What does this mean?
When AMD's Bulldozer four-module, eight-core architecture was first announced, the provided figures suggested that the FX-8150 was constructed of two billion transistors. AMD has since revised this figure down to a 'meagre' 1.2 billion transistors.
Well, for starters it means that the Bulldozer architecture isn't a lost cause when it comes to design efficiency. With the previous two-billion figure, the FX-8150 would have had almost double the transistor count of Intel's hex-core Core i7 990X, even though it had struggled to hold its own when benchmarked against the Intel competition. A figure of 1.2bn suggests that AMD did indeed manage to cut down on core logic and successfully share processing components in the new design, to good effect, as promised.
On the other hand this raises several questions. Had AMD been using a wasteful, heavily-automated system for layout of its architecture? If so are two billion transistors actually present on the die but simply not all in use? Given the die area this seems unlikely but possible, or perhaps AMD had initially intended to have more on-die cache? Was this related to manufacturing troubles at GlobalFoundries? Does all this mean that there's a good level of wiggle room for future optimisation of the architecture?
So many questions, so few answers, as AMD's official response to the matter remains that the firm was simply correcting a mistake and that the previous 2.0 figure had been a rough early estimate. 800m transistors: that's some mistake.