Passing scalars by reference about principia

[pleroy]

Interesting analysis. It's particularly nice that clang is able to do a tail call on 64-bit.

FWIW we don't care about 32-bit in this day and age. We must support the architecture. but we surely won't optimize for it.

[pleroy]

Tried to do that on Visual Studio and the n-body benchmark got worse by 3x. Revisit if/when we use clang for code generation or generate code for a 64-bit architecture.

Benchmarking on 1 X 3310 MHz CPU
2014/10/11-20:15:14
Benchmark                              Time(ns)    CPU(ns) Iterations
---------------------------------------------------------------------
BM_SolarSystemMajorBodiesOnly         66533596492  66331625200          1                                 1.0002759262678920e+00 ua
BM_SolarSystemMinorAndMajorBodies    142212392068 141680108200          1                                 1.0002759263137868e+00 ua
BM_SolarSystemAllBodiesAndOblateness 159236476875 158840218200          1                                 1.0002759263001231e+00 ua