bswap: Fix up a thinko with empty CONSTRUCTORs [PR98378]
The code I've added recently in find_bswap_or_nop for VECTOR CONSTRUCTORs
is missing punt on an important case - namely empty CONSTRUCTORs, because in that
case the loop will not initialize *n and the code after the loop will then
use the uninitialized structure.
2020-12-19 Jakub Jelinek <jakub@redhat.com>
PR tree-optimization/98378
* gimple-ssa-store-merging.c (find_bswap_or_nop): Punt if CONSTRUCTOR
has no elements.