People are rehashing the same myths about ISA written 25 years ago.
Variable length instructions are not a significant impediment in high wattage cpus (>5W?). The first byte of an instruction is enough to indicate how long an instruction is and hardware can look at the stream in parallel. Minor penalty with arguably a couple of benefits. The larger issue for CISC is that more instructions access memory in more ways so decoding requires breaking those down into micro-ops that are more RISC like, in order that the dependencies can get worked out.
RISC already won where ISA matters -- like AVR and ARM thumb. You have a handful of them in a typical laptop plus like a hundred throughout your house and car, with some PIC thrown in for good measure. So it won. CISC is inferior. Where ISA matters it loses. Nobody actually advocates for CISC design because you're going to have to decode it into smaller ops anyway.
Also variable length instruction is not really a RISC vs CISC thing as much as also a pre vs post 1980 thing. Memory was so scarce in the 70s that wasting a few bits for simplicity sake was anathema and would not be allowed.
System performance is a lot more than ISA as computers have become very complicated with many many I/Os. Think about why American automakers lost market share at the end of last century. Was it because their engineering was that bad? Maybe a bit. But really it was total system performance and cost of ownership that they got killed on, not any particular commitment to a solely inferior technical framework.
Variable length instructions are not a significant impediment in high wattage cpus (>5W?). The first byte of an instruction is enough to indicate how long an instruction is and hardware can look at the stream in parallel. Minor penalty with arguably a couple of benefits. The larger issue for CISC is that more instructions access memory in more ways so decoding requires breaking those down into micro-ops that are more RISC like, in order that the dependencies can get worked out.
RISC already won where ISA matters -- like AVR and ARM thumb. You have a handful of them in a typical laptop plus like a hundred throughout your house and car, with some PIC thrown in for good measure. So it won. CISC is inferior. Where ISA matters it loses. Nobody actually advocates for CISC design because you're going to have to decode it into smaller ops anyway.
Also variable length instruction is not really a RISC vs CISC thing as much as also a pre vs post 1980 thing. Memory was so scarce in the 70s that wasting a few bits for simplicity sake was anathema and would not be allowed.
System performance is a lot more than ISA as computers have become very complicated with many many I/Os. Think about why American automakers lost market share at the end of last century. Was it because their engineering was that bad? Maybe a bit. But really it was total system performance and cost of ownership that they got killed on, not any particular commitment to a solely inferior technical framework.