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

[Pedro Alves <palves@redhat.com>]

On 10/03/2014 05:44 PM, Joel Brobecker wrote:
>>> Sorry, but obfuscating code to make compilers happy is *not* the way to go.
>>>
>>
>> OK, I can understand, but for me, these is no other better ways for it,
>> except let gdb give up "-Werror" (if always need "--disable-werror"
>> during "configure").
> 
> I have to agree with Mark on this one, the proposed solution looks
> awful. There has to be another way. Maybe declaring a local constant
> whose value is I387_XMM0_REGNUM (tdep)?

Likely, after transformations and intra-procedural analyses, gcc would
end up with the same.

This:

 for (i = I387_ST0_REGNUM (tdep); i < I387_XMM0_REGNUM (tdep); i++)

always iterates exactly 16 times, because I387_XMM0_REGNUM
is defined like:

 #define I387_XMM0_REGNUM(tdep) (I387_ST0_REGNUM (tdep) + 16)

An alternative I think might work would be to give that magic
16 constant a name, say:

 #define I387_NUM_ST_REGS 16

and then do:

 for (i = 0; i < i < I387_NUM_ST_REGS; i++)
   {
      int r = I387_ST0_REGNUM (tdep) + i;

      ... use 'r' instead of 'i' ...
   }

Thanks,
Pedro Alves