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"
50 /// PointKind - The type of a collector-safe point.
53 Loop, ///< Instr is a loop (backwards branch).
54 Return, ///< Instr is a return instruction.
55 PreCall, ///< Instr is a call instruction.
56 PostCall ///< Instr is the return address of a call.
60 /// GCPoint - Metadata for a collector-safe point in machine code.
63 GC::PointKind Kind; ///< The kind of the safe point.
64 MCSymbol *Label; ///< A label.
67 GCPoint(GC::PointKind K, MCSymbol *L, DebugLoc DL)
68 : Kind(K), Label(L), Loc(DL) {}
71 /// GCRoot - Metadata for a pointer to an object managed by the garbage
74 int Num; ///< Usually a frame index.
75 int StackOffset; ///< Offset from the stack pointer.
76 const Constant *Metadata; ///< Metadata straight from the call
79 GCRoot(int N, const Constant *MD) : Num(N), StackOffset(-1), Metadata(MD) {}
83 /// GCFunctionInfo - Garbage collection metadata for a single function.
85 class GCFunctionInfo {
87 typedef std::vector<GCPoint>::iterator iterator;
88 typedef std::vector<GCRoot>::iterator roots_iterator;
89 typedef std::vector<GCRoot>::const_iterator live_iterator;
95 std::vector<GCRoot> Roots;
96 std::vector<GCPoint> SafePoints;
98 // FIXME: Liveness. A 2D BitVector, perhaps?
100 // BitVector Liveness;
102 // bool islive(int point, int root) =
103 // Liveness[point * SafePoints.size() + root]
105 // The bit vector is the more compact representation where >3.2% of roots
106 // are live per safe point (1.5% on 64-bit hosts).
109 GCFunctionInfo(const Function &F, GCStrategy &S);
112 /// getFunction - Return the function to which this metadata applies.
114 const Function &getFunction() const { return F; }
116 /// getStrategy - Return the GC strategy for the function.
118 GCStrategy &getStrategy() { return S; }
120 /// addStackRoot - Registers a root that lives on the stack. Num is the
121 /// stack object ID for the alloca (if the code generator is
122 // using MachineFrameInfo).
123 void addStackRoot(int Num, const Constant *Metadata) {
124 Roots.push_back(GCRoot(Num, Metadata));
127 /// removeStackRoot - Removes a root.
128 roots_iterator removeStackRoot(roots_iterator position) {
129 return Roots.erase(position);
132 /// addSafePoint - Notes the existence of a safe point. Num is the ID of the
133 /// label just prior to the safe point (if the code generator is using
134 /// MachineModuleInfo).
135 void addSafePoint(GC::PointKind Kind, MCSymbol *Label, DebugLoc DL) {
136 SafePoints.push_back(GCPoint(Kind, Label, DL));
139 /// getFrameSize/setFrameSize - Records the function's frame size.
141 uint64_t getFrameSize() const { return FrameSize; }
142 void setFrameSize(uint64_t S) { FrameSize = S; }
144 /// begin/end - Iterators for safe points.
146 iterator begin() { return SafePoints.begin(); }
147 iterator end() { return SafePoints.end(); }
148 size_t size() const { return SafePoints.size(); }
150 /// roots_begin/roots_end - Iterators for all roots in the function.
152 roots_iterator roots_begin() { return Roots.begin(); }
153 roots_iterator roots_end () { return Roots.end(); }
154 size_t roots_size() const { return Roots.size(); }
156 /// live_begin/live_end - Iterators for live roots at a given safe point.
158 live_iterator live_begin(const iterator &p) { return roots_begin(); }
159 live_iterator live_end (const iterator &p) { return roots_end(); }
160 size_t live_size(const iterator &p) const { return roots_size(); }
164 /// GCModuleInfo - Garbage collection metadata for a whole module.
166 class GCModuleInfo : public ImmutablePass {
167 typedef StringMap<GCStrategy*> strategy_map_type;
168 typedef std::vector<std::unique_ptr<GCStrategy>> list_type;
169 typedef DenseMap<const Function*,GCFunctionInfo*> finfo_map_type;
171 strategy_map_type StrategyMap;
172 list_type StrategyList;
173 finfo_map_type FInfoMap;
175 GCStrategy *getOrCreateStrategy(const Module *M, const std::string &Name);
178 typedef list_type::const_iterator iterator;
184 /// clear - Resets the pass. Any pass, which uses GCModuleInfo, should
185 /// call it in doFinalization().
189 /// begin/end - Iterators for used strategies.
191 iterator begin() const { return StrategyList.begin(); }
192 iterator end() const { return StrategyList.end(); }
194 /// get - Look up function metadata.
196 GCFunctionInfo &getFunctionInfo(const Function &F);