On 2023-12-12 15:01, Jan Beulich wrote:
On 12.12.2023 14:38, Nicola Vetrini wrote:
On 2023-12-12 11:07, Jan Beulich wrote:
On 12.12.2023 11:04, Jan Beulich wrote:
On 11.12.2023 11:30, Nicola Vetrini wrote:
The string literal inside the expansion of BUILD_BUG_ON is
considered
unreachable code; however, such statement can be moved earlier
with no functional change.
First: Why is this deemed dead code in its present position, but
okay
when
moved? Second: While moving is indeed no functional change (really
BUILD_BUG_ON() can be moved about anywhere, for not producing any
code
in
the final binary), it removes the connection between it and the
respective
asm() (where %z would have been nice to use).
Oh, and third: Which string literal? I expect you're not building
with
an ancient compiler, so it got to be
#define BUILD_BUG_ON(cond) ({ _Static_assert(!(cond), "!(" #cond
")");
})
which you see in use. Yet that string literal isn't "code" or "data",
but
an argument to _Static_assert(). Is Eclair perhaps not properly aware
of
_Static_assert()?
On further inspection, this should have fallen into the deviation for
pure decls. This patch can be dropped, we'll adjust this inside
ECLAIR.
What's the connection to "pure" here? Or are you merely piggybacking on
that attribute for this non-function?
Jan
Just a naming coincidence, there aren't any attributes involved. No
change to Xen code is needed.
--
Nicola Vetrini, BSc
Software Engineer, BUGSENG srl (https://bugseng.com)
