Hacker News Reader

There's little benefit in going substantially wider than Cyclone, but there's still a ton of room to improve performance.

Didn't AMD, and Intel more or less say the same thing about 3 wide? No real benefit from going wider. Is that because of the differences in micro architecture or is it more about getting a little more performance without having to ramp the clock speed? What makes 6 wide good for ARM but not x86 or x64?

View on HN

This is probably completely and utterly wrong as it's just a guess, but potentially the Thumb [1] instructions (small, limited subset of shorter instructions in ARM) might allow for a wider setup. Thumb instructions make a bunch of simplifying assumptions that might remove some of the issues with going wider. Not that I have any idea if Cyclone even supports them in the first place.

[1] http://en.wikipedia.org/wiki/ARM_architecture#Thumb

The biggest wart on the ARM instruction set was the predicate attached to basically every instruction. That's gone in the 64-bit ARM ISA, so there's no need for a 64-bit Thumb (and there isn't one).

Reply on news.ycombinator.com