e7d8668a6a
Func.Names was []*LocalSlot, so every entry was a separately heap-allocated LocalSlot. Most named values are scalars that are never decomposed, yet each one still allocated a LocalSlot when it was first recorded in addNamedValue. Change Func.Names to []LocalSlot. addNamedValue now appends the slot by value and no longer eagerly fills CanonicalLocalSlots. The canonical *LocalSlot used for SplitOf chains and split deduplication is created lazily by localSlotAddr, so only slots that are actually decomposed pay for it. The names stay contiguous and the garbage collector has one fewer pointer per name to scan. This is a follow-up to CL 790300, the addNamedValue escape fix for issue #79990. That change stopped the slot escaping; this one removes the remaining per-name allocation for slots that are never decomposed. Passes toolstash -cmp; std and cmd build byte-identical. allocs/op via compilebench -alloc, linux/amd64 (-count 20); all packages ±0%, p<=0.001. "vs parent" is the win over CL 790300, "vs master" folds in CL 790300 too: allocs/op vs parent vs master Template 814.0k -0.16% -0.76% Unicode 573.7k -0.03% -0.10% GoTypes 4.956M -0.26% -1.08% SSA 46.32M -0.37% -1.51% Flate 811.6k -0.30% -1.45% GoParser 785.8k -0.23% -0.78% Reflect 2.293M -0.41% -1.11% Tar 927.5k -0.34% -1.02% XML 1.088M -0.32% -0.92% geomean 1.755M -0.27% -0.97% Updates #79990 Change-Id: Ib277056a47585d7805438955062c2f59bd77d42f Reviewed-on: https://go-review.googlesource.com/c/go/+/790920 Reviewed-by: Michael Podtserkovskii <michaelpo@meta.com> LUCI-TryBot-Result: golang-scoped@luci-project-accounts.iam.gserviceaccount.com <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: Keith Randall <khr@golang.org> Reviewed-by: Michael Pratt <mpratt@google.com> Reviewed-by: Keith Randall <khr@google.com> Auto-Submit: Michael Pratt <mpratt@google.com>
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