swc-project/swc - CodSpeed

swc

Performance History

Latest Results

fix(html/minifier): Preserve JSON script boundaries (#12080) **Description:** Preserve JSON `script` element boundaries during HTML minification. The JSON serializer normalizes Unicode escapes, which can turn escaped less-than signs into literal characters and change how the HTML parser delimits the containing element. Re-escape less-than signs after serialization so the minified document retains the same element structure. Add fixture coverage for encoded element-like content. **Related issue (if exists):** None. **Verification:** - `cargo test -p swc_html_minifier` - `cargo fmt --all` - `cargo clippy --all --all-targets -- -D warnings`

main

14 hours ago

test(html/minifier): Clarify JSON boundary fixture

kdy1/preserve-json-script-boundaries

14 hours ago

perf(es/minifier): Apply pending substitutions in batch for if-dense statement lists The optimizer flushed pending substitutions into each `if` statement individually before `merge_similar_ifs` (one Finalizer + one NormalMultiReplacer walk per `if`). On typescript.js this produced ~68k double walks per optimize() call with 0.4-1.7% hit rates. Apply the substitutions to the whole statement list in a single batch walk when the list is if-dense (>= 16 ifs), and keep the per-if loop otherwise. Both forms are semantically equivalent: the substitution maps only mutate via consumption of applied entries, which happens in the same statement order either way. es/minifier/libs benchmarks: 2.5-13.8% faster across all 12 lib fixtures (typescript -13.8%, echarts -11.8%, lodash -10.5%), byte-identical output on the entire fixture corpus.

hamidrezahanafi:perf/minifier-batch-substitutions

17 hours ago

fix(es/minifier): Preserve top-level declarations referenced only by direct eval (#12029) ## Description The DCE tree-shaker protects declarations reachable by a direct `eval` only within function scopes (added in #4693). `found_direct_eval` is propagated to the root scope, but `visit_mut_module` / `visit_mut_script` never consumed it, so top-level declarations referenced only through a direct `eval` were dropped — the `eval` then observes a missing binding at runtime. This consumes `found_direct_eval` at the root: when a direct `eval` reaches the root scope, the root-scope declarations are pinned so DCE cannot remove them. "Root-scope" means the module/script's own bindings — immediate top-level declarations (var/fn/class + imports) plus `var`s hoisted out of nested top-level statements — collected **without** descending into nested function scopes, so a top-level `eval` doesn't pin bindings it can't resolve. Each is pinned both as a graph entry (so `subtract_cycles` never subtracts it across Repeat passes — this covers reachable class cycles) and marked used (this covers lone bindings that have no in-graph references). Localized to the two root entry points; the added work only runs when a direct `eval` reaches the root scope, so it should be performance-neutral. Regression tests added to `simplify_dce` (each fails without the fix): a top-level `var`, a top-level class cycle, a top-level binding referenced by a nested `eval`, and a `var` hoisted out of a top-level block. Scope note: an `eval` inside an unreachable (dead) nested function still pins the enclosing top-level declarations, matching the existing function-scope behavior since #4693, which likewise doesn't gate on reachability. This only ever over-preserves, which is safe. ## Related issue Fixes #12028

main

1 day ago

fix(es/optimization): preserve JSON numeric values (#12051) **Description:** The JSON parse optimization had a number fast path that cast through `i64`. That path could be unsafe for out-of-range values and for `-0`, changing observable results. This PR keeps the optimization but only uses the `i64` path when safe: when the number is an integer within `i64` range and does not alter the zero sign. Other finite numbers are serialized via `serde_json::Number::from_f64`, and non-finite handling is updated so `NaN` is rejected while `±Infinity` is emitted as `±2e308`. **Related issue (if exists):** - #12043 - #12047 - #12050 - #12048 - **#12051** (current) - #12052 - #12053 - #12054 - #12055 - #12056 - #12057 - #12058 - #12049 - #12059 - #12060

main

1 day ago

refactor(es/ast)!: use Function for object accessors

refactor/ast-object-get-set

1 day ago

refactor(es/ast)!: use Function for object accessors

refactor/ast-object-get-set

1 day ago

refactor(es/ast)!: use Function for object accessors

refactor/ast-object-get-set

1 day ago

Latest Branches

fix(html/minifier): Preserve JSON script boundaries#12080

14 hours ago

9f96a72

kdy1/preserve-json-script-boundaries

perf(es/minifier): Apply pending substitutions in batch for if-dense statement lists#12079

17 hours ago

85c8c60

hamidrezahanafi:perf/minifier-batch-substitutions

+1%

refactor(es/ast)!: use Function for object accessors#12077

1 day ago

21951b3

refactor/ast-object-get-set

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