swift

056132cc - [move-function] Add a new pass that propagates debug_value [moved] into coroutine func-lets.

[move-function] Add a new pass that propagates debug_value [moved] into coroutine func-lets. NOTE: debug_value [moved] appearing in the source code implies a _move was used. So this will not effect current stable swift code. This is just a first version of this that I am using to commit/bring up tests for IRGen supporting a full dataflow version of this patch. Big picture is that there is a bunch of work that is done in the LLVM level in the coroutine splitter to work around communicating live variables in the various coroutine func-lets. This logic is all done with debug.declare and we would need to update that logic in the coroutine splitter to handle debug.addr. Rather than do this, after some conversation, AdrianP and I realized that we could get the same effect of a debug.declare by just redeclaring the current live set of debug_value after each possible coroutine funclet start. To do this in full generality, we need a full dataflow but just to bring this up we initially perform a dominance propagation algorithm of the following sort: 1. We walk the CFG along successors. By doing this we guarantee that we visit blocks after their dominators. 2. When we visit a block, we walk the block from start->end. During this walk: a. We grab a new block state from the centralized block->blockState map. This state is a [SILDebugVariable : DebugValueInst]. b. If we see a debug_value, we map blockState[debug_value.getDbgVar()] = debug_value. This ensures that when we get to the bottom of the block, we have pairs of SILDebugVariable + last debug_value on it. c. If we see any coroutine funclet boundaries, we clone the current tracked set of our block state and then walk up the dom tree dumping in each block any debug_value with a SILDebugVariable that we have not already dumped. This is maintained by using a visited set of SILDebugVariable for each funclet boundary. The end result is that at the beginning of each funclet we will basically declare the debug info for an addr. This is insufficient of course for moves that are in conditional control flow, e.x.: ``` let x = Klass() if boolValue { await asyncCall() let _ = _move(x) } ``` but this at least lets me begin to write tests for this in lldb using straight line code and work out the rest of the issues in CodeGen using those tests.