<html>
    <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 - Instnamer pass produces broken ir?"
   href="https://bugs.llvm.org/show_bug.cgi?id=37800">37800</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>Instnamer pass produces broken ir?
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>libraries
          </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>Transformation Utilities
          </td>
        </tr>

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

        <tr>
          <th>Reporter</th>
          <td>lebedev.ri@gmail.com
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>llvm-bugs@lists.llvm.org
          </td>
        </tr></table>
      <p>
        <div>
        <pre><a href="https://godbolt.org/g/Vj3jnC">https://godbolt.org/g/Vj3jnC</a>

Given:

define dso_local void @_Z4testi(i32) local_unnamed_addr #0 {
  %2 = icmp sgt i32 %0, 0
  br i1 %2, label %4, label %3

  ret void

  %5 = phi i32 [ %6, %4 ], [ 0, %1 ]
  tail call void @_Z4calli(i32 %5) #2
  %6 = add nuw nsw i32 %5, 1
  %7 = icmp eq i32 %6, %0
  br i1 %7, label %3, label %4
}
declare dso_local void @_Z4calli(i32) local_unnamed_addr #1

After running instnamer:


define dso_local void @_Z4testi(i32 %arg) local_unnamed_addr {
  %tmp = icmp sgt i32 %arg, 0
  br i1 %tmp, label %.preheader, label %.loopexit

.loopexit: ; preds = %.preheader, %bb
  ret void

.preheader: ; preds = %bb, %.preheader
  %tmp1 = phi i32 [ %tmp2, %.preheader ], [ 0, %bb ]
  tail call void @_Z4calli(i32 %tmp1)
  %tmp2 = add nuw nsw i32 %tmp1, 1
  %tmp3 = icmp eq i32 %tmp2, %arg
  br i1 %tmp3, label %.loopexit, label %.preheader
}

declare dso_local void @_Z4calli(i32) local_unnamed_addr

After invoking opt on that new ir:

/opt/compiler-explorer/clang-trunk/bin/opt: <source>:10:48: error: use of
undefined value '%bb'
  %tmp1 = phi i32 [ %tmp2, %.preheader ], [ 0, %bb ]
                                               ^
Compiler returned: 1</pre>
        </div>
      </p>


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