[DAG] extractShiftForRotate - Assertion `(OppShift.getOpcode() == ISD::SHL || OppShift.getOpcode() == ISD::SRL) && "Existing shift must be valid as a rotate half" #57474
Description
Pulled out of #57283
define void @f() {
BB:
br label %BB1
BB1: ; preds = %BB
%A = alloca <1 x i16>, align 2
%L1 = load <1 x i16>, <1 x i16>* %A, align 2
%I = insertelement <1 x i16> %L1, i16 -1, i16 0
%B6 = add <1 x i16> %I, %I
%B3 = srem <1 x i16> %B6, %I
%B1 = add <1 x i16> %B3, %B3
%B5 = sdiv <1 x i16> %B1, %I
%B4 = udiv <1 x i16> %B3, <i16 -32768>
%B2 = or <1 x i16> %B4, %B5
%B = lshr <1 x i16> <i16 -32768>, %B2
store <1 x i16> %B, <1 x i16>* %A, align 2
ret void
}