[llvm-bugs] [Bug 33880] New: clang hangs in llvm::JumpThreadingPass::ComputeValueKnownInPredecessors on a tiny input

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=33880

            Bug ID: 33880
           Summary: clang hangs in
                    llvm::JumpThreadingPass::ComputeValueKnownInPredecesso
                    rs on a tiny input
           Product: new-bugs
           Version: unspecified
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: new bugs
          Assignee: unassignedbugs at nondot.org
          Reporter: kcc at google.com
                CC: llvm-bugs at lists.llvm.org, max.kazantsev at azul.com

found with clang-proto-fuzzer on r308641.

clang  -cc1 -triple x86_64-unknown-linux-gnu -O2  -emit-obj slow5.c

All time is spent in a recursive call to
llvm::JumpThreadingPass::ComputeValueKnownInPredecessors


void foo(int *a) {
  while ((1 + 1)) {
    while ((a[96] * a[96])) {
      a[0] = (1024);
      while (a[0]) {
        while (a[0]) {
          (void)0;
          while ((a[96] * ((a[96] * a[96]) < 1))) {
            a[96] = (1 + 1);
          }
          a[0] = (a[0] + a[0]);
        }
      }
    }
  }
}

(Not sure if this is related to https://bugs.llvm.org/show_bug.cgi?id=33753 or
https://bugs.llvm.org/show_bug.cgi?id=33494

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