[flang-dev] MLIR for clang

[Michael Kruse via flang-dev]

Am Mo., 17. Feb. 2020 um 10:58 Uhr schrieb Prashanth N R
<prashanth.nr at gmail.com>:
> 1. We intent to fork clang for MLIR at a particular release and develop. We will mostly merge with the master as soon as we reach a good milestones. Most of the development is expected to happen in github or some such version control system.

Once you did the conversion, I think it becomes unfeasible to merge in
LLVM master on a regular basis. For instance, you will have changed
every occurrence of llvm::Instruction to mlir::Operation and its API,
affecting about every line of code starting with clangCodeGen. Even if
you introduce compatibility layer, upstream LLVM will continue to use
llvm::Instruction.

Another case is MLIR's use of BasicBlock arguments instead of PHINode.
This is a change we potentially would want in LLVM as well, but would
require every line that assumes PHI nodes at once, so has not been
done yet.


Michael