This patch:
* removes the "default" opt level, on the basis that it has no definition and
is referred to nowhere in the compiler.
* renames the "fastest" level to "none". The resulting set of transformations
is unchanged.
* renames the "best" level to "speed_and_size". The resulting set of
transformations is unchanged.
* adds a new level, "speed". This is the same as "speed_and_size" except that
it omits transformations aimed only at reducing code size. Currently it
omits only the insn shrinking pass.
-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.
