[vim/vim] Dictionary items() allocates pair elements separately (PR #21384)
mattn
Dictionary items() currently allocates each [key, value] list and its two items separately. Allocate the pair together using list_alloc_with_items(2), reducing three allocations to one per pair while preserving value references. Add a regression test covering pair mutation and shared values after the source dictionary is freed.
Before/after measurements for repeated items() calls on dictionaries with decimal string keys and Number values (median of five runs, GCC -O2; baseline 1b405bb705, patched 26ac0a447b):
| Dictionary entries | Calls per run | Before | After | Time reduction |
|---|---|---|---|---|
| 4,096 | 4,882 | 2.603719 s | 1.557332 s | 40.2% |
| 65,536 | 305 | 3.323465 s | 1.876700 s | 43.5% |
Dictionary setup is excluded from timing; replacing and freeing the previous result is included. These are focused microbenchmarks, not editor-wide speedups, and runs were not CPU-pinned.
Validation: make -C src -j4 completed without compiler warnings, all 59 tests in test_listdict.vim passed, and git diff --check passed.
You can view, comment on, or merge this pull request online at:
https://github.com/vim/vim/pull/21384
Commit Summary
- 26ac0a4 patch 9.2.NNNN: dictionary items() allocates pair elements separately
File Changes
(2 files)
- M src/dict.c (8)
- M src/testdir/test_listdict.vim (18)
Patch Links:
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Christian Brabandt
chrisbra left a comment (vim/vim#21384)thanks
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