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| author | Edward Tomasz Napierala <trasz@FreeBSD.org> | 2020-10-29 15:36:20 +0000 |
|---|---|---|
| committer | Edward Tomasz Napierala <trasz@FreeBSD.org> | 2020-10-29 15:36:20 +0000 |
| commit | b1497fb64985d8b741d4e374227cd67f09863dd9 (patch) | |
| tree | dc342eaedeed143f4a372e3df060665552185416 /sys | |
| parent | e3c51151a09a22dd416caf74f70bda961088832d (diff) | |
| download | src-b1497fb64985d8b741d4e374227cd67f09863dd9.tar.gz src-b1497fb64985d8b741d4e374227cd67f09863dd9.zip | |
Optimize set_syscall_retval for riscv by predicting the return
value to be zero.
Reviewed by: mhorne, kp
MFC after: 2 weeks
Sponsored by: EPSRC
Differential Revision: https://reviews.freebsd.org/D26990
Notes
Notes:
svn path=/head/; revision=367138
Diffstat (limited to 'sys')
| -rw-r--r-- | sys/riscv/riscv/vm_machdep.c | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/sys/riscv/riscv/vm_machdep.c b/sys/riscv/riscv/vm_machdep.c index f00928e385b1..f38f1c04caa8 100644 --- a/sys/riscv/riscv/vm_machdep.c +++ b/sys/riscv/riscv/vm_machdep.c @@ -132,12 +132,14 @@ cpu_set_syscall_retval(struct thread *td, int error) frame = td->td_frame; - switch (error) { - case 0: + if (__predict_true(error == 0)) { frame->tf_a[0] = td->td_retval[0]; frame->tf_a[1] = td->td_retval[1]; frame->tf_t[0] = 0; /* syscall succeeded */ - break; + return; + } + + switch (error) { case ERESTART: frame->tf_sepc -= 4; /* prev instruction */ break; |