Previously, cretonne-wasm used its own Local struct for identifying
local variables. However, now that cretonne-frontend provides a
Variable struct, just use that instead.
Frontends can still use their own types with `ILBuilder` and
`FunctionBuilder`. This just provides a basic `Variable` struct
for frontends that want it.
* Replace FunctionBuilder's Drop impl with a finalize function.
This has the advantage of not triggering assertion failures in the event
of abandoning a partially-built function. It has the disadvantage of
requiring users to call finalize() explicitly.
Ebb parameters are appended explicitly by whoever calls create_block,
so they don't need to also be inferred from branches. This makes the
frontend code more flexible for producers that want to create things
in a different order, and it eliminates more temporary allocations.
FunctionBuilder no longer maintains its own list of the function
parameter values; these can be obtained from the ebb parameter list
on the entry block.
switch_to_block doesn't need its jump_args argument, since jump
arguments are handled by the `jump` instruction and others, rather
than on the switch to a new ebb itself.
Rename the ArgumentType type to AbiParam since it describes the ABI
characteristics of a parameter or return value, not just the value type.
In Signature, rename members argument_types and return_types to "params"
and "returns". Again, they are not just types.
Fix a couple lingering references to "EBB arguments".
Add EBB parameter and EBB argument to the langref glossary to clarify
the distinction between formal EBB parameter values and arguments passed
to branches.
- Replace "ebb_arg" with "ebb_param" in function names that deal with
EBB parameters.
- Rename the ValueDef variants to Result and Param.
- A bunch of other small langref fixes.
No functional changes intended.
