Out of memory during compilation

[Matt Gamble]

I have a large program (for me) with several thousand lines of 
code. Recently when I've tried to compile under debug (-g 
-unittest)  with VS2017, dmd2.076.1, windows 10, 8Gb ram), I've 
had the following output:

Compiling SKaTERoptimizerD.d...
Fatal Error: Out of memory
Building x64\Debug\SKaTERoptimizerD.exe failed!

When compiled under release (-O -release -inline 
-boundscheck=off) mode it works fine.

Any advice on how to combat this? Do I need to start compiling 
DLLs? Does that change how the linking would be done? Would that 
affect the debugger?

Any help is appreciated,
Matt