Based on this RFC:
https://discourse.llvm.org/t/rfc-allow-the-scalarizer-pass-to-scalarize-vectors-returned-in-structs/82306
LLVM intrinsics do not support out params. To get around this limitation
implementers will make intrinsics return structs to capture a return
type and an out param. This implementation detail should not impact
scalarization since these cases should be elementwise operations.
## Three changes are needed.
- The CallInst visitor needs to be updated to handle Structs
- A new visitor is needed for `ExtractValue` instructions
- finsh needs to be update to handle structs so that insert elements are
properly propogated.
## Testing changes
- Add support for `llvm.frexp`
- Add support for `llvm.dx.splitdouble`
fixes https://github.com/llvm/llvm-project/issues/111437
Line ending policies were changed in the parent, dccebddb3b80. To make
it easier to resolve downstream merge conflicts after line-ending
policies are adjusted this is a separate whitespace-only commit. If you
have merge conflicts as a result, you can simply `git add --renormalize
-u && git merge --continue` or `git add --renormalize -u && git rebase
--continue` - depending on your workflow.
Since we are using the Scalarizer pass in the backend we needed a way to
allow this pass to operate on Target intrinsics.
We achieved this by adding `TargetTransformInfo ` to the Scalarizer
pass. This allowed us to call a function available to the DirectX
backend to know if an intrinsic is a target intrinsic that should be
scalarized.
