This does not alter much at the moment, but allows const pointers to be
passed as Op0 and Op1, simplifying later patches

These are not diagnosed because implementations hide the methods of the base class rather than overriding them.
This works as long as a hiding function is callable with the same arguments as the same function from the base class.

Pull Request: https://github.com/llvm/llvm-project/pull/136655

Making `TargetTransformInfo::Model::Impl` `const` makes sure all
interface methods are `const`, in `BasicTTIImpl`, its bases, and in all
derived classes.

Pull Request: https://github.com/llvm/llvm-project/pull/136598

The main change is making `thisT` method `const`, the rest of the
changes is fixing compilation errors (*).

(*) There are two tricky methods, `getVectorInstrCost()` and
`getIntImmCost()`.
They have several overloads; some of these overloads are typically
pulled in to derived classes using the `using` directive, and then
hidden by methods in the derived class.
The compiler does not complain if the hiding methods are not marked as
`const`, which means that clients will use the methods from the base
class. If after this change your target fails cost model tests, this
must be the reason. To resolve the issue you need  to make all hiding
overloads `const`. See the second commit in this PR.

Pull Request: https://github.com/llvm/llvm-project/pull/136575

Similar to https://github.com/llvm/llvm-project/pull/96902, this adds
`getDataLayout()` helpers to Function and GlobalValue, replacing the
current `getParent()->getDataLayout()` pattern.

It seems TypeSize is currently broken in the sense that:

  TypeSize::Fixed(4) + TypeSize::Scalable(4) => TypeSize::Fixed(8)

without failing its assert that explicitly tests for this case:

  assert(LHS.Scalable == RHS.Scalable && ...);

The reason this fails is that `Scalable` is a static method of class
TypeSize,
and LHS and RHS are both objects of class TypeSize. So this is
evaluating
if the pointer to the function Scalable == the pointer to the function
Scalable,
which is always true because LHS and RHS have the same class.

This patch fixes the issue by renaming `TypeSize::Scalable` ->
`TypeSize::getScalable`, as well as `TypeSize::Fixed` to
`TypeSize::getFixed`,
so that it no longer clashes with the variable in
FixedOrScalableQuantity.

The new methods now also better match the coding standard, which
specifies that:
* Variable names should be nouns (as they represent state)
* Function names should be verb phrases (as they represent actions)

In order to allow targets to disable interleaving for scalable vectors, pass the entire VF's ElementCount to getMaxInterleaveFactor.
This is based off of the approach used here: https://repo.hca.bsc.es/gitlab/rferrer/llvm-epi/-/commit/8d36708507b3c378078b9fe364bc548354aaec86

The plan would then be to disable interleaving on scalable VFs on RISC-V in a follow up patch.
See https://reviews.llvm.org/D143723#4132349

Reviewed By: reames

Differential Revision: https://reviews.llvm.org/D144474

LoopUnroll estimates the loop size via getInstructionCost(),
but getInstructionCost() cannot pass CostKind to getVectorInstrCost().
And so does getShuffleCost() to getBroadcastShuffleOverhead(),
getPermuteShuffleOverhead(), getExtractSubvectorOverhead(),
and getInsertSubvectorOverhead().

To address this, this patch adds an argument CostKind to these
functions.

Reviewed By: RKSimon

Differential Revision: https://reviews.llvm.org/D142116

Need to include the cost of the initial insertelement to the cost of the
broadcasts. Also, need to adjust the cost of the gather/buildvector if
the element is inserted into poison/undef vector.

Differential Revision: https://reviews.llvm.org/D140498