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Diffstat (limited to 'skills/chapter25-codex-notes.md')
| -rw-r--r-- | skills/chapter25-codex-notes.md | 68 |
1 files changed, 62 insertions, 6 deletions
diff --git a/skills/chapter25-codex-notes.md b/skills/chapter25-codex-notes.md index 1709d689..ac3b1c5a 100644 --- a/skills/chapter25-codex-notes.md +++ b/skills/chapter25-codex-notes.md @@ -40,13 +40,69 @@ still uses the old store-at-exit path. Fresh fields contain `TypeScalar.BOT`, independent of errors and physical calloc zeroes. It survives a missing live merge arm; an initialized unknown integer is `TypeInteger.BOT`. Ordinary TypeMem/TypeStruct flow proves initialization at -Loads and merged Returns. `InitMemory` is removed. Checks retain source Loads -and run after an optimistic solve of existing node types using the Iter worklist; -a pessimistic BOT seed cannot prove an unchanged initialized loop field. -Private-memory loop Phis widen numeric fields. Internal memory parameters use -actual allocation/initializer callers, not their hypothetical external caller. +Loads and merged Returns. `InitMemory` is removed. Checks now run at TypeCheck using the existing Iter/Opto passes; the extra +Construction.check/Iter.types solve and source-use keeps are removed. Numeric +operations and conversions preserve Scalar.BOT. Genuinely unused bad reads may +die. A partial-only ConstructNode preserves self/^ body restrictions through +inlining; Load alias comparisons look through that view without dropping its +type restriction. Hidden initializer/constructor helpers have only allocator +callers, and the visible constructor binding denotes the allocator. Parm typing +is ordinary merging, without private-memory or forced-partial exceptions. +See chapter29/docs/deferred-construction.md. Do not restore the early pass. +Private-memory loop Phis widen numeric fields. SCCP retains Returns during its +existing reset walk while rebuilding call edges, then releases those keeps. Function fields retain declared signatures in private summaries to avoid unfolding a constructor whose returned memory includes its own function field. +Store waits at TOP when its memory is TOP; the optimistic singleton bit is not +proof of private memory. StopCU must not expose a class initializer's synthetic +self as a pre-existing external argument: that can revive dead local functions +through broad function-valued field types. Chapter19's golden string omits dead +helper Returns and follows Add's node-ID operand ordering. The String spill +regression came from two-address operand order, not retained dead functions. +RegAlloc's self-conflict splitter now reuses its failed-range traversal/scratch +list to commute onto a single-use RHS in another live range before inserting +copies. Exclude SplitNode RHS values: their apparent single use can conceal +an earlier split of a longer-lived value. Normal coloring retries rebuild the +ranges; no new whole-IR pass or analysis structure is needed. + +Chapter29 Iter setup no longer resets/reseeds the whole graph. `Node.init()` +queues initialized nodes; Calls queue themselves to retry linking after imported +targets are installed. Imports reset only newly loaded nodes and repair affected +neighbors. Type upgrades and FRef resolution now share Opto's existing reset +walk; do not restore a separate post-parse node walk. Setup must not peephole a +partly reset graph. Resolved FRefs propagate their input type during SCCP; +ConstructNode identities wait until closed declarations are installed. Old Iter +types are change-detection snapshots, not upper bounds across recursive type +closure; SCCP's own falling-type/worklist checks remain. Upgrade changes also +register post-SCCP cleanup dependencies. Load forwarding must preserve the +computed pointer shape and qualifiers; Escape retains the private value's +escapes before declaration narrowing. StopCU/GlobalEscape preserve FULL escape +bounds for unknown values; do not narrow them to public sets or accumulate +previous results. Value refinement must only lift, including queued summaries. +There is no escape-summary repair hook in IterPeeps. `Iter.repair` remains for +structural changes from importing bodies and linking calls. FunNode depends on +its Return's type; Calls waiting for an absent target depend on Start and are +woken when a linker mapping is installed. FldOffNode's data base +belongs in slot 1, not control slot 0; +otherwise inliner body discovery can exclude an unresolved field offset. + +The FULL-escape experiment is not yet at test parity: the latest run passes +590/594 tests (raw0 400/404). Chapter10 `testIfOrNull` is restored to its valid +original `return bar;` and runs TypeCheck. Both Chapter17b forward tests now pass +their original goldens: EscapeNode uses cached public FIDX and alias defaults +for opaque external types, preserving prior input escapes. Before Opto installs +closed IR types, the default remains FULL; only open `_fref` structs get the +narrower fallback afterwards. Ordinary unknown values still require FULL. +The four remaining failing programs pass TypeCheck but retain extra private +constructors. In +`Chapter12Test.testPrivateRecursiveReturn`, SCCP gives the root Return BOTTOM +and FULL escapes. Post-SCCP forwarding fixes its value to `_B`, but FULL persists +through Start's incoming-memory cycle. Do not bless those extra functions in +the goldens or restore the nonmonotone public-only cap. The details and failing +test names are in `chapter29/docs/deferred-construction.md`. Its escape audit +also records concrete opaque Store/Return/native-argument precision losses, +CLInit's unconditional worst-case effects, and unknown CallEnd effects. Do not +blindly cap these at public sets: explicit private escapes must survive. Incomplete references now have only a yes/no restriction. Constructor self and `C ^arg` / `C? ^arg` are incomplete; a new result is incomplete iff an actual @@ -54,7 +110,7 @@ argument is incomplete. Only self may be read while incomplete. Other calls and publication require complete references. `TypeMemPtr._partial` carries the restriction through ordinary type flow, including backedges; meet ORs it and dual complements it. `ConstructNode` qualifies each new result from its actual -arguments and disappears after source checks. No provenance walk, root/result +arguments and disappears after TypeCheck. No provenance walk, root/result bitsets, group identities, inferred field sets, or hidden `^` memory arguments remain. Exact local self aliases use current private memory. A ^ formal stays restricted even with complete callers. The optimistic type solve proves a |