* Add ability to run CLIF IR using `clif-util run [-v] {file}` and add `test run` to cranelift-filetests to allow executing CLIF
This re-factors the compile/execute parts to a FunctionRunner that is shared between cranelift-filetests and clif-util. CLIF can be now be run using `clif-util run` as well as during `clif-util test` for files with a `test run` header. As before, only functions suffixed with a `run` comment are executed. The `run: fn(...) == ...` expression syntax is left for a subsequent change.
-Add resumable_trap, safepoint, isnull, and null instructions
-Add Stackmap struct and StackmapSink trait
Co-authored-by: Mir Ahmed <mirahmed753@gmail.com>
Co-authored-by: Dan Gohman <sunfish@mozilla.com>
The result of the emitter is a vector of bytes holding machine code,
jump tables, and (in the future) other read-only data. Some clients,
notably Firefox's Wasm compiler, needs to separate the machine code
from the data in order to insert more code directly after the code
generated by Cranelift.
To make such separation possible, we record more information about the
emitted bytes: the sizes of each of the sections of code, jump tables,
and read-only data, as well as the locations within the code that
reference (PC-relatively) the jump tables and read-only data.
Also:
- make sure to apply diversions when determining offsets for code
relaxation.
- select the smallest encoding when selecting a relaxed branch
instruction.
This was previously using the following condition to decide that a block
hadn't been visited yet: either dest_offset is non-0 or the block isn't
the entry block. Unfortunately, this didn't work when the first block
would be non-empty but wouldn't generate code at all.
Since the original code would do at least one pass over the entire code,
the first pass that determines initial EBB offsets is done separately,
without considering branch relaxation. This ensures that all EBBs have
been visited and have correct initial offsets, and doesn't require a
special check to know whether an EBB has been visited or not.
