Allow preinitializing RuntimeType instances #94405
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Unblock serializing `RuntimeType` instances from the static constructor interpreter. With this we can now preinitialize `static readonly Type s_foo = typeof(Foo)` and RyuJIT will optimize reads of `s_foo` into loading a constant value. Contributes to dotnet#91704.
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Tagging subscribers to this area: @agocke, @MichalStrehovsky, @jkotas Issue DetailsUnblock serializing With this we can now preinitialize Contributes to #91704. Cc @dotnet/ilc-contrib
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| @@ -8989,6 +8989,7 @@ void Compiler::impImportBlockCode(BasicBlock* block) | |||
| FALLTHROUGH; | |||
| case CORINFO_FIELD_STATIC_SHARED_STATIC_HELPER: | |||
| case CORINFO_FIELD_STATIC_ADDRESS: | |||
| case CORINFO_FIELD_STATIC_RELOCATABLE: | |||
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@EgorBo could you have a look at this? This affects a lot more than just RuntimeType and I might be missing why we weren't doing this before. (We might also want to do this for STATIC_RVA_ADDRESS.)
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@MichalStrehovsky wow, it's actually a good catch! It should improve some things, e.g.:
static readonly string Fld = "Hello";
[MethodImpl(MethodImplOptions.NoInlining)]
static string Test() => Fld;; Assembly listing for method Benchmarks:Test():System.String (FullOpts)
- mov rax, qword ptr [(reloc 0x400000000042c388)]
- mov rax, gword ptr [rax+0x08]
+ lea rax, gword ptr [(reloc 0x400000000042c398)] ; '"Hello"'
ret
; Total bytes of code 12There was a problem hiding this comment.
Basically, static readonly wasn't foldable for gc types for NAOT
| @@ -689,6 +689,8 @@ class C3<T> : IInterface, IInterface<T> | |||
| static IInterface<object> s_c3a = new C3<object>(); | |||
| static IInterface s_c3b = new C3<object>(); | |||
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| // Works around https://github.com/dotnet/runtime/pull/94342 | |||
| [MethodImpl(MethodImplOptions.NoOptimization)] | |||
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This found a new bug. The Run method is essentially optimized to a throw. It's ridiculous how well this optimizes:
- We figured out the value assigned to the static is read only using whole program view (the static is not marked read only in source code)
- RyuJIT then figured out exact type information from the preinit data blob.
- RyuJIT then devirtualized the call (into the wrong method, but that's the bug)
- RyuJIT then folded the string constant comparison.
All that's left is the throw (and a couple garbage instructions I couldn't fully make sense of).
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/azp run runtime-nativeaot-outerloop |
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Azure Pipelines successfully started running 1 pipeline(s). |
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@dotnet/ilc-contrib could someone have a look? |
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System.Threading.Tasks tests are failing with a message that we have not seen before: Is it a pre-existing problem or a regression introduced by this change? |
I think I've seen this once on one of my PRs. |
This test sometimes fails, always with a failure mode that doesn't produce dumps. It never reproed for me locally. |
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/azp run runtime-nativeaot-outerloop |
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Azure Pipelines successfully started running 1 pipeline(s). |
Co-authored-by: Michal Strehovský <MichalStrehovsky@users.noreply.github.com>
Unblock serializing
RuntimeTypeinstances from the static constructor interpreter.With this we can now preinitialize
static readonly Type s_foo = typeof(Foo)and RyuJIT will optimize reads ofs_foointo loading a constant value.Contributes to #91704.
Cc @dotnet/ilc-contrib