Coverage Report

Created: 2019-04-21 11:35

/Users/buildslave/jenkins/workspace/clang-stage2-coverage-R/llvm/include/llvm/Analysis/CallGraph.h
Line
Count
Source (jump to first uncovered line)
1
//===- CallGraph.h - Build a Module's call graph ----------------*- C++ -*-===//
2
//
3
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4
// See https://llvm.org/LICENSE.txt for license information.
5
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6
//
7
//===----------------------------------------------------------------------===//
8
/// \file
9
///
10
/// This file provides interfaces used to build and manipulate a call graph,
11
/// which is a very useful tool for interprocedural optimization.
12
///
13
/// Every function in a module is represented as a node in the call graph.  The
14
/// callgraph node keeps track of which functions are called by the function
15
/// corresponding to the node.
16
///
17
/// A call graph may contain nodes where the function that they correspond to
18
/// is null.  These 'external' nodes are used to represent control flow that is
19
/// not represented (or analyzable) in the module.  In particular, this
20
/// analysis builds one external node such that:
21
///   1. All functions in the module without internal linkage will have edges
22
///      from this external node, indicating that they could be called by
23
///      functions outside of the module.
24
///   2. All functions whose address is used for something more than a direct
25
///      call, for example being stored into a memory location will also have
26
///      an edge from this external node.  Since they may be called by an
27
///      unknown caller later, they must be tracked as such.
28
///
29
/// There is a second external node added for calls that leave this module.
30
/// Functions have a call edge to the external node iff:
31
///   1. The function is external, reflecting the fact that they could call
32
///      anything without internal linkage or that has its address taken.
33
///   2. The function contains an indirect function call.
34
///
35
/// As an extension in the future, there may be multiple nodes with a null
36
/// function.  These will be used when we can prove (through pointer analysis)
37
/// that an indirect call site can call only a specific set of functions.
38
///
39
/// Because of these properties, the CallGraph captures a conservative superset
40
/// of all of the caller-callee relationships, which is useful for
41
/// transformations.
42
///
43
//===----------------------------------------------------------------------===//
44
45
#ifndef LLVM_ANALYSIS_CALLGRAPH_H
46
#define LLVM_ANALYSIS_CALLGRAPH_H
47
48
#include "llvm/ADT/GraphTraits.h"
49
#include "llvm/ADT/STLExtras.h"
50
#include "llvm/IR/Function.h"
51
#include "llvm/IR/InstrTypes.h"
52
#include "llvm/IR/Intrinsics.h"
53
#include "llvm/IR/PassManager.h"
54
#include "llvm/IR/ValueHandle.h"
55
#include "llvm/Pass.h"
56
#include <cassert>
57
#include <map>
58
#include <memory>
59
#include <utility>
60
#include <vector>
61
62
namespace llvm {
63
64
class CallGraphNode;
65
class Module;
66
class raw_ostream;
67
68
/// The basic data container for the call graph of a \c Module of IR.
69
///
70
/// This class exposes both the interface to the call graph for a module of IR.
71
///
72
/// The core call graph itself can also be updated to reflect changes to the IR.
73
class CallGraph {
74
  Module &M;
75
76
  using FunctionMapTy =
77
      std::map<const Function *, std::unique_ptr<CallGraphNode>>;
78
79
  /// A map from \c Function* to \c CallGraphNode*.
80
  FunctionMapTy FunctionMap;
81
82
  /// This node has edges to all external functions and those internal
83
  /// functions that have their address taken.
84
  CallGraphNode *ExternalCallingNode;
85
86
  /// This node has edges to it from all functions making indirect calls
87
  /// or calling an external function.
88
  std::unique_ptr<CallGraphNode> CallsExternalNode;
89
90
  /// Replace the function represented by this node by another.
91
  ///
92
  /// This does not rescan the body of the function, so it is suitable when
93
  /// splicing the body of one function to another while also updating all
94
  /// callers from the old function to the new.
95
  void spliceFunction(const Function *From, const Function *To);
96
97
  /// Add a function to the call graph, and link the node to all of the
98
  /// functions that it calls.
99
  void addToCallGraph(Function *F);
100
101
public:
102
  explicit CallGraph(Module &M);
103
  CallGraph(CallGraph &&Arg);
104
  ~CallGraph();
105
106
  void print(raw_ostream &OS) const;
107
  void dump() const;
108
109
  using iterator = FunctionMapTy::iterator;
110
  using const_iterator = FunctionMapTy::const_iterator;
111
112
  /// Returns the module the call graph corresponds to.
113
914k
  Module &getModule() const { return M; }
114
115
4.11k
  inline iterator begin() { return FunctionMap.begin(); }
116
4.11k
  inline iterator end() { return FunctionMap.end(); }
117
3
  inline const_iterator begin() const { return FunctionMap.begin(); }
118
3
  inline const_iterator end() const { return FunctionMap.end(); }
119
120
  /// Returns the call graph node for the provided function.
121
0
  inline const CallGraphNode *operator[](const Function *F) const {
122
0
    const_iterator I = FunctionMap.find(F);
123
0
    assert(I != FunctionMap.end() && "Function not in callgraph!");
124
0
    return I->second.get();
125
0
  }
126
127
  /// Returns the call graph node for the provided function.
128
303k
  inline CallGraphNode *operator[](const Function *F) {
129
303k
    const_iterator I = FunctionMap.find(F);
130
303k
    assert(I != FunctionMap.end() && "Function not in callgraph!");
131
303k
    return I->second.get();
132
303k
  }
133
134
  /// Returns the \c CallGraphNode which is used to represent
135
  /// undetermined calls into the callgraph.
136
50.1k
  CallGraphNode *getExternalCallingNode() const { return ExternalCallingNode; }
137
138
862
  CallGraphNode *getCallsExternalNode() const {
139
862
    return CallsExternalNode.get();
140
862
  }
141
142
  //===---------------------------------------------------------------------
143
  // Functions to keep a call graph up to date with a function that has been
144
  // modified.
145
  //
146
147
  /// Unlink the function from this module, returning it.
148
  ///
149
  /// Because this removes the function from the module, the call graph node is
150
  /// destroyed.  This is only valid if the function does not call any other
151
  /// functions (ie, there are no edges in it's CGN).  The easiest way to do
152
  /// this is to dropAllReferences before calling this.
153
  Function *removeFunctionFromModule(CallGraphNode *CGN);
154
155
  /// Similar to operator[], but this will insert a new CallGraphNode for
156
  /// \c F if one does not already exist.
157
  CallGraphNode *getOrInsertFunction(const Function *F);
158
};
159
160
/// A node in the call graph for a module.
161
///
162
/// Typically represents a function in the call graph. There are also special
163
/// "null" nodes used to represent theoretical entries in the call graph.
164
class CallGraphNode {
165
public:
166
  /// A pair of the calling instruction (a call or invoke)
167
  /// and the call graph node being called.
168
  using CallRecord = std::pair<WeakTrackingVH, CallGraphNode *>;
169
170
public:
171
  using CalledFunctionsVector = std::vector<CallRecord>;
172
173
  /// Creates a node for the specified function.
174
256k
  inline CallGraphNode(Function *F) : F(F) {}
175
176
  CallGraphNode(const CallGraphNode &) = delete;
177
  CallGraphNode &operator=(const CallGraphNode &) = delete;
178
179
256k
  ~CallGraphNode() {
180
256k
    assert(NumReferences == 0 && "Node deleted while references remain");
181
256k
  }
182
183
  using iterator = std::vector<CallRecord>::iterator;
184
  using const_iterator = std::vector<CallRecord>::const_iterator;
185
186
  /// Returns the function that this call graph node represents.
187
1.94M
  Function *getFunction() const { return F; }
188
189
711k
  inline iterator begin() { return CalledFunctions.begin(); }
190
2.65M
  inline iterator end() { return CalledFunctions.end(); }
191
16
  inline const_iterator begin() const { return CalledFunctions.begin(); }
192
23
  inline const_iterator end() const { return CalledFunctions.end(); }
193
  inline bool empty() const { return CalledFunctions.empty(); }
194
  inline unsigned size() const { return (unsigned)CalledFunctions.size(); }
195
196
  /// Returns the number of other CallGraphNodes in this CallGraph that
197
  /// reference this node in their callee list.
198
15.0k
  unsigned getNumReferences() const { return NumReferences; }
199
200
  /// Returns the i'th called function.
201
  CallGraphNode *operator[](unsigned i) const {
202
    assert(i < CalledFunctions.size() && "Invalid index");
203
    return CalledFunctions[i].second;
204
  }
205
206
  /// Print out this call graph node.
207
  void dump() const;
208
  void print(raw_ostream &OS) const;
209
210
  //===---------------------------------------------------------------------
211
  // Methods to keep a call graph up to date with a function that has been
212
  // modified
213
  //
214
215
  /// Removes all edges from this CallGraphNode to any functions it
216
  /// calls.
217
41.4k
  void removeAllCalledFunctions() {
218
68.9k
    while (!CalledFunctions.empty()) {
219
27.4k
      CalledFunctions.back().second->DropRef();
220
27.4k
      CalledFunctions.pop_back();
221
27.4k
    }
222
41.4k
  }
223
224
  /// Moves all the callee information from N to this node.
225
663
  void stealCalledFunctionsFrom(CallGraphNode *N) {
226
663
    assert(CalledFunctions.empty() &&
227
663
           "Cannot steal callsite information if I already have some");
228
663
    std::swap(CalledFunctions, N->CalledFunctions);
229
663
  }
230
231
  /// Adds a function to the list of functions called by this one.
232
1.03M
  void addCalledFunction(CallBase *Call, CallGraphNode *M) {
233
1.03M
    assert(!Call || !Call->getCalledFunction() ||
234
1.03M
           !Call->getCalledFunction()->isIntrinsic() ||
235
1.03M
           !Intrinsic::isLeaf(Call->getCalledFunction()->getIntrinsicID()));
236
1.03M
    CalledFunctions.emplace_back(Call, M);
237
1.03M
    M->AddRef();
238
1.03M
  }
239
240
11.9k
  void removeCallEdge(iterator I) {
241
11.9k
    I->second->DropRef();
242
11.9k
    *I = CalledFunctions.back();
243
11.9k
    CalledFunctions.pop_back();
244
11.9k
  }
245
246
  /// Removes the edge in the node for the specified call site.
247
  ///
248
  /// Note that this method takes linear time, so it should be used sparingly.
249
  void removeCallEdgeFor(CallBase &Call);
250
251
  /// Removes all call edges from this node to the specified callee
252
  /// function.
253
  ///
254
  /// This takes more time to execute than removeCallEdgeTo, so it should not
255
  /// be used unless necessary.
256
  void removeAnyCallEdgeTo(CallGraphNode *Callee);
257
258
  /// Removes one edge associated with a null callsite from this node to
259
  /// the specified callee function.
260
  void removeOneAbstractEdgeTo(CallGraphNode *Callee);
261
262
  /// Replaces the edge in the node for the specified call site with a
263
  /// new one.
264
  ///
265
  /// Note that this method takes linear time, so it should be used sparingly.
266
  void replaceCallEdge(CallBase &Call, CallBase &NewCall,
267
                       CallGraphNode *NewNode);
268
269
private:
270
  friend class CallGraph;
271
272
  Function *F;
273
274
  std::vector<CallRecord> CalledFunctions;
275
276
  /// The number of times that this CallGraphNode occurs in the
277
  /// CalledFunctions array of this or other CallGraphNodes.
278
  unsigned NumReferences = 0;
279
280
207k
  void DropRef() { --NumReferences; }
281
1.03M
  void AddRef() { ++NumReferences; }
282
283
  /// A special function that should only be used by the CallGraph class.
284
9.59k
  void allReferencesDropped() { NumReferences = 0; }
285
};
286
287
/// An analysis pass to compute the \c CallGraph for a \c Module.
288
///
289
/// This class implements the concept of an analysis pass used by the \c
290
/// ModuleAnalysisManager to run an analysis over a module and cache the
291
/// resulting data.
292
class CallGraphAnalysis : public AnalysisInfoMixin<CallGraphAnalysis> {
293
  friend AnalysisInfoMixin<CallGraphAnalysis>;
294
295
  static AnalysisKey Key;
296
297
public:
298
  /// A formulaic type to inform clients of the result type.
299
  using Result = CallGraph;
300
301
  /// Compute the \c CallGraph for the module \c M.
302
  ///
303
  /// The real work here is done in the \c CallGraph constructor.
304
42
  CallGraph run(Module &M, ModuleAnalysisManager &) { return CallGraph(M); }
305
};
306
307
/// Printer pass for the \c CallGraphAnalysis results.
308
class CallGraphPrinterPass : public PassInfoMixin<CallGraphPrinterPass> {
309
  raw_ostream &OS;
310
311
public:
312
0
  explicit CallGraphPrinterPass(raw_ostream &OS) : OS(OS) {}
313
314
  PreservedAnalyses run(Module &M, ModuleAnalysisManager &AM);
315
};
316
317
/// The \c ModulePass which wraps up a \c CallGraph and the logic to
318
/// build it.
319
///
320
/// This class exposes both the interface to the call graph container and the
321
/// module pass which runs over a module of IR and produces the call graph. The
322
/// call graph interface is entirelly a wrapper around a \c CallGraph object
323
/// which is stored internally for each module.
324
class CallGraphWrapperPass : public ModulePass {
325
  std::unique_ptr<CallGraph> G;
326
327
public:
328
  static char ID; // Class identification, replacement for typeinfo
329
330
  CallGraphWrapperPass();
331
  ~CallGraphWrapperPass() override;
332
333
  /// The internal \c CallGraph around which the rest of this interface
334
  /// is wrapped.
335
0
  const CallGraph &getCallGraph() const { return *G; }
336
326k
  CallGraph &getCallGraph() { return *G; }
337
338
  using iterator = CallGraph::iterator;
339
  using const_iterator = CallGraph::const_iterator;
340
341
  /// Returns the module the call graph corresponds to.
342
0
  Module &getModule() const { return G->getModule(); }
343
344
0
  inline iterator begin() { return G->begin(); }
345
0
  inline iterator end() { return G->end(); }
346
0
  inline const_iterator begin() const { return G->begin(); }
347
0
  inline const_iterator end() const { return G->end(); }
348
349
  /// Returns the call graph node for the provided function.
350
0
  inline const CallGraphNode *operator[](const Function *F) const {
351
0
    return (*G)[F];
352
0
  }
353
354
  /// Returns the call graph node for the provided function.
355
0
  inline CallGraphNode *operator[](const Function *F) { return (*G)[F]; }
356
357
  /// Returns the \c CallGraphNode which is used to represent
358
  /// undetermined calls into the callgraph.
359
0
  CallGraphNode *getExternalCallingNode() const {
360
0
    return G->getExternalCallingNode();
361
0
  }
362
363
0
  CallGraphNode *getCallsExternalNode() const {
364
0
    return G->getCallsExternalNode();
365
0
  }
366
367
  //===---------------------------------------------------------------------
368
  // Functions to keep a call graph up to date with a function that has been
369
  // modified.
370
  //
371
372
  /// Unlink the function from this module, returning it.
373
  ///
374
  /// Because this removes the function from the module, the call graph node is
375
  /// destroyed.  This is only valid if the function does not call any other
376
  /// functions (ie, there are no edges in it's CGN).  The easiest way to do
377
  /// this is to dropAllReferences before calling this.
378
0
  Function *removeFunctionFromModule(CallGraphNode *CGN) {
379
0
    return G->removeFunctionFromModule(CGN);
380
0
  }
381
382
  /// Similar to operator[], but this will insert a new CallGraphNode for
383
  /// \c F if one does not already exist.
384
0
  CallGraphNode *getOrInsertFunction(const Function *F) {
385
0
    return G->getOrInsertFunction(F);
386
0
  }
387
388
  //===---------------------------------------------------------------------
389
  // Implementation of the ModulePass interface needed here.
390
  //
391
392
  void getAnalysisUsage(AnalysisUsage &AU) const override;
393
  bool runOnModule(Module &M) override;
394
  void releaseMemory() override;
395
396
  void print(raw_ostream &o, const Module *) const override;
397
  void dump() const;
398
};
399
400
//===----------------------------------------------------------------------===//
401
// GraphTraits specializations for call graphs so that they can be treated as
402
// graphs by the generic graph algorithms.
403
//
404
405
// Provide graph traits for tranversing call graphs using standard graph
406
// traversals.
407
template <> struct GraphTraits<CallGraphNode *> {
408
  using NodeRef = CallGraphNode *;
409
  using CGNPairTy = CallGraphNode::CallRecord;
410
411
  static NodeRef getEntryNode(CallGraphNode *CGN) { return CGN; }
412
1.93M
  static CallGraphNode *CGNGetValue(CGNPairTy P) { return P.second; }
413
414
  using ChildIteratorType =
415
      mapped_iterator<CallGraphNode::iterator, decltype(&CGNGetValue)>;
416
417
493k
  static ChildIteratorType child_begin(NodeRef N) {
418
493k
    return ChildIteratorType(N->begin(), &CGNGetValue);
419
493k
  }
420
421
2.42M
  static ChildIteratorType child_end(NodeRef N) {
422
2.42M
    return ChildIteratorType(N->end(), &CGNGetValue);
423
2.42M
  }
424
};
425
426
template <> struct GraphTraits<const CallGraphNode *> {
427
  using NodeRef = const CallGraphNode *;
428
  using CGNPairTy = CallGraphNode::CallRecord;
429
  using EdgeRef = const CallGraphNode::CallRecord &;
430
431
  static NodeRef getEntryNode(const CallGraphNode *CGN) { return CGN; }
432
7
  static const CallGraphNode *CGNGetValue(CGNPairTy P) { return P.second; }
433
434
  using ChildIteratorType =
435
      mapped_iterator<CallGraphNode::const_iterator, decltype(&CGNGetValue)>;
436
  using ChildEdgeIteratorType = CallGraphNode::const_iterator;
437
438
6
  static ChildIteratorType child_begin(NodeRef N) {
439
6
    return ChildIteratorType(N->begin(), &CGNGetValue);
440
6
  }
441
442
13
  static ChildIteratorType child_end(NodeRef N) {
443
13
    return ChildIteratorType(N->end(), &CGNGetValue);
444
13
  }
445
446
5
  static ChildEdgeIteratorType child_edge_begin(NodeRef N) {
447
5
    return N->begin();
448
5
  }
449
5
  static ChildEdgeIteratorType child_edge_end(NodeRef N) { return N->end(); }
450
451
11
  static NodeRef edge_dest(EdgeRef E) { return E.second; }
452
};
453
454
template <>
455
struct GraphTraits<CallGraph *> : public GraphTraits<CallGraphNode *> {
456
  using PairTy =
457
      std::pair<const Function *const, std::unique_ptr<CallGraphNode>>;
458
459
16.3k
  static NodeRef getEntryNode(CallGraph *CGN) {
460
16.3k
    return CGN->getExternalCallingNode(); // Start at the external node!
461
16.3k
  }
462
463
0
  static CallGraphNode *CGGetValuePtr(const PairTy &P) {
464
0
    return P.second.get();
465
0
  }
466
467
  // nodes_iterator/begin/end - Allow iteration over all nodes in the graph
468
  using nodes_iterator =
469
      mapped_iterator<CallGraph::iterator, decltype(&CGGetValuePtr)>;
470
471
0
  static nodes_iterator nodes_begin(CallGraph *CG) {
472
0
    return nodes_iterator(CG->begin(), &CGGetValuePtr);
473
0
  }
474
475
0
  static nodes_iterator nodes_end(CallGraph *CG) {
476
0
    return nodes_iterator(CG->end(), &CGGetValuePtr);
477
0
  }
478
};
479
480
template <>
481
struct GraphTraits<const CallGraph *> : public GraphTraits<
482
                                            const CallGraphNode *> {
483
  using PairTy =
484
      std::pair<const Function *const, std::unique_ptr<CallGraphNode>>;
485
486
2
  static NodeRef getEntryNode(const CallGraph *CGN) {
487
2
    return CGN->getExternalCallingNode(); // Start at the external node!
488
2
  }
489
490
  static const CallGraphNode *CGGetValuePtr(const PairTy &P) {
491
    return P.second.get();
492
  }
493
494
  // nodes_iterator/begin/end - Allow iteration over all nodes in the graph
495
  using nodes_iterator =
496
      mapped_iterator<CallGraph::const_iterator, decltype(&CGGetValuePtr)>;
497
498
  static nodes_iterator nodes_begin(const CallGraph *CG) {
499
    return nodes_iterator(CG->begin(), &CGGetValuePtr);
500
  }
501
502
  static nodes_iterator nodes_end(const CallGraph *CG) {
503
    return nodes_iterator(CG->end(), &CGGetValuePtr);
504
  }
505
};
506
507
} // end namespace llvm
508
509
#endif // LLVM_ANALYSIS_CALLGRAPH_H