On 17/12/2021 15.16, Janosch Frank wrote:
On 12/17/21 14:47, Thomas Huth wrote:
On 17/12/2021 11.31, Nico Boehr wrote:
We clobber r0 and thus should let the compiler know we're doing so.
Because we change from basic to extended ASM, we need to change the
register names, as %r0 will be interpreted as a token in the assembler
template.
For consistency, we align with the common style in kvm-unit-tests which
is just 0.
Signed-off-by: Nico Boehr <nrb@xxxxxxxxxxxxx>
---
s390x/diag288.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/s390x/diag288.c b/s390x/diag288.c
index 072c04a5cbd6..da7b06c365bf 100644
--- a/s390x/diag288.c
+++ b/s390x/diag288.c
@@ -94,11 +94,12 @@ static void test_bite(void)
/* Arm watchdog */
lc->restart_new_psw.mask = extract_psw_mask() & ~PSW_MASK_EXT;
diag288(CODE_INIT, 15, ACTION_RESTART);
- asm volatile(" larl %r0, 1f\n"
- " stg %r0, 424\n"
+ asm volatile(" larl 0, 1f\n"
+ " stg 0, 424\n"
Would it work to use %%r0 instead?
Yes, but I told him that looks weird, so that one is on me.
@claudio @thomas What's your preferred way of dealing with this?
I think it's mostly a matter of taste. I slightly prefer %%r0 to just 0 so
that it is clear from the first sight that it is a register and not an
immediate constant.
Additionally, there used to be a problem with older versions of Clang that
required the %%rX syntax, see:
https://git.qemu.org/?p=qemu.git;a=commitdiff;h=052b66e7211af6
But we're not supporting those Clang versions for the kvm-unit-tests anyway,
so that doesn't really count.
Thus, I don't mind too much, if everybody else prefers the bare numbers,
then let's go with this.
Thomas
