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

[Thorsten Schütt via llvm-commits]

tschuett wrote:

This is the wrong approach. Please reconsider https://github.com/llvm/llvm-project/pull/96225. We loose the `.legalFor`. https://github.com/llvm/llvm-project/pull/97513 showed issues with `.customFor` .  There are less constants in the pipeline.
AArch64 shows https://github.com/llvm/llvm-project/blob/fec1b6f9d3cf5347b67ffb2078c995eb496acf47/llvm/lib/Target/AArch64/GISel/AArch64InstructionSelector.cpp#L2580 how to handle constant pool loads in the selector.

Gisel has a typed-bases legalizer. There are no illegal values.

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