[xstormy16] Efficient HImode rotate left by a single bit.

This patch contains some minor tweak to xstormy16's machine description
most significantly providing a pattern for HImode rotate left by a single
bit that requires only two instructions.

unsigned short foo(unsigned short x)
{
  return (x << 1) | (x >> 15);
}

currently with -O2 generates:
foo:    mov r7,r2
        shr r7,#15
        shl r2,#1
        or r2,r7
        ret

with this patch, GCC now generates:
foo:	shl r2,#1 | adc r2,#0
        ret

Additionally neghi2 is converted to a define_insn (so that the RTL
optimizers see the negation semantics), and HImode rotations by
8-bits can now be recognized and implemented using swpb.

2023-04-29  Roger Sayle  <roger@nextmovesoftware.com>

gcc/ChangeLog
	* config/stormy16/stormy16.md (neghi2): Convert from a define_expand
	to a define_insn.
	(*rotatehi_1): New define_insn for efficient 2 insn sequence.
	(*rotatehi_8, *rotaterthi_8): New define_insn to emit a swpb.

gcc/testsuite/ChangeLog
	* gcc.target/xstormy16/neghi2.c: New test case.
	* gcc.target/xstormy16/rotatehi-1.c: Likewise.

0 files changed, 0 insertions, 0 deletions