aarch64: Fix up 2 other combine opt regressions vs. GCC8 [PR100075]

aarch64: Fix up 2 other combine opt regressions vs. GCC8 [PR100075]

The testcase used to be compiled at -O2 by GCC8 and earlier to:
f1:
        neg     w1, w0, asr 16
        and     w1, w1, 65535
        orr     w0, w1, w0, lsl 16
        ret
f2:
        neg     w1, w0
        extr    w0, w1, w0, 16
        ret
but since GCC9 (r9-3594 for f1 and r9-6926 for f2) we compile it into:
f1:
        mov     w1, w0
        sbfx    x0, x1, 16, 16
        neg     w0, w0
        bfi     w0, w1, 16, 16
        ret
f2:
        neg     w1, w0
        sbfx    x0, x0, 16, 16
        bfi     w0, w1, 16, 16
        ret
instead, i.e. one insn longer each.  With this patch we get:
f1:
        mov     w1, w0
        neg     w0, w1, asr 16
        bfi     w0, w1, 16, 16
        ret
f2:
        neg     w1, w0
        extr    w0, w1, w0, 16
        ret
i.e. identical f2 and same number of insns as in GCC8 in f1.
The combiner unfortunately doesn't try splitters when doing 2 -> 1
combination, so it can't be implemented as combine splitters, but
it could be implemented as define_insn_and_split if desirable.

2021-04-16  Jakub Jelinek  <jakub@redhat.com>

	PR target/100075
	* config/aarch64/aarch64.md (*neg_asr_si2_extr, *extrsi5_insn_di): New
	define_insn patterns.

	* gcc.target/aarch64/pr100075.c: New test.