https://github.com/llvm-mirror/llvm/blob/master/lib/AsmParser/LLParser.cpp https://github.com/llvm-mirror/llvm/blob/master/lib/AsmParser/LLParser.h
https://github.com/llvm-mirror/llvm/blob/master/utils/llvm.grm
https://github.com/llvm-mirror/llvm/tree/master/lib/AsmParser
https://github.com/llvm-mirror/llvm/blob/master/lib/AsmParser/LLToken.h
https://github.com/llvm-mirror/llvm/blob/master/lib/AsmParser/LLLexer.cpp https://github.com/llvm-mirror/llvm/blob/master/lib/AsmParser/LLLexer.h
also should look at the remarks in LLVM Language Reference Manual http://llvm.org/docs/LangRef.html
and http://augustss.blogspot.com/2009/01/llvm-llvm-low-level-virtual-machine-is.html by lennar augustsson is a good exposition of the llvm hs lib