This adds a "colocated" flag to function and symbolic global variables which
indicates that they are defined along with the current function, so they can
use PC-relative addressing.
This also changes the function decl syntax; the name now always precedes the
signature, and the "function" keyword is no longer included.
`iter()` iterates over both keys and values, while `values()` iterates over
just values. Also add `_mut()` versions.
These replace the otherwise common idiom of iterating with `keys()` and using
indexing to get the values, allowing for simpler code.
* First draft of TrapSink implementation.
* Add trap sink calls to 'trapif' and 'trapff' recipes.
* Add SourceLoc to trap sink calls, and add trap sink calls to all loads and stores.
* Add IntegerDivisionByZero trap to div recipe.
* Only emit load/store traps if 'notrap' flag is not set on the instruction.
* Update filetest machinery to add new trap sink functionality.
* Update filetests to include traps in output.
* Add a few more trap outputs to filetests.
* Add trap output to CLI tool.
This allows us to run the tests via a library call rather than just
as a command execution. And, it's a step toward a broader goal, which
is to keep the code in the top-level src directory minimal, with
important functionality exposed as crates.
