agra 837b5d375f fix(0124): large stack arrays lower to in-place access, not first-class values ...

Two lowering sites materialized a local array as a whole LLVM value;
the legalizer scalarizes each such op into one SelectionDAG node per
element, and at ~64K elements the DAG combiner segfaults
(DAGCombiner::visitMERGE_VALUES → ReplaceAllUsesWith).

- lowerVarDecl: an array-typed `---` initializer emits NO store — the
  slot stays uninitialized instead of receiving a whole-array undef
  store. The tuple zero-init carve-out stays; non-array `---` keeps
  the undef store. The interp is unchanged either way (slots start
  .undef).
- lowerIndexExpr: element reads on an array with addressable storage
  GEP the storage and load one element — the general-expression
  sibling of 0110's lowerFor fix — without value-lowering the object
  (a dead whole-array load would still reach the DAG). Storage-less
  arrays keep the index_get fallback.

Sibling shape filed as 0125: any_to_string's per-array-type arms still
pass the array by value, so a 64K+ array type + any {} print crashes.

Regression: examples/0055-basic-large-stack-array.sx (sx build
segfaulted pre-fix). 22 .ir snapshots re-pinned: removed undef stores
and ig.tmp spills, in-place gep+load (instruction-shape-only churn,
reviewed).

2026-06-12 08:19:20 +03:00

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