Comment Re:This is a response to RISC-V (Score 1) 63
Somehow you have the impression that MIPSfpga is Release 6 - it is not.
Thanks for clarifying. There was nothing in the web page to indicate this (a fairly common omission on ImagTec blog postings, by the way).
Although you are correct that the ISA has been updated in Release 6, the instructions that have been removed are really old and not used by existing software
I'm sorry, but that's complete nonsense. All of the branch-likely instructions were removed and replaced by the compact branches. These are emitted by gcc and are very common in gcc-compiled code (which appears to use them when it can't find an instruction to fill the delay slot with). Trust me on this - I spend a huge amount of my life looking at objdump output from MIPS binaries and instruction traces.
Even so, we still have trap and emulate mechanisms that ensure we do not break compatibility.
No you don't. You reused the opcodes, unless there's a newer version of the spec than the one I've seen.