correctly: skipping instructions by incorrectly incrementing the pointer.

Also adds support for building a reg-to-regclass map, and splits the function
for saving register to stack into two, one suitable for virtual registers
(which also assigns it a physical register) and one for simply storing back
physical registers.

llvm-svn: 4898

* Added saving of register values to the stack

llvm-svn: 4858

llvm-svn: 4828