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//===-- GCMetadata.h - Garbage collector metadata ---------------*- C++ -*-===//
//
// 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"
#include "llvm/Support/DebugLoc.h"
namespace llvm {
class AsmPrinter;
class GCStrategy;
class Constant;
class MCSymbol;
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.
MCSymbol *Label; ///< A label.
DebugLoc Loc;
GCPoint(GC::PointKind K, MCSymbol *L, DebugLoc DL)
: Kind(K), Label(L), Loc(DL) {}
};
/// 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.
const Constant *Metadata; ///< Metadata straight from the call
///< to llvm.gcroot.
GCRoot(int N, const 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, const Constant *Metadata) {
Roots.push_back(GCRoot(Num, Metadata));
}
/// removeStackRoot - Removes a root.
roots_iterator removeStackRoot(roots_iterator position) {
return Roots.erase(position);
}
/// 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, MCSymbol *Label, DebugLoc DL) {
SafePoints.push_back(GCPoint(Kind, Label, DL));
}
/// 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
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