Garbage Collector profiling and the dynamic array reserve() function

[bauss]

On Wednesday, 18 October 2017 at 15:39:43 UTC, Steven 
Schveighoffer wrote:
> On 10/18/17 1:40 AM, Tony wrote:
>> On Tuesday, 17 October 2017 at 13:27:24 UTC, Steven 
>> Schveighoffer wrote:
>> 
>>>
>>> I don't know what "allocations" represents, but reserve 
>>> actually calls gc_malloc, and the others do not (the space is 
>>> available to expand into the block). There should be only one 
>>> allocation IMO.
>>>
>> 
>> So there should be a bug report written for this?
>> 
>
> It all depends on what "allocations" means. I'd wait to find 
> out from someone who is familiar with the GC profiling.
>
> -Steve

I don't have a lot of clues on how the GC profiling work, but 
looking at reserve() it calls mem.xmalloc() for allocations which 
in fact calls GC.malloc().

Looking at the profiling for GC though:
https://github.com/dlang/dmd/blob/69567a32c5bffae5513b41e7691c91b50766b552/src/ddmd/e2ir.d#L5952

It doesn't look like there's anything for array reserve calls, 
unless:
  [ RTLSYM_ALLOCMEMORY, RTLSYM_TRACEALLOCMEMORY ]
are triggered from the allocations done in reserve(), but I have 
no idea about that.