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- code generation that are correct for sequential programs may have incorrect semantics for concurrent programs
- solutions that make correctness guarantees state potentially unreasonable requirements for the library designer and end programmer
- by forbidding optimization, performance gains are lessened, which is often the reason for concurrency in the first place
- requiring explicit deactivation of optimizations requires deep knowledge of the compiler, its optimizations, and may result is wildly different behaviour and correctness guarantees depending on the compiler implementation
- the conclusion of this paper is that concurrency is a linguistic feature that affects code generation
- compiler loads variables into a register, then data modification doesn't get written back to the variable as needed and other threads won't see the changes
- Dekker's and Petersons' algorthims (software solutions) use assignment
- compiler might reorder instructions for optimization, which may cause reordering at the boundaries of critical sections
- requires explicit language facilities (
volatile) or concurrency constructs to disable optimization
- instruction substitution (for multiple) can turn atomic operations into non-atomic operations