For now, PowerPC will using several instructions to get the constant and "and" it with the following case:
define i32 @test1(i32 %a) {
%and = and i32 %a, -2
ret i32 %and
}
However, we could exploit it with the rotate mask instructions.
MB ME
+----------------------+
|xxxxxxxxxxx00011111000|
+----------------------+
0 32 64
Notice that, we can only do it if the MB is larger than 32 and MB <= ME as
RLWINM will replace the content of [0 - 32) with [32 - 64) even we didn't rotate it.
Differential Revision: https://reviews.llvm.org/D71829
QingShan Zhang