[llvm-bugs] [Bug 37455] New: clang crashes with "-mllvm -enable-newgvn": Only PHI nodes may reference their own value!

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=37455

            Bug ID: 37455
           Summary: clang crashes with "-mllvm -enable-newgvn": Only PHI
                    nodes may reference their own value!
           Product: clang
           Version: trunk
          Hardware: PC
                OS: All
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: LLVM Codegen
          Assignee: unassignedclangbugs at nondot.org
          Reporter: helloqirun at gmail.com
                CC: llvm-bugs at lists.llvm.org

It happens at -O2 and above.


$ clang-trunk -v
clang version 7.0.0 (trunk 332220)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /usr/local/bin


$ clang-trunk -mllvm -enable-newgvn -O2 abc.c
Only PHI nodes may reference their own value!
  %mul35 = mul nsw i64 %mul35, %conv34
fatal error: error in backend: Broken function found, compilation aborted!
clang-7: error: clang frontend command failed with exit code 70 (use -v to see
invocation)
clang version 7.0.0 (trunk 332220)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /usr/local/bin
clang-7: note: diagnostic msg: PLEASE submit a bug report to
https://bugs.llvm.org/ and include the crash backtrace, preprocessed source,
and associated run script.
clang-7: note: diagnostic msg:
********************

PLEASE ATTACH THE FOLLOWING FILES TO THE BUG REPORT:
Preprocessed source(s) and associated run script(s) are located at:
clang-7: note: diagnostic msg: /tmp/abc-5f6f17.c
clang-7: note: diagnostic msg: /tmp/abc-5f6f17.sh
clang-7: note: diagnostic msg:

********************


$ cat abc.c
long a, e;
char b;
short c, d;
long *f;
void fn1() {
  char g = 6;
  char *h = &g;
  if (c) {
    short *i = &d;
    for (; d;)
      *h = 3;
    for (; a;) {
      long j;
      if (b)
        for (;;) {
          e = (j *= c) * (*i ?: *f);
          for (; h; h++)
            ;
          *i = 1;
        l1:;
        }
      if (0 >= (0 != (c | g)))
        goto l1;
    }
  }
}

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