1 //===-- GCMetadata.h - Garbage collector metadata ---------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
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.
15 // The GCFunctionInfo class logs the data necessary to build a type accurate
16 // stack map. The code generator outputs:
18 // - Safe points as specified by the GCStrategy's NeededSafePoints.
19 // - Stack offsets for GC roots, as specified by calls to llvm.gcroot
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.
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.
31 //===----------------------------------------------------------------------===//
33 #ifndef LLVM_CODEGEN_GCMETADATA_H
34 #define LLVM_CODEGEN_GCMETADATA_H
36 #include "llvm/ADT/DenseMap.h"
37 #include "llvm/ADT/StringMap.h"
38 #include "llvm/IR/DebugLoc.h"
39 #include "llvm/Pass.h"
49 /// PointKind - The type of a collector-safe point.
52 Loop, ///< Instr is a loop (backwards branch).
53 Return, ///< Instr is a return instruction.
54 PreCall, ///< Instr is a call instruction.
55 PostCall ///< Instr is the return address of a call.
59 /// GCPoint - Metadata for a collector-safe point in machine code.
62 GC::PointKind Kind; ///< The kind of the safe point.
63 MCSymbol *Label; ///< A label.
66 GCPoint(GC::PointKind K, MCSymbol *L, DebugLoc DL)
67 : Kind(K), Label(L), Loc(DL) {}
70 /// GCRoot - Metadata for a pointer to an object managed by the garbage
73 int Num; ///< Usually a frame index.
74 int StackOffset; ///< Offset from the stack pointer.
75 const Constant *Metadata; ///< Metadata straight from the call
78 GCRoot(int N, const Constant *MD) : Num(N), StackOffset(-1), Metadata(MD) {}
82 /// Garbage collection metadata for a single function. Currently, this
83 /// information only applies to GCStrategies which use GCRoot.
84 class GCFunctionInfo {
86 typedef std::vector<GCPoint>::iterator iterator;
87 typedef std::vector<GCRoot>::iterator roots_iterator;
88 typedef std::vector<GCRoot>::const_iterator live_iterator;
94 std::vector<GCRoot> Roots;
95 std::vector<GCPoint> SafePoints;
97 // FIXME: Liveness. A 2D BitVector, perhaps?
99 // BitVector Liveness;
101 // bool islive(int point, int root) =
102 // Liveness[point * SafePoints.size() + root]
104 // The bit vector is the more compact representation where >3.2% of roots
105 // are live per safe point (1.5% on 64-bit hosts).
108 GCFunctionInfo(const Function &F, GCStrategy &S);
111 /// getFunction - Return the function to which this metadata applies.
113 const Function &getFunction() const { return F; }
115 /// getStrategy - Return the GC strategy for the function.
117 GCStrategy &getStrategy() { return S; }
119 /// addStackRoot - Registers a root that lives on the stack. Num is the
120 /// stack object ID for the alloca (if the code generator is
121 // using MachineFrameInfo).
122 void addStackRoot(int Num, const Constant *Metadata) {
123 Roots.push_back(GCRoot(Num, Metadata));
126 /// removeStackRoot - Removes a root.
127 roots_iterator removeStackRoot(roots_iterator position) {
128 return Roots.erase(position);
131 /// addSafePoint - Notes the existence of a safe point. Num is the ID of the
132 /// label just prior to the safe point (if the code generator is using
133 /// MachineModuleInfo).
134 void addSafePoint(GC::PointKind Kind, MCSymbol *Label, DebugLoc DL) {
135 SafePoints.push_back(GCPoint(Kind, Label, DL));
138 /// getFrameSize/setFrameSize - Records the function's frame size.
140 uint64_t getFrameSize() const { return FrameSize; }
141 void setFrameSize(uint64_t S) { FrameSize = S; }
143 /// begin/end - Iterators for safe points.
145 iterator begin() { return SafePoints.begin(); }
146 iterator end() { return SafePoints.end(); }
147 size_t size() const { return SafePoints.size(); }
149 /// roots_begin/roots_end - Iterators for all roots in the function.
151 roots_iterator roots_begin() { return Roots.begin(); }
152 roots_iterator roots_end () { return Roots.end(); }
153 size_t roots_size() const { return Roots.size(); }
155 /// live_begin/live_end - Iterators for live roots at a given safe point.
157 live_iterator live_begin(const iterator &p) { return roots_begin(); }
158 live_iterator live_end (const iterator &p) { return roots_end(); }
159 size_t live_size(const iterator &p) const { return roots_size(); }
162 /// An analysis pass which caches information about the entire Module.
163 /// Records both the function level information used by GCRoots and a
164 /// cache of the 'active' gc strategy objects for the current Module.
165 class GCModuleInfo : public ImmutablePass {
166 typedef StringMap<GCStrategy*> strategy_map_type;
167 typedef std::vector<std::unique_ptr<GCStrategy>> list_type;
169 strategy_map_type StrategyMap;
170 list_type StrategyList;
172 GCStrategy *getOrCreateStrategy(const Module *M, const std::string &Name);
175 /// List of per function info objects. In theory, Each of these
176 /// may be associated with a different GC.
177 typedef std::vector<std::unique_ptr<GCFunctionInfo>> FuncInfoVec;
179 FuncInfoVec::iterator funcinfo_begin() { return Functions.begin(); }
180 FuncInfoVec::iterator funcinfo_end() { return Functions.end(); }
184 /// Owning list of all GCFunctionInfos associated with this Module
185 FuncInfoVec Functions;
187 /// Non-owning map to bypass linear search when finding the GCFunctionInfo
188 /// associated with a particular Function.
189 typedef DenseMap<const Function*,GCFunctionInfo*> finfo_map_type;
190 finfo_map_type FInfoMap;
193 typedef list_type::const_iterator iterator;
199 /// clear - Resets the pass. Any pass, which uses GCModuleInfo, should
200 /// call it in doFinalization().
204 /// begin/end - Iterators for used strategies.
206 iterator begin() const { return StrategyList.begin(); }
207 iterator end() const { return StrategyList.end(); }
209 /// get - Look up function metadata. This is currently assumed
210 /// have the side effect of initializing the associated GCStrategy. That
211 /// will soon change.
212 GCFunctionInfo &getFunctionInfo(const Function &F);