Skip to content

gh-124951: Optimize base64 encode & decode for an easy 2-3x speedup [no SIMD] #143262

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
gpshead merged 13 commits into from
Jan 2, 2026
+134 −23
Merged

gh-124951: Optimize base64 encode & decode for an easy 2-3x speedup [no SIMD] #143262

Changes from 1 commit
Commits
Show all changes
13 commits
Select commit Hold shift + click to select a range
2d2be30
Add base64 benchmark tool and optimize encoding/decoding
gpshead Dec 28, 2025
573eaf3
Fix MSVC build: move table_b2a_base64 before inline functions
gpshead Dec 29, 2025
eaac671
NEWS entry
gpshead Dec 29, 2025
060dbf5
Add a whatsnew entry
gpshead Dec 29, 2025
1e12273
expose the benchmark defaults in the help text.
gpshead Dec 29, 2025
ef38895
Align base64 tables to 64-byte cache line boundaries
gpshead Dec 29, 2025
7458c99
Use BASE64_PAD macro instead of literal '=' in fast path
gpshead Dec 29, 2025
1f8ff74
Simplify block comment for base64 helpers
gpshead Dec 29, 2025
4b1245b
Remove binasciibench in favor of pyperformance bm_base64 addition PR.
gpshead Dec 29, 2025
4b50c73
reword L1 cache line comment
gpshead Jan 2, 2026
f7b27ee
doc Contributed by
gpshead Jan 2, 2026
2b13b81
Remove redundant PAD check in base64 decode fast path
gpshead Jan 2, 2026
30976a9
Use pointer increment in base64_encode_fast
gpshead Jan 2, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
Prev Previous commit
Next Next commit
Use BASE64_PAD macro instead of literal '=' in fast path 
Replace hardcoded '=' characters with the BASE64_PAD macro
for consistency with the rest of the codebase.

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>
  • Loading branch information
@gpshead @claude
gpshead and claude committed Dec 29, 2025
commit 7458c99764b5d590282f126d868c25e11ec0cada
3 changes: 2 additions & 1 deletion Modules/binascii.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -188,7 +188,8 @@ base64_decode_fast(const unsigned char *in, Py_ssize_t in_len,
* approach; on modern pipelined CPUs this is faster than bitmask tricks
* like XOR+SUB+AND for zero-detection which have data dependencies.
*/
if (inp[0] == '=' || inp[1] == '=' || inp[2] == '=' || inp[3] == '=') {
if (inp[0] == BASE64_PAD || inp[1] == BASE64_PAD ||
inp[2] == BASE64_PAD || inp[3] == BASE64_PAD) {
break;
}

Expand Down
Loading