When I converted xstormy16's neghi2 pattern from a define_expand to a
define_insn, I forgot that define_expand implicitly produces a
sequence of instructions, but a define_insn is an implicit parallel,
thereby messing up the clobber (reg:BI CARRY_REG), which can then cause
an ICE in the auto-generated added_clobbers_hard_reg_p.  Whilst stripping
the superfluous PARALLEL resolves this issue, an even better fix is to
use xstormy16's INC instruction, that (like NOT) doesn't affect the carry
flag, resulting in a neghi2 implementation that can more easily be CSE'd
and scheduled.

Many thanks (again) to Jeff Law for testing/reporting this issue.
This patch has been tested by building a cross compiler to xstormy16-elf
from x86_64-pc-linux-gnu.  Committed as obvious (in hindsight).


2023-04-30  Roger Sayle  <roger@nextmovesoftware.com>

gcc/ChangeLog
        * config/stormy16/stormy16.md (neghi2): Rewrite pattern using
        inc to avoid clobbering the carry flag.

gcc/testsuite/ChangeLog
        * gcc.target/xstormy16/neghi2.c: Update expected implementation.

Sorry for any inconvenience.
Roger
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