[x86] add test to show missing optimization

This should make it clearer how this proposed patch:
http://reviews.llvm.org/D11393
...will change codegen.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@262875 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed