Re: [Xen-devel] [PATCH for-4.13 3/6] xen/arm: cpuerrata: Match register size with value size in check_workaround_*

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Wed, 2 Oct 2019, Julien Grall wrote:
> Hi Andrew,
> 
> On 10/2/19 7:42 PM, Andrew Cooper wrote:
> > On 02/10/2019 19:00, Julien Grall wrote:
> > > Clang is pickier than GCC for the register size in asm statement. It
> > > expects the register size to match the value size.
> > > 
> > > The asm statement expects a 32-bit (resp. 64-bit) value on Arm32
> > > (resp. Arm64) whereas the value is a boolean (Clang consider to be
> > > 32-bit).
> > > 
> > > It would be possible to impose 32-bit register for both architecture
> > > but this require the code to use __OP32. However, it does not really
> > > improve the assembly generated. Instead, replace switch the variable
> > > to use register_t.
> > > 
> > > Signed-off-by: Julien Grall <julien.grall@xxxxxxx>
> > > 
> > > ---
> > >      Changes in v2:
> > >          - Use !! per Stefano's request
> > 
> > You are aware that unlikley(), deliberately, has an embedded !! ?
> 
> I forgot it, sorry about that :/. Stefano are you happy if I revert to v1?

I forgot about that too. Yes, that's fine and add my acked-by.


> > 
> > include/xen/compiler.h:11:#define unlikely(x)   __builtin_expect(!!(x),0)
> > 
> > ~Andrew

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