[llvm-bugs] [Bug 45689] New: Failure to optimize away range check of modulo based on known ranges

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=45689

            Bug ID: 45689
           Summary: Failure to optimize away range check of modulo based
                    on known ranges
           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

int f(int a, int b)
{
    assume(a > -4);
    assume(b > -6 && b < 10);
    int c = a % b;
    return c >= -3 && c <= 8;
}

This can be optimized to `return true;`. This transformation is done by GCC,
not by LLVM.

Comparison here : https://godbolt.org/z/hnYFTA

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