fixes #140321

Specifically it fixes ` error: Cannot create BufferLoad operation:
Invalid overload type`
https://hlsl.godbolt.org/z/dTq4q7o58
but no new DML shaders are building. This change now exposes #144747.

The change does two things it adds i64 support for intrinsic expansion
for the `dx_resource_load_typedbuffer`, and
`dx_resource_store_typedbuffer` intrinsics.

It also lets loaded typedbuffers crash more gracefully because of ` auto
*EVI = cast<ExtractValueInst>(U);` is now a `dyn_cast` and
`llvm_unreachable`.

typedBufferLoad of double/double2 is expanded to a typedBufferLoad of a
<2 x i32>/<4 x i32> and asdouble
typedBufferStore of a double/double2 is expanded to a splitdouble and a
typedBufferStore of a <2 x i32>/<4 x i32>
Add tests showing result of intrinsic expansion for typedBufferLoad and
typedBufferStore
Add tests showing dxil op lowering can handle typedBufferLoad and
typedBufferStore where the target type doesn't match the typedBufferLoad
and typedBufferStore type
Closes #104423

Replaces the deprecated `report_fatal_error` function with
`reportFatalUsageError`

Fixes #137209

This PR:
- Adds a case to `expandIntrinsic()` in `DXILIntrinsicExpansion.cpp` to
expand the `Intrinsic::is_fpclass` in the case of
`FPClassTest::fcNegZero`
- Defines the `IsNaN`, `IsFinite`, `IsNormal` DXIL ops in `DXIL.td`
- Adds a case to `lowerIntrinsics()` in `DXILOpLowering.cpp` to handle
the lowering of `Intrinsic::is_fpclass` to the DXIL ops `IsNaN`,
`IsInf`, `IsFinite`, `IsNormal` when the FPClassTest is `fcNan`,
`fcInf`, `fcFinite`, and `fcNormal` respectively
- Creates a test `llvm/test/CodeGen/DirectX/is_fpclass.ll` to exercise
the intrinsic expansion and DXIL op lowering of `Intrinsic::is_fpclass`

~~A separate PR will be made to remove the now-redundant `dx_isinf`
intrinsic to address #87777.~~

A proper implementation for the lowering of the `llvm.is.fpclass`
intrinsic to handle all possible combinations of FPClassTest can be
implemented in a separate PR. This PR's implementation focuses primarily
on addressing the current use-cases for DirectML and HLSL intrinsics.

This implements the result of the discussion at:

https://discourse.llvm.org/t/rfc-report-fatal-error-and-the-default-value-of-gencrashdialog/73587

There are two different use cases for report_fatal_error, so replace it
with two functions reportFatalInternalError() and
reportFatalUsageError(). The former indicates a bug in LLVM and
generates a crash dialog. The latter does not. The names have been
suggested by rnk and people seemed to like them.

This replaces a lot of the usages that passed an explicit value for
GenCrashDiag. I did not bulk replace remaining report_fatal_error usage
-- they probably require case by case review for which function to use.

The `dx.dot2`, `dot3`, and `dot4` intrinsics exist purely to lower
`dx.fdot`, and they map exactly to the DXIL ops of the same name. Using
vectors for their arguments adds unnecessary complexity and causes us to
have vector operations that are not trivial to lower post-scalarizer.

Similarly, the `dx.dot2add` intrinsic is overly generic for something
that only needs to lower to a single `dot2AddHalf` DXIL op. Update its
signature to match the operation it lowers to.

Fixes #134569.

fixes #135285

This change implements the `usub.sat` intrinsic to perform an unsigned
saturating subtraction on the 2 arguments.
The minimum value this operation is clamp to is 0.

fixes #135221
- have powi use the same legalization path as pow
- use CreateSIToFP to cast the int back to a float type
- add tests for powi

## Changes
- Delete DirectX length intrinsic
- Delete HLSL length lang builtin
- Implement length algorithm entirely in the header.

## History
- In the past if an HLSL intrinsic lowered to either a spirv op code or
a DXIL opcode we represented it with intrinsics

## Why we are moving away?
- To make HLSL apis more portable the team decided that it makes sense
for some intrinsics to be defined only in the header.
- Since there tends to be more SPIRV opcodes than DXIL opcodes the plan
is to support SPIRV opcodes either with target specific builtins or via
pattern matching.