cgassign had dedicated N_DOT-store arms for a local-ptr base, a global
value-struct, and chained bases, but none for a global-pointer scalar
field. That case fell through to the generic cgplaceaddr/dotchainaddr
route, which folds the field offset (ADDQ $foff,BX) then stores to (BX).
cstage emits a single displacement store (MOVQ AX,foff(BX)) via its
via_ptr global scalar arm, so the two stages diverged on asm shape
(rule 10). Both forms are runtime-correct here -- BX is a fresh throwaway
in the generic route -- so this was a byte-id divergence, not a
miscompile.
Add the missing displacement-store arm, predicate-mirroring cstage's
via_ptr global scalar arm exactly: plain assignment only, scalar field
only; non-scalar field types stay on the generic path (their global-ptr
deref is a separate deferred item). glob_ptr_field_test.ww gains an
off-8 row as the regression pin -- offset-0 cannot catch it because
ADDQ $0 is suppressed.
Surfaced by the fold-2 Fam-5 migration.
Hojun-Cho
214ced303f