I am looking for opinions on how to create a code sequence that is written in "C" that must be performed as an uninterruptable sequence. I want to disable interrupts (globally) execute a code sequence and then re-enable interrupts. I am looking for your inputs as I don't see how to guarantee this from what I know about the "C" standard. I think the compiler is allowed to optimize the sequence so that the actual linear code could be placed outside my expected enable interrupt and disable interrupt sequence (start/end points). The compiler knows that the enable/disable of the interrupt is volatile and must be performed but it doesn't know that there is an architectural dependency to the code order I want. In other words it could be that part of my sequence gets optimized outside of where the interrupt is not globally disabled. As the opcode creation behavior is still correct but it is not from a system behavior point of view.
Outside of writing it in assembly has anyone experienced this and how did you end up handling it. Thanks in advance for your inputs.
Processors with multiplie cores or intended to share memory has special instructions to force synchronization of cache contents, to make sure that writes aren't stuck in pipelines.
But that is a very different issue from the single-processor problem of synchronizing several software threads, or a main thread and an interrupt handler.
But in both situations, you often end up needing the use of assembler, to create code blocks that the compiler just can't fiddle with. And you need a "dumb" linker that doesn't try to reorder or rewrite code.