The branch main has been updated by trasz:
URL:
https://cgit.FreeBSD.org/src/commit/?id=fb8c2f743ab695f6004650b58bf96972e2535b20
commit fb8c2f743ab695f6004650b58bf96972e2535b20
Author: Edward Tomasz Napierala <tr...@freebsd.org>
AuthorDate: 2021-02-08 10:46:29 +0000
Commit: Edward Tomasz Napierala <tr...@freebsd.org>
CommitDate: 2021-02-08 10:46:47 +0000
arm64: optimize set_syscall_retval()
Microoptimize set_syscall_retval() for arm64 by predicting
the return value to be zero. This is similar to what has
been done for other architectures
Reviewed By: emaste, mhorne
Differential Revision: https://reviews.freebsd.org/D26991
---
sys/arm64/arm64/vm_machdep.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/sys/arm64/arm64/vm_machdep.c b/sys/arm64/arm64/vm_machdep.c
index 9e9b588c7db1..d4dd32caef06 100644
--- a/sys/arm64/arm64/vm_machdep.c
+++ b/sys/arm64/arm64/vm_machdep.c
@@ -143,12 +143,14 @@ cpu_set_syscall_retval(struct thread *td, int error)
frame = td->td_frame;
- switch (error) {
- case 0:
+ if (__predict_true(error == 0)) {
frame->tf_x[0] = td->td_retval[0];
frame->tf_x[1] = td->td_retval[1];
frame->tf_spsr &= ~PSR_C; /* carry bit */
- break;
+ return;
+ }
+
+ switch (error) {
case ERESTART:
frame->tf_elr -= 4;
break;
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