Hello LLVM Devs,
Hope you are doing well.
I am implementing LLVM back-end for an architecture which has instruction that performs byte by byte comparison and stores result for each byte.
pcmpbf rD, rA, rB → bytewise comparison returning position of first match in rd
So with this regard I wanted to find similar instruction lowering for nay other architecture which have similar instruction.
I found some thing similar on PPC. If I am wrong kindly suggest some example.
I am trying to understand following statement from PPCInstrInfo.td file:
def CMPRB : X_BF3_L1_RS5_RS5<31, 192, (outs crbitrc:$BF),
(ins u1imm:$L, g8rc:$rA, g8rc:$rB),
“cmprb $BF, $L, $rA, $rB”, IIC_IntCompare, >,
Here I am not able to understand against which DAG pattern this gets matched ? By doing grep I don’t get any code which provide me the required info.
Basically I want to know which LLVM IR instruction or intrinsic has similar semantics and then how I can lower it correctly.