Re: Memory ordering

On Tue, 3 Dec 2024 23:37:41 +0000, Stefan Monnier wrote:

                                          If there are places
in the code it doesn't know this can't happen it won't optimize
across it, more or less.

>
The problem is HOW to TELL the COMPILER that these memory references
are "more special" than normal--when languages give few mechanisms.

>
We could start with something like
>
    critical_region {
      ...
    }

In the spirit of Fortran rule about obeying parenthesis; one could
write::
     {
       ...
     }
and the compiler would not allow code motion beyond the {s or }s.
{{You may want to disable code motion even when the region is not
critical--just dangerous in some way.}}

such that the compiler must refrain from any code motion within
those sections but is free to move things outside of those sections as
if execution was singlethreaded.

You identify a second problem. Is it that you don't want code motion
across the boundary or you do not want code motion within the boundary??

>
        Stefan