fix Issue 14105 - strideImpl fails for 0xFF

[MartinNowak]

• bsr(0) returns an undefined result

Issue 14105 – strideImpl fails for 0xFF

[burner]

correct me if I'm wrong: isn't !~c equal to c == 0. you comment sort of also implies that.

[MartinNowak]

It's equivalent to ~c == 0.

[schveiguy]

Auto-merge toggled on

[andralex]

fwiw dmd generates better code for c == 0xff: http://goo.gl/yy3Vdd

[MartinNowak]

That's what LDC sez ;).

bool bug2.fun(char):
    movzbl %dil,%eax
    cmp    $0xff,%eax
    sete   %al
    retq   

bool bug2.gun(char):
    movzbl %dil,%eax
    cmp    $0xff,%eax
    sete   %al
    retq 

And GDC's opinion.

bool bug2.fun(char):
    cmp    $0xff,%dil
    sete   %al
    retq   

bool bug2.gun(char):
    cmp    $0xff,%dil
    sete   %al
    retq 

It's a pity for the endless hours we're wasting to optimize for dmd's backend.