Summary:
If await_suspend returns a coroutine_handle, as in the example below:
```
coroutine_handle<> await_suspend(coroutine_handle<> h) {
coro.promise().waiter = h;
return coro;
}
```
suspensionExpression processing will resume the coroutine pointed at by that handle.
Related LLVM change rL311751 makes resume calls of this kind `musttail` at any optimization level.
This enables unlimited symmetric control transfer from coroutine to coroutine without blowing up the stack.
Reviewers: GorNishanov
Reviewed By: GorNishanov
Subscribers: rsmith, EricWF, cfe-commits
Differential Revision: https://reviews.llvm.org/D37131
llvm-svn: 311762
Summary:
The title says it all.
Reviewers: GorNishanov, rsmith
Reviewed By: GorNishanov
Subscribers: rjmccall, cfe-commits
Differential Revision: https://reviews.llvm.org/D34194
llvm-svn: 305496
SemaCoroutine forms expressions referring to the coroutine frame of the enclosing coroutine using coro.frame builtin.
During codegen, we emit llvm.coro.begin intrinsic that returns the address of the coroutine frame.
When coro.frame is emitted, we replace it with SSA value of coro.begin.
llvm-svn: 303598
Details:
Emit suspend expression which roughly looks like:
auto && x = CommonExpr();
if (!x.await_ready()) {
llvm_coro_save();
x.await_suspend(...); (*)
llvm_coro_suspend(); (**)
}
x.await_resume();
where the result of the entire expression is the result of x.await_resume()
(*) If x.await_suspend return type is bool, it allows to veto a suspend:
if (x.await_suspend(...))
llvm_coro_suspend();
(**) llvm_coro_suspend() encodes three possible continuations as a switch instruction:
%where-to = call i8 @llvm.coro.suspend(...)
switch i8 %where-to, label %coro.ret [ ; jump to epilogue to suspend
i8 0, label %yield.ready ; go here when resumed
i8 1, label %yield.cleanup ; go here when destroyed
]
llvm-svn: 298784
Gor Nishanov