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/Pass.h"
37 #include "llvm/ADT/DenseMap.h"
38 #include "llvm/ADT/StringMap.h"
39 #include "llvm/Support/DebugLoc.h"
48 /// PointKind - The type of a collector-safe point.
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.
58 /// GCPoint - Metadata for a collector-safe point in machine code.
61 GC::PointKind Kind; //< The kind of the safe point.
62 MCSymbol *Label; //< A label.
65 GCPoint(GC::PointKind K, MCSymbol *L, DebugLoc DL)
66 : Kind(K), Label(L), Loc(DL) {}
69 /// GCRoot - Metadata for a pointer to an object managed by the garbage
72 int Num; //< Usually a frame index.
73 int StackOffset; //< Offset from the stack pointer.
74 const Constant *Metadata;//< Metadata straight from the call to llvm.gcroot.
76 GCRoot(int N, const Constant *MD) : Num(N), StackOffset(-1), Metadata(MD) {}
80 /// GCFunctionInfo - Garbage collection metadata for a single function.
82 class GCFunctionInfo {
84 typedef std::vector<GCPoint>::iterator iterator;
85 typedef std::vector<GCRoot>::iterator roots_iterator;
86 typedef std::vector<GCRoot>::const_iterator live_iterator;
92 std::vector<GCRoot> Roots;
93 std::vector<GCPoint> SafePoints;
95 // FIXME: Liveness. A 2D BitVector, perhaps?
97 // BitVector Liveness;
99 // bool islive(int point, int root) =
100 // Liveness[point * SafePoints.size() + root]
102 // The bit vector is the more compact representation where >3.2% of roots
103 // are live per safe point (1.5% on 64-bit hosts).
106 GCFunctionInfo(const Function &F, GCStrategy &S);
109 /// getFunction - Return the function to which this metadata applies.
111 const Function &getFunction() const { return F; }
113 /// getStrategy - Return the GC strategy for the function.
115 GCStrategy &getStrategy() { return S; }
117 /// addStackRoot - Registers a root that lives on the stack. Num is the
118 /// stack object ID for the alloca (if the code generator is
119 // using MachineFrameInfo).
120 void addStackRoot(int Num, const Constant *Metadata) {
121 Roots.push_back(GCRoot(Num, Metadata));
124 /// addSafePoint - Notes the existence of a safe point. Num is the ID of the
125 /// label just prior to the safe point (if the code generator is using
126 /// MachineModuleInfo).
127 void addSafePoint(GC::PointKind Kind, MCSymbol *Label, DebugLoc DL) {
128 SafePoints.push_back(GCPoint(Kind, Label, DL));
131 /// getFrameSize/setFrameSize - Records the function's frame size.
133 uint64_t getFrameSize() const { return FrameSize; }
134 void setFrameSize(uint64_t S) { FrameSize = S; }
136 /// begin/end - Iterators for safe points.
138 iterator begin() { return SafePoints.begin(); }
139 iterator end() { return SafePoints.end(); }
140 size_t size() const { return SafePoints.size(); }
142 /// roots_begin/roots_end - Iterators for all roots in the function.
144 roots_iterator roots_begin() { return Roots.begin(); }
145 roots_iterator roots_end () { return Roots.end(); }
146 size_t roots_size() const { return Roots.size(); }
148 /// live_begin/live_end - Iterators for live roots at a given safe point.
150 live_iterator live_begin(const iterator &p) { return roots_begin(); }
151 live_iterator live_end (const iterator &p) { return roots_end(); }
152 size_t live_size(const iterator &p) const { return roots_size(); }
156 /// GCModuleInfo - Garbage collection metadata for a whole module.
158 class GCModuleInfo : public ImmutablePass {
159 typedef StringMap<GCStrategy*> strategy_map_type;
160 typedef std::vector<GCStrategy*> list_type;
161 typedef DenseMap<const Function*,GCFunctionInfo*> finfo_map_type;
163 strategy_map_type StrategyMap;
164 list_type StrategyList;
165 finfo_map_type FInfoMap;
167 GCStrategy *getOrCreateStrategy(const Module *M, const std::string &Name);
170 typedef list_type::const_iterator iterator;
177 /// clear - Resets the pass. The metadata deleter pass calls this.
181 /// begin/end - Iterators for used strategies.
183 iterator begin() const { return StrategyList.begin(); }
184 iterator end() const { return StrategyList.end(); }
186 /// get - Look up function metadata.
188 GCFunctionInfo &getFunctionInfo(const Function &F);