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"Just solve it in decoder" is a perfectly valid approach for now, and if this turns out to be unrealistic then they can go ahead and add a conditional move exte
by onjectic 2y ago
"Just solve it in decoder" is a perfectly valid approach for now, and if this turns out to be unrealistic then they can go ahead and add a conditional move extension or whatever it is.
It’s far easier to add things to interfaces than remove them.
One mistake they have made that may bite them later is their compressed instructions extension. It takes up far too much of the instruction set space for the amount of utility it provides, even on microcontrollers in my opinion. It also introduces lots of edge cases around word alignment across cache and memory protection boundaries.
- brucehoult 2y agoPoint of order! The RISC-V C extension takes up 75% of the opcode space. The 16 bit Thumb1 instructions take up 87.5% of the ARMv7 opcode space. Not to mention predication taking up 92.75% of the classic ARMv1-ARMv6 instruction set. RISC-V has comparatively twice as much "32 bit" opcode space as ARMv7, and 3.45x more than classic ARM A32.