On Sunday, 15 August 2021 at 16:49:22 UTC, Paul Backus wrote:
On Sunday, 15 August 2021 at 07:10:17 UTC, JG wrote:
Hi,
This is exactly the behaviour I was trying to obtain.
It however comes with a fair amount of overhead, as can be
seen in the following llvm ir:
[...]
I'm not really familiar with llvm ir, but looking at it on
godbolt, it seems like the main difference is that taking the
address of `s.x` forces the compiler to place `s` in memory,
rather than keeping it entirely in registers:
https://d.godbolt.org/z/1afbsM6fv
The function `std.stdio.writeln!(example.Ref!(int))` is not
trivial. I doubt there is a reasonable
optimization/transformation path from a call to
`std.stdio.writeln!(example.Ref!(int))` to a call to
`std.stdio.writeln!(int).writeln(int)`.
Without being able to simplify it to that call, `s` has to be put
in memory. It's the opaqueness of
`std.stdio.writeln!(example.Ref!(int))` and that it (must) takes
the address of `s.x` as parameter.
-Johan
