[MIPS GlobalISel] Select instructions to load and store i32 on stack

Add code for selection of G_LOAD, G_STORE, G_GEP, G_FRAMEINDEX and
G_CONSTANT. Support loads and stores of i32 values.

Patch by Petar Avramovic.

Differential Revision: https://reviews.llvm.org/D48957


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@337168 91177308-0d34-0410-b5e6-96231b3b80d8
7 files changed