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Optimize riscv's cpu_fetch_syscall_args()

Authored by trasz on Sep 23 2020, 11:31 AM.



Optimize riscv's cpu_fetch_syscall_args(), making it possible
for the compiler to inline the memcpy.

Diff Detail

rS FreeBSD src repository
Automatic diff as part of commit; lint not applicable.
Automatic diff as part of commit; unit tests not applicable.

Event Timeline

arichardson added a subscriber: arichardson.

If anyone is interested, here is some compiler output to show that the latest version avoids a branch compared to the first one:

This revision is now accepted and ready to land.Thu, Oct 1, 3:42 PM
mhorne added inline comments.
101 ↗(On Diff #77728)

No longer needed.

124 ↗(On Diff #77728)

Should be dst_ap ?

trasz marked 2 inline comments as done.Thu, Oct 1, 6:50 PM
trasz added inline comments.
124 ↗(On Diff #77728)

Sigh, you're right. It's been manually cherry-picked from another tree.

trasz marked an inline comment as done.

Make it actually build.

This revision now requires review to proceed.Thu, Oct 1, 6:50 PM

Looks good. Presumably this passed basic testing in CheriBSD?

This revision is now accepted and ready to land.Thu, Oct 1, 7:04 PM

Yes, it passed our basic CI testing (boot to multiuser, SSH in, run our own cheri(abi)test unit test programs and run the cat kyua tests).

NB: arm and arm64 are the same as riscv currently is, so if we're changing riscv we should really make the same change to those two ports too.