Don't use floating point to do an integer's job.

Don't use floating point to do an integer's job.

This code makes different decisions when compiled into x87 instructions
because of different rounding behavior.  That caused phase 2/3
miscompares on 32-bit Linux when the phase 1 compiler was built with gcc
(using x87), and the phase 2 compiler was built with clang (using SSE).

This fixes PR11200.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@143006 91177308-0d34-0410-b5e6-96231b3b80d8