Re:Addressing Criticism of RISC-V Microprocessors
by wmf on Sunday March 20, 2022 @02:40PM
(#30745334)
Most of the complaints about RISC-V are extremely basic things like array indexing and conditional execution. These will never not be needed.
Re:Addressing Criticism of RISC-V Microprocessors
by zik on Sunday March 20, 2022 @10:20PM
(#30749334)
The problem is that those criticisms are almost always wrong. For instance the ARM proponents criticise RISC-V for having long instruction encodings and then they quote a few carefully cherry picked examples. But if you look at actual compiled programs RISC-V is nearly always 10-15% smaller than ARM.
Re:Addressing Criticism of RISC-V Microprocessors
by tsmi on Sunday March 20, 2022 @03:39PM
(#30745874)
I’m sure that’s what the team that invented segment registers said too.
The question is does it make sense to add these to the ISA long term? In the short term, given die density and how memory works today, it has advantages. But die density increases, making OoO cores cheaper, and memory technology changes. It’s not obvious that these are long term improvements.
Re:Addressing Criticism of RISC-V Microprocessors
by brucehoult on Sunday March 20, 2022 @07:57PM
(#30748153)
It's not that the examples given are not correct, in isolation, it's that they are not common enough in real code to matter.
One of the most important goals of RISC-V is to make an architecture which can stand the test of time. In this space adding the wrong kind of instructions is a bigger problem than not adding particular instructions.
Whether you look at x86, HTML or just about anything the problem is nearly always about having to support old junk which no longer makes sense to support, or lacking the ability to grow. Remember 640K is enough for everyone? RISC-V has a lot of room to grow.
If you want an architecture for the future you would want a minimalist one with room to grow a lot. By keeping the instruction count very low and building in a system for extensions they have made a future proof ISA. Okay we cannot know the future, but it is more likely to survive for decades than something like x86 or maybe even ARM.