Huge memory usage compiling Kernel with clang.

[martyngigg]

This issue was originally TRAC 10700

I was having a quick play with the include-what-you-use tool after merging in the changes from http://trac.mantidproject.org/mantid/ticket/10685 locally. It seems that clang requires about ~12Gb of memory to compile Kernel. It looks as if it is the linking step that ramps up the memory usage.

I don't it's anything to do with those changes but something about the code in Kernel. We should find out why.

It's worth noting that when compiling with gcc the linking step seems to take a disproportionate amount of time to the size of the library.

My suspicion is all of the static objects in Atom.cpp but that's just a guess.

[martyngigg]

@martyngigg (2014-12-06T10:07:01):
Pete, I assigned this to you just because you had http://trac.mantidproject.org/mantid/ticket/10685 and I wanted to make sure we didn't forget about it.

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@NickDraper (2015-04-27T08:10:34):
Moved to R3.5 at the R3.4 code freeze

[DavidFair]

Just done a quick test with my copy of clang 8 locally, compiling Kernel used < 2gb memory so I suspect it was a compiler bug rather than a code-gen issue