llvm-6502/include/llvm/CodeGen/Collector.h

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//===-- 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