Why many programmers don't like GC?

[welkam]

On Friday, 15 January 2021 at 11:28:55 UTC, Ola Fosheim Grøstad 
wrote:
> On Friday, 15 January 2021 at 11:11:14 UTC, Mike Parker wrote:
>> That's the whole point of being able to mix and match. Anyone 
>> avoiding the GC completely is missing it (unless they really, 
>> really, must be GC-less).
>
> Has DMD switched to using the GC as the default?

No. And it will never will. Currently DMD uses custom allocator 
for almost everything. It works as follows. Allocate a big 
chunk(1MB) of memory using malloc. Have a internal pointer that 
points to the beginning of unallocated memory. When someone ask 
for memory return that pointer and increment internal pointer 
with the 16 byte aligned size of allocation. Meaning the new 
pointer is pointing to unused memory and everything behind the 
pointer has been allocated. This simple allocation strategy is 
called bump the pointer and it improved DMD performance by ~70%.

You can use GC with D compiler by passing -lowmem flag. I didnt 
measure but I heard it can increase compilation time by 3x.

https://github.com/dlang/dmd/blob/master/src/dmd/root/rmem.d#L153