We'd introduced separate versions of `llvm.dx.resource.load` with a
struct return to handle the CheckAccessFullyMapped case without making
the IR for the common case unnecessarily complicated. However, at this
point the common case is really `resource.getpointer`, so the ergonomics
of a simplified version of `load` don't actually gain us as much as the
cost of having multiple opcodes.
Drop the `dx.resource.loadchecked` functions and have `dx.resource.load`
consistently return `{element_type, i1}`.
The `@llvm.dx.typedBufferLoad` intrinsic is lowered to `@dx.op.bufferLoad`.
There's some complexity here in translating to scalarized IR, which I've
abstracted out into a function that should be useful for samples, gathers, and
CBuffer loads.
I've also updated the DXILResources.rst docs to match what I'm doing here and
the proposal in llvm/wg-hlsl#59. I've removed the content about stores and raw
buffers for now with the expectation that it will be added along with the work.
Note that this change includes a bit of a hack in how it deals with
`getOverloadKind` for the `dx.ResRet` types - we need to adjust how we deal
with operation overloads to generate a table directly rather than proxy through
the OverloadKind enum, but that's left for a later change here.
Part of #91367
Pull Request: https://github.com/llvm/llvm-project/pull/104252
