This was added long ago at this point to assist with caching, but
caching has moved to a different level such that this wonky second level
of a `Module` isn't necessary. This commit removes the `ModuleLocal`
type to simplify accessors and generally make it easier to work with.
The implementation is pretty straightforward. Wasm atomic instructions fall
into 5 groups
* atomic read-modify-write
* atomic compare-and-swap
* atomic loads
* atomic stores
* fences
and the implementation mirrors that structure, at both the CLIF and AArch64
levels.
At the CLIF level, there are five new instructions, one for each group. Some
comments about these:
* for those that take addresses (all except fences), the address is contained
entirely in a single `Value`; there is no offset field as there is with
normal loads and stores. Wasm atomics require alignment checks, and
removing the offset makes implementation of those checks a bit simpler.
* atomic loads and stores get their own instructions, rather than reusing the
existing load and store instructions, for two reasons:
- per above comment, makes alignment checking simpler
- reuse of existing loads and stores would require extension of `MemFlags`
to indicate atomicity, which sounds semantically unclean. For example,
then *any* instruction carrying `MemFlags` could be marked as atomic, even
in cases where it is meaningless or ambiguous.
* I tried to specify, in comments, the behaviour of these instructions as
tightly as I could. Unfortunately there is no way (per my limited CLIF
knowledge) to enforce the constraint that they may only be used on I8, I16,
I32 and I64 types, and in particular not on floating point or vector types.
The translation from Wasm to CLIF, in `code_translator.rs` is unremarkable.
At the AArch64 level, there are also five new instructions, one for each
group. All of them except `::Fence` contain multiple real machine
instructions. Atomic r-m-w and atomic c-a-s are emitted as the usual
load-linked store-conditional loops, guarded at both ends by memory fences.
Atomic loads and stores are emitted as a load preceded by a fence, and a store
followed by a fence, respectively. The amount of fencing may be overkill, but
it reflects exactly what the SM Wasm baseline compiler for AArch64 does.
One reason to implement r-m-w and c-a-s as a single insn which is expanded
only at emission time is that we must be very careful what instructions we
allow in between the load-linked and store-conditional. In particular, we
cannot allow *any* extra memory transactions in there, since -- particularly
on low-end hardware -- that might cause the transaction to fail, hence
deadlocking the generated code. That implies that we can't present the LL/SC
loop to the register allocator as its constituent instructions, since it might
insert spills anywhere. Hence we must present it as a single indivisible
unit, as we do here. It also has the benefit of reducing the total amount of
work the RA has to do.
The only other notable feature of the r-m-w and c-a-s translations into
AArch64 code, is that they both need a scratch register internally. Rather
than faking one up by claiming, in `get_regs` that it modifies an extra
scratch register, and having to have a dummy initialisation of it, these new
instructions (`::LLSC` and `::CAS`) simply use fixed registers in the range
x24-x28. We rely on the RA's ability to coalesce V<-->R copies to make the
cost of the resulting extra copies zero or almost zero. x24-x28 are chosen so
as to be call-clobbered, hence their use is less likely to interfere with long
live ranges that span calls.
One subtlety regarding the use of completely fixed input and output registers
is that we must be careful how the surrounding copy from/to of the arg/result
registers is done. In particular, it is not safe to simply emit copies in
some arbitrary order if one of the arg registers is a real reg. For that
reason, the arguments are first moved into virtual regs if they are not
already there, using a new method `<LowerCtx for Lower>::ensure_in_vreg`.
Again, we rely on coalescing to turn them into no-ops in the common case.
There is also a ridealong fix for the AArch64 lowering case for
`Opcode::Trapif | Opcode::Trapff`, which removes a bug in which two trap insns
in a row were generated.
In the patch as submitted there are 6 "FIXME JRS" comments, which mark things
which I believe to be correct, but for which I would appreciate a second
opinion. Unless otherwise directed, I will remove them for the final commit
but leave the associated code/comments unchanged.
* Refactor where results of compilation are stored
This commit refactors the internals of compilation in Wasmtime to change
where results of individual function compilation are stored. Previously
compilation resulted in many maps being returned, and compilation
results generally held all these maps together. This commit instead
switches this to have all metadata stored in a `CompiledFunction`
instead of having a separate map for each item that can be stored.
The motivation for this is primarily to help out with future
module-linking-related PRs. What exactly "module level" is depends on
how we interpret modules and how many modules are in play, so it's a bit
easier for operations in wasmtime to work at the function level where
possible. This means that we don't have to pass around multiple
different maps and a function index, but instead just one map or just
one entry representing a compiled function.
Additionally this change updates where the parallelism of compilation
happens, pushing it into `wasmtime-jit` instead of `wasmtime-environ`.
This is another goal where `wasmtime-jit` will have more knowledge about
module-level pieces with module linking in play. User-facing-wise this
should be the same in terms of parallel compilation, though.
The ultimate goal of this refactoring is to make it easier for the
results of compilation to actually be a set of wasm modules. This means
we won't be able to have a map-per-metadata where the primary key is the
function index, because there will be many modules within one "object
file".
* Don't clear out fields, just don't store them
Persist a smaller set of fields in `CompilationArtifacts` instead of
trying to clear fields out and dynamically not accessing them.
* Don't re-parse wasm for debuginfo
This commit updates debuginfo parsing to happen during the main
translation of the original wasm module. This avoid re-parsing the wasm
module twice (at least the section-level headers). Additionally this
ties debuginfo directly to a `ModuleTranslation` which makes it easier
to process debuginfo for nested modules in the upcoming module linking
proposal.
The changes here are summarized by taking the `read_debuginfo` function
and merging it with the main module translation that happens which is
driven by cranelift. Some new hooks were added to the module environment
trait to support this, but most of it was integrating with existing hooks.
* Fix tests in debug crate
* virtfs file: update cursor position on fd_read
If a handle is backed by InMemoryFile, fd_read (turned into
Handle::read_vectored) doesn't update the cursor position properly and
thus prevents the caller from detecting EOF.
* virtfs file: fd_{pread,pwrite}: update offset in iovec iteration
If multiple iovec's are supplied, fd_pread and fd_pwrite previously
access data at the same offset for each iovec.
* move caching to the CompilationArtifacts
* mv cache_config from Compiler to CompiledModule
* hash isa flags
* no cache for wasm2obj
* mv caching to wasmtime crate
* account each Compiler field when hash
* Use AsRef<Path> instead of AsRef<OsStr> in yanix functions.
`AsRef<Path>` makes these more consistent with `std` interfaces, making
them easier to use outside of wasi-common.
Also, refactor the conversion to `CString` into a helper function.
* Reduce clutter from fully-qualifying names.
* rustfmt
This commit updates our CI to verify that all crates are publish-able at
all times on every commit. During the 0.19.0 release we found another
case where the crates as they live in this repository weren't
publish-able, so the hope is that this no longer comes up again!
The script added in this commit also takes the time/liberty to remove
the existing bump/publish scripts and instead replace them with one Rust
script originally sourced from wasm-bindgen. The intention of this
script is that it has three modes:
* `./publish bump` - bumps version numbers which are sent as a PR to get
reviewed (probably with a changelog as well)
* `./publish verify` - run on CI on every commit, builds every crate we
publish as if it's being published to crates.io, notably without raw
access to other crates in the repository.
* `./publish publish` - publishes all crates to crates.io, passing the
`--no-verify` flag to make this a much speedier process than it is
today.
This commit fixes `Clone for wasm_val_t` to avoid attempting to chase a
null pointer. It also fixes the implementation for `FuncRef` values by
cloning their internal `wasm_ref_t` as well.
Currently `Func::new` will panic if one of the arguments of the function
is a reference type and the `Store` doesn't have reference types
enabled. This happens because cranelift isn't configure to enable stack
maps but the register allocators expects them to exist when reference
types are seen.
The fix here is to always enable reference types in cranelift for our
trampoline generation and `Func::new`. This should hopefully ensure that
trampolines are generated correctly and they'll just not be able to get
hooked up to an `Instance` because validation will prevent reference
types from being used elsewhere.
* wasmtime-c-api: Only drop non-null `*mut wasm_ref_t`s
* wasmtime-c-api: Handle null refs in `wasm_val_t` to `Val` conversion
* wasmtime-c-api: Don't unwrap and rewrap `Option`s
The `unwrap` can panic, and there isn't any point to this unwrap+rewrap.
* wasmtime-c-api: Add conversions between `funcref` and `wasm_func_t`
* wasmtime-c-api: More ownership documentation for `wasmtime.h`
Before this patch, running the x64 new backend would require both
compiling with --features experimental_x64 and running with
`use_new_backend`.
This patches changes this behavior so that the runtime flag is not
needed anymore: using the feature flag will enforce usage of the new
backend everywhere, making using and testing it much simpler:
cargo run --features experimental_x64 ;; other CLI options/flags
This also gives a hint at what the meta language generation would look
like after switching to the new backend.
Compiling only with the x64 codegen flag gives a nice compile time speedup.
This commit is intended to update wasmparser to 0.59.0. This primarily
includes bytecodealliance/wasm-tools#40 which is a large update to how
parsing and validation works. The impact on Wasmtime is pretty small at
this time, but over time I'd like to refactor the internals here to lean
more heavily on that upstream wasmparser refactoring.
For now, though, the intention is to get on the train of wasmparser's
latest `main` branch to ensure we get bug fixes and such.
As part of this update a few other crates and such were updated. This is
primarily to handle the new encoding of `ref.is_null` where the type is
not part of the instruction encoding any more.
We were accidentally always running the `fib-debug/main` example because of
shenanigans with alphabetical ordering and hard coding "main.exe" as the command
we run. Now we properly detect which example we built and run the appropriate
executable.
The canonical examples tests will be the examples run via `cargo run -p
run-examples` from now on. Those tests have two advantages over the ones being
deleted:
1. They will automatically pick up new examples and run/test them.
2. They support all of Linux, MacOS, and Windows, while the tests being deleted
are Linux only.
This required that `wasm_val_t` have a `Drop` implementation, an explicit
`Clone` implementation, and no longer be `Copy`, which rippled out through the
crate a bit.
Additionally, `wasm_func_call` and friends were creating references to
uninitialized data for its out pointers and assigning to them. As soon as
`wasm_val_t` gained a `Drop` impl and tried to drop the old value of the
assignment (which is uninitialized data), then things blew up. The fix is to
properly represent the out pointers with `MaybeUninit`, and use `ptr::write` to
initialize them without dropping the old data.
Part of #929
