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discussion of this change. Boy are my fingers tired. ;-) git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@45411 91177308-0d34-0410-b5e6-96231b3b80d8
134 lines
4.8 KiB
C++
134 lines
4.8 KiB
C++
//===-- 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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#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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#include <string>
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namespace llvm {
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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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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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list_type Functions;
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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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public:
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Collector();
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virtual ~Collector();
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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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/// 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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/// 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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/// 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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virtual void finishAssembly(std::ostream &OS, AsmPrinter &AP,
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const TargetAsmInfo &TAI);
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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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/// insertFunctionMetadata - Creates metadata for a function.
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///
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CollectorMetadata *insertFunctionMetadata(const Function &F);
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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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#endif
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