search for: shift_amount

On 7/2/2018 3:16 PM, Sanjay Patel wrote: > I also agree that the per-element rotate for vectors is what we want for > this intrinsic. > > So I have this so far: > > declare i32 @llvm.catshift.i32(i32 %a, i32 %b, i32 %shift_amount) > declare <2 x i32> @llvm.catshift.v2i32(<2 x i32> %a, <2 x i32> %b, <2 x i32> %shift_amount) > > For scalars, @llvm.catshift concatenates %a and %b, shifts the > concatenated value right by the number of bits specified by > %shift_amount modulo the...

1. I'm not sure what you mean by "full vector" here - using the same shift distance for all lanes (as opposed to per-lane distances), or doing a treat-the-vector-as-bag-of-bits shift that doesn't have any internal lane boundaries? If the latter, that doesn't really help you much with implementing a per-lane rotate. I think the most useful generalization of a vector

We have these transforms from funnel shift to a simpler shift op: // fshl(X, 0, C) -> shl X, C // fshl(X, undef, C) -> shl X, C // fshl(0, X, C) -> lshr X, (BW-C) // fshl(undef, X, C) -> lshr X, (BW-C) These were part of: https://reviews.llvm.org/D54778 In all cases, one operand must be 0 or undef and the shift amount is a constant, so I think these are safe.