My choice to pick Go over D ( and Rust ), mostly non-technical

[H. S. Teoh]

On Tue, Feb 06, 2018 at 09:44:16PM +0000, Ralph Doncaster via Digitalmars-d wrote:
[...]
> Although I'm new to D, I do know crypto quite well, and especially
> sha3/keccak.  One reason I considered porting was to see if dmd outputs
> better code than gcc.  On x86_64 with the xmm registers there is enough room
> for 1600 bits of the keccak state to be stored in registers, but gcc 5.4
> will still use RAM for the state.  It stays in L1, but storing all the state
> in registers should be much faster as it would avoid a lot of mov
> instructions loading parts of the state into registers.

Don't have high expectations of dmd's codegen. If you're looking for
highly-optimized codegen, you want to be using ldc or gdc instead.
In my own projects, I routinely find that executables produced by dmd
are about 30-50% slower than executables produced by gdc or ldc.

What dmd is very good at is lightning fast compilation, and also having
the latest and greatest D features, being the reference compiler and all
that.  However, it's optimizer leaves much to be desired.  For
performance-sensitive code, my recommendation is, don't even bother with
dmd.  That's not to say that dmd codegen is bad; it's pretty decent for
your average non-performance-sensitive GUI app. But it doesn't hold a
candle to gdc/ldc, especially when it comes to loop optimizations.


T

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