Joel Sing 6fb7bdc96d cmd/compile: intrinsify math/bits.TrailingZeros on riscv64
For riscv64/rva22u64 and above, we can intrinsify math/bits.TrailingZeros
using the CTZ/CTZW machine instructions.

On a StarFive VisionFive 2 with GORISCV64=rva22u64:

                  │   ctz.b.1    │               ctz.b.2               │
                  │    sec/op    │   sec/op     vs base                │
TrailingZeros-4     25.500n ± 0%   8.052n ± 0%  -68.42% (p=0.000 n=10)
TrailingZeros8-4     14.76n ± 0%   10.74n ± 0%  -27.24% (p=0.000 n=10)
TrailingZeros16-4    26.84n ± 0%   10.74n ± 0%  -59.99% (p=0.000 n=10)
TrailingZeros32-4   25.500n ± 0%   8.052n ± 0%  -68.42% (p=0.000 n=10)
TrailingZeros64-4   25.500n ± 0%   8.052n ± 0%  -68.42% (p=0.000 n=10)
geomean              23.09n        9.035n       -60.88%

Change-Id: I71edf2b988acb7a68e797afda4ee66d7a57d587e
Reviewed-on: https://go-review.googlesource.com/c/go/+/652320
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Mark Ryan <markdryan@rivosinc.com>
Reviewed-by: David Chase <drchase@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Meng Zhuo <mengzhuo1203@gmail.com>
2025-03-15 19:07:53 -07:00
..
2024-03-25 19:21:35 +00:00
2023-01-31 19:43:07 +00:00
2023-04-11 20:56:32 +00:00
2023-10-06 21:01:50 +00:00
2024-04-04 14:29:45 +00:00
2021-10-06 15:53:04 +00:00

The test directory contains tests of the Go tool chain and runtime. It includes black box tests, regression tests, and error output tests. They are run as part of all.bash.

To run just these tests, execute:

../bin/go test cmd/internal/testdir

To run just tests from specified files in this directory, execute:

../bin/go test cmd/internal/testdir -run='Test/(file1.go|file2.go|...)'

Standard library tests should be written as regular Go tests in the appropriate package.

The tool chain and runtime also have regular Go tests in their packages. The main reasons to add a new test to this directory are:

  • it is most naturally expressed using the test runner; or
  • it is also applicable to gccgo and other Go tool chains.