[docs] Guide prospective TableGen backend writers.

Boilerplate is often the hardest part of getting started with these
kinds of things, so throw them a bone.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@173969 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/docs/TableGenFundamentals.rst b/docs/TableGenFundamentals.rst
index 526795f53d0b4c0e64b070315a1455bf50b33474..4fe4bb986a2f6f81ee498f5961186e310f8a7921 100644 (file)
--- a/docs/TableGenFundamentals.rst
+++ b/docs/TableGenFundamentals.rst
@@ -791,6 +791,10 @@ Expressions used by code generator to describe instructions and isel patterns:
 TableGen backends
 =================
 
+Until we get a step-by-step HowTo for writing TableGen backends, you can at
+least grab the boilerplate (build system, new files, etc.) from Clang's
+r173931.
+
 TODO: How they work, how to write one.  This section should not contain details
 about any particular backend, except maybe ``-print-enums`` as an example.  This
 should highlight the APIs in ``TableGen/Record.h``.