JIT does not use BT instruction for constant mask

[rameel]

public static bool CheckLetterOrDigit(int uc)
{
    return (LetterOrDigitCategories & (1 << uc)) != 0;
}

L0000: mov eax, 1
L0005: shlx eax, eax, ecx
L000a: test eax, 0x11f
L000f: setne al
L0012: movzx eax, al
L0015: ret

public static bool CheckLetterOrDigit(int mask, int uc)
{
    return (mask & (1 << uc)) != 0;
}

L0000: bt ecx, edx
L0003: setb al
L0006: movzx eax, al
L0009: ret

A more complete example sharplab where

L0032: mov eax, 1
L0037: shlx eax, eax, edx
L003c: test eax, 0x11f
L0041: je short L0056

could be optimized to

L0032: mov eax, 0x11f
L0037: bt eax, edx
L003a: jae short L0056

[dotnet-policy-service]

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