[Spice-devel] [PATCH spice-gtk v3 1/5] Avoid clang warnings on casts with stricter alignment requirements

[Christophe de Dinechin]

> On 17 May 2017, at 11:55, Christophe Fergeau <cfergeau at redhat.com> wrote:
> 
> On Wed, May 17, 2017 at 11:45:50AM +0200, Christophe de Dinechin wrote:
>>> I'm really sure no architecture on hearth can do check and print in
>>> a single machine instruction.
>> 
>> This is not what I said. I said that the cost in the likely case was one extra instruction.
>> 
>>> Actually I don't know any architecture
>>> where a single check like this can be done in a single instruction.
>> 
>> Reduced source code: https://pastebin.com/ibZEVThA.
>> 
>> Machine code for x86 with clang: https://pastebin.com/Vmtwpkhf
>> 
>> The test follows the call to malloc. It’s a single “testb” instruction
>> followed by a never-taken conditional jump to cold-code.
> 
> NB: feel free to annotate such tests with G_LIKELY/G_UNLIKELY

Thanks. It’s already in my version, but I have not shared it yet.

Christophe
> 
> Christophe