llvm upgrade: apply applicable old patches

[vtjnash]

A couple have not yet been updated, but this is a start towards updating the patch list Only one is missing now for LLVM 8. LLVM 7 is complete.

Also, this currently fails an offsetarray test. tracked this down to bad TBAA information and fixed it

Needs nanosoldier, and Keno suggested it should have a PkgEval run too.

[vchuravy]

Needs the version bump for windows

[vtjnash]

Almost working now (doesn't need to block merging though).

• One bug in a new X86 pass: https://bugs.llvm.org/show_bug.cgi?id=41629 (just disabled it for now)
• And one bug that I've isolated down to coming out of LICM (it moves a store after its use): https://gist.github.com/vtjnash/8a073c01e0a6e6b29789bb3f7080e72b, but haven't yet been able to trigger this outside of Julia

[vtjnash]

Ah, it wasn't LICM's fault (sorry LICM), someone (emit_select) was creating bad TBAA data for it. We should probably backport that commit fix.

[vchuravy]

Probably separate f826bba out into it's own PR? It currently fails tests:

      From worker 6:	signal (6): Aborted
      From worker 6:	in expression starting at /buildworker/worker/tester_linux32/build/share/julia/test/bitarray.jl:1097
      From worker 6:	gsignal at /lib/i386-linux-gnu/libc.so.6 (unknown line)
      From worker 6:	abort at /lib/i386-linux-gnu/libc.so.6 (unknown line)
      From worker 6:	unknown function (ip: 0xf72780f5)
      From worker 6:	__assert_fail at /lib/i386-linux-gnu/libc.so.6 (unknown line)
      From worker 6:	mark_julia_slot at /buildworker/worker/package_linux32/build/src/codegen.cpp:624
      From worker 6:	mark_julia_slot at /buildworker/worker/package_linux32/build/src/intrinsics.cpp:854 [inlined]
      From worker 6:	emit_ifelse at /buildworker/worker/package_linux32/build/src/intrinsics.cpp:851 [inlined]

Would be good to have the backport for the scev patch for LLVM 8, otherwise LGTM.

cc: @banex19 since this might impact you.

[Keno]

https://gist.github.com/Keno/0107cea84de827845d204fc398d877ff for a llvm 8.0 version of the scev patch. It's a backport of the current state of the review rather than a forward port of the current patch, FYI.

[vchuravy]

LGTM

[vchuravy]

cc: @maleadt