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cmd/compile: intrinsify math/bits.Bswap on riscv64

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For riscv64/rva22u64 and above, we can intrinsify math/bits.Bswap
using the REV8 machine instruction.

On a StarFive VisionFive 2 with GORISCV64=rva22u64:

                 │     rb.1     │                rb.2                 │
                 │    sec/op    │   sec/op     vs base                │
ReverseBytes-4     18.790n ± 0%   4.026n ± 0%  -78.57% (p=0.000 n=10)
ReverseBytes16-4    6.710n ± 0%   5.368n ± 0%  -20.00% (p=0.000 n=10)
ReverseBytes32-4   13.420n ± 0%   5.368n ± 0%  -60.00% (p=0.000 n=10)
ReverseBytes64-4   17.450n ± 0%   4.026n ± 0%  -76.93% (p=0.000 n=10)
geomean             13.11n        4.649n       -64.54%

Change-Id: I26eee34270b1721f7304bb1cddb0fda129b20ece
Reviewed-on: https://go-review.googlesource.com/c/go/+/660855
Reviewed-by: Mark Ryan <markdryan@rivosinc.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Meng Zhuo <mengzhuo1203@gmail.com>
Reviewed-by: Carlos Amedee <carlos@golang.org>
Reviewed-by: Junyang Shao <shaojunyang@google.com>
This commit is contained in:
Joel Sing 2025-03-20 01:09:23 +11:00
parent 6fc1e34100
commit 90e8b8cdae
8 changed files with 118 additions and 20 deletions
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1
src/cmd/compile/internal/ssa/_gen/RISCV64Ops.go
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@ -237,6 +237,7 @@ func init() {
{name: "OR", argLength: 2, reg: gp21, asm: "OR", commutative: true}, // arg0 | arg1
{name: "ORN", argLength: 2, reg: gp21, asm: "ORN"}, // ^arg0 | arg1
{name: "ORI", argLength: 1, reg: gp11, asm: "ORI", aux: "Int64"}, // arg0 | auxint
{name: "REV8", argLength: 1, reg: gp11, asm: "REV8"}, // reverse bytes
{name: "ROL", argLength: 2, reg: gp21, asm: "ROL"}, // rotate left arg0 by (arg1 & 63)
{name: "ROLW", argLength: 2, reg: gp21, asm: "ROLW"}, // rotate left least significant word of arg0 by (arg1 & 31), sign extended
{name: "ROR", argLength: 2, reg: gp21, asm: "ROR"}, // rotate right arg0 by (arg1 & 63)