[llvm-bugs] [Bug 45709] New: misoptimization with defaulting to POWER7 and newer

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=45709

            Bug ID: 45709
           Summary: misoptimization with defaulting to POWER7 and newer
           Product: libraries
           Version: 10.0
          Hardware: Other
                OS: FreeBSD
            Status: NEW
          Severity: normal
          Priority: P
         Component: Backend: PowerPC
          Assignee: unassignedbugs at nondot.org
          Reporter: pkubaj at anongoth.pl
                CC: llvm-bugs at lists.llvm.org, nemanja.i.ibm at gmail.com

Reduced test case:
class a {
  void b();
  void m_fn2();
  int c;
  float d[];
};
void a ::b() {
  float e;
  for (int f; f <= c; f++)
    if (e < d[f])
      e = d[f];
  if (e)
    m_fn2();
}

Compile with:
c++ -ffast-math -O2 -c sms.cpp

It builds fine without -ffast-math, or when lowering optimizations to -O1, or
after adding -mcpu=power7 (power8 or power9 are also ok for clang).

Result:
Illegal instruction

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