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Diffstat (limited to 'docs/chapter-backports.md')
| -rw-r--r-- | docs/chapter-backports.md | 55 |
1 files changed, 48 insertions, 7 deletions
diff --git a/docs/chapter-backports.md b/docs/chapter-backports.md index 5b16c7fe..a7e05a9d 100644 --- a/docs/chapter-backports.md +++ b/docs/chapter-backports.md @@ -22,15 +22,15 @@ Splitting Chapter 25 is deferred, not an instruction to renumber. ## Pending corrections -- **Forward Chapter 10b memory partitioning through 17-24.** The 10a/10b split - introduces whole-memory SSA first, then `MemMerge`, `MemPhi`, and `BulkMemPhi`. - Cliff reviewed and committed the port through 15 in `684c23f1`. Chapter 16 is - implemented and tested; stop here for review of constructor integration and - removal of `ScopeMinNode`. The next boundary is call/return aggregation in 18. +- **Forward Chapter 10b memory partitioning through 19-24.** Cliff reviewed + and committed the port through 16 in `75b57151`. Chapters 17 and 18 are now + implemented and tested. Stop at 18 for review of function memory: parameters, + calls, and returns carry whole memory; aliases split lazily within functions. Keep private constructor memory, escape tracking, and incomplete-type inference in 25. Carry generalized Phi factoring, its one-step Load guard, and dependency fixes with the next ports; later snapshots already have parts - of that rewrite. + of that rewrite. Calls must keep their last input as the function pointer; + scheduling must not append anti-dependence edges to their argument lists. ### Chapter 15 allocation design (implemented) @@ -64,7 +64,7 @@ Global code motion and the evaluator scheduler both follow an alias through MemMerge to discover the allocation's ordering constraint. MemMerge is packaging, not itself a clobber. The viewer and evaluator use the new slot conventions. -### Chapter 16 constructor integration (implemented, review checkpoint) +### Chapter 16 constructor integration (reviewed) ScopeNode now owns the variable records and one `$mem` binding; the obsolete ScopeMin alias table is removed. New inputs are `{ctrl, $mem, size, fields...}`, @@ -80,8 +80,31 @@ memory result has more users than a per-alias result, so it permits fewer folds. both runtime results remain checked. Other changed printed expectations only adjust Region/Loop IDs after removing parser memory nodes. +### Chapter 18 function memory (implemented, review checkpoint) + +Chapter 17 retains readonly casts, forward reference type updates, lexical +guards, and increment/assignment semantics while replacing ScopeMin with one +memory binding. Chapter 18 keeps its top-level Var class and makes MemMerge an +ordinary optimizer node rather than a parser alias table. Memory Parm 1 stays +opaque; local branches, loops, and merged returns use BulkMemPhi/MemPhi. +Function entry and CallEnd memory have unknown contents, including heap arguments. +Calls consume and return the complete memory state. There are no alias summaries +or private constructor effects. Inlining can expose the existing alias rewrites. + +New retains `{ctrl, $mem, size, fields...}` inputs and `{ptr, $mem}` outputs. +The evaluator, Eval2, graph viewer, and scheduling use those slots. Call is a +clobber for every alias. GCM raises a Load before the Call's block terminator; +it must not append the Load to the Call's inputs, which encode arguments and a +last-slot function pointer. The one-step Phi Load guard also stops at Calls. + ### Other pending corrections +- **Existing Chapter 18 floating-array assertion.** The unchanged + `TypeStruct.makeAry` assertion accepts integers and nullable references but + excludes TypeFloat; `return new flt[1];` fails under `-ea`. The Chapter 18 + memory probe uses floating struct fields for initialization coverage instead. + Investigate separately; this port does not change the array type lattice. + - **Chapter 24 Load BOTTOM-on-error backport, unwound/deferred (2026-09-28).** Cliff requested starting with 24 and analyzing failures before proceeding. Literal global BOTTOM memory/pointer inputs already propagate BOTTOM. The @@ -270,6 +293,24 @@ The top-level runner accepts explicit chapter lists, e.g. ## Validation record +- **Lazy memory through 17 and 18.** Baselines: 17 has 288 tests; 18 has 318 + plus its fuzzer wrapper. The port passes **298 tests in 17** and **331 tests + plus the fuzzer wrapper in 18**. Both carry the nine memory regressions and + constructor regression; 18 adds checks for non-inlined calls, recursive heap + updates, and allocation inside an inlined function. The non-inlined check + also verifies Call's input count and last-slot function pointer after GCM. + **7,700 / 9,800 evaluations across 100 optimizer seeds** pass in 17 / 18, + checking final memory values, complete scheduling, partial New inputs, and + two-result New. Full suites and both release jars build with Make alone. + Logs: `build/memory17-18-baseline.log`, `build/memory17-18-final.log`, + `build/memory17-seeds.log`, and `build/memory18-seeds.log`. + Chapter 17's And graph remains unfactored when the result would widen; the + existing runtime assertion is unchanged. Shared allocation memory retains + the `.y` Load in its inherited array example, as in 16. Nullable diagnostics + select the earlier array dereference in 17/18. The Chapter 17 null test now + makes `p2` mutable so its setup does not fail first on an unrelated final-field + store. Chapters 19+ remain unchanged for the Chapter 18 review checkpoint. + - **Chapter 16 lazy memory and constructors.** Baseline: 237 tests. The port passes 247 tests, including nine carried memory regressions and one constructor case combining reads, writes, a loop, and an unrelated alias. Full Make tests |