I am a little confused by your answer. While you see the
bb instruction as a herald instruction, hinting to the processor that a branch is coming, I see it more as a hint to the processor that the next block of instructions is a basic block. So, the instruction’s intent, to me, is to recreate a fundamental aspect of the Mill’s operation: that it computes on basic blocks (however, the Mill doesn’t do so for the same reason: it requires the compiler to optimize the data flow a priori, and uses the basic blocks for exit prediction and split-stream encoding). Or, am I missing something basic from my skim over the paper?
Reply To: Meltdown and Spectre Thomas D