<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 - [licm] LICM cannot terminate"
   href="https://bugs.llvm.org/show_bug.cgi?id=41291">41291</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>[licm] LICM cannot terminate
          </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>Scalar Optimizations
          </td>
        </tr>

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

        <tr>
          <th>Reporter</th>
          <td>cszide@163.com
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>llvm-bugs@lists.llvm.org
          </td>
        </tr></table>
      <p>
        <div>
        <pre>Created <span class=""><a href="attachment.cgi?id=21700" name="attach_21700" title=".bc file of the source code">attachment 21700</a> <a href="attachment.cgi?id=21700&action=edit" title=".bc file of the source code">[details]</a></span>
.bc file of the source code

$clang -v
clang version 9.0.0 (trunk 355281)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /home/jack-zhou/Documents/llvm/llvm_truck/llvm/build4/bin
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/8
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5.5.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/6
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/6.5.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7.3.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/8
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7.3.0
Candidate multilib: .;@m64
Candidate multilib: 32;@m32
Candidate multilib: x32;@mx32
Selected multilib: .;@m64

$clang -O3 -c -emit-llvm  -mllvm -disable-llvm-optzns small.c

$opt -structurizecfg -reg2mem small.bc -o small-opt.bc

$opt -licm small-opt.bc
In this step, opt will consume too much memory and not terminate.
By using godbolt, it shows that the llvm 7/truck version also has this problem.

/compiler-explorer/c-preload/compiler-wrapper: line 21: 22186 Killed           
      "$@"

Compiler returned: 137

---------------------------------------
struct S0 {
  int f2;
  int f5;
  int e
};
struct f {};
union U4 {
  int f0;
};
a;
union U4 *b;
struct S0 g_1231;
g_1237;
struct S0 c;
struct S0 d;
func_1_i;
union U4 i() {
  int j;
  for (0; a; a)
    if (0) {
      int l_3671;
      for (; 0;) {
        for (; func_1_i; func_1_i) {
          struct S0 l_3685;
          for (; 0;) {
            int l_3678;
            if ((g(0, 0)))
              for (; 0; g_1237) {
                union U4 h;
                return h;
              }
          }
        }
      }
      union U4 *l_3860;
    lbl_4065:
      for (; 0;) {
        struct f l_4102;
        for (; 0;) {
          const l_3993;
          for (; 0;) {
            int l_4111;
            if ((j))
              for (; 0; g_1231)
                return (*l_3860);
          }
        }
        for (; 0;)
          for (d.f2; 0; d)
            for (0; 0; c.f5 -= 1) {
              return (*b);
            }
      }
    }
}
int main(int argc, char *argv[]) {}</pre>
        </div>
      </p>


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