mirror of
https://github.com/nim-lang/Nim.git
synced 2026-04-05 23:28:24 +00:00
854c1f15ba
fixes #25687 This pull request introduces an optimization for sequence (`seq`) assignments and copies in the Nim compiler, enabling bulk memory copying for sequences whose element types are trivially copyable (i.e., no GC references or destructors). This can significantly improve performance for such types by avoiding per-element loops. Key changes: ### Compiler code generation improvements * Added the `elemSupportsCopyMem` function in `compiler/liftdestructors.nim` to detect if a sequence's element type is trivially copyable (no GC refs, no destructors). * Updated the `fillSeqOp` procedure to use a new `genBulkCopySeq` code path for eligible element types, generating a call to `nimCopySeqPayload` for efficient bulk copying. Fallback to the element-wise loop remains for non-trivial types. [[1]](diffhunk://#diff-456118dde9a4e21f1b351fd72504d62fc16e9c30354dbb9a3efcb95a29067863R665-R670) [[2]](diffhunk://#diff-456118dde9a4e21f1b351fd72504d62fc16e9c30354dbb9a3efcb95a29067863R623-R655) ### Runtime support * Introduced the `nimCopySeqPayload` procedure in `lib/system/seqs_v2.nim`, which performs the actual bulk memory copy of sequence data using `copyMem`. This is only used for types that are safe for such an operation. These changes collectively improve the efficiency of sequence operations for simple types, while maintaining correctness for complex types. ### Benchmarked the original micro-benchmark: refc: 3.52s user 0.02s system 99% cpu 3.538 total orc (after change): 3.46s user 0.01s system 99% cpu 3.476 total --------- Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>