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Unified handling of Resolve calls #1979

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merged 4 commits into from
Apr 22, 2021
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marek-safar
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This change introduces a commonplace for resolving definition for types,
methods and fields. This is useful for following reasons

  • Speeds up linker by 20% for default Blazor app (more for large apps)
  • Any custom step can avoid building local mapping cache
  • Custom steps could support --skip-unresolved linker option
  • Consistent error handling for unresolved references

Most of the changes are just mechanical method replacement and
Link context passing.

Contributes to #918
Fixes #1953

This change introduces a commonplace for resolving definition for types,
methods and fields. This is useful for following reasons

- Speeds up linker by 20% for default Blazor app (more for large apps)
- Any custom step can avoid building local mapping cache
- Custom steps could support `--skip-unresolved` linker option
- Consistent error handling for unresolved references

Most of the changes are just mechanical method replacement and
Link context passing.

Contributes to dotnet#918
Fixes dotnet#1953
@marek-safar marek-safar requested a review from vitek-karas April 20, 2021 09:45
src/linker/Linker.Dataflow/ValueNode.cs Outdated Show resolved Hide resolved
src/linker/Linker.Dataflow/ReflectionMethodBodyScanner.cs Outdated Show resolved Hide resolved
src/linker/Linker/LinkContext.cs Show resolved Hide resolved
Comment on lines +792 to +800
if (typeReference is TypeSpecification ts) {
if (typeReference is FunctionPointerType) {
td = null;
} else {
//
// It returns element-type for arrays and also element type for wrapping types like ByReference, PinnedType, etc
//
td = TryResolveTypeDefinition (ts.GetElementType ());
}
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Should we create an issue to handle at least some of these at the callsite - resolving to element-type is dangerous. Not counting that it also hides generic instantiations.

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I actually experimented with it a bit and I think this logic is fine. Most code still needs to resolve to the element so the separation would not have benefits beyond perhaps type system purity.

src/linker/Linker/LinkContext.cs Outdated Show resolved Hide resolved
src/linker/Linker.Steps/MarkStep.cs Outdated Show resolved Hide resolved
@marek-safar marek-safar merged commit 012efef into dotnet:main Apr 22, 2021
@marek-safar marek-safar deleted the resolve branch April 22, 2021 07:26
MichalStrehovsky added a commit to MichalStrehovsky/runtimelab that referenced this pull request Apr 29, 2021
This just gets dotnet/linker#1979 out of the way since it's very noisy and doesn't apply to us.
jkotas pushed a commit to dotnet/runtimelab that referenced this pull request Apr 29, 2021
This just gets dotnet/linker#1979 out of the way since it's very noisy and doesn't apply to us.
sbomer added a commit to sbomer/linker that referenced this pull request May 19, 2021
This will allow extension methods that take an `IMetadataResolver` like
in dotnet/java-interop#842 to use the
LinkContext Resolve cache.

Context: dotnet/android#5748 (comment)

The Resolve cache added in dotnet#1979
requires calling `Resolve*Definition` methods directly on `LinkContext`,
which means that any extension methods that do resolution logic need to
take a `LinkContext`. This doesn't work well with the layering in
xamarin-android, where java.interop uses a resolution cache with cecil,
but doesn't depend on the linker. Instead it uses a custom
`TypeResolutionCache` for extension methods like `GetBaseDefinition`:
https://github.com/xamarin/java.interop/blob/main/src/Java.Interop.Tools.Cecil/Java.Interop.Tools.Cecil/MethodDefinitionRocks.cs#L16
These extension methods are also used from xamarin-android, but there's
a desire to use the `LinkContext` cache in this case.

@jonpryor had the idea to change the extension methods to use cecil's
`IMetadataResolver`, which can be implemented by `TypeDefinitionCache`
and by `LinkContext`. Java.interop will continue using their `TypeDefinitionCache`,
and xamarin-android will use `LinkContext`.

One limitation of this approach is that `LinkContext.TryResolve*Definition`
(renamed to just `TryResolve` for consistency) methods aren't usable from
the extension methods.
sbomer added a commit that referenced this pull request May 20, 2021
This will allow extension methods that take an `IMetadataResolver` like
in dotnet/java-interop#842 to use the
LinkContext Resolve cache.

Context: dotnet/android#5748 (comment)

The Resolve cache added in #1979
requires calling `Resolve*Definition` methods directly on `LinkContext`,
which means that any extension methods that do resolution logic need to
take a `LinkContext`. This doesn't work well with the layering in
xamarin-android, where java.interop uses a resolution cache with cecil,
but doesn't depend on the linker. Instead it uses a custom
`TypeResolutionCache` for extension methods like `GetBaseDefinition`:
https://github.com/xamarin/java.interop/blob/main/src/Java.Interop.Tools.Cecil/Java.Interop.Tools.Cecil/MethodDefinitionRocks.cs#L16
These extension methods are also used from xamarin-android, but there's
a desire to use the `LinkContext` cache in this case.

@jonpryor had the idea to change the extension methods to use cecil's
`IMetadataResolver`, which can be implemented by `TypeDefinitionCache`
and by `LinkContext`. Java.interop will continue using their `TypeDefinitionCache`,
and xamarin-android will use `LinkContext`.

One limitation of this approach is that `LinkContext.TryResolve*Definition`
(renamed to just `TryResolve` for consistency) methods aren't usable from
the extension methods.
jonpryor pushed a commit to dotnet/android that referenced this pull request Jun 2, 2021
Context: dotnet/linker#1953
Context: dotnet/linker#1774
Context: dotnet/linker#1774 (comment)
Context: dotnet/linker#1979
Context: dotnet/linker#2019
Context: dotnet/linker#2045
Context: dotnet/java-interop@2573dc8
Context: #5870
Context: #5878

Update the custom linker steps to use the new `IMarkHandler` API
which runs logic during "MarkStep".

(See [this list][0] of pipeline steps for additional context.)

As part of this, I've removed the workaround that loads all referenced
assemblies up-front and simplified some of the linker MSBuild targets.
Some of the `MonoDroid.Tuner` steps were duplicated and changed to
implement the new `IMarkHandler` interface, to avoid touching the
`MonoDroid.Tuner` code.

In my analysis of the custom steps, most of them "just work" if we
call them only for marked members, because they ultimately either:

  - Just call `AddPreserved*()` to conditionally keep members of types
    (which with the new API will just happen when the type is marked)

  - In the case of `FixAbstractMethodsStep()`, inject missing interface
    implementations which will only be kept if they are marked for some
    other reason.

Most of the steps have been updated in a straightforward way based on
the above.

The exceptions are:

  - `AddKeepAlivesStep` needs to run on all code that survived
    linking, and can run as a normal step.

  - `ApplyPreserveAttribute`: this step globally marks members with
    `PreserveAttribute`.
    - The step is only active for non-SDK link assemblies.  Usually we
      root non-SDK assemblies, but it will be a problem if linking all
      assemblies.
    - For now, I updated it to use the new custom step API on assembly
      mark -- so it will scan for the attribute in all marked
      assemblies -- but we should investigate whether this is good
      enough.
    - This can't be migrated to use `IMarkHandler` because it needs
      to scan code for attributes, including unmarked code.

  - `PreserveExportedTypes`: similar to the above, this globally marks
    members with `Export*Attribute`.  It's used for java interop in
    cases where the java methods aren't referenced statically, like
    from xml, or for special serialization methods.
    - It's only active for non-SDK assemblies, so like above it will
      be a problem only if linking all assemblies.
    - Like above, I've made it scan marked assemblies.

  - `PreserveApplications`: globally scans for `ApplicationAttribute`
    on types/assemblies, and sets the `TypePreserve` annotation for
    any types referenced by the attribute.
    - This step technically does a global scan, but it's likely to work
      on "mark type"/"mark assembly", as `ApplicationAttribute` is only
      used on types/assembies that are already kept.
    - I've updated it to use the new `IMarkHandler` API.

Additionally, as per dotnet/java-interop@2573dc8c, stop using
`TypeDefinitionCache` everywhere and instead use `IMetadataResolver`
to support caching `TypeDefinition`s across shared steps.
For .NET 6, `LinkContextMetadataResolver` implements the
`IMetadataResolver` interface in terms of `LinkContext`.

[0]: https://github.com/mono/linker/blob/main/src/linker/Linker/Driver.cs#L714-L730
agocke pushed a commit to dotnet/runtime that referenced this pull request Nov 16, 2022
* Unified handling of Resolve calls

This change introduces a commonplace for resolving definition for types,
methods and fields. This is useful for following reasons

- Speeds up linker by 20% for default Blazor app (more for large apps)
- Any custom step can avoid building local mapping cache
- Custom steps could support `--skip-unresolved` linker option
- Consistent error handling for unresolved references

Most of the changes are just mechanical method replacement and
Link context passing.

Contributes to dotnet/linker#918
Fixes dotnet/linker#1953

* Update src/linker/Linker/LinkContext.cs

Co-authored-by: Vitek Karas <[email protected]>

* PR feedback

* Simplify MethodReturnValue node construction

Co-authored-by: Vitek Karas <[email protected]>

Commit migrated from dotnet/linker@012efef
agocke pushed a commit to dotnet/runtime that referenced this pull request Nov 16, 2022
This will allow extension methods that take an `IMetadataResolver` like
in dotnet/java-interop#842 to use the
LinkContext Resolve cache.

Context: dotnet/android#5748 (comment)

The Resolve cache added in dotnet/linker#1979
requires calling `Resolve*Definition` methods directly on `LinkContext`,
which means that any extension methods that do resolution logic need to
take a `LinkContext`. This doesn't work well with the layering in
xamarin-android, where java.interop uses a resolution cache with cecil,
but doesn't depend on the linker. Instead it uses a custom
`TypeResolutionCache` for extension methods like `GetBaseDefinition`:
https://github.com/xamarin/java.interop/blob/main/src/Java.Interop.Tools.Cecil/Java.Interop.Tools.Cecil/MethodDefinitionRocks.cs#L16
These extension methods are also used from xamarin-android, but there's
a desire to use the `LinkContext` cache in this case.

@jonpryor had the idea to change the extension methods to use cecil's
`IMetadataResolver`, which can be implemented by `TypeDefinitionCache`
and by `LinkContext`. Java.interop will continue using their `TypeDefinitionCache`,
and xamarin-android will use `LinkContext`.

One limitation of this approach is that `LinkContext.TryResolve*Definition`
(renamed to just `TryResolve` for consistency) methods aren't usable from
the extension methods.

Commit migrated from dotnet/linker@aaf4880
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Sharing state between custom steps
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