The x86-64 and aarch64 psABIs (and the unwritten ia64 psABI part) say that
the padding bits of _BitInt are undefined, while the expansion internally
typically assumes that non-mode precision integers are sign/zero extended
and extends after operations. We handle that mismatch with EXTEND_BITINT
done when reading from untrusted sources like function arguments, reading
_BitInt from memory etc. but otherwise keep relying on stuff being extended
internally (say in pseudos).
The return value of a function is an ABI boundary though too and we need
to extend that too.
2024-03-15 Jakub Jelinek <jakub@redhat.com>
PR middle-end/114332
* expr.cc (expand_expr_real_1): EXTEND_BITINT also CALL_EXPR results.