commit 8bd3690ab06c3eda2f4996ca60b94fdcc9f76105
author Nate Biggs <natebiggs@google.com> Tue Jul 30 03:13:58 2024 +0000
committer Commit Queue <dart-scoped@luci-project-accounts.iam.gserviceaccount.com> Tue Jul 30 03:13:58 2024 +0000
tree 52d7d3ad0ecf554b6465d1a33481b4c2920a7b5c
parent 90162cc1f616ec22fc6751fba478cda9d59d4e35

Reland "[ddc] Update DDC compiler to start using the new async transform."

This is a reland of commit d84f908641eb5e93c5e1b519ff76f5e5da1f69cc

Includes fixes:
--- Catch scope fix ---
Each catch block should define its own scope, but the compiler was not treating the body of these catch blocks as a scope. This was leading to incorrect variable renaming.


--- Duplicate label fix ---
Labels weren't being removed from the _labelNames Map after being used so multiple nodes were getting tagged with the same label. Note: This didn't actually cause any bugs because the label closer to the break statements using those labels was the correct one.

--- addAsyncCallback cleanup ---
The new async semantics actually don't require managing addAsyncCallback and removeAsyncCallback calls (proxies for async_helper.asyncStart and async_helper.asyncEnd). None of the other backends manage these themselves. It's up to tests to ensure they call async_helper.asyncStart and async_helper.asyncEnd.


Original change's description:
> [ddc] Update DDC compiler to start using the new async transform.
>
> Updates compiler.dart to use the new async transformation.
>
> Some key things to note:
> - Dart Let and BlockExpression expressions are represented as IIFEs in DDC compiled code. For non-async code this works fine but this doesn't work when they contain "await" expressions. When these expressions contain awaits we use the same lowering as we would for an async function, but instead apply it to the IIFE function. Then we simply await the IIFE Call expression as the IIFE will return a future after the transform.
> - For async/sync*/async* functions we want to make sure parameter initialization happens synchronously before any of the async logic is hit. To do this we first apply the async transform the user-code function body. We then prepend the paramter initialization logic to the body of the transformed function.
> - We add support for JS_RAW_EXCEPTION which allows the machinery in async_patch to access the wrapped JS exception in a catch block rather than the unwrapped Dart exception.
> - Stacktraces and sourcemaps have some differences. There is still room for improvement in these but they should at least allow users to reasonably step through parts of the async code.
>
>
> There are also several test fixes/updates associated with this change. The test_runner wrapper no longer has to inject in asyncStart/asyncEnd calls, these are handled by the new async logic.
>
> Change-Id: I0f9f547cd9eb52ff7d850d277876d4d57568a14e
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/374444
> Reviewed-by: Bob Nystrom <rnystrom@google.com>
> Reviewed-by: Mark Zhou <markzipan@google.com>
> Reviewed-by: Johnni Winther <johnniwinther@google.com>
> Reviewed-by: Nicholas Shahan <nshahan@google.com>

Change-Id: Idfe05c0628b2b91f474d08d99427961381debeb5
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/376000
Reviewed-by: Johnni Winther <johnniwinther@google.com>
Reviewed-by: Bob Nystrom <rnystrom@google.com>
Reviewed-by: Mark Zhou <markzipan@google.com>