On 17/10/17 13:32, David Brown wrote: > No, you can't - not always. Memory clobbers enforce an ordering on data > that is stored in memory or loaded from memory. They don't affect data > in registers, and they don't affect code execution and calculations. Yes, of course. So you need to insert *artificial* dependencies, as needed, to make the ordering explicit. > And memory clobbers are expensive on many targets, as are alternatives > like making extra volatile variables. But you show in the rest of your mail that you do understand the issue, and some solutions. The "do not perform this expensive operation while interrupts are disabled" problem is indeed tricky because GCC doesn't model time at this level. But there are ways to be explicit, and you evidently know what they are. -- Andrew Haley Java Platform Lead Engineer Red Hat UK Ltd. <https://www.redhat.com> EAC8 43EB D3EF DB98 CC77 2FAD A5CD 6035 332F A671
