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134 lines
5.1 KiB
C
134 lines
5.1 KiB
C
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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 was developed by Gordon Henriksen and is distributed under
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// the University of Illinois Open Source License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// GCInfo 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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// GCSafePointPass identifies the GC safe points in the machine code. (Roots are
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// identified in SelectionDAGISel.)
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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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#include "llvm/CodeGen/CollectorMetadata.h"
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#include <iosfwd>
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namespace llvm {
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class AsmPrinter;
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class FunctionPassManager;
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class PassManager;
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class TargetAsmInfo;
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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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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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/// If any of the actions are set to Custom, this is expected to be
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/// overriden to create a transform to lower those actions to LLVM IR.
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virtual Pass *createCustomLoweringPass() const;
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public:
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Collector();
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virtual ~Collector();
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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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/// 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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/// 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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/// 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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/// 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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/// 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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/// Adds LLVM IR transforms to handle collection intrinsics. By default,
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/// read- and write barriers are replaced with direct memory accesses, and
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/// roots are passed on to the code generator.
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void addLoweringPasses(FunctionPassManager &PM) const;
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/// Same as addLoweringPasses(FunctionPassManager &), except uses a
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/// PassManager for compatibility with unusual backends (such as MSIL or
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/// CBackend).
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void addLoweringPasses(PassManager &PM) const;
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/// Adds target-independent MachineFunction pass to mark safe points. This
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/// is added very late during code generation, just prior to output, and
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/// importantly after all CFG transformations (like branch folding).
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void addGenericMachineCodePass(FunctionPassManager &PM,
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const TargetMachine &TM, bool Fast) const;
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/// beginAssembly/finishAssembly - Emit module metadata as assembly code.
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virtual void beginAssembly(Module &M, std::ostream &OS, AsmPrinter &AP,
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const TargetAsmInfo &TAI) const;
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virtual void finishAssembly(Module &M, CollectorModuleMetadata &CMM,
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std::ostream &OS, AsmPrinter &AP,
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const TargetAsmInfo &TAI) const;
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private:
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bool NeedsDefaultLoweringPass() const;
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bool NeedsCustomLoweringPass() const;
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};
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/// If set, the code generator should generate garbage collection as specified
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/// by the collector properties.
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extern const Collector *TheCollector; // FIXME: Find a better home!
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}
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#endif
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