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Diffstat (limited to 'docs')
| -rw-r--r-- | docs/chapter-backports.md | 15 |
1 files changed, 14 insertions, 1 deletions
diff --git a/docs/chapter-backports.md b/docs/chapter-backports.md index 15bf73e6..76c2f06c 100644 --- a/docs/chapter-backports.md +++ b/docs/chapter-backports.md @@ -7,7 +7,6 @@ live in the [AI notes](../skills/chapter25-codex-notes.md). ## Investigate next Establish an earlier-chapter failure before changing compiler behavior. -The remaining candidate below is not yet confirmed. ### SCCP function revival: Chapter 24 @@ -24,6 +23,20 @@ Dependency propagation already exists in Chapter 24's SCCP; only port a specific missing dependency with a reproducer. Keep Chapter 25's escape and external-caller machinery out of this investigation. +Investigation on 2026-10-19 found no cleanup loss. A shadow Opto checked the +linker entry before and after every `linkCG` lookup while running all 513 +Chapter 24 tests: 787 SCCP runs, 297 lookups, 74 links to functions with only +their null input remaining, and zero structurally dead targets or removed +entries. All tests passed. The remaining null lookups are not evidence of a +cleanup loss: their entries were already null before the lookup. + +The factorial trace shows the distinction: FunNode#1309 loses Start and has +one input, four uses, and type TOP; it then reaches XCONTROL before a real +call links it. `isDead()` stays false, since it requires no inputs, no uses, +and a null type. Thus the observed temporary lack of callers does not trigger +`link()` cleanup. Keep this candidate unconfirmed rather than backporting the +Chapter 25 lookup change on textual differences alone. + ## Deferred until the Chapter 25 split ### Deterministic inlining |