Re: [PATCH] gdb/i387-tdep.c: Avoid warning for "-Werror=strict-overflow"

Chen Gang
2014-10-06T13:29:38Z

On 10/6/14 16:41, Pedro Alves wrote:
> On 10/04/2014 06:18 AM, Chen Gang wrote:
>>
>> OK, thanks. It is really one way, it is a little better than my original
>> way. But for me, it is still not a good idea: it introduces a new macro
>> and a new variable for each area (originally, it is only one statement).
>
> I see no problem with adding the new macro. We already have a ton
> of similar macros, see i386-tdep.h and i387-tdep.h. Looks
> like the existing I387_NUM_REGS is what we'd need here?
>
> BTC, OOC, did you try Joel's idea with the local variable?
> In case Mark prefers that, it'd be good to know whether it works.
> I can't seem to get my gcc to emit that warning.
>
> Combining both ideas, for clarity, we end up with something
> like:
>
> int end;
>
> end = I387_ST0_REGNUM (tdep) + I387_NUM_REGS;
> for (i = I387_ST0_REGNUM (tdep); i < end; i++)
>
> ...
>
> end = I387_XMM0_REGNUM (tdep) + I387_NUM_XMM_REGS (tdep);
> for (i = I387_XMM0_REGNUM (tdep); i < end; i++)
>
>
> That's way clearer to me than the existing:
>

That's way not quite bad to me than the existing:

- It is easier understanding, although a little complex than origin.

- For compiler, 'end' is simple enough to be sure to be optimized.

- And I guess, compiler will understand, and will not worry about it.

> for (i = I387_ST0_REGNUM (tdep); i < I387_XMM0_REGNUM (tdep); i++)
> ...
> for (i = I387_XMM0_REGNUM (tdep); i < I387_MXCSR_REGNUM (tdep); i++)
>
> anyway, which assumes the reader knows register numbers are
> ordered like st -> xmm -> mxcrsr.
>
> If this works, I think it's my preference.
>

OK, thanks, at least, what you said is acceptable to me. If no any
additional reply within this week (within 2014-10-12), I shall send
patch v2 for it.

>> For me, "-Werror" need always be optional, but not mandatory.
>
> It's mandatory only on development builds. -Werror is not on by
> default on released GDBs.
>

OK, thanks.

Thanks.
--
Chen Gang

Open, share, and attitude like air, water, and life which God blessed