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/SmallVector.h" 38 #include "llvm/ADT/StringMap.h" 39 #include "llvm/CodeGen/GCStrategy.h" 40 #include "llvm/IR/DebugLoc.h" 41 #include "llvm/Pass.h" 42 #include <memory> 43 44 namespace llvm { 45 class AsmPrinter; 46 class Constant; 47 class MCSymbol; 48 49 /// GCPoint - Metadata for a collector-safe point in machine code. 50 /// 51 struct GCPoint { 52 GC::PointKind Kind; ///< The kind of the safe point. 53 MCSymbol *Label; ///< A label. 54 DebugLoc Loc; 55 56 GCPoint(GC::PointKind K, MCSymbol *L, DebugLoc DL) 57 : Kind(K), Label(L), Loc(DL) {} 58 }; 59 60 /// GCRoot - Metadata for a pointer to an object managed by the garbage 61 /// collector. 62 struct GCRoot { 63 int Num; ///< Usually a frame index. 64 int StackOffset; ///< Offset from the stack pointer. 65 const Constant *Metadata; ///< Metadata straight from the call 66 ///< to llvm.gcroot. 67 68 GCRoot(int N, const Constant *MD) : Num(N), StackOffset(-1), Metadata(MD) {} 69 }; 70 71 /// Garbage collection metadata for a single function. Currently, this 72 /// information only applies to GCStrategies which use GCRoot. 73 class GCFunctionInfo { 74 public: 75 typedef std::vector<GCPoint>::iterator iterator; 76 typedef std::vector<GCRoot>::iterator roots_iterator; 77 typedef std::vector<GCRoot>::const_iterator live_iterator; 78 79 private: 80 const Function &F; 81 GCStrategy &S; 82 uint64_t FrameSize; 83 std::vector<GCRoot> Roots; 84 std::vector<GCPoint> SafePoints; 85 86 // FIXME: Liveness. A 2D BitVector, perhaps? 87 // 88 // BitVector Liveness; 89 // 90 // bool islive(int point, int root) = 91 // Liveness[point * SafePoints.size() + root] 92 // 93 // The bit vector is the more compact representation where >3.2% of roots 94 // are live per safe point (1.5% on 64-bit hosts). 95 96 public: 97 GCFunctionInfo(const Function &F, GCStrategy &S); 98 ~GCFunctionInfo(); 99 100 /// getFunction - Return the function to which this metadata applies. 101 /// 102 const Function &getFunction() const { return F; } 103 104 /// getStrategy - Return the GC strategy for the function. 105 /// 106 GCStrategy &getStrategy() { return S; } 107 108 /// addStackRoot - Registers a root that lives on the stack. Num is the 109 /// stack object ID for the alloca (if the code generator is 110 // using MachineFrameInfo). 111 void addStackRoot(int Num, const Constant *Metadata) { 112 Roots.push_back(GCRoot(Num, Metadata)); 113 } 114 115 /// removeStackRoot - Removes a root. 116 roots_iterator removeStackRoot(roots_iterator position) { 117 return Roots.erase(position); 118 } 119 120 /// addSafePoint - Notes the existence of a safe point. Num is the ID of the 121 /// label just prior to the safe point (if the code generator is using 122 /// MachineModuleInfo). 123 void addSafePoint(GC::PointKind Kind, MCSymbol *Label, DebugLoc DL) { 124 SafePoints.emplace_back(Kind, Label, DL); 125 } 126 127 /// getFrameSize/setFrameSize - Records the function's frame size. 128 /// 129 uint64_t getFrameSize() const { return FrameSize; } 130 void setFrameSize(uint64_t S) { FrameSize = S; } 131 132 /// begin/end - Iterators for safe points. 133 /// 134 iterator begin() { return SafePoints.begin(); } 135 iterator end() { return SafePoints.end(); } 136 size_t size() const { return SafePoints.size(); } 137 138 /// roots_begin/roots_end - Iterators for all roots in the function. 139 /// 140 roots_iterator roots_begin() { return Roots.begin(); } 141 roots_iterator roots_end() { return Roots.end(); } 142 size_t roots_size() const { return Roots.size(); } 143 144 /// live_begin/live_end - Iterators for live roots at a given safe point. 145 /// 146 live_iterator live_begin(const iterator &p) { return roots_begin(); } 147 live_iterator live_end(const iterator &p) { return roots_end(); } 148 size_t live_size(const iterator &p) const { return roots_size(); } 149 }; 150 151 /// An analysis pass which caches information about the entire Module. 152 /// Records both the function level information used by GCRoots and a 153 /// cache of the 'active' gc strategy objects for the current Module. 154 class GCModuleInfo : public ImmutablePass { 155 /// An owning list of all GCStrategies which have been created 156 SmallVector<std::unique_ptr<GCStrategy>, 1> GCStrategyList; 157 /// A helper map to speedup lookups into the above list 158 StringMap<GCStrategy*> GCStrategyMap; 159 160 public: 161 /// Lookup the GCStrategy object associated with the given gc name. 162 /// Objects are owned internally; No caller should attempt to delete the 163 /// returned objects. 164 GCStrategy *getGCStrategy(const StringRef Name); 165 166 /// List of per function info objects. In theory, Each of these 167 /// may be associated with a different GC. 168 typedef std::vector<std::unique_ptr<GCFunctionInfo>> FuncInfoVec; 169 170 FuncInfoVec::iterator funcinfo_begin() { return Functions.begin(); } 171 FuncInfoVec::iterator funcinfo_end() { return Functions.end(); } 172 173 private: 174 /// Owning list of all GCFunctionInfos associated with this Module 175 FuncInfoVec Functions; 176 177 /// Non-owning map to bypass linear search when finding the GCFunctionInfo 178 /// associated with a particular Function. 179 typedef DenseMap<const Function *, GCFunctionInfo *> finfo_map_type; 180 finfo_map_type FInfoMap; 181 182 public: 183 typedef SmallVector<std::unique_ptr<GCStrategy>,1>::const_iterator iterator; 184 185 static char ID; 186 187 GCModuleInfo(); 188 189 /// clear - Resets the pass. Any pass, which uses GCModuleInfo, should 190 /// call it in doFinalization(). 191 /// 192 void clear(); 193 194 /// begin/end - Iterators for used strategies. 195 /// 196 iterator begin() const { return GCStrategyList.begin(); } 197 iterator end() const { return GCStrategyList.end(); } 198 199 /// get - Look up function metadata. This is currently assumed 200 /// have the side effect of initializing the associated GCStrategy. That 201 /// will soon change. 202 GCFunctionInfo &getFunctionInfo(const Function &F); 203 }; 204 } 205 206 #endif 207
