Hi,

These weeks I fixed the final bugs of the new _d_arraycatnTX hook. When cleaning up the code, Razvan and I took a closer look at the extra lines produced by -profile-gc. They are referring to the new _d_arraycatnTX and seemed to indicate that it allocates some extra memory. In this forum post I asked how to deal with them. Following Max's advice, I did some digging and 2 things turned out:

1. the old hook uses a private function called __arrayAlloc() to allocate the concatenated array, which is not instrumented, whereas the new one simply sets the .length of the resulting array. This expression is further lowered to _d_arraysetlengthT and this hook is instrumented. It is possible that this is the cause of the differences.

2. My implementation of _d_arraycatnTXTrace() was buggy. This caused some unnecessary bytes to be allocated. After fixing this, I'll be able to better look into point 1 from above and be more certain regarding the newly added lines when -profile-gc is enabled.

Regarding _d_newitemU, we decided it would be more rational to move more of the lowering logic to the hook, as DRuntime already handles struct and context pointer initialisation in copyEmplace(). I am going to use the same logic in the new _d_newitemT (instead of _d_newitemU) hook, together with calling the struct's ctor. What's problematic with this approach is that I need to make the compiler create a "dummy" object before calling _d_newitemT, so the lowering would look like this:

// original expression:
S* s = new S(args);

// lowering:
S* s = (void[0] ctxPointerTmp, _d_newitemT!S(ctxPointerTmp))

I would like to be able to obtain the context pointer in the frontend of the compiler without having to allocate any other objects. I asked about this in this forum. I am looking forward that the community will help me find a cleaner solution.

Thanks,
Teodor

On Tuesday, 29 November 2022 at 21:04:22 UTC, rikki cattermole wrote:

Absolutely. All these PRs add new template hooks and also remove the old ones.
And most of the old hooks are in rt. For example, all the old hooks I am working to replace now are in rt/lifetime.d.