runtime: improve index on ppc64x/power10
Rewrite index asm function to use the new power10 instruction lxvl,
stxvl or the load, store vector with length which can specify the
number of bytes to be stored in a register. This avoids the need to
create a separator mask and extra AND instructions. It also allows
us to process the tail end of the string using a lot fewer instructions
as we can load bytes of separator length directly rather than loading
16 bytes and masking out bytes that are greater than separator length
On power9 and power8 the code remains unchanged.
The performance for smaller sizes improve the most, on larger sizes
we see minimal improvement.
name old time/op new time/op delta
Index/10 10.6ns ± 3% 9.8ns ± 2% -7.20%
Index/11 11.2ns ± 4% 10.6ns ± 0% -5.99%
Index/12 12.7ns ± 3% 11.3ns ± 0% -11.21%
Index/13 13.5ns ± 2% 11.7ns ± 0% -13.11%
Index/14 14.1ns ± 1% 12.0ns ± 0% -14.43%
Index/15 14.3ns ± 2% 12.4ns ± 0% -13.39%
Index/16 14.5ns ± 1% 12.7ns ± 0% -12.57%
Index/17 26.7ns ± 0% 25.9ns ± 0% -2.99%
Index/18 27.3ns ± 0% 26.4ns ± 1% -3.35%
Index/19 35.7ns ±16% 26.1ns ± 1% -26.87%
Index/20 29.4ns ± 0% 27.3ns ± 1% -7.06%
Index/21 29.3ns ± 0% 26.9ns ± 1% -8.37%
Index/22 30.0ns ± 0% 27.4ns ± 0% -8.68%
Index/23 29.9ns ± 0% 27.7ns ± 0% -7.15%
Index/24 31.0ns ± 0% 28.0ns ± 0% -9.92%
Index/25 31.7ns ± 0% 28.4ns ± 0% -10.54%
Index/26 30.6ns ± 0% 28.9ns ± 1% -5.67%
Index/27 31.4ns ± 0% 29.3ns ± 0% -6.71%
Index/28 32.7ns ± 0% 29.6ns ± 1% -9.36%
Index/29 33.3ns ± 0% 30.1ns ± 1% -9.70%
Index/30 32.4ns ± 0% 30.7ns ± 0% -5.23%
Index/31 33.2ns ± 0% 30.6ns ± 1% -7.83%
Index/32 34.3ns ± 0% 30.9ns ± 0% -9.94%
Index/64 46.8ns ± 0% 44.2ns ± 0% -5.66%
Index/128 71.2ns ± 0% 67.3ns ± 0% -5.43%
Index/256 129ns ± 0% 127ns ± 0% -1.67%
Index/2K 838ns ± 0% 804ns ± 0% -4.03%
Index/4K 1.65µs ± 0% 1.58µs ± 0% -4.25%
Index/2M 829µs ± 0% 793µs ± 0% -4.42%
Index/4M 1.65ms ± 0% 1.59ms ± 0% -4.19%
Index/64M 26.5ms ± 0% 25.4ms ± 0% -4.18%
IndexHard2 412µs ± 0% 396µs ± 0% -3.76%
IndexEasy/10 10.0ns ± 0% 9.3ns ± 1% -7.20%
IndexEasy/11 10.8ns ± 1% 11.0ns ± 1% +2.22%
IndexEasy/12 12.3ns ± 2% 11.5ns ± 1% -6.37%
IndexEasy/13 13.1ns ± 0% 11.7ns ± 2% -10.83%
IndexEasy/14 13.8ns ± 2% 11.9ns ± 1% -13.52%
IndexEasy/15 14.0ns ± 2% 12.4ns ± 2% -11.46%
IndexEasy/16 14.3ns ± 1% 12.5ns ± 0% -12.40%
CountHard2 415µs ± 0% 396µs ± 0% -4.48%
Change-Id: Id3efa5ed9c662a29f58125c7f866a09f29a59b6c
Reviewed-on: https://go-review.googlesource.com/c/go/+/478918
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Paul Murphy <murp@ibm.com>
Run-TryBot: Archana Ravindar <aravind5@in.ibm.com>
Reviewed-by: David Chase <drchase@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Lynn Boger <laboger@linux.vnet.ibm.com>