llvm.org GIT mirror llvm / release_24 include / llvm / CodeGen / GCMetadata.h
release_24

Tree @release_24 (Download .tar.gz)

GCMetadata.h @release_24

5eca075
fc32822
 
 
7ed47a1
 
fc32822
 
 
5eca075
 
 
 
fc32822
5eca075
 
 
 
 
fc32822
5eca075
 
 
fc32822
5eca075
 
 
 
 
fc32822
 
 
5eca075
 
fc32822
 
 
ad93c4f
fc32822
 
 
ad93c4f
5eca075
fc32822
ad93c4f
fc32822
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
ad93c4f
fc32822
 
 
 
 
5eca075
fc32822
5eca075
fc32822
 
 
 
 
 
 
5eca075
fc32822
 
 
 
 
 
 
 
 
 
 
 
 
 
 
5eca075
 
fc32822
ad93c4f
 
fc32822
 
5eca075
ad93c4f
5eca075
ad93c4f
fc32822
5eca075
 
fc32822
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
5eca075
fc32822
5eca075
 
 
 
fc32822
5eca075
 
 
ad93c4f
5eca075
fc32822
 
ad93c4f
fc32822
 
 
5eca075
 
fc32822
5eca075
 
fc32822
 
5eca075
fc32822
5eca075
 
fc32822
ad93c4f
fc32822
5eca075
fc32822
 
 
 
 
//===-- GCMetadata.h - Garbage collector metadata -------------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file declares the GCFunctionInfo and GCModuleInfo classes, which are
// used as a communication channel from the target code generator to the target
// garbage collectors. This interface allows code generators and garbage
// collectors to be developed independently.
//
// The GCFunctionInfo class logs the data necessary to build a type accurate
// stack map. The code generator outputs:
// 
//   - Safe points as specified by the GCStrategy's NeededSafePoints.
//   - Stack offsets for GC roots, as specified by calls to llvm.gcroot
//
// As a refinement, liveness analysis calculates the set of live roots at each
// safe point. Liveness analysis is not presently performed by the code
// generator, so all roots are assumed live.
//
// GCModuleInfo simply collects GCFunctionInfo instances for each Function as
// they are compiled. This accretion is necessary for collectors which must emit
// a stack map for the compilation unit as a whole. Therefore, GCFunctionInfo
// outlives the MachineFunction from which it is derived and must not refer to
// any code generator data structures.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_CODEGEN_GCMETADATA_H
#define LLVM_CODEGEN_GCMETADATA_H

#include "llvm/Pass.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/StringMap.h"

namespace llvm {
  
  class AsmPrinter;
  class GCStrategy;
  class Constant;
  class TargetAsmInfo;
  
  
  namespace GC {
    /// PointKind - The type of a collector-safe point.
    /// 
    enum PointKind {
      Loop,    //< Instr is a loop (backwards branch).
      Return,  //< Instr is a return instruction.
      PreCall, //< Instr is a call instruction.
      PostCall //< Instr is the return address of a call.
    };
  }
  
  /// GCPoint - Metadata for a collector-safe point in machine code.
  /// 
  struct GCPoint {
    GC::PointKind Kind; //< The kind of the safe point.
    unsigned Num;       //< Usually a label.
    
    GCPoint(GC::PointKind K, unsigned N) : Kind(K), Num(N) {}
  };
  
  /// GCRoot - Metadata for a pointer to an object managed by the garbage
  /// collector.
  struct GCRoot {
    int Num;            //< Usually a frame index.
    int StackOffset;    //< Offset from the stack pointer.
    Constant *Metadata; //< Metadata straight from the call to llvm.gcroot.
    
    GCRoot(int N, Constant *MD) : Num(N), StackOffset(-1), Metadata(MD) {}
  };
  
  
  /// GCFunctionInfo - Garbage collection metadata for a single function.
  /// 
  class GCFunctionInfo {
  public:
    typedef std::vector<GCPoint>::iterator iterator;
    typedef std::vector<GCRoot>::iterator roots_iterator;
    typedef std::vector<GCRoot>::const_iterator live_iterator;
    
  private:
    const Function &F;
    GCStrategy &S;
    uint64_t FrameSize;
    std::vector<GCRoot> Roots;
    std::vector<GCPoint> SafePoints;
    
    // FIXME: Liveness. A 2D BitVector, perhaps?
    // 
    //   BitVector Liveness;
    //   
    //   bool islive(int point, int root) =
    //     Liveness[point * SafePoints.size() + root]
    // 
    // The bit vector is the more compact representation where >3.2% of roots
    // are live per safe point (1.5% on 64-bit hosts).
    
  public:
    GCFunctionInfo(const Function &F, GCStrategy &S);
    ~GCFunctionInfo();
    
    /// getFunction - Return the function to which this metadata applies.
    /// 
    const Function &getFunction() const { return F; }
    
    /// getStrategy - Return the GC strategy for the function.
    /// 
    GCStrategy &getStrategy() { return S; }
    
    /// addStackRoot - Registers a root that lives on the stack. Num is the
    ///                stack object ID for the alloca (if the code generator is
    //                 using  MachineFrameInfo).
    void addStackRoot(int Num, Constant *Metadata) {
      Roots.push_back(GCRoot(Num, Metadata));
    }
    
    /// addSafePoint - Notes the existence of a safe point. Num is the ID of the
    /// label just prior to the safe point (if the code generator is using 
    /// MachineModuleInfo).
    void addSafePoint(GC::PointKind Kind, unsigned Num) {
      SafePoints.push_back(GCPoint(Kind, Num));
    }
    
    /// getFrameSize/setFrameSize - Records the function's frame size.
    /// 
    uint64_t getFrameSize() const { return FrameSize; }
    void setFrameSize(uint64_t S) { FrameSize = S; }
    
    /// begin/end - Iterators for safe points.
    /// 
    iterator begin() { return SafePoints.begin(); }
    iterator end()   { return SafePoints.end();   }
    size_t size() const { return SafePoints.size(); }
    
    /// roots_begin/roots_end - Iterators for all roots in the function.
    /// 
    roots_iterator roots_begin() { return Roots.begin(); }
    roots_iterator roots_end  () { return Roots.end();   }
    size_t roots_size() const { return Roots.size(); }
    
    /// live_begin/live_end - Iterators for live roots at a given safe point.
    /// 
    live_iterator live_begin(const iterator &p) { return roots_begin(); }
    live_iterator live_end  (const iterator &p) { return roots_end();   }
    size_t live_size(const iterator &p) const { return roots_size(); }
  };
  
  
  /// GCModuleInfo - Garbage collection metadata for a whole module.
  /// 
  class GCModuleInfo : public ImmutablePass {
    typedef StringMap<GCStrategy*> strategy_map_type;
    typedef std::vector<GCStrategy*> list_type;
    typedef DenseMap<const Function*,GCFunctionInfo*> finfo_map_type;
    
    strategy_map_type StrategyMap;
    list_type StrategyList;
    finfo_map_type FInfoMap;
    
    GCStrategy *getOrCreateStrategy(const Module *M, const std::string &Name);
    
  public:
    typedef list_type::const_iterator iterator;
    
    static char ID;
    
    GCModuleInfo();
    ~GCModuleInfo();
    
    /// clear - Resets the pass. The metadata deleter pass calls this.
    /// 
    void clear();
    
    /// begin/end - Iterators for used strategies.
    /// 
    iterator begin() const { return StrategyList.begin(); }
    iterator end()   const { return StrategyList.end();   }
    
    /// get - Look up function metadata.
    /// 
    GCFunctionInfo &getFunctionInfo(const Function &F);
  };
  
}

#endif