1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
|
//===-- GCMetadata.h - Garbage collector metadata ---------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file declares the GCFunctionInfo and GCModuleInfo classes, which are
// used as a communication channel from the target code generator to the target
// garbage collectors. This interface allows code generators and garbage
// collectors to be developed independently.
//
// The GCFunctionInfo class logs the data necessary to build a type accurate
// stack map. The code generator outputs:
//
// - Safe points as specified by the GCStrategy's NeededSafePoints.
// - Stack offsets for GC roots, as specified by calls to llvm.gcroot
//
// As a refinement, liveness analysis calculates the set of live roots at each
// safe point. Liveness analysis is not presently performed by the code
// generator, so all roots are assumed live.
//
// GCModuleInfo simply collects GCFunctionInfo instances for each Function as
// they are compiled. This accretion is necessary for collectors which must emit
// a stack map for the compilation unit as a whole. Therefore, GCFunctionInfo
// outlives the MachineFunction from which it is derived and must not refer to
// any code generator data structures.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_CODEGEN_GCMETADATA_H
#define LLVM_CODEGEN_GCMETADATA_H
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/CodeGen/GCStrategy.h"
#include "llvm/IR/DebugLoc.h"
#include "llvm/Pass.h"
#include <memory>
namespace llvm {
class AsmPrinter;
class Constant;
class MCSymbol;
/// GCPoint - Metadata for a collector-safe point in machine code.
///
struct GCPoint {
GC::PointKind Kind; ///< The kind of the safe point.
MCSymbol *Label; ///< A label.
DebugLoc Loc;
GCPoint(GC::PointKind K, MCSymbol *L, DebugLoc DL)
: Kind(K), Label(L), Loc(DL) {}
};
/// GCRoot - Metadata for a pointer to an object managed by the garbage
/// collector.
struct GCRoot {
int Num; ///< Usually a frame index.
int StackOffset; ///< Offset from the stack pointer.
const Constant *Metadata; ///< Metadata straight from the call
///< to llvm.gcroot.
GCRoot(int N, const Constant *MD) : Num(N), StackOffset(-1), Metadata(MD) {}
};
/// Garbage collection metadata for a single function. Currently, this
/// information only applies to GCStrategies which use GCRoot.
class GCFunctionInfo {
public:
typedef std::vector<GCPoint>::iterator iterator;
typedef std::vector<GCRoot>::iterator roots_iterator;
typedef std::vector<GCRoot>::const_iterator live_iterator;
private:
const Function &F;
GCStrategy &S;
uint64_t FrameSize;
std::vector<GCRoot> Roots;
std::vector<GCPoint> SafePoints;
// FIXME: Liveness. A 2D BitVector, perhaps?
//
// BitVector Liveness;
//
// bool islive(int point, int root) =
// Liveness[point * SafePoints.size() + root]
//
// The bit vector is the more compact representation where >3.2% of roots
// are live per safe point (1.5% on 64-bit hosts).
public:
GCFunctionInfo(const Function &F, GCStrategy &S);
~GCFunctionInfo();
/// getFunction - Return the function to which this metadata applies.
///
const Function &getFunction() const { return F; }
/// getStrategy - Return the GC strategy for the function.
///
GCStrategy &getStrategy() { return S; }
/// addStackRoot - Registers a root that lives on the stack. Num is the
/// stack object ID for the alloca (if the code generator is
// using MachineFrameInfo).
void addStackRoot(int Num, const Constant *Metadata) {
Roots.push_back(GCRoot(Num, Metadata));
}
/// removeStackRoot - Removes a root.
roots_iterator removeStackRoot(roots_iterator position) {
return Roots.erase(position);
}
/// addSafePoint - Notes the existence of a safe point. Num is the ID of the
/// label just prior to the safe point (if the code generator is using
/// MachineModuleInfo).
void addSafePoint(GC::PointKind Kind, MCSymbol *Label, DebugLoc DL) {
SafePoints.emplace_back(Kind, Label, DL);
}
/// getFrameSize/setFrameSize - Records the function's frame size.
///
uint64_t getFrameSize() const { return FrameSize; }
void setFrameSize(uint64_t S) { FrameSize = S; }
/// begin/end - Iterators for safe points.
///
iterator begin() { return SafePoints.begin(); }
iterator end() { return SafePoints.end(); }
size_t size() const { return SafePoints.size(); }
/// roots_begin/roots_end - Iterators for all roots in the function.
///
roots_iterator roots_begin() { return Roots.begin(); }
roots_iterator roots_end() { return Roots.end(); }
size_t roots_size() const { return Roots.size(); }
/// live_begin/live_end - Iterators for live roots at a given safe point.
///
live_iterator live_begin(const iterator &p) { return roots_begin(); }
live_iterator live_end(const iterator &p) { return roots_end(); }
size_t live_size(const iterator &p) const { return roots_size(); }
};
/// An analysis pass which caches information about the entire Module.
/// Records both the function level information used by GCRoots and a
/// cache of the 'active' gc strategy objects for the current Module.
class GCModuleInfo : public ImmutablePass {
/// An owning list of all GCStrategies which have been created
SmallVector<std::unique_ptr<GCStrategy>, 1> GCStrategyList;
/// A helper map to speedup lookups into the above list
StringMap<GCStrategy*> GCStrategyMap;
public:
/// Lookup the GCStrategy object associated with the given gc name.
/// Objects are owned internally; No caller should attempt to delete the
/// returned objects.
GCStrategy *getGCStrategy(const StringRef Name);
/// List of per function info objects. In theory, Each of these
/// may be associated with a different GC.
typedef std::vector<std::unique_ptr<GCFunctionInfo>> FuncInfoVec;
FuncInfoVec::iterator funcinfo_begin() { return Functions.begin(); }
FuncInfoVec::iterator funcinfo_end() { return Functions.end(); }
private:
/// Owning list of all GCFunctionInfos associated with this Module
FuncInfoVec Functions;
/// Non-owning map to bypass linear search when finding the GCFunctionInfo
/// associated with a particular Function.
typedef DenseMap<const Function *, GCFunctionInfo *> finfo_map_type;
finfo_map_type FInfoMap;
public:
typedef SmallVector<std::unique_ptr<GCStrategy>,1>::const_iterator iterator;
static char ID;
GCModuleInfo();
/// clear - Resets the pass. Any pass, which uses GCModuleInfo, should
/// call it in doFinalization().
///
void clear();
/// begin/end - Iterators for used strategies.
///
iterator begin() const { return GCStrategyList.begin(); }
iterator end() const { return GCStrategyList.end(); }
/// get - Look up function metadata. This is currently assumed
/// have the side effect of initializing the associated GCStrategy. That
/// will soon change.
GCFunctionInfo &getFunctionInfo(const Function &F);
};
}
#endif
|
