The boxed-source walks of one parameter-binding pass share what they found unchanged - #7378
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matz merged 3 commits intoOct 5, 2026
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…ady found unchanged widen_boxed_array_sources (with widen_boxed_elem_sources) follows every write of a local to depth 6 with nothing to remember what it already walked, so a function writing one local W times walked W^6 paths, from every boxed push or index write and every call binding a boxed argument whose parameter takes stores. A large machine-generated program (6.9k lines) that writes the same few locals thousands of times, and shifts them as `l0 << 1`, which counts as a push, spent 45 of its 48 seconds of C generation here. The walk writes the analysis state as it goes, so only a visit that changed nothing is remembered: under the current generation, with the depth it ran at. A later visit of the same node, at that depth or deeper and in the same generation, makes a subset of the same calls in the same state, which change nothing either, and is skipped. Each walk from outside opens and closes a generation, and so does every call in it that may write the state, whether or not it reports a change (the pin a local re-derived from its writes takes again writes without one). The widenings, and the generated C, are unchanged.
…found unchanged With each walk remembering only what it found itself, every call site binding a boxed argument walked the caller's locals again, and a read of a local walked the local's writes again from every read: a function of W writes and C calls still cost C * W^2 per pass. A large machine-generated program (53k lines), where one function calls the same callee thousands of times with the same locals, stayed over two minutes in this walk alone. A boxed local now has its own record, since every read of it walks the same, and the records carry the element kind they were made for. Within infer_param_types the walks share one generation, which ends wherever the pass reports a change: after each node it binds, and before each walk in bind_args_params once the binding has changed something, as well as at every write in the walk itself. The work is linear in the nodes and locals reached per generation. A write between two walks that the pass does not report would make a shared record stale. With SPINEL_WBAS_SHADOW=1, every visit skipped on another walk's record is made anyway, in a fresh generation, and the compiler stops if it widens or writes anything. The test corpus (5,746 tests, both overflow modes) and large machine-generated programs run clean under it, and the generated C is unchanged.
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Included review availability: This review used your included allowance. Your plan provides up to 8 included reviews per hour; 4 remain after this review. 📝 WalkthroughWalkthroughThe analysis pass now memoizes boxed-array source walks by value or local, element kind, depth, and generation. Parameter inference shares memoized results across bindings and includes changes accumulated across generation boundaries. ChangesBoxed-array analysis
Priority: ➖ Normal Estimated code review effort: 3 (Moderate) | ~25 minutes Change: Refactor Suggested reviewers: Merge Risk: ⚪ Minimal · up to No actionable issue remains in the supplied review evidence; the change is mergeable after normal checks. Architecture SummaryArchitecture risk: 🟡 Medium · up to The change affects 1 system. Changed systems: Architecture concerns Review detailsSystems and components
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Review comments at @src/analyze_pass.c:
- Around line 7721-7725: Update bind_args_params, including its forwarding early
return, to advance the wbas_share generation when that binding reports changes,
so later bindings on the same node do not reuse stale walk records. In
infer_param_types, also advance the generation after direct slot_take, lv_widen,
or ivar_types writes that precede another binding.
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…rce generation Within infer_param_types the walks of widen_boxed_array_sources share their records until the pass reports a change, and the generation moved only at the end of each node and, inside bind_args_params, before a walk once that binding had changed something. A node that binds more than once (a method and its overrides, each initialize a dynamic `new` may reach, the candidates of a poly call) could change something after the last walk of one binding, or between two bindings, and the next binding then walked on records made before that change. bind_args_params now ends the generation as it returns if it changed anything, and as it starts if the pass changed anything since the last step (the pass hands it its own `changed`), and the direct ivar write in bind_dynamic_new_initializers ends it too. This only ends generations sooner, so it can only make the walks skip less.
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A correction to the description: the comparison of every |
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…share what they found unchanged Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
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A note on where this stands: master has this pull request as of 2ca3627 (merged in 085c21d), which was its head before the review. The commit that answers the review thread above, 99e1459, is the one commit still open here; it is not in master yet. #7384 is stacked on it and contains it too, so merging either brings it in. |
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Following a call into its callee's value scans every ReturnNode and every scope of the program
#7403
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Refs #7376 (stacked on #7377)
This pull request is stacked on #7377 and contains its commit with the same SHA; review that one first. Only the last commit is new here.
What changes
With #7377 each walk of
widen_boxed_array_sourcesremembers only what it found itself, so the work is still (call sites × the caller's locals): every call site that binds a boxed argument walks the same locals again, and a local read inWplaces walks the local'sWwrites once per read.LocalVar(an open-addressed table whose entries of an older generation count as empty).infer_param_typespass, the walks share one generation. The records now also carry the element kind they were made for, since walks started from different call sites carry different kinds. The generation still moves at every write inside a walk, and in addition wherever the pass reports a change: after each node it binds (wbas_share_stepin the loop's increment), and inbind_args_paramsbefore each walk once the binding has changed something. Walks started elsewhere (the push and index-write sites ininfer_write_container_usage) keep a generation of their own, as before.A write between two walks that the pass does not report would make a shared record stale. That cannot be argued from the code alone as it was for #7377, so the change carries a check: with
SPINEL_WBAS_SHADOW=1, every visit skipped on a record that another walk left is made anyway, in a fresh generation (where no other walk's records are visible), and the compiler stops with an internal error if that visit widens or writes anything. The check costs about what #7377's walks cost and is off by default.Why the results do not change
All on e5e8f79, with this change (and #7377 under it) and #7375 together, from the same worktree as master, with the same input paths, in both overflow modes:
SPINEL_WBAS_SHADOW=1 spinel -con everytest/*.rb(5,746 files × raise/promote = 11,492 compilations): no internal error. The 7 compilations that are refused are refused with the same message by master.for(test/*.rbmatchingboxed|widen|method|proc|splice|poly_arr|push|lambda|for_) is identical to master's for 1,875 of the 1,876 compilations; the remaining one is refused by both with the same message. Machine-generated programs of 300 to 6,900 lines (9 programs, both modes): identical, with no internal error.After the rebase onto 92510d6, with #7375: 72 programs (63 tests and 9 machine-generated programs), both modes, with
SPINEL_WBAS_SHADOW=1: identical to master, no internal error.The comparison of every
test/*.rbwith this change alone is running; its result will be added to this pull request as a comment.Before / after
The generator from the issue, counting the bodies of
widen_boxed_array_sourcesthat run (a local counter, not part of this change):Twice the steps per doubling of
K: linear.On a family of synthetic machine-generated programs that doubles in size per step, with the walks of #7365 and #7367 switched off: 19k, 38k and 76k steps at the 512, 1024 and 2048 steps (5.8 M at 512 with #7377 alone), and 18 s at 2048. On a 53k-line machine-generated program, with the same two walks switched off, C generation went from over 120 s to 36 s.
(Timings are from a shared machine under load.)
Testing
make gate:The stamp line above names the
origin/masterthe clone had fetched when the gate finished (725905f); the tree the gate ran was based on e5e8f79, as described below.SPINEL_INT_OVERFLOW=promote make test: 5861 pass, 15 fail, 14 error. The 29 failures are exactly the set master e5e8f79 fails with (0 new, 0 fixed).The gate ran on a branch based on e5e8f79 that combines this change (with #7377 under it) and the other compile-time fixes from the same investigation (#7375, #7365, #7367, #7369, since merged). This branch was then rebased onto 92510d6 without conflicts; after the rebase, the generated C for 72 programs (63 tests and 9 machine-generated programs) in both modes was checked again against master, with
SPINEL_WBAS_SHADOW=1, and is unchanged with no internal error.Summary by CodeRabbit