Add a spiller option to llc. A simple spiller will come soon. When we get CFG in the machine code represenation a global spiller will also be possible. Also document the linear scan register allocator but mark it as experimental for now.

llvm-svn: 12062

llvm-svn: 12058

that they are as far away from the loads as possible.

llvm-svn: 11895

llvm-svn: 11892

MRegisterInfo::is{Physical,Virtual}Register.

llvm-svn: 11849

to objects.

llvm-svn: 11840

allocator.

The implementation is completely rewritten and now employs several
optimizations not exercised before. For example for 164.gzip we have
997 loads and 699 stores vs the 1221 loads and 880 stores we have
before.

llvm-svn: 11798

251 (providing a generic machine code rewriter/spiller).

llvm-svn: 11780