[llvm] [GlobalISel][ARM] Legalization of G_CONSTANT using constant pool (PR #98308)

[Thorsten Schütt via llvm-commits]

tschuett wrote:

I may be blind but,
```
 getActionDefinitionsBuilder(G_SEXT_INREG)
      .legalFor({s32, s64})
      .legalFor(PackedVectorAllTypeList)
      .maxScalar(0, s64)
      .clampNumElements(0, v8s8, v16s8)
      .clampNumElements(0, v4s16, v8s16)
      .clampNumElements(0, v2s32, v4s32)
      .clampMaxNumElements(0, s64, 2)
      .lower();
```
looks type-based. I am still searching for immediates/values.

https://github.com/llvm/llvm-project/pull/98308