On Monday, 31 January 2022 at 08:54:16 UTC, Patrick Schluter wrote:

One of the historical reasons for favoring -O2 optimization level over -O3 was the necessity for Linux distributions to fit on a CD or DVD. Also if everyone is using -O2 optimizations, then -O3 optimizations get a lot less testing coverage and are more likely to have compiler bugs. This makes -O2 even more attractive for those, who prefer safety and stability...

I think that it's a good thing that LDC is breaking out of this -O2 vs. -O3 dilemma by just mapping "-O" option to -O3 ("aggressive optimizations"):

Setting the optimization level:
  -O                                   - Equivalent to -O3
  --O0                                  - No optimizations (default)
  --O1                                  - Simple optimizations
  --O2                                  - Good optimizations
  --O3                                  - Aggressive optimizations
  --O4                                  - Equivalent to -O3
  --O5                                  - Equivalent to -O3
  --Os                                  - Like -O2 with extra optimizations for size
  --Oz                                  - Like -Os but reduces code size further

I wonder if GDC can do the same?

On Monday, 31 January 2022 at 10:33:49 UTC, Siarhei Siamashka wrote:

GDC as a front-end doesn't dictate what the optimization passes are doing, nor does it have any real control what each level means. It is only ensured that semantic doesn't break because of an optimization pass.