On 08/15/2014 08:34 AM, Richard Henderson wrote: > On 08/11/2014 09:23 AM, Tom Musta wrote: >> The rlwinm specification includes the ROTL32 operation, which is defined >> to be a left rotation of two copies of the least significant 32 bits of >> the source GPR. >> >> The current implementation is incorrect on 64-bit implementations in that >> it rotates a single copy of the least significant 32 bits, padding with >> zeroes in the most significant bits. > > Yes, it does describe rotate_32 as a double-copy of the low 32 bits. But it > also describes the mask as having "0 bits elsewhere". Thus, post mask, I > don't > see how you could distinguish the implementations. > > Have you an example that doesn't work with the current code?
Let me guess the answer myself -- it's MB > ME, and wraparound of the mask. I think I was distracted by the text "For all the uses given above, the high-order 32 bits of register RA are cleared." without clearly reading the examples. r~
