NativeAOT: avoid helper calls for static fields

[EgorBo]

Based on #63620 for non-gc fields for now (looking into gc now)

static int s;

static int GetS() => s;

Was:

       4883EC28             sub      rsp, 40
       E800000000           call     CORINFO_HELP_READYTORUN_NONGCSTATIC_BASE
       8B00                 mov      eax, dword ptr [rax]
       4883C428             add      rsp, 40
       C3                   ret
; Total bytes of code 16

Now:

       8B0500000000         mov      eax, dword ptr [(reloc 0x4000000000425290)]
       C3                   ret
; Total bytes of code 7

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Issue Details

---

Based on #63620 for non-gc fields for now (looking into gc now)

static int s;

static int GetS() => s;

Was:

       4883EC28             sub      rsp, 40
       E800000000           call     CORINFO_HELP_READYTORUN_NONGCSTATIC_BASE
       8B00                 mov      eax, dword ptr [rax]
       4883C428             add      rsp, 40
       C3                   ret
; Total bytes of code 16

Now:

       8B0500000000         mov      eax, dword ptr [(reloc 0x4000000000425290)]
       C3                   ret
; Total bytes of code 7

Author:	EgorBo
Assignees:	EgorBo
Labels:	area-CodeGen-coreclr
Milestone:	-

[EgorBo]

/azp list

[EgorBo]

/azp run runtime-extra-platforms

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[am11]

Nice! Does it help property initializers in R2R as well: https://godbolt.org/z/EvTjxcG9a (get_Bar())?

[EgorBo]

Nice! Does it help property initializers in R2R as well: https://godbolt.org/z/EvTjxcG9a (get_Bar())?

This is optimized to just 42 in NativeAOT now (in .NET 8.0) via some previous PR I merged 🙂

[EgorBo]

@jakobbotsch @dotnet/jit-contrib PTAL the JIT side, I'll handle statics of GC types separately due to additional complexity (double indirect + new type of const handle in jit for it).

@MichalStrehovsky PTAL NAOT side, it's copied from your PR 🙂

[MichalStrehovsky]

The AOT side looks good!

I think we'd also be able to do the case when the bases are accessed from shared code if we changed pResult->fieldLookup from CORINFO_CONST_LOOKUP to CORINFO_LOOKUP.

The compiler side can compute the lookup with ComputeLookup(ref pResolvedToken, field.OwningType, ReadyToRunHelperId.GetNonGCStaticBase, ref pResult->fieldLookup).

It can also be done separately, just want to make sure the JIT side doesn't make assumptions that would make it more difficult.

[EgorBo]

@SingleAccretion thanks for the review, can you look again please?

[EgorBo]

/azp run runtime-extra-platforms

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[EgorBo]

@SingleAccretion can you please take another look?

Failures in runtime-extra-platforms don't look to be related as they fail in other PRs too - I'll file an issue if we don't have one already.