"General comment: this may sound weird, but in the long term, it might
be easier to deal with a really complicated bunch of instruction
formats, than with a complex set of addressing modes, because at least
the former is more amenable to pre-decoding into a cache of
decoded instructions that can be pipelined reasonably, whereas the pipeline
on the latter can get very tricky (examples to follow)."
So the distinction is more about how 'easy' an ISA lends itself to pipelining (critical paths, dependencies between instructions/operands & so on), than about how rich the instruction set is or how much work 1 instruction may do.
Comments
As the article explains:
"General comment: this may sound weird, but in the long term, it might be easier to deal with a really complicated bunch of instruction formats, than with a complex set of addressing modes, because at least the former is more amenable to pre-decoding into a cache of decoded instructions that can be pipelined reasonably, whereas the pipeline on the latter can get very tricky (examples to follow)."
So the distinction is more about how 'easy' an ISA lends itself to pipelining (critical paths, dependencies between instructions/operands & so on), than about how rich the instruction set is or how much work 1 instruction may do.