[llvm-bugs] [Bug 42901] New: Optimization introduces branch where none existed in the LLVM IR

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=42901

            Bug ID: 42901
           Summary: Optimization introduces branch where none existed in
                    the LLVM IR
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Interprocedural Optimizations
          Assignee: unassignedbugs at nondot.org
          Reporter: npmccallum at redhat.com
                CC: llvm-bugs at lists.llvm.org

First, I'm not sure if I've picked the correct component. Please move it
elsewhere if needed.

And example of the problem is here:

https://godbolt.org/z/mTzWxX

Notice that the optimized code introduces a conditional operation which isn't
great given the fact that the input was crafted to avoid conditional
operations.

I ran this through llc over a loop of architectures and this problem occurs on
all architectures.

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