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Re: [Qemu-devel] [PATCH v5 04/10] softfloat: Drop [u]int16 types in favo

From: Peter Maydell
Subject: Re: [Qemu-devel] [PATCH v5 04/10] softfloat: Drop [u]int16 types in favor of [u]int_fast16_t
Date: Mon, 7 Mar 2011 23:14:11 +0000

On 7 March 2011 09:56, Aurelien Jarno <address@hidden> wrote:
> On Mon, Mar 07, 2011 at 01:34:07AM +0100, Andreas Färber wrote:
>> AIX already didn't use our definition, so let's start ripping out this one:
>> As pointed out by Peter Maydell, int16 is currently int on most
>> supported platforms, so let's replace it with int_fast16_t,
>> allowing the system to use a wider type if appropriate.
> Do you have a rationale about the use of the fast version of the types?
> As you said it allows the compiler to use a wider type if appropriate,
> and this usually doesn't play very well when shifts are involved, which
> is the case of the softfloat code. Have you verified that each
> conversion is correct? On the other hand I really doubt it has a
> measurable impact on speed.
> I would really go for uint16_t for now. This might be changed to the fast
> version in a second step if we are sure everything is correct, but let's
> don't mix the two steps for now.

As Andreas says, the code as it is at the moment makes the "wider
is OK" vs "exact width only" distinction, it just isn't using the
standard typenames to do it. So changing "int16" to "int16_t" would
be the change of semantics (both in theory and in practice, since at
the moment "int16" is int).

-- PMM

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