[PATCH] [ARM] Do not select SMULW[BT] or SMLAW[BT]

[Oliver Stannard]

Thanks, committed as r220196.

I don't have any immediate plans to work on http://llvm.org/bugs/show_bug.cgi?id=21297, as I don't expect that pattern to appear often in real C code.

http://reviews.llvm.org/D5824