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/IR/GCStrategy.h"
40 #include "llvm/Pass.h"
48 /// GCPoint - Metadata for a collector-safe point in machine code.
51 GC::PointKind Kind; ///< The kind of the safe point.
52 MCSymbol *Label; ///< A label.
55 GCPoint(GC::PointKind K, MCSymbol *L, DebugLoc DL)
56 : Kind(K), Label(L), Loc(DL) {}
59 /// GCRoot - Metadata for a pointer to an object managed by the garbage
62 int Num; ///< Usually a frame index.
63 int StackOffset; ///< Offset from the stack pointer.
64 const Constant *Metadata; ///< Metadata straight from the call
67 GCRoot(int N, const Constant *MD) : Num(N), StackOffset(-1), Metadata(MD) {}
70 /// Garbage collection metadata for a single function. Currently, this
71 /// information only applies to GCStrategies which use GCRoot.
72 class GCFunctionInfo {
74 typedef std::vector<GCPoint>::iterator iterator;
75 typedef std::vector<GCRoot>::iterator roots_iterator;
76 typedef std::vector<GCRoot>::const_iterator live_iterator;
82 std::vector<GCRoot> Roots;
83 std::vector<GCPoint> SafePoints;
85 // FIXME: Liveness. A 2D BitVector, perhaps?
87 // BitVector Liveness;
89 // bool islive(int point, int root) =
90 // Liveness[point * SafePoints.size() + root]
92 // The bit vector is the more compact representation where >3.2% of roots
93 // are live per safe point (1.5% on 64-bit hosts).
96 GCFunctionInfo(const Function &F, GCStrategy &S);
99 /// getFunction - Return the function to which this metadata applies.
101 const Function &getFunction() const { return F; }
103 /// getStrategy - Return the GC strategy for the function.
105 GCStrategy &getStrategy() { return S; }
107 /// addStackRoot - Registers a root that lives on the stack. Num is the
108 /// stack object ID for the alloca (if the code generator is
109 // using MachineFrameInfo).
110 void addStackRoot(int Num, const Constant *Metadata) {
111 Roots.push_back(GCRoot(Num, Metadata));
114 /// removeStackRoot - Removes a root.
115 roots_iterator removeStackRoot(roots_iterator position) {
116 return Roots.erase(position);
119 /// addSafePoint - Notes the existence of a safe point. Num is the ID of the
120 /// label just prior to the safe point (if the code generator is using
121 /// MachineModuleInfo).
122 void addSafePoint(GC::PointKind Kind, MCSymbol *Label, DebugLoc DL) {
123 SafePoints.push_back(GCPoint(Kind, Label, DL));
126 /// getFrameSize/setFrameSize - Records the function's frame size.
128 uint64_t getFrameSize() const { return FrameSize; }
129 void setFrameSize(uint64_t S) { FrameSize = S; }
131 /// begin/end - Iterators for safe points.
133 iterator begin() { return SafePoints.begin(); }
134 iterator end() { return SafePoints.end(); }
135 size_t size() const { return SafePoints.size(); }
137 /// roots_begin/roots_end - Iterators for all roots in the function.
139 roots_iterator roots_begin() { return Roots.begin(); }
140 roots_iterator roots_end() { return Roots.end(); }
141 size_t roots_size() const { return Roots.size(); }
143 /// live_begin/live_end - Iterators for live roots at a given safe point.
145 live_iterator live_begin(const iterator &p) { return roots_begin(); }
146 live_iterator live_end(const iterator &p) { return roots_end(); }
147 size_t live_size(const iterator &p) const { return roots_size(); }
150 /// An analysis pass which caches information about the entire Module.
151 /// Records both the function level information used by GCRoots and a
152 /// cache of the 'active' gc strategy objects for the current Module.
153 class GCModuleInfo : public ImmutablePass {
154 /// A list of GCStrategies which are active in this Module. These are
155 /// not owning pointers.
156 std::vector<GCStrategy *> StrategyList;
159 /// List of per function info objects. In theory, Each of these
160 /// may be associated with a different GC.
161 typedef std::vector<std::unique_ptr<GCFunctionInfo>> FuncInfoVec;
163 FuncInfoVec::iterator funcinfo_begin() { return Functions.begin(); }
164 FuncInfoVec::iterator funcinfo_end() { return Functions.end(); }
167 /// Owning list of all GCFunctionInfos associated with this Module
168 FuncInfoVec Functions;
170 /// Non-owning map to bypass linear search when finding the GCFunctionInfo
171 /// associated with a particular Function.
172 typedef DenseMap<const Function *, GCFunctionInfo *> finfo_map_type;
173 finfo_map_type FInfoMap;
176 typedef std::vector<GCStrategy *>::const_iterator iterator;
182 /// clear - Resets the pass. Any pass, which uses GCModuleInfo, should
183 /// call it in doFinalization().
187 /// begin/end - Iterators for used strategies.
189 iterator begin() const { return StrategyList.begin(); }
190 iterator end() const { return StrategyList.end(); }
192 /// get - Look up function metadata. This is currently assumed
193 /// have the side effect of initializing the associated GCStrategy. That
194 /// will soon change.
195 GCFunctionInfo &getFunctionInfo(const Function &F);