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Re: [PATCH] gdb/i387-tdep.c: Avoid warning for "-Werror=strict-overflow"
- From: Chen Gang <gang dot chen dot 5i5j at gmail dot com>
- To: Pedro Alves <palves at redhat dot com>, Joel Brobecker <brobecker at adacore dot com>
- Cc: Mark Kettenis <mark dot kettenis at xs4all dot nl>, amodra at gmail dot com, gbenson at redhat dot com, michael dot sturm at intel dot com, walfred dot tedeschi at intel dot com, binutils at sourceware dot org, gdb-patches at sourceware dot org
- Date: Mon, 06 Oct 2014 21:35:22 +0800
- Subject: Re: [PATCH] gdb/i387-tdep.c: Avoid warning for "-Werror=strict-overflow"
- Authentication-results: sourceware.org; auth=none
- References: <542EC11C dot 3020406 at gmail dot com> <201410031546 dot s93FknOM002165 at glazunov dot sibelius dot xs4all dot nl> <542EC9FC dot 8050107 at gmail dot com> <20141003164420 dot GK6927 at adacore dot com> <542EE1BF dot 7060203 at redhat dot com> <542F831D dot 1000502 at gmail dot com> <543255B6 dot 7060509 at redhat dot com>
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
> 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.
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