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| author | Julien Cretel <jub0bsinthecloud@gmail.com> | 2026-03-28 15:18:23 +0000 |
|---|---|---|
| committer | Gopher Robot <gobot@golang.org> | 2026-03-30 07:09:16 -0700 |
| commit | acc2ce075982cea15636f018c421f96105049282 (patch) | |
| tree | ae55a9352deb1edf5deb18128a776d9c32351dbd /src/encoding | |
| parent | 3de9e7a0678abeecf9c4b7879ff53213ae879d08 (diff) | |
| download | go-acc2ce075982cea15636f018c421f96105049282.tar.xz | |
encoding/hex: speed up Decode
This CL eliminates the remaining bounds check for index expressions on
Encode's src parameter within the function's loop.
Here are some benchmark results (no change to allocations):
goos: darwin
goarch: arm64
pkg: encoding/hex
cpu: Apple M4
│ old │ new │
│ sec/op │ sec/op vs base │
Decode/256-10 166.2n ± 0% 142.9n ± 0% -14.02% (n=180)
Decode/1024-10 626.9n ± 0% 532.7n ± 0% -15.03% (n=180)
Decode/4096-10 2.472µ ± 0% 2.079µ ± 0% -15.90% (n=180)
Decode/16384-10 9.843µ ± 0% 8.266µ ± 0% -16.02% (n=180)
geomean 1.262µ 1.069µ -15.25%
│ old │ new │
│ B/s │ B/s vs base │
Decode/256-10 1.434Gi ± 0% 1.669Gi ± 0% +16.32% (p=0.000 n=180)
Decode/1024-10 1.521Gi ± 0% 1.790Gi ± 0% +17.69% (p=0.000 n=180)
Decode/4096-10 1.543Gi ± 0% 1.834Gi ± 0% +18.87% (p=0.000 n=180)
Decode/16384-10 1.550Gi ± 0% 1.846Gi ± 0% +19.08% (p=0.000 n=180)
geomean 1.512Gi 1.783Gi +17.98%
Change-Id: Ibf0471a75087feed528e6b547c7c2c88c6e14d38
GitHub-Last-Rev: dcda1b6a81011649d08db5093f38b12d1ac52f7d
GitHub-Pull-Request: golang/go#78436
Reviewed-on: https://go-review.googlesource.com/c/go/+/760781
Auto-Submit: Keith Randall <khr@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
Diffstat (limited to 'src/encoding')
| -rw-r--r-- | src/encoding/hex/hex.go | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/src/encoding/hex/hex.go b/src/encoding/hex/hex.go index ba9cc0f967..4499974325 100644 --- a/src/encoding/hex/hex.go +++ b/src/encoding/hex/hex.go @@ -85,10 +85,10 @@ func DecodedLen(x int) int { return x / 2 } // If the input is malformed, Decode returns the number // of bytes decoded before the error. func Decode(dst, src []byte) (int, error) { - i, j := 0, 1 - for ; j < len(src); j += 2 { - p := src[j-1] - q := src[j] + i, j := 0, 0 + for ; j < len(src)-1; j += 2 { + p := src[j] + q := src[j+1] a := reverseHexTable[p] b := reverseHexTable[q] @@ -104,8 +104,8 @@ func Decode(dst, src []byte) (int, error) { if len(src)%2 == 1 { // Check for invalid char before reporting bad length, // since the invalid char (if present) is an earlier problem. - if reverseHexTable[src[j-1]] > 0x0f { - return i, InvalidByteError(src[j-1]) + if reverseHexTable[src[j]] > 0x0f { + return i, InvalidByteError(src[j]) } return i, ErrLength } |