Yeah, you're wrong. :) I mean, sure, people exaggerate how important ISA is but it is important. Especially if your instruction set is heavily intertwined with a bunch of characteristics of various subsystems (e.g. memory). Size of the decoder, your ability to hide latency (which you pay for with caches and yet more logic), bandwidth cost for most of the crappy user more code - that drains power. It's not "OMG 10x costlier" but it adds up in terms of power and space.
Today it probably matters little. But 5-10 years ago it did matter. And x86 was magically worse than ARM simply by not being ARM. Sure, ARM proper w/o thumb would do nothing but ultimately savings simplicity brought to the table paid off. Today power is less of an issue and manufacturers (esp. low- and mid-end ones) care about space the most.
And sure, if Intel weren't addicted to margins they'd demolish ARM. And this, not architecture, causes their pains today. But as much as I love you man (signed copy of Inside... is one of my most treasured possessions), your "no ARM performance elves" is just way too simplistic a view.
I said that it mattered years ago, and doesn't matter now. Also, I wasn't talking about backwards compatibility, at least not directly. ISA matters a great deal for compatibility and software, but not at all for performance as of the past decade or so. None of the x86 lock-in tactics I describe above would be possible if ISA didn't matter at all -- it just doesn't matter for performance/watt.
Today it probably matters little. But 5-10 years ago it did matter. And x86 was magically worse than ARM simply by not being ARM. Sure, ARM proper w/o thumb would do nothing but ultimately savings simplicity brought to the table paid off. Today power is less of an issue and manufacturers (esp. low- and mid-end ones) care about space the most.
And sure, if Intel weren't addicted to margins they'd demolish ARM. And this, not architecture, causes their pains today. But as much as I love you man (signed copy of Inside... is one of my most treasured possessions), your "no ARM performance elves" is just way too simplistic a view.