diff options
Diffstat (limited to 'skills')
| -rw-r--r-- | skills/chapter25-codex-notes.md | 51 |
1 files changed, 37 insertions, 14 deletions
diff --git a/skills/chapter25-codex-notes.md b/skills/chapter25-codex-notes.md index 4be72a96..04bdcce2 100644 --- a/skills/chapter25-codex-notes.md +++ b/skills/chapter25-codex-notes.md @@ -6,8 +6,8 @@ the implementation. `WIP-HANDOFF.md` and `parser-simplification-plan.md` retain the detailed history; portions of their old branch/status reports are stale after the Chapter 25 squash. For cross-chapter work, read [the backport queue and validation record](../docs/chapter-backports.md). -It owns pending items and detailed reproductions; these notes capture reusable -lessons rather than duplicating that history. +It owns pending reproductions and a condensed completion record; these notes +capture reusable lessons. Detailed superseded validation history remains in Git. ## Collaboration preferences @@ -44,7 +44,8 @@ lessons rather than duplicating that history. affected directories explicitly listed. Establish the destination baseline before changing it; older Makefiles may need a forced rebuild after API changes. - Keep unrelated discoveries separate in `docs/chapter-backports.md`. Completed - fixes leave the pending queue; preserve their validation history. A green suite + fixes leave the pending queue; retain a concise validation summary and move + unresolved discoveries out of the history into the actual queue. A green suite after changing graph/test order does not prove an intermittent failure fixed. - Store disposable probes/logs under an appropriate ignored build directory. Preserve durable reproducers in tests or the review record, not only scratch @@ -153,11 +154,9 @@ lessons rather than duplicating that history. the JUnit listener labels individual cases and sums CPU/ABI and cohort totals. Assertions stay enabled and failures propagate. Do not silently change cohort membership, seeds, or targets when comparing chapters. -- Chapter 20's corrected baseline costs one extra weighted move (354->355 over - 39 compilations); document this as a correctness cost. Advanced quality - heuristics remain staged. Chapters 20-24 are now implemented; common correctness - fixes and diagnostic hooks have also been forwarded through 25 at Cliff's request. - Resume the quality/cohort/README review at 25. Chapter 21's shortened README links the retained encoding reference. +- The staged review is complete through 25. Keep 21's shortened README and its + separate encoding reference. The final narrow-store mask fixes changed the + measured totals for 20 and 21; use the current READMEs, not older review counts. - Chapter 21 changed several inherited inputs/ABIs. Its Chapter20Test now freezes all 13 original programs; Chapter21AllocTest retains the four revised cases, counted with the native variants as cohort 21. On Windows the cohorts are @@ -190,8 +189,8 @@ lessons rather than duplicating that history. - Validate the instruction masks independently of the chosen register: a broad mask can hide behind favorable color bias. Byte/short x86 and RISC-V stores must exclude floating-point registers. Size fields such as `_sz` may hold a - printable character: compare to `'4'`, not integer `2`. Chapters 22-24 now carry - 25's store restrictions; x86 20-21 and RISC-V 21 remain queued. + printable character: compare to `'4'`, not integer `2`. The narrow-store + restrictions are now present from x86 20 and RISC-V 21 onward. - The historical Chapter 22 seed sweep exposed failures outside allocation; it is not a template for routine allocator validation. Chapter 22's frozen String source fails before allocation and its returned @@ -200,8 +199,8 @@ lessons rather than duplicating that history. Do not replace the seed or add a return merely to make the sweep green. - Use an ablation in the same compiler to measure each staged heuristic. Native ABI/lowering changes make the Chapter 20 and 21 totals different even with the - same sources. In 21, coalescing saves 127 weighted moves, but deferring later - heuristics costs 174 against the old combined snapshot; disclose both. + same sources. Include the same legality fixes on both sides. Mask corrections + can substantially change coalescing results; refresh old tables and commentary. - Chapter 21's spill reporter defers quality-golden failures until reporting ends, so all target/runtime checks still run. The command must still exit nonzero. Keep full native process exit codes and check each emulator's own result memory. @@ -236,8 +235,32 @@ lessons rather than duplicating that history. each chapter's quality heuristics and historical cohort/README review staged. Compare each destination's unchanged local suite before/after for such a batch; do not present those unequal local suites as the chapter progression table. -- The staged plan and historical fix inventory are in - `docs/chapter-backports.md`; its review is not evidence of completed backports. +- Chapter 25's spill corpus preserves the earlier 212 source/target entries, + with documented constructor, receiver, library and mutability adaptations. + These are allocation/legality replays, not historical runtime harnesses. Its + own cohort includes current Chapter25Test allocations and a fresh library + encoding. See `chapter25/src/test/java/com/seaofnodes/simple/spill/README.md`. + Do not silently use current inherited tests as though their sources were frozen. +- Rebuild and measure the system library even if sys.o is up to date. In the + final 25 review, the older ranking and a multi-use-clone preference looked + better on clients but exhausted allocation rounds on fresh sys compilation. + Both trials were rejected. Keep the existing area/cost ranking; client-only + totals do not prove whole-suite improvement. The driver uses seed 456, old + cohort replay uses 123, and current test helpers normally use 126. +- ARM load/store opcodes must follow the allocated register bank, not the + source Type. Emit the SIMD bit for both addressing modes, normalize D0-D31 + to register numbers 0-31, and permit FP registers only at supported widths. + A GPR-only float-store mask made 25's old Newton programs repeatedly split + the wrong side of a loop. The paired fixes start in 21's executable backend. + Emulator FP memory operations must preserve bits and scale double offsets + by eight. Use independent instruction words as well as compiler round trips. +- Fixed-neighbor bias must clear the computed register, including a neighbor's + sole allowed register before it is colored; `_reg` can still be -1. The shared + correction and regression start in 20. A passing corpus can miss this path. +- Chapter 25's extra multi-def/fixed-use thresholds and kill/rematerialization + choices remain local strategies. Earlier splitEmptyMaskSimple lacks the extra + branch that needs 25's original-def-use-count snapshot. Do not label a textual + difference a missing correctness fix without establishing the affected path. ## Null guards: B13 / issue #246 lessons |