Avoid andn and generate shorter not;and with -Oz on x86.

Avoid andn and generate shorter not;and with -Oz on x86.

The x86 instruction encoding for SImode andn is longer than the
equivalent notl/andl sequence when the source for the not operand
is the same register as the destination.  This patch adds post_reload
splitters to i386.md to avoid "-mbmi" (which enables andn) increasing
code size with "-Oz".

One minor subtlety with this patch is that the splitter for
*andn_si_ccno swaps the order of operands (match_dup 2 and match_dup 3)
as memory operands need to appear first in *test<mode>_1 patterns.

2022-05-18  Roger Sayle  <roger@nextmovesoftware.com>

gcc/ChangeLog
	* config/i386/i386.md (define_split):  Split *andsi_1
	and *andn_si_ccno after reload with -Oz.

gcc/testsuite/ChangeLog
	* gcc.target/i386/bmi-andn-3.c: New test case.