i386: Eliminate sign extension after logic operation [PR89954]

i386: Eliminate sign extension after logic operation [PR89954]

Convert (sign_extend:WIDE (any_logic:NARROW (memory, immediate)))
to (any_logic:WIDE (sign_extend (memory)), (sign_extend (immediate))).
This eliminates sign extension after logic operation.

2021-09-30  Uroš Bizjak  <ubizjak@gmail.com>

gcc/
	PR target/89954
	* config/i386/i386.md
	(sign_extend:WIDE (any_logic:NARROW (memory, immediate)) splitters):
	New splitters.

gcc/testsuite/
	PR target/89954
	* gcc.target/i386/pr89954.c: New test.