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Author	SHA1	Message	Date
Benedikt Stebner	42bba0b859	[Text] Unicode and text layout optimizations (#21400 ) * perf(text): O(1) width queries on ShapedBuffer, cached LB-class lookup - ShapedBuffer: lazy, pooled cluster-prefix cache shared across Split; adds TotalGlyphAdvance / MeasureCharactersThatFit. - GlyphRun/TextFormatterImpl/Skia GlyphRunImpl: read the cache, drop duplicate scans; SplitTextRuns now returns firstLength via out. - LineBreakEnumerator: cache Next/PreviousClass per advance; remove unused LineBreakPairTable. - Tests + benchmarks for the new paths and a dotnet-trace harness. ~1.32x faster / -5% alloc on the emoji-wrap micro-benchmark; no observable behaviour or public API change. * perf(TextFormatting): inline LineBreakEnumerator rule dispatch Replace the BreakUnitDelegate[] s_rules array dispatch in LineBreakEnumerator.ExecuteRules with a sequence of direct static calls and a `goto Done` early-exit. This removes 42 indirect calls per codepoint and lets the JIT reason across rule boundaries, which in turn makes [MethodImpl(AggressiveInlining)] meaningful — JIT cannot inline through delegate.Invoke, so the attribute was a no-op in the previous shape. Selectively apply AggressiveInlining to the small single-condition rules (LB03, LB04, LB06, LB07, LB08a, LB11–LB15d, LB18, LB20, LB21b, LB22, LB29, LB31) and let the JIT decide on the larger ones to avoid bloating the merged ExecuteRules. The static BreakUnitDelegate[] s_rules array is removed. Benchmarks (BDN default job, --inProcess, N=13–22, rel. StdDev <1.5%): UnicodeBreakEnumeratorBenchmark.LineBreakEnumerator_Sequence Ascii 154.6 µs -> 24.84 µs (6.22x) Bmp 190.2 µs -> 32.81 µs (5.80x) Supplementary 227.6 µs -> 37.56 µs (6.06x) TextLayoutProfile.BuildEmojisWrapped Before (branch, pre-inline) 804.5 µs / 570.15 KB After (branch, post-inline) 547.0 µs / 570.15 KB (-32.0%) vs upstream/master (1061 µs) -> ~1.94x total speedup No allocation change; CPU-only dispatch reshape. All LineBreakEnumerator unit tests pass (5/5). * Refactor ShapedBuffer to share pool storage via IRef + generation counter Wrap the ArrayPool-rented glyph and cluster-cache arrays in a small PooledArray<T> disposable and expose them through IRef<T>. Split children and WithBidiLevel aliases now Clone() the refs instead of borrowing raw pool arrays, so the backing storage survives until every sibling has been disposed - eliminating the UAF risk that existed when a parent was disposed before its children. Add a per-glyph-holder generation counter (Volatile.Read / Interlocked .Increment). The indexer setter bumps the counter on every write, and EnsureClusterCache compares its recorded generation against the holder's current value, rebuilding on mismatch. This lets us drop the previous "no mutation after Split/WithBidiLevel" contract: mutations performed through any sibling now propagate to the others' caches transparently. Dispose is made idempotent via a _disposed guard so overlapping cache eviction and TextLine teardown only release the IRefs once. Adds ShapedBufferSharedStorageTests covering sibling lifetime, Dispose idempotency, and generation-driven cache invalidation across Split children and WithBidiLevel aliases. * test(ShapedBuffer): cover cluster-cache sharing across Split/WithBidiLevel aliases Add a regression test hook (`ClusterPrefix`) exposing the backing cluster-prefix array reference, plus two tests that mutate a parent buffer before aliasing it and assert the alias reuses the parent's pooled prefix array instead of rebuilding. Guards against forgetting to propagate `_cacheGeneration` to alias buffers, which would silently defeat the cached-split fast path. * Correctly use MathUtilities.LessThanOrClose --------- Co-authored-by: Julien Lebosquain <julien@lebosquain.net>	4 months ago

Author

SHA1

Message

Date

Benedikt Stebner

42bba0b859

[Text] Unicode and text layout optimizations (#21400 )

* perf(text): O(1) width queries on ShapedBuffer, cached LB-class lookup

- ShapedBuffer: lazy, pooled cluster-prefix cache shared across Split;
  adds TotalGlyphAdvance / MeasureCharactersThatFit.
- GlyphRun/TextFormatterImpl/Skia GlyphRunImpl: read the cache, drop
  duplicate scans; SplitTextRuns now returns firstLength via out.
- LineBreakEnumerator: cache Next/PreviousClass per advance; remove
  unused LineBreakPairTable.
- Tests + benchmarks for the new paths and a dotnet-trace harness.

~1.32x faster / -5% alloc on the emoji-wrap micro-benchmark; no
observable behaviour or public API change.

* perf(TextFormatting): inline LineBreakEnumerator rule dispatch

Replace the BreakUnitDelegate[] s_rules array dispatch in
LineBreakEnumerator.ExecuteRules with a sequence of direct static
calls and a `goto Done` early-exit. This removes 42 indirect calls
per codepoint and lets the JIT reason across rule boundaries, which
in turn makes [MethodImpl(AggressiveInlining)] meaningful — JIT
cannot inline through delegate.Invoke, so the attribute was a no-op
in the previous shape.

Selectively apply AggressiveInlining to the small single-condition
rules (LB03, LB04, LB06, LB07, LB08a, LB11–LB15d, LB18, LB20,
LB21b, LB22, LB29, LB31) and let the JIT decide on the larger ones
to avoid bloating the merged ExecuteRules.

The static BreakUnitDelegate[] s_rules array is removed.

Benchmarks (BDN default job, --inProcess, N=13–22, rel. StdDev <1.5%):

  UnicodeBreakEnumeratorBenchmark.LineBreakEnumerator_Sequence
    Ascii          154.6 µs -> 24.84 µs  (6.22x)
    Bmp            190.2 µs -> 32.81 µs  (5.80x)
    Supplementary  227.6 µs -> 37.56 µs  (6.06x)

  TextLayoutProfile.BuildEmojisWrapped
    Before (branch, pre-inline)  804.5 µs / 570.15 KB
    After  (branch, post-inline) 547.0 µs / 570.15 KB  (-32.0%)
    vs upstream/master (1061 µs) -> ~1.94x total speedup

No allocation change; CPU-only dispatch reshape. All
LineBreakEnumerator unit tests pass (5/5).

* Refactor ShapedBuffer to share pool storage via IRef + generation counter

Wrap the ArrayPool-rented glyph and cluster-cache arrays in a small
PooledArray<T> disposable and expose them through IRef<T>. Split children
and WithBidiLevel aliases now Clone() the refs instead of borrowing raw
pool arrays, so the backing storage survives until every sibling has
been disposed - eliminating the UAF risk that existed when a parent was
disposed before its children.

Add a per-glyph-holder generation counter (Volatile.Read / Interlocked
.Increment). The indexer setter bumps the counter on every write, and
EnsureClusterCache compares its recorded generation against the holder's
current value, rebuilding on mismatch. This lets us drop the previous
"no mutation after Split/WithBidiLevel" contract: mutations performed
through any sibling now propagate to the others' caches transparently.

Dispose is made idempotent via a _disposed guard so overlapping cache
eviction and TextLine teardown only release the IRefs once.

Adds ShapedBufferSharedStorageTests covering sibling lifetime,
Dispose idempotency, and generation-driven cache invalidation across
Split children and WithBidiLevel aliases.

* test(ShapedBuffer): cover cluster-cache sharing across Split/WithBidiLevel aliases

Add a regression test hook (`ClusterPrefix`) exposing the
backing cluster-prefix array reference, plus two tests that mutate a
parent buffer before aliasing it and assert the alias reuses the
parent's pooled prefix array instead of rebuilding. Guards against
forgetting to propagate `_cacheGeneration` to alias buffers, which
would silently defeat the cached-split fast path.

* Correctly use MathUtilities.LessThanOrClose

---------

Co-authored-by: Julien Lebosquain <julien@lebosquain.net>

4 months ago

1 Commits (main)