[release/8.0] Fix fgOptimizeAddition opt for AOT

[github-actions]

Backport of #94350 to release/8.0

/cc @EgorBo

Customer Impact

RyuJIT had an optimization that wasn't NativeAOT/R2R friendly:

(X + Const1) + (Y + Const2) was transformed into (X + Y) + Const3 (where Const3 is Const1 + Const2)

while in some cases it's not allowed to fold constants which require "relocs" (AOT). It seems that this transformation had this bug for several releases but only in .NET 8.0 we start to hit it because unrelated optimizations (like early expansion of fields) introduced more opportunities for it. A small repro is demonstrated in #94332

Testing

outerloop/NativeAOT testing, local tests

Risk

Low

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Issue Details

---

Backport of #94350 to release/8.0

/cc @EgorBo

Customer Impact

Testing

Risk

IMPORTANT: If this backport is for a servicing release, please verify that:

• The PR target branch is release/X.0-staging, not release/X.0.

• If the change touches code that ships in a NuGet package, you have added the necessary package authoring and gotten it explicitly reviewed.

Author:	github-actions[bot]
Assignees:	-
Labels:	area-CodeGen-coreclr
Milestone:	-

[EgorBo]

Is it too late to target .NET 8.0? I think this is not super important and can go to servicing

[akoeplinger]

@EgorBo if you want this for 8.0 servicing then you need to target the release/8.0-staging branch