This makes the details of the spiderwasm prologue configurable so it is
easier to modify SpiderMonkey without having to change Cretonne.
Create a stack object representing the SpiderMonkey prologue words
before calculating the stack layout so they won't be overwritten by
Cretonne's stack objects.
The flag guarantees that the generated function does not have any
internal return instructions. If the function returns at all, the return
must be the last instruction.
For now just implement a verifier check for this property. When we get
CFG simplifiers and block layout optimizations, they will need to heed
the flag.
This is off by default, but enabled by the parser when reading a textual
IL file. Test files can still override the default to turn off
verification.
The setting enables IL verifier passes at critical points of the
compilation pipeline.
The intel, arm32, and arm32 targets were only defined in the meta
language previously. Add Rust implementations too.
This is mostly boilerplate, except for the unit tests in the
registers.rs files.
