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    <head>
      <base href="https://bugs.llvm.org/">
    </head>
    <body><table border="1" cellspacing="0" cellpadding="8">
        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - A null pointer dereference error in GIMatchTree::writeDOTGraphEdges"
   href="https://bugs.llvm.org/show_bug.cgi?id=48117">48117</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>A null pointer dereference error in GIMatchTree::writeDOTGraphEdges
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>tools
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>trunk
          </td>
        </tr>

        <tr>
          <th>Hardware</th>
          <td>PC
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>Linux
          </td>
        </tr>

        <tr>
          <th>Status</th>
          <td>NEW
          </td>
        </tr>

        <tr>
          <th>Severity</th>
          <td>enhancement
          </td>
        </tr>

        <tr>
          <th>Priority</th>
          <td>P
          </td>
        </tr>

        <tr>
          <th>Component</th>
          <td>TableGen
          </td>
        </tr>

        <tr>
          <th>Assignee</th>
          <td>unassignedbugs@nondot.org
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>alansnape3058@gmail.com
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>llvm-bugs@lists.llvm.org
          </td>
        </tr></table>
      <p>
        <div>
        <pre>According to the bug reports of my clang static analyzer fork, in class
`llvm::GIMatchTree`, if `Partitioner` is not set or set to nullptr, when
calling function `GIMatchTree::writeDOTGraph`, a null pointer dereference will
occur in function `GIMatchTree::writeDOTGraphEdges`.

1. call function GIMatchTree::writeDOTGraph:
llvm/utils/TableGen/GlobalISel/GIMatchTree.cpp:24
24 void GIMatchTree::writeDOTGraph(raw_ostream &OS) const {

2. call function GIMatchTree::writeDOTGraphNode:
llvm/utils/TableGen/GlobalISel/GIMatchTree.cpp:26
26   writeDOTGraphNode(OS);

3. assume `Partitioner` is null, take the false branch:
llvm/utils/TableGen/GlobalISel/GIMatchTree.cpp:32
32   if (Partitioner) {

4. assume `Partitioner` is null, take the false branch:
llvm/utils/TableGen/GlobalISel/GIMatchTree.cpp:48
48   if (!Partitioner && !IsFullyTraversed)

5. assume `Partitioner` is null, take the false branch:
llvm/utils/TableGen/GlobalISel/GIMatchTree.cpp:50
50   if (!Partitioner && !IsFullyTested) {

6. assume `Partitioner` is null, take the false branch:
llvm/utils/TableGen/GlobalISel/GIMatchTree.cpp:63
63   if (!Partitioner &&

7. call function GIMatchTree::writeDOTGraphEdges:
llvm/utils/TableGen/GlobalISel/GIMatchTree.cpp:69
69   writeDOTGraphEdges(OS);

8. dereference null smart pointer `Partitioner`:
llvm/utils/TableGen/GlobalISel/GIMatchTree.cpp:76
76     Partitioner->emitPartitionName(OS, Child.index());

Although the problem will not be triggered with the path presented, the problem
still worth noting.
See the attached HTML report for more details.</pre>
        </div>
      </p>


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