Start a new implementation for edsc::Builder

This CL reworks the design of EDSCs from first principles.
It introduces a ValueHandle which can hold either:
1. an eagerly typed, delayed Value*
2. a precomputed Value*

A ValueHandle can be manipulated with intrinsic operations a nested within a NestedBuilder. These NestedBuilder are a more idiomatic nested builder abstraction that should feel intuitive to program in C++.

Notably, this abstraction does not require an AST to stage the construction of MLIR snippets from C++. Instead, the abstraction makes use of orderings between definition and declaration of ValueHandles and provides a NestedBuilder and a LoopBuilder helper classes to handle those orderings.

All instruction creations are meant to use the templated ValueHandle::create<> which directly calls mlir::Builder.create<>.

For now the EDSC AST and the builders live side-by-side until the C API is ported.

PiperOrigin-RevId: 237030945
6 files changed