[llvm-bugs] [Bug 47432] New: Optimization for a * 10 == b * 10

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=47432

            Bug ID: 47432
           Summary: Optimization for a * 10 == b * 10
           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

bool f(int a, int b)
{
  return a * 9 == b * 9;
}

bool g(int a, int b)
{
  return a * 10 == b * 10;
}

bool h(int a, int b)
{
  return a * 11 == b * 11;
}

Clang:

f(int, int):                                 # @f(int, int)
        cmp     edi, esi
        sete    al
        ret
g(int, int):                                 # @g(int, int)
        xor     edi, esi
        test    edi, 2147483647
        sete    al
        ret
h(int, int):                                 # @h(int, int)
        cmp     edi, esi
        sete    al
        ret


Why 10 is so special here?

https://godbolt.org/z/jdPhf5

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