On 27/03/2019 18:45, 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 instruction clz is expecting the two operands to be the same size
> (i.e 32-bit or 64-bit). As the flsl function is dealing with 64-bit
> value, we need to make the destination variable 64-bit as well.
>
> While at it, add a newline before the return statement.
>
> Signed-off-by: Julien Grall <julien.gr...@arm.com>
> ---
> xen/include/asm-arm/arm64/bitops.h | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/xen/include/asm-arm/arm64/bitops.h
> b/xen/include/asm-arm/arm64/bitops.h
> index 6bf1922680..05045f1109 100644
> --- a/xen/include/asm-arm/arm64/bitops.h
> +++ b/xen/include/asm-arm/arm64/bitops.h
> @@ -34,12 +34,13 @@ static /*__*/always_inline unsigned long __ffs(unsigned
> long word)
>
> static inline int flsl(unsigned long x)
> {
> - int ret;
> + uint64_t ret;
>
> if (__builtin_constant_p(x))
> return generic_flsl(x);
>
> asm("clz\t%0, %1" : "=r" (ret) : "r" (x));
As x is fixed by the ABI, ret should be unsigned long to match, surely?
This will compile as it is arm64 specific, but it looks just as wrong
(per the commit message) as using int in the first place.
~Andrew
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