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