[LIR] General refactoring to simplify code and the ease future code review.

Move several checks into isLegalStores. Also, delineate between those stores
that are memset-able and those that are memcpy-able.

http://reviews.llvm.org/D15683
Patch by Haicheng Wu <haicheng@codeaurora.org>!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@256336 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed