CodeGen: enable mov.w/mov.t pairs with minsize for WoA

Windows on ARM uses COFF/PE which is intrinsically position independent.  For
the case of 32-bit immediates, use a pair-wise relocation as otherwise we may
exceed the range of operators.  This fixes a code generation crash when using
-Oz when targeting Windows on ARM.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210814 91177308-0d34-0410-b5e6-96231b3b80d8
[FastIsel][X86] Add support for lowering the first 8 floating-point arguments.

Recommit with fixed argument attribute checking code, which is required to bail
out of all the cases we don't handle yet.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210815 91177308-0d34-0410-b5e6-96231b3b80d8
[FastISel][X86] Argument lowering test case

This test case is supposed to xfail, because we do not handle structs or byval
arguments.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210816 91177308-0d34-0410-b5e6-96231b3b80d8
LangRef: clarify that global declarations can have section and alignment info.

I'm not sure what it means to set a section for a declaration in another
translation unit, but there are some tests in the tree that do it so it seems
to be legal now regardless.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210819 91177308-0d34-0410-b5e6-96231b3b80d8