<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/76431>76431</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            opt-18 crash: LLVM ERROR: Instruction Combining did not reach a fixpoint after 1 iterations
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            new issue
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          iamanonymouscs
      </td>
    </tr>
</table>

<pre>
    opt-18 crash at "Combine redundant instructions" when compiled with -fsanitize=address.
Compiler explorer: https://godbolt.org/z/r1esW5hcK
```
$cat mutant.c
char *a;
int **b;
int c;
void d() { a[c] = a[c] + b[0][c]; }

$clang-18 -fsanitize=address -O3 -mllvm -disable-llvm-optzns -c -emit-llvm mutant.c -o mutant.bc
$opt-18 -passes=instcombine mutant.bc -o mutant.opt.bc
LLVM ERROR: Instruction Combining did not reach a fixpoint after 1 iterations
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace.
Stack dump:
0.      Program arguments: opt-18 -passes=instcombine mutant.bc -o mutant.opt.bc
 #0 0x00007fa3e181d266 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/usr/lib/llvm-18/bin/../lib/libLLVM-18.so.1+0xd2b266)
 #1 0x00007fa3e181b170 llvm::sys::RunSignalHandlers() (/usr/lib/llvm-18/bin/../lib/libLLVM-18.so.1+0xd29170)
 #2 0x00007fa3e181d940 (/usr/lib/llvm-18/bin/../lib/libLLVM-18.so.1+0xd2b940)
 #3 0x00007fa3e08e5980 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x12980)
 #4 0x00007fa3dfaffe87 raise /build/glibc-CVJwZb/glibc-2.27/signal/../sysdeps/unix/sysv/linux/raise.c:51:0
 #5 0x00007fa3dfb017f1 abort /build/glibc-CVJwZb/glibc-2.27/stdlib/abort.c:81:0
 #6 0x00007fa3e1778cfc llvm::report_fatal_error(llvm::Twine const&, bool) (/usr/lib/llvm-18/bin/../lib/libLLVM-18.so.1+0xc86cfc)
 #7 0x00007fa3e2575f05 (/usr/lib/llvm-18/bin/../lib/libLLVM-18.so.1+0x1a83f05)
 #8 0x00007fa3e257559f llvm::InstCombinePass::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (/usr/lib/llvm-18/bin/../lib/libLLVM-18.so.1+0x1a8359f)
 #9 0x00007fa3e47f1add (/usr/lib/llvm-18/bin/../lib/libLLVM-18.so.1+0x3cffadd)
#10 0x00007fa3e1998b04 llvm::PassManager<llvm::Function, llvm::AnalysisManager<llvm::Function>>::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (/usr/lib/llvm-18/bin/../lib/libLLVM-18.so.1+0xea6b04)
#11 0x00007fa3e381dadd (/usr/lib/llvm-18/bin/../lib/libLLVM-18.so.1+0x2d2badd)
#12 0x00007fa3e199c311 llvm::ModuleToFunctionPassAdaptor::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (/usr/lib/llvm-18/bin/../lib/libLLVM-18.so.1+0xeaa311)
#13 0x00007fa3e381d8fd (/usr/lib/llvm-18/bin/../lib/libLLVM-18.so.1+0x2d2b8fd)
#14 0x00007fa3e1997864 llvm::PassManager<llvm::Module, llvm::AnalysisManager<llvm::Module>>::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (/usr/lib/llvm-18/bin/../lib/libLLVM-18.so.1+0xea5864)
#15 0x000055f9b6d079b9 llvm::runPassPipeline(llvm::StringRef, llvm::Module&, llvm::TargetMachine*, llvm::TargetLibraryInfoImpl*, llvm::ToolOutputFile*, llvm::ToolOutputFile*, llvm::ToolOutputFile*, llvm::StringRef, llvm::ArrayRef<llvm::PassPlugin>, llvm::opt_tool::OutputKind, llvm::opt_tool::VerifierKind, bool, bool, bool, bool, bool, bool, bool) (/usr/lib/llvm-18/bin/opt+0x1d9b9)
#16 0x000055f9b6d148a4 main (/usr/lib/llvm-18/bin/opt+0x2a8a4)
#17 0x00007fa3dfae2c87 __libc_start_main /build/glibc-CVJwZb/glibc-2.27/csu/../csu/libc-start.c:344:0
#18 0x000055f9b6d0201a _start (/usr/lib/llvm-18/bin/opt+0x1801a)
Aborted (core dumped)
********************
```
</pre>
<img width="1px" height="1px" alt="" src="http://email.email.llvm.org/o/eJzMWEtv2zoa_TX0hrBBUe-FF0pcYzq3RYO06ACzMT4-JHOuRAok1ST99QNKfsk3vUhusmggIOLzfOd8R3wYnFONlnKN0huUbhYw-L2xawUdaKOfOjM47hbMiKe16f0yKjC34PYYPEaU3pqOKS2xlWLQArTHSjtvB-6V0Q5Rih_2UmNuul61UuAH5fd4WTvQyqufEsUbEMJK51aIbBCpbqeOFsvHvjVWWhRXeO9971BcIbpFdNsYwUzrV8Y2iG5_Irq1kXT_Sff8j2kOlJHDMxVpwsHjbvCg_YpPlXwPFiNaAYpvphqlA6EK0YrN6vip9MMogQWiBaIlRvkNBpTecJRuMIo3FwV6gxlKbwhKN4c6FN9glG8O8ZyiakE3QdDn9MDLLzFedm37o8NLoRywVi5DaWl6_1M7vOR4KTvlx8oTO7w0x3fGT0iHxC17cE46FG9CkvghdafuF2NNfx7_6dP3z_jD_f2X-5CLj-f04in5SjdYKIG18dhK4HsMuFaPvQnqQe2lxRFWXlqYPDFOevfpQ_X1A3YD65THgNnQYCt7Yz325jrhyu8HtuKmQ3Qb2B7-LXtr_ie5R3SrnBukQ3SLQQusNG8HIbHfy4NZGfA_vQUuDzb76oH_icXQ9QFlrCIrPP7dWdNY6DDYZuik9iEO_CYBMaIxweSREELyGmIZFZGgWYZHLnGF4so9uenlzirtx-i-hXARLc6dLDzsjPNWQodohugtVtqPXgyW3A7OBmEUO8oThVqmNKLb1ercpFjI6DIqVs6sIkRvyKOgjGYZouU54OgqYBbl5LmA7wf9VTUa2n-BFq207vh9vD2mMsrJLCZ6LWKZkHchXyZzoPgSiBQyLQuCdzsrnTdW7qw_oE6TPhbZLkuWrdLD47LRw9TQ-72VIAIOGXEiWhZzmOQCRtRQ17LIsQXlJA7BD6oVwf6tYnx5-_3fD_9lpyJd0RzRrRulP3J0T07IPnwGg1aPU8WPMRo9hOI49YqjuEojFFfkHEk6i4SRKK8jDMyMTF8WiReTGuOoEaS4Aslm6cvzgtf8wlLT57-rwUO7k9YaO3P_t4fwrXGjnT-4nxnTvovVeJHxms9Sk1_GStM8rUn6dqAIirgm6QypuEZKy_pClbDeHjbZO3CHj84OeqbNdtDjinwQ5txQaWifnHKfQUMTNtPbZwbFH8Zx7yBk4JeW9YxfeckvyesIhHg7UszrGoQ4IYUVa77GlmXBSHKhRZDvb3X4R8qF53dOiYSMkWSm02xpj4tIvEtGqKDsOiP0KiM8gJ_pfjZiaOU3c6QdMlQJ6L2xz4s6DXiVpIch7ykoxFE0oxlfC1rU7yRoUc8FTa4EzYvsJRY_6vZ60X5l798jE2mRza193MfStC5ZJkhesvJyixlGj92pXrZKz09XX71VurmX9ZzRL4h-A9tI_xn4fpyneq71k2IW7NNHXZuPXd_-tZcx7ZfB94PfqvaZSd7U_As6lbXwFGovMzNq0g6Nmhaey_6m9zsf9tmxNOH9obT4u17fpVW1kvbYb9qnX_v_JQYxvZ_2HVGycmaEbG6EKCkgwR0o_YpZKRQwt1c-P7BJyosc73bhHLRzHqzfHSBedGTibjiafHodG8d5xvNTnCTnA1SAL67cTUkEeAJ-jVgFieBEqwrHNTkuV9xYOd6J5OWi84ZnfhtfiHUsyriEhVxHOYmzLE1JvNivy5TxlFPJE1ZzJhkvWA08IiBryTIhFmpNSdhNaE4KmpJ4FeUxEMhKIuuyyGSEEiI7UO0qcF4Z2yzGC-E6z5I4WrTAZOvG3zco1fIBj42IUpRuFnY96sSGxqGEtMp5d57FK9_K2c8e4TL4zhfixWDb9T-_8Y4c_x8AAP__4zlC2w">