[llvm-bugs] [Bug 41173] New: Shifts on non negative numbers

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=41173

            Bug ID: 41173
           Summary: Shifts on non negative numbers
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Scalar Optimizations
          Assignee: unassignedbugs at nondot.org
          Reporter: david.bolvansky at gmail.com
                CC: llvm-bugs at lists.llvm.org

int foo(int x) {
    if (x>=0) {
        unsigned xx = x;
        return xx >> 8;
    } else {
        return x >> 8;
    }
}

foo(int):                               # @foo3(int)
        mov     ecx, edi
        shr     ecx, 8
        mov     eax, edi
        sar     eax, 8
        test    edi, edi
        cmovns  eax, ecx
        ret


Maybe we can simplify foo to use just one shift?

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