tree 56af84b00a740c98d46865f30bd033af2c86d4f2
parent fcc916988596e83bd81993b02e0f12b024375f61
author Alexander Markov <alexmarkov@google.com> 1651194230 +0000
committer Commit Bot <commit-bot@chromium.org> 1651194230 +0000

[vm] New async/await implementation in the VM, part 2 - vm

The new implementation moves away from desugaring of async
functions on kernel AST, state machine generated in the flow graph and
capturing all local variables in the context.

Instead, async/await is implemented using a few stubs
(InitSuspendableFunction, Suspend, Resume, Return and
AsyncExceptionHandler). The stubs are implemented in a
platform-independent way using (macro-)assembler helpers.
When suspending a function, its frame is copied into a SuspendState
object, and when resuming a function it is copied back onto the stack.
No extra code is generated for accessing local variables.
Callback closures are created lazily on the first await.

Design doc: go/compact-async-await.

Part 1 (kernel): https://dart-review.googlesource.com/c/sdk/+/241842

TEST=ci

Issue: https://github.com/dart-lang/sdk/issues/48378
Change-Id: Ibad757035b7cc438ebdff80b460728b1d3eff1f5
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/242000
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Reviewed-by: Slava Egorov <vegorov@google.com>