Richard Kenner wrote:
Right, but it would seem this is a good canididate for combination. This is especially true since often Volatile is used with the sense of Atomic in Ada, and it is not a bad idea to combine these in practice, giving an atomic update (right, nothing in the language requires it, but it is definitely useful!)I don't disagree that "this" is a good candidate for combination, but one problem is that by the time you're at that level, you don't easily have the source correspondance you want. E.g., y |= 2; and t1 = y | 2; y = t1; are very hard to tell apart at the RTL level. Though it's clear that a single instruction might best match the expect semantics of the former, it's a lot less clear that it would for the latter.
I think it would still be OK for the latter, why not?
