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That' s funny, you are posting this exact same message in every RISC-V news I read. > It is hard to understand how it could have been omitted. This has not be

That' s funny, you are posting this exact same message in every RISC-V news I read. > It is hard to understand how it could have been omitted. This has not been omitted at all. The spec of the bitmanip extension, which contains the popcount instruction among others, has been around for a long time. > If it could be evolved to have POPCOUNT The goal of the HPC group is clearly not to add this type of extension. It focuses on the software and hardware requirements to enable the use of RISC-V for HPC. So it will focus on compilers and libraries used for high performance and possibly some ISA extension like the SIMD one or the crypto acceleration one. But you'll probably be happy to know that there's actually some movement around the bitmanip extension right now. The spec 1.0 is under review and we can expect a freeze of this extension soon. And this extension is split into 4 sub-extensions that can be taken individually.

brucehoult 5y ago
BitManip consists of more than four ISA extensions, but only the first four are being ratified at the moment. Those four extensions (including Zbc which contains popcount) are frozen in terms of the Task Group, and are in a 45 day public review period. In theory public review could cause some change, but really it's highly unlikely as the instructions in these four extensions are uncontroversial and conventional with a lot of existing experience from other ISAs. Also it's very easy for anyone with interest and expertise to have joined RISC-V International as a no-fee individual member and joined the Task Group during the last couple of years to put their point of view. But really BitManip has far less room for disagreement than the Vector extension, which should enter public review in a few weeks. Ratification should take place very soon after the end of the public review period.
- avianes 5y ago
  Thank you for your notes ! I saw a few months ago that there were more than 4 extensions in BitManip, but when I recently checked the github page only 4 were left. Is there a better source of information than the github page to know the development status of an extension? > But really BitManip has far less room for disagreement than the Vector extension Yes I've heard lots of criticism about the V extension.

brucehoult 5y ago

BitManip consists of more than four ISA extensions, but only the first four are being ratified at the moment. Those four extensions (including Zbc which contains popcount) are frozen in terms of the Task Group, and are in a 45 day public review period. In theory public review could cause some change, but really it's highly unlikely as the instructions in these four extensions are uncontroversial and conventional with a lot of existing experience from other ISAs. Also it's very easy for anyone with interest and expertise to have joined RISC-V International as a no-fee individual member and joined the Task Group during the last couple of years to put their point of view. But really BitManip has far less room for disagreement than the Vector extension, which should enter public review in a few weeks. Ratification should take place very soon after the end of the public review period.

avianes 5y ago
Thank you for your notes ! I saw a few months ago that there were more than 4 extensions in BitManip, but when I recently checked the github page only 4 were left. Is there a better source of information than the github page to know the development status of an extension? > But really BitManip has far less room for disagreement than the Vector extension Yes I've heard lots of criticism about the V extension.