having the bitcode writer materialize mdnodes for all the
debug location tuples when writing out the bc file and
stores the information in a more compact form. For example,
the -O0 -g bc file for combine.c in 176.gcc shrinks from
739392 to 512096 bytes.
This concludes my planned short-term debug info work.
llvm-svn: 100261
07d09ed49a