On Saturday, 23 November 2019 at 09:51:13 UTC, Sebastiaan Koppe
wrote:
This is my proposal for porting D runtime to WebAssembly. I
would like to ask you to review it. You can find it here:
https://gist.github.com/skoppe/7617ceba6afd67b2e20c6be4f922725d
On the GC part. It says "The only unknown part is how to dump the
registers to the stack to ensure no pointers are held in the
registers only."
Please correct me where I'm wrong, but on the level of
WebAssembly there are no registers, there is an operand stack
outside the address space, there are local variables to the
current function, again outside the accessible address space of
program's linear memory, and there is the linear memory itself.
So scanning the stack becomes a really hard (should I say
impossible?) part. What some compilers do is they organize
another stack manually in the linear memory and store the values
that would otherwise be on the normal stack, there. Which means
in case of D you'll have to seriously change the codegen, to
change how local variables are stored, and to use a kind of
shadow stack for temporaries in expressions that may be pointers.
Do you really have a plan about it?
