"What is the minimum number of instructions a compiler could make use of to get everything done that it needs?"
I didn't go for the absolute minimum, but I did aim for useful and reasonable minimum with the ggx[1] ISA (now called moxie[1]) by defining the ISA incrementally and only adding instructions used by GCC.
I didn't go for the absolute minimum, but I did aim for useful and reasonable minimum with the ggx[1] ISA (now called moxie[1]) by defining the ISA incrementally and only adding instructions used by GCC.
The approach I took is described here: [1] https://github.com/atgreen/ggx
[2] http://moxielogic.org/