-//===-- 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.
- bool UsesMetadata; //< If set, backend must emit metadata tables.
-
- 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; }
-
- /// If set, appropriate metadata tables must be emitted by the back-end
- /// (assembler, JIT, or otherwise).
- bool usesMetadata() const { return UsesMetadata; }
-
- /// 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);
- };
-
- // GCMetadataPrinter - Emits GC metadata as assembly code.
- class GCMetadataPrinter {
- public:
- typedef Collector::list_type list_type;
- typedef Collector::iterator iterator;
-
- private:
- Collector *Coll;
-
- friend class AsmPrinter;
-
- protected:
- // May only be subclassed.
- GCMetadataPrinter();
-
- // Do not implement.
- GCMetadataPrinter(const GCMetadataPrinter &);
- GCMetadataPrinter &operator=(const GCMetadataPrinter &);
-
- public:
- Collector &getCollector() { return *Coll; }
- const Module &getModule() const { return Coll->getModule(); }
-
- iterator begin() { return Coll->begin(); }
- iterator end() { return Coll->end(); }
-
- /// 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);
-
- virtual ~GCMetadataPrinter();
- };
-
-}
-
-#endif
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