On Monday, 9 May 2022 at 00:25:43 UTC, H. S. Teoh wrote:
In the past, the argument was that write barriers represented an unacceptable performance hit to D code. But I don't think this has ever actually been measured. (Or has it?) Maybe somebody should make a dmd fork that introduces write barriers, plus a generational GC (even if it's a toy, proof-of-concept-only implementation) to see if the performance hit is really as bad as believed to be.
Implementing write barriers in the compiler (by instrumenting code) means that you're no longer allowed to copy pointers to managed memory in non-D code. This is a stricter assumption that the current ones we have; for instance, copying a struct (which has indirections) with memcpy would be forbidden.
