[llvm] [RISCV] Implement RISCVInsrInfo::getConstValDefinedInReg (PR #77610)

[Roger Ferrer Ibáñez via llvm-commits]

rofirrim wrote:

Hi @asb,

bisecting a failure on `riscv64-unknown-linux-gnu` in the `llvm-testsuite` showed that this change causes a failure on 

```
Failed Tests (1):
  test-suite :: MultiSource/Benchmarks/MiBench/consumer-typeset/consumer-typeset.test
```

Can you reproduce it too, locally?

https://github.com/llvm/llvm-project/pull/77610