Question about inter-thread stack references

If a process has two or more threads running in it, what are the rules
regarding one thread referencing memory in a different thread's stack?


In the usual way that paging hardware works both stacks can be made
visible to both threads, but interstack visibility could also be
prevented (assuming that stacks occupied whole pages). However, if a
stack object can be referenced by a concurrent thread running in another
core then it becomes impossible to optimize and move stack objects into
registers because they might be referenced at any time. Even if the
program were required to declare such data volatile there would still be
locking needed.


I vaguely (so vague that I can't find citations) remember that on some,
possibly legacy, hardware it was physically impossible to do
inter-thread stack accesses; stacks were strictly per-thread and
private. I also vaguely recall that some languages (or thread packages)
banned the practice even if it were physically possible.


Is anyone aware of language/thread package/hardware rules about required
semantics for such usage? Is it explicitly permitted, explicitly banned,
stated to be implementation defined, stated to be undefined, or simply
not mentioned?


Thanks for your help.


Ivan

Return to the comp.compilers page.
Search the comp.compilers archives again.