors. |
| bool initializeRoots() const { return InitRoots; } |
| |
| |
| /// beginAssembly/finishAssembly - Emit module metadata as assembly code. |
| virtual void beginAssembly(std::ostream &OS, AsmPrinter &AP, |
| const TargetAsmInfo &TAI); |
| virtual void finishAssembly(std::ostream &OS, AsmPrinter &AP, |
| const TargetAsmInfo &TAI); |
| |
| /// begin/end - Iterators for function metadata. |
| /// |
| iterator begin() { return Functions.begin(); } |
| iterator end() { return Functions.end(); } |
| |
| /// insertFunctionMetadata - Creates metadata for a function. |
| /// |
| CollectorMetadata *insertFunctionMetadata(const Function &F); |
| |
| /// initializeCustomLowering/performCustomLowering - If any of the actions |
| /// are set to custom, performCustomLowering must be overriden to create a |
| /// transform to lower those actions to LLVM IR. initializeCustomLowering |
| /// is optional to override. These are the only Collector methods through |
| /// which the LLVM IR can be modified. |
| virtual bool initializeCustomLowering(Module &F); |
| virtual bool performCustomLowering(Function &F); |
| }; |
| |
| } |
| |
| #endif |