Re: cmsg newgroup alt.sex.fetish.bool (was Re: [PATCH] arch: all: include: asm: bitops: Use bool instead of int for all bit test functions)

Al Viro
2016-09-04T05:07:08Z

On Sun, Sep 04, 2016 at 06:36:56AM +0800, Chen Gang wrote:

> And for all: shall I provide the proof for another archs?
>
> For me, Boolean gives additional chance to compiler to improve the code.

Whereas for compiler it gives nothing. Not in those cases.

> If the compiler can not improve the code, it can treat it as int simply.
> So theoretically, at least, Boolean should not be worse than int.

Except for pointless code churn and pandering to irrational beliefs, that is...
Please, RTFISO9899 and learn the semantics of _Bool; it's not that complicated.
Start with 6.2.5[2,6] and 6.3.1.2, then look through 6.8.4 and 6.8.5 to
figure out the semantics of conditions in if/while/for. Note also 6.5.8,
6.5.9, 6.5.13 and 6.5.14 and observe that type of (x > 5 && y < 1) is *NOT*
_Bool; it's int.

If you can show any improvement or loss in code generation in this case
(static inline int converted to static inline bool), I would really like to
see the details. As in .config/file/function/gcc version/target architecture.
Optimizer bugs happens, but they should be reported when found, and I would
expect _Bool handling to be _less_ exercised than that of normal logical
expressions, so loss is probably more likely. And yes, it also should be
reported.