1 //===-- GCMetadata.h - Garbage collector metadata ---------------*- C++ -*-===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This file declares the GCFunctionInfo and GCModuleInfo classes, which are 11 // used as a communication channel from the target code generator to the target 12 // garbage collectors. This interface allows code generators and garbage 13 // collectors to be developed independently. 14 // 15 // The GCFunctionInfo class logs the data necessary to build a type accurate 16 // stack map. The code generator outputs: 17 // 18 // - Safe points as specified by the GCStrategy's NeededSafePoints. 19 // - Stack offsets for GC roots, as specified by calls to llvm.gcroot 20 // 21 // As a refinement, liveness analysis calculates the set of live roots at each 22 // safe point. Liveness analysis is not presently performed by the code 23 // generator, so all roots are assumed live. 24 // 25 // GCModuleInfo simply collects GCFunctionInfo instances for each Function as 26 // they are compiled. This accretion is necessary for collectors which must emit 27 // a stack map for the compilation unit as a whole. Therefore, GCFunctionInfo 28 // outlives the MachineFunction from which it is derived and must not refer to 29 // any code generator data structures. 30 // 31 //===----------------------------------------------------------------------===// 32 33 #ifndef LLVM_CODEGEN_GCMETADATA_H 34 #define LLVM_CODEGEN_GCMETADATA_H 35 36 #include "llvm/ADT/DenseMap.h" 37 #include "llvm/ADT/StringMap.h" 38 #include "llvm/Pass.h" 39 #include "llvm/Support/DebugLoc.h" 40 41 namespace llvm { 42 class AsmPrinter; 43 class GCStrategy; 44 class Constant; 45 class MCSymbol; 46 47 namespace GC { 48 /// PointKind - The type of a collector-safe point. 49 /// 50 enum PointKind { 51 Loop, ///< Instr is a loop (backwards branch). 52 Return, ///< Instr is a return instruction. 53 PreCall, ///< Instr is a call instruction. 54 PostCall ///< Instr is the return address of a call. 55 }; 56 } 57 58 /// GCPoint - Metadata for a collector-safe point in machine code. 59 /// 60 struct GCPoint { 61 GC::PointKind Kind; ///< The kind of the safe point. 62 MCSymbol *Label; ///< A label. 63 DebugLoc Loc; 64 GCPointGCPoint65 GCPoint(GC::PointKind K, MCSymbol *L, DebugLoc DL) 66 : Kind(K), Label(L), Loc(DL) {} 67 }; 68 69 /// GCRoot - Metadata for a pointer to an object managed by the garbage 70 /// collector. 71 struct GCRoot { 72 int Num; ///< Usually a frame index. 73 int StackOffset; ///< Offset from the stack pointer. 74 const Constant *Metadata; ///< Metadata straight from the call 75 ///< to llvm.gcroot. 76 GCRootGCRoot77 GCRoot(int N, const Constant *MD) : Num(N), StackOffset(-1), Metadata(MD) {} 78 }; 79 80 81 /// GCFunctionInfo - Garbage collection metadata for a single function. 82 /// 83 class GCFunctionInfo { 84 public: 85 typedef std::vector<GCPoint>::iterator iterator; 86 typedef std::vector<GCRoot>::iterator roots_iterator; 87 typedef std::vector<GCRoot>::const_iterator live_iterator; 88 89 private: 90 const Function &F; 91 GCStrategy &S; 92 uint64_t FrameSize; 93 std::vector<GCRoot> Roots; 94 std::vector<GCPoint> SafePoints; 95 96 // FIXME: Liveness. A 2D BitVector, perhaps? 97 // 98 // BitVector Liveness; 99 // 100 // bool islive(int point, int root) = 101 // Liveness[point * SafePoints.size() + root] 102 // 103 // The bit vector is the more compact representation where >3.2% of roots 104 // are live per safe point (1.5% on 64-bit hosts). 105 106 public: 107 GCFunctionInfo(const Function &F, GCStrategy &S); 108 ~GCFunctionInfo(); 109 110 /// getFunction - Return the function to which this metadata applies. 111 /// getFunction()112 const Function &getFunction() const { return F; } 113 114 /// getStrategy - Return the GC strategy for the function. 115 /// getStrategy()116 GCStrategy &getStrategy() { return S; } 117 118 /// addStackRoot - Registers a root that lives on the stack. Num is the 119 /// stack object ID for the alloca (if the code generator is 120 // using MachineFrameInfo). addStackRoot(int Num,const Constant * Metadata)121 void addStackRoot(int Num, const Constant *Metadata) { 122 Roots.push_back(GCRoot(Num, Metadata)); 123 } 124 125 /// removeStackRoot - Removes a root. removeStackRoot(roots_iterator position)126 roots_iterator removeStackRoot(roots_iterator position) { 127 return Roots.erase(position); 128 } 129 130 /// addSafePoint - Notes the existence of a safe point. Num is the ID of the 131 /// label just prior to the safe point (if the code generator is using 132 /// MachineModuleInfo). addSafePoint(GC::PointKind Kind,MCSymbol * Label,DebugLoc DL)133 void addSafePoint(GC::PointKind Kind, MCSymbol *Label, DebugLoc DL) { 134 SafePoints.push_back(GCPoint(Kind, Label, DL)); 135 } 136 137 /// getFrameSize/setFrameSize - Records the function's frame size. 138 /// getFrameSize()139 uint64_t getFrameSize() const { return FrameSize; } setFrameSize(uint64_t S)140 void setFrameSize(uint64_t S) { FrameSize = S; } 141 142 /// begin/end - Iterators for safe points. 143 /// begin()144 iterator begin() { return SafePoints.begin(); } end()145 iterator end() { return SafePoints.end(); } size()146 size_t size() const { return SafePoints.size(); } 147 148 /// roots_begin/roots_end - Iterators for all roots in the function. 149 /// roots_begin()150 roots_iterator roots_begin() { return Roots.begin(); } roots_end()151 roots_iterator roots_end () { return Roots.end(); } roots_size()152 size_t roots_size() const { return Roots.size(); } 153 154 /// live_begin/live_end - Iterators for live roots at a given safe point. 155 /// live_begin(const iterator & p)156 live_iterator live_begin(const iterator &p) { return roots_begin(); } live_end(const iterator & p)157 live_iterator live_end (const iterator &p) { return roots_end(); } live_size(const iterator & p)158 size_t live_size(const iterator &p) const { return roots_size(); } 159 }; 160 161 162 /// GCModuleInfo - Garbage collection metadata for a whole module. 163 /// 164 class GCModuleInfo : public ImmutablePass { 165 typedef StringMap<GCStrategy*> strategy_map_type; 166 typedef std::vector<GCStrategy*> list_type; 167 typedef DenseMap<const Function*,GCFunctionInfo*> finfo_map_type; 168 169 strategy_map_type StrategyMap; 170 list_type StrategyList; 171 finfo_map_type FInfoMap; 172 173 GCStrategy *getOrCreateStrategy(const Module *M, const std::string &Name); 174 175 public: 176 typedef list_type::const_iterator iterator; 177 178 static char ID; 179 180 GCModuleInfo(); 181 ~GCModuleInfo(); 182 183 /// clear - Resets the pass. Any pass, which uses GCModuleInfo, should 184 /// call it in doFinalization(). 185 /// 186 void clear(); 187 188 /// begin/end - Iterators for used strategies. 189 /// begin()190 iterator begin() const { return StrategyList.begin(); } end()191 iterator end() const { return StrategyList.end(); } 192 193 /// get - Look up function metadata. 194 /// 195 GCFunctionInfo &getFunctionInfo(const Function &F); 196 }; 197 198 } 199 200 #endif 201