Coverage Report

Created: 2020-09-22 08:39

/Users/buildslave/jenkins/workspace/coverage/llvm-project/clang/lib/Analysis/CFGReachabilityAnalysis.cpp
Line
Count
Source
1
//===- CFGReachabilityAnalysis.cpp - Basic reachability analysis ----------===//
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
//
9
// This file defines a flow-sensitive, (mostly) path-insensitive reachability
10
// analysis based on Clang's CFGs.  Clients can query if a given basic block
11
// is reachable within the CFG.
12
//
13
//===----------------------------------------------------------------------===//
14
15
#include "clang/Analysis/Analyses/CFGReachabilityAnalysis.h"
16
#include "clang/Analysis/CFG.h"
17
#include "llvm/ADT/BitVector.h"
18
#include "llvm/ADT/SmallVector.h"
19
20
using namespace clang;
21
22
CFGReverseBlockReachabilityAnalysis::CFGReverseBlockReachabilityAnalysis(
23
    const CFG &cfg)
24
3.07k
    : analyzed(cfg.getNumBlockIDs(), false) {}
25
26
bool CFGReverseBlockReachabilityAnalysis::isReachable(const CFGBlock *Src,
27
3.16k
                                          const CFGBlock *Dst) {
28
3.16k
  const unsigned DstBlockID = Dst->getBlockID();
29
30
  // If we haven't analyzed the destination node, run the analysis now
31
3.16k
  if (!analyzed[DstBlockID]) {
32
1.69k
    mapReachability(Dst);
33
1.69k
    analyzed[DstBlockID] = true;
34
1.69k
  }
35
36
  // Return the cached result
37
3.16k
  return reachable[DstBlockID][Src->getBlockID()];
38
3.16k
}
39
40
// Maps reachability to a common node by walking the predecessors of the
41
// destination node.
42
1.69k
void CFGReverseBlockReachabilityAnalysis::mapReachability(const CFGBlock *Dst) {
43
1.69k
  SmallVector<const CFGBlock *, 11> worklist;
44
1.69k
  llvm::BitVector visited(analyzed.size());
45
46
1.69k
  ReachableSet &DstReachability = reachable[Dst->getBlockID()];
47
1.69k
  DstReachability.resize(analyzed.size(), false);
48
49
  // Start searching from the destination node, since we commonly will perform
50
  // multiple queries relating to a destination node.
51
1.69k
  worklist.push_back(Dst);
52
1.69k
  bool firstRun = true;
53
54
60.0k
  while (!worklist.empty()) {
55
58.3k
    const CFGBlock *block = worklist.pop_back_val();
56
57
58.3k
    if (visited[block->getBlockID()])
58
9.52k
      continue;
59
48.8k
    visited[block->getBlockID()] = true;
60
61
    // Update reachability information for this node -> Dst
62
48.8k
    if (!firstRun) {
63
      // Don't insert Dst -> Dst unless it was a predecessor of itself
64
47.1k
      DstReachability[block->getBlockID()] = true;
65
47.1k
    }
66
1.69k
    else
67
1.69k
      firstRun = false;
68
69
    // Add the predecessors to the worklist.
70
48.8k
    for (CFGBlock::const_pred_iterator i = block->pred_begin(),
71
107k
         e = block->pred_end(); i != e; 
++i59.0k
) {
72
59.0k
      if (*i)
73
56.6k
        worklist.push_back(*i);
74
59.0k
    }
75
48.8k
  }
76
1.69k
}