Re: [Xen-devel] [PATCH v6 1/4] xen: introduce SYMBOL

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 18.01.19 at 11:48, <julien.grall@xxxxxxx> wrote:
> On 18/01/2019 09:54, Jan Beulich wrote:
>>>>> On 18.01.19 at 02:24, <sstabellini@xxxxxxxxxx> wrote:
>>> On Thu, 17 Jan 2019, Jan Beulich wrote:
>>>>>>> On 17.01.19 at 01:37, <sstabellini@xxxxxxxxxx> wrote:
>>>>> On Wed, 16 Jan 2019, Jan Beulich wrote:
>> Stop. No. We very much can prove they are - _end points at
>> one past the last element of _start[]. It is the compiler which
>> can't prove the opposite, and hence it can't leverage
>> undefined behavior for optimization purposes.
> 
> You keep saying the compiler can't leverage it for optimization purpose, 
> however 
> there are confirmations that GCC may actually leverage it (e.g [1]). You 
> actually need to trick the compiler to avoid the optimization (e.g 
> RELOC_HIDE).

Correct - that's the case I'm referring to when saying it can't leverage
undefined behavior optimizations anymore. Without the hiding of
course it can.

Jan



_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-devel