[mattarm]

I don't think "DMD is a reference compiler and not meant as a production tool" is a great way to characterize it. There are certainly valid reasons for choosing LLVM and GCC for "production", but also valid reasons for choosing DMD.

[anta40]

As far as I know, DMD doesn't offer much optimisations.

So you use DMD for development, and once the testing is done, built the production release with LDC or GDC.

[WalterBright]

DMD does do all the basic data flow analysis optimizations, along with register allocation by coloring, etc.

The problem is there are just a ton of special cases needed to generate good code, especially with the x86 instruction set which is nothing but special cases <g>. Doing these takes a lot of developer time, one by one.