[llvm] r182991 - X86: change MOV64ri64i32 into MOV32ri64

[Tim Northover]

> X86: change MOV64ri64i32 into MOV32ri64

Hmm, it seems this broke the gdb 7.5 bot:
http://lab.llvm.org:8011/builders/clang-x86_64-ubuntu-gdb-75/builds/5399.

It looks like the test itself is dodgy: it consists of a few inline
asm blocks, marked to clobber %eax and so on. However, it expects the
compiler won't use those registers in *between* either. Previously
this was true, but now on -O0 instead of:
    movl $data, %r9d
we produce:
    movl $data, %eax
    movl %eax, %r9d

The extra instruction goes away (as it should) at higher
optimisations, and I think it's perfectly valid, but the test doesn't
like it.

Can we XFAIL individual tests on this gdb7.5 bot, or do we usually do
something else? I can't believe this hasn't come up before.

Cheers.

Tim.