[llvm-bugs] [Bug 45758] New: Failure to recognize bounds of sign function

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=45758

            Bug ID: 45758
           Summary: Failure to recognize bounds of sign function
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Scalar Optimizations
          Assignee: unassignedbugs at nondot.org
          Reporter: gabravier at gmail.com
                CC: llvm-bugs at lists.llvm.org

inline int sign(int x)
{
    return (x >> 31) | ((unsigned)-x >> 31);
}

bool f(int x)
{
    return (sign(x) >= -1) && (sign(x) <= 1);
}

`f` can be optimized to `return true;`. GCC does this transformation, but LLVM
does not.

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