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Diffstat (limited to 'skills/chapter25-codex-notes.md')
| -rw-r--r-- | skills/chapter25-codex-notes.md | 7 |
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diff --git a/skills/chapter25-codex-notes.md b/skills/chapter25-codex-notes.md index f16407e7..9b861a18 100644 --- a/skills/chapter25-codex-notes.md +++ b/skills/chapter25-codex-notes.md @@ -757,6 +757,13 @@ Consequences: widen only below-center nonconstant ranges: above-center widening can fall to an unwidened constant, violating SCCP monotonicity. Existing Chapter14/21 tests exposed this during the backport. +- Recursion needs two widening points in Chapters 24-25: ParmNode for arguments, + and CallEndNode for results. The return cycle in `f(x-1)+1` never crosses the + Parm. Keep the comments at both sites and PhiNode cross-linked. Chapter 25's + FunPtrNode follows the live Return range; join that range before widening, + then bound widening by the callee signatures, not that live range. Apply the + same rule before and after linking, and retain narrow results such as i32. + `Chapter24Test.testRecursiveWidening` checks both cycles in both chapters. - TypeConAry's `_make(any,widen)` shares the backing array and returns an uninterned type. `xdual()` must leave interning to Type.intern's dual-pair setup; ordinary factories and ymeet's widening replacement intern their results. |