Add a SequenceToOffsetTable to TableGen.

This is similar to the StringToOffsetTable we use to produce string
tables, but it can be used for other sequences than strings, and it
eliminates entries for suffixes.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153760 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed