JF Bastien caf175c28c WebAssembly: handle ret void.
Summary:
Use -1 as numoperands for the return SDTypeProfile, denoting that return is variadic. Note that the patterns in InstrControl.td still need to match the inputs, so this ins't an "anything goes" variadic on ret!

The next step will be to handle other local types (not just int32).

Reviewers: sunfish

Subscribers: llvm-commits, jfb

Differential Revision: http://reviews.llvm.org/D11692

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@243783 91177308-0d34-0410-b5e6-96231b3b80d8
2015-07-31 21:04:18 +00:00
..
2015-07-27 23:25:54 +00:00

//===-- README.txt - Notes for WebAssembly code gen -----------------------===//

This WebAssembly backend is presently in a very early stage of development.
The code should build and not break anything else, but don't expect a lot more
at this point.

For more information on WebAssembly itself, see the design documents:
  * https://github.com/WebAssembly/design/blob/master/README.md

The following documents contain some information on the planned semantics and
binary encoding of WebAssembly itself:
  * https://github.com/WebAssembly/design/blob/master/AstSemantics.md
  * https://github.com/WebAssembly/design/blob/master/BinaryEncoding.md

Interesting work that remains to be done:
* Write a pass to restructurize irreducible control flow. This needs to be done
  before register allocation to be efficient, because it may duplicate basic
  blocks and WebAssembly performs register allocation at a whole-function
  level. Note that LLVM's GPU code has such a pass, but it linearizes control
  flow (e.g. both sides of branches execute and are masked) which is undesirable
  for WebAssembly.
* Basic relooper to expose control flow as an AST.
* Figure out how to properly use MC for virtual ISAs. This may require some
  refactoring of MC.

//===---------------------------------------------------------------------===//