This approach is not the best but avoids an extra instruction; perhaps at some point, as mentioned in https://github.com/bytecodealliance/wasmtime/pull/2248, we will add the extra instruction or refactor things in such a way that this `Inst` variant is unnecessary.
This also passes `fixed_frame_storage_size` (previously `total_sp_adjust`)
into `gen_clobber_save` so that it can be combined with other stack
adjustments.
Copyright (c) 2020, Arm Limited.
As part of a Wasm JIT update, SpiderMonkey is changing its internal
WebAssembly function ABI. The new ABI's frame format includes "caller
TLS" and "callee TLS" slots. The details of where these come from are
not important; from Cranelift's point of view, the only relevant
requirement is that we have two on-stack args that are always present
(offsetting other on-stack args), and that we define special argument
purposes so that we can supply values for these slots.
Note that this adds a *new* ABI (a variant of the Baldrdash ABI) because
we do not want to tightly couple the landing of this PR to the landing
of the changes in SpiderMonkey; it's better if both the old and new
behavior remain available in Cranelift, so SpiderMonkey can continue to
vendor Cranelift even if it does not land (or backs out) the ABI change.
Furthermore, note that this needs to be a Cranelift-level change (i.e.
cannot be done purely from the translator environment implementation)
because the special TLS arguments must always go on the stack, which
would not otherwise happen with the usual argument-placement logic; and
there is no primitive to push a value directly in CLIF code (the notion
of a stack frame is a lower-level concept).
This commit splits "increments" in two; they previously contained both the
linearized left- and right-hand sides. But only the first increment ever had any
actions, so it was confusing (and space wasting) that all increments had an
"actions" vector. No more!
This commit separates the linearized left-hand side ("matches") from the
linearized right-hand side ("actions").
While the goal is definitely still Cranelift focused, (a) this should be obvious
based on the fact that this is nested under the `cranelift/` directory, and (b)
Peepmatic *is* now generic over the IR it is optimizing, so it could potentially
be used on (say) rustc's MIR now.
Andrew Brown
Joey Gouly
Benjamin Bouvier
Chris Fallin
bjorn3
Nick Fitzgerald
Anton Kirilov
Alex Crichton
Joshua Warner
zhiqiangxu