* Update the wasm-tools family of crates
This commit updates these crates as used by Wasmtime for the recently
published versions to pull in changes necessary to support the component
model. I've split this out from #4005 to make it clear what's impacted
here and #4005 can simply rebase on top of this to pick up the necessary
changes.
* More test fixes
* Upgrade to regalloc2 0.1.3.
This pulls in bytecodealliance/regalloc2#49, which slightly improves
codegen in some cases where a safepoint (for reference-typed values)
occurs in the same liverange as a register-constrained use. For
example, in bytecodealliance/wasmtime#3785, an extra move instruction
appeared and a callee-save register was used (necessitating a more
expensive prologue) because of suboptimal splitting heuristics, which
this PR fixes. The updated RA2 heuristics appear to have no measured
downsides in existing benchmarks and improve the manually-observed
codegen issue.
* Update filetests where regalloc2 improvement altered behavior with reftypes.
This PR fixes#4066: it modifies the Cranelift `build.rs` workflow to
invoke the ISLE DSL compiler on every compilation, rather than only
when the user specifies a special "rebuild ISLE" feature.
The main benefit of this change is that it vastly simplifies the mental
model required of developers, and removes a bunch of failure modes
we have tried to work around in other ways. There is now just one
"source of truth", the ISLE source itself, in the repository, and so there
is no need to understand a special "rebuild" step and how to handle
merge errors. There is no special process needed to develop the compiler
when modifying the DSL. And there is no "noise" in the git history produced
by constantly-regenerated files.
The two main downsides we discussed in #4066 are:
- Compile time could increase, by adding more to the "meta" step before the main build;
- It becomes less obvious where the source definitions are (everything becomes
more "magic"), which makes exploration and debugging harder.
This PR addresses each of these concerns:
1. To maintain reasonable compile time, it includes work to cut down the
dependencies of the `cranelift-isle` crate to *nothing* (only the Rust stdlib),
in the default build. It does this by putting the error-reporting bits
(`miette` crate) under an optional feature, and the logging (`log` crate) under
a feature-controlled macro, and manually writing an `Error` impl rather than
using `thiserror`. This completely avoids proc macros and the `syn` build slowness.
The user can still get nice errors out of `miette`: this is enabled by specifying
a Cargo feature `--features isle-errors`.
2. To allow the user to optionally inspect the generated source, which nominally
lives in a hard-to-find path inside `target/` now, this PR adds a feature `isle-in-source-tree`
that, as implied by the name, moves the target for ISLE generated source into
the source tree, at `cranelift/codegen/isle_generated_source/`. It seems reasonable
to do this when an explicit feature (opt-in) is specified because this is how ISLE regeneration
currently works as well. To prevent surprises, if the feature is *not* specified, the
build fails if this directory exists.
As discussed previously, we need a way to be able to configure Wasmtime when running it in the Sightglass benchmark infrastructure. The easiest way to do this seemed to be to pass a string from Sightglass to the `bench-api` library and parse this in the same way that Wasmtime parses its CLI flags. The structure that contains these flags is `CommonOptions`, so it has been moved to its own crate to be depended on by both `wasmtime-cli` and `wasmtime-bench-api`. Also, this change adds an externally-visible function for parsing a string into `CommonOptions`, which is used for configuring an engine.
* Update to clap 3.0
This commit migrates all CLI commands internally used in this project
from structopt/clap2 to clap 3. The intent here is to ensure that we're
using maintained versions of the dependencies as structopt and clap 2
are less maintained nowadays. Most transitions were pretty
straightforward and mostly dealing with structopt/clap3 differences.
* Fix a number of `cargo deny` errors
This commit fixes a few errors around duplicate dependencies which
arose from the prior update to clap3. This also uses a new feature in
`deny.toml`, `skip-tree`, which allows having a bit more targeted
ignores for skips of duplicate version checks. This showed a few more
locations in Wasmtime itself where we could update some dependencies.
* Run a `cargo update` over our dependencies
This'll notably fix a `cargo audit` error where we have a pinned version
of the `regex` crate which has a CVE assigned to it.
* Update to `object` and `hashbrown` crates
Prune some duplicate versions showing up from the previous `cargo update`
With these fixes, all this PR has to do is instantiate and run the
checker on the `regalloc2::Output`. This is off by default, and is
enabled by setting the `regalloc_checker` Cranelift option.
This restores the old functionality provided by e.g. the
`backtracking_checked` regalloc algorithm setting rather than
`backtracking` when we were still on regalloc.rs.
This commit removes support for the `userfaultfd` or "uffd" syscall on
Linux. This support was originally added for users migrating from Lucet
to Wasmtime, but the recent developments of kernel-supported
copy-on-write support for memory initialization wound up being more
appropriate for these use cases than usefaultfd. The main reason for
moving to copy-on-write initialization are:
* The `userfaultfd` feature was never necessarily intended for this
style of use case with wasm and was susceptible to subtle and rare
bugs that were extremely difficult to track down. We were never 100%
certain that there were kernel bugs related to userfaultfd but the
suspicion never went away.
* Handling faults with userfaultfd was always slow and single-threaded.
Only one thread could handle faults and traveling to user-space to
handle faults is inherently slower than handling them all in the
kernel. The single-threaded aspect in particular presented a
significant scaling bottleneck for embeddings that want to run many
wasm instances in parallel.
* One of the major benefits of userfaultfd was lazy initialization of
wasm linear memory which is also achieved with the copy-on-write
initialization support we have right now.
* One of the suspected benefits of userfaultfd was less frobbing of the
kernel vma structures when wasm modules are instantiated. Currently
the copy-on-write support has a mitigation where we attempt to reuse
the memory images where possible to avoid changing vma structures.
When comparing this to userfaultfd's performance it was found that
kernel modifications of vmas aren't a worrisome bottleneck so
copy-on-write is suitable for this as well.
Overall there are no remaining benefits that userfaultfd gives that
copy-on-write doesn't, and copy-on-write solves a major downsides of
userfaultfd, the scaling issue with a single faulting thread.
Additionally copy-on-write support seems much more robust in terms of
kernel implementation since it's only using standard memory-management
syscalls which are heavily exercised. Finally copy-on-write support
provides a new bonus where read-only memory in WebAssembly can be mapped
directly to the same kernel cache page, even amongst many wasm instances
of the same module, which was never possible with userfaultfd.
In light of all this it's expected that all users of userfaultfd should
migrate to the copy-on-write initialization of Wasmtime (which is
enabled by default).
This PR switches Cranelift over to the new register allocator, regalloc2.
See [this document](https://gist.github.com/cfallin/08553421a91f150254fe878f67301801)
for a summary of the design changes. This switchover has implications for
core VCode/MachInst types and the lowering pass.
Overall, this change brings improvements to both compile time and speed of
generated code (runtime), as reported in #3942:
```
Benchmark Compilation (wallclock) Execution (wallclock)
blake3-scalar 25% faster 28% faster
blake3-simd no diff no diff
meshoptimizer 19% faster 17% faster
pulldown-cmark 17% faster no diff
bz2 15% faster no diff
SpiderMonkey, 21% faster 2% faster
fib(30)
clang.wasm 42% faster N/A
```
Relevant to Wasmtime, this fixes undefined references to `utimensat` and
`futimens` on macOS 10.12 and earlier. See bytecodealliance/rustix#157
for details.
It also contains a fix for s390x which isn't currently needed by Wasmtime
itself, but which is needed to make rustix's own testsuite pass on s390x,
which helps people packaging rustix for use in Wasmtime. See
bytecodealliance/rustix#277 for details.
This makes the generator more similar to `wasm-smith` where it is keeping track
of what is on the stack and making choices about what instructions are valid to
generate given the current stack state. This should in theory allow the
generator to emit GC calls while there are live refs on the stack.
Fixes#3917
* Update wasm-tools crates
This commit updates the wasm-tools family of crates as used in Wasmtime.
Notably this brings in the update which removes module linking support
as well as a number of internal refactorings around names and such
within wasmparser itself. This updates all of the wasm translation
support which binds to wasmparser as appropriate.
Other crates all had API-compatible changes for at least what Wasmtime
used so no further changes were necessary beyond updating version
requirements.
* Update a test expectation
* Bump to 0.36.0
* Add a two-week delay to Wasmtime's release process
This commit is a proposal to update Wasmtime's release process with a
two-week delay from branching a release until it's actually officially
released. We've had two issues lately that came up which led to this proposal:
* In #3915 it was realized that changes just before the 0.35.0 release
weren't enough for an embedding use case, but the PR didn't meet the
expectations for a full patch release.
* At Fastly we were about to start rolling out a new version of Wasmtime
when over the weekend the fuzz bug #3951 was found. This led to the
desire internally to have a "must have been fuzzed for this long"
period of time for Wasmtime changes which we felt were better
reflected in the release process itself rather than something about
Fastly's own integration with Wasmtime.
This commit updates the automation for releases to unconditionally
create a `release-X.Y.Z` branch on the 5th of every month. The actual
release from this branch is then performed on the 20th of every month,
roughly two weeks later. This should provide a period of time to ensure
that all changes in a release are fuzzed for at least two weeks and
avoid any further surprises. This should also help with any last-minute
changes made just before a release if they need tweaking since
backporting to a not-yet-released branch is much easier.
Overall there are some new properties about Wasmtime with this proposal
as well:
* The `main` branch will always have a section in `RELEASES.md` which is
listed as "Unreleased" for us to fill out.
* The `main` branch will always be a version ahead of the latest
release. For example it will be bump pre-emptively as part of the
release process on the 5th where if `release-2.0.0` was created then
the `main` branch will have 3.0.0 Wasmtime.
* Dates for major versions are automatically updated in the
`RELEASES.md` notes.
The associated documentation for our release process is updated and the
various scripts should all be updated now as well with this commit.
* Add notes on a security patch
* Clarify security fixes shouldn't be previewed early on CI
* Update to rustix 0.33.5, to fix a link error on Android
This updates to rustix 0.33.5, which includes bytecodealliance/rustix#258,
which fixes bytecodealliance/rustix#256, a link error on Android.
Fixes#3965.
* Bump the rustix versions in the Cargo.toml files too.
Updates the OpenVINO backend for wasi-nn to pre-configure all inputs as `NHWC`. This is not a long-term fix but no worse than the status quo, which configures all input tensors to the same layout. This change updates the CI script to use the latest version of OpenVINO. Closes#3948.
Co-authored-by: Andrew Brown <andrew.brown@intel.com>
A recently discovered fuzz bug reported a difference in execution result
between Wasmtime and v8. The module in question had an exported function
which had multiple results, including floats. About a year ago I
reported a bug on v8 about functions with multiple results leading to
incorrect results, and it was fixed many months back but I don't think
that we ever actually pulled in that update. After updating v8 I saw the
test failure go away, so this update is being done to fix the fuzz bug
test failure I saw.
Currently, the use of the downcast method means that you have to use one
of the hard-coded types. But Enarx needs to define its own `WasiFile`
implementations. This works fine, except the resulting files cannot be
used in poll because they aren't part of the hard-coded list.
Replace this with an accessor method for the pollable type in
`WasiFile`. Because we provide a default implementation of the method
and manually implement it on all the hard-coded types, this is backwards
compatible.
Signed-off-by: Nathaniel McCallum <nathaniel@profian.com>
Add support for implicit type conversions to ISLE.
This feature allows the DSL user to register to the compiler that a
particular term (used as a constructor or extractor) converts from one
type to another. The compiler will then *automatically* insert this term
whenever a type mismatch involving that specific pair of types occurs.
This significantly cleans up many uses of the ISLE DSL. For example,
when defining the compiler backends, we often have newtypes like `Gpr`
around `Reg` (signifying a particular type of register); we can define
a conversion from Gpr to Reg automatically.
Conversions can also have side-effects, as long as these side-effects
are idempotent. For example, `put_value_in_reg` in a compiler backend
has the effect of marking the value as used, causing codegen to produce
it, and assigns a register to the value; but multiple invocations of
this will return the same register for the same value. Thus it is safe
to use it as an implicit conversion that may be invoked multiple times.
This is documented in the ISLE-Cranelift integration document.
This PR also adds some testing infrastructure to the ISLE compiler,
checking that "pass" tests pass through the DSL compiler, "fail" tests
do not, and "link" tests are able to generate code and link that code
with corresponding Rust code.
* fuzzing: Add a custom mutator based on `wasm-mutate`
* fuzz: Add a version of the `compile` fuzz target that uses `wasm-mutate`
* Update `wasmparser` dependencies
Ended up being a routine update but seemed good to go ahead and hook up
updates. While I was at it I went ahead and hooked up multi-value
swarm fuzzing as well now that wasm-smith implements it.
* x64: enable VTune support by default
After significant work in the `ittapi-rs` crate, this dependency should
build without issue on Wasmtime's supported operating systems: Windows,
Linux, and macOS. The difference in the release binary is <20KB, so this
change makes `vtune` a default build feature. This change upgrades
`ittapi-rs` to v0.2.0 and updates the documentation.
* review: add configuration for defaults in more places
* review: remove OS conditional compilation, add architecture
* review: do not default vtune feature in wasmtime-jit
* Fuzz cranelift cpu flag settings with Wasmtime
This commit updates the `Config` fuzz-generator to consume some of the
input as configuration settings for codegen flags we pass to cranelift.
This should allow for ideally some more coverage where settings are
disabled or enabled, ideally finding possible bugs in feature-specific
implementations or generic implementations that are rarely used if the
feature-specific ones almost always take precedent.
The technique used in this commit is to weight selection of codegen
settings less frequently than using the native settings. Afterwards each
listed feature is individually enabled or disabled depending on the
input fuzz data, and if a feature is enabled but the host doesn't
actually support it then the fuzz input is rejected with a log message.
The goal here is to still have many fuzz inputs accepted but also ensure
determinism across hosts. If there's a bug specifically related to
enabling a flag then running it on a host without the flag should
indicate that the flag isn't supported rather than silently leaving it
disabled and reporting the fuzz case a success.
* Use built-in `Unstructured::ratio` method
* Tweak macro
* Bump arbitrary dep version
This commit has a few minor updates and some improvements to the
instantiation benchmark harness:
* A `once_cell::unsync::Lazy` type is now used to guard creation of
modules/engines/etc. This enables running singular benchmarks to be
much faster since the benchmark no longer compiles all other
benchmarks that are filtered out. Unfortunately I couldn't find a way
in criterion to test whether a `BenchmarkId` is filtered out or not so
we rely on the runtime laziness to initialize on the first run for
benchmarks that do so.
* All files located in `benches/instantiation` are now loaded for
benchmarking instead of a hardcoded list. This makes it a bit easier
to throw files into the directory and have them benchmarked instead of
having to recompile when working with new files.
* Finally a module deserialization benchmark was added to measure the
time it takes to deserialize a precompiled module from disk (inspired
by discussion on #3787)
While I was at it I also upped some limits to be able to instantiate
cfallin's `spidermonkey.wasm`.
In working on #3787 I see now that our coverage of loading precompiled
files specifically is somewhat lacking, so this adds a config option to
the fuzzers where, if enabled, will round-trip all compiled modules
through the filesystem to test out the mmapped-file case.
Other than doc updates, this just contains bytecodealliance/cap-std#235,
a fix for compilation errors on Rust nightly that look like this:
```
error[E0308]: mismatched types
--> cap-primitives/src/fs/via_parent/rename.rs:22:58
|
22 | let (old_dir, old_basename) = open_parent(old_start, &old_path)?;
| ^^^^^^^^^ expected struct `Path`, found opaque type
|
::: cap-primitives/src/rustix/fs/dir_utils.rs:67:48
|
67 | pub(crate) fn strip_dir_suffix(path: &Path) -> impl Deref<Target = Path> + '_ {
| ------------------------------ the found opaque type
|
= note: expected struct `Path`
found opaque type `impl Deref<Target = Path>`
```
This patch implements CLI options to insert pre-opened sockets.
`--listenfd` : Inherit environment variables and file descriptors following
the systemd listen fd specification (UNIX only).
`--tcplisten <SOCKET ADDRESS>`: Grant access to the given TCP listen socket.
Signed-off-by: Harald Hoyer <harald@profian.com>
This primary motivation of this large commit (apologies for its size!) is to
introduce `Gpr` and `Xmm` newtypes over `Reg`. This should help catch
difficult-to-diagnose register class mixup bugs in x64 lowerings.
But having a newtype for `Gpr` and `Xmm` themselves isn't enough to catch all of
our operand-with-wrong-register-class bugs, because about 50% of operands on x64
aren't just a register, but a register or memory address or even an
immediate! So we have `{Gpr,Xmm}Mem[Imm]` newtypes as well.
Unfortunately, `GprMem` et al can't be `enum`s and are therefore a little bit
noisier to work with from ISLE. They need to maintain the invariant that their
registers really are of the claimed register class, so they need to encapsulate
the inner data. If they exposed the underlying `enum` variants, then anyone
could just change register classes or construct a `GprMem` that holds an XMM
register, defeating the whole point of these newtypes. So when working with
these newtypes from ISLE, we rely on external constructors like `(gpr_to_gpr_mem
my_gpr)` instead of `(GprMem.Gpr my_gpr)`.
A bit of extra lines of code are included to add support for register mapping
for all of these newtypes as well. Ultimately this is all a bit wordier than I'd
hoped it would be when I first started authoring this commit, but I think it is
all worth it nonetheless!
In the process of adding these newtypes, I didn't want to have to update both
the ISLE `extern` type definition of `MInst` and the Rust definition, so I move
the definition fully into ISLE, similar as aarch64.
Finally, this process isn't complete. I've introduced the newtypes here, and
I've made most XMM-using instructions switch from `Reg` to `Xmm`, as well as
register class-converting instructions, but I haven't moved all of the GPR-using
instructions over to the newtypes yet. I figured this commit was big enough as
it was, and I can continue the adoption of these newtypes in follow up commits.
Part of #3685.
As a followup to the recent memfd allocator work, this PR makes the
memfd image creation occur on the first instantiation, rather than
immediately when the `Module` is loaded.
This shaves off a potentially surprising cost spike that would have
otherwise occurred: prior to the memfd work, no allocator eagerly read
the module's initial heap state into RAM. The behavior should now more
closely resemble what happened before (and the improvements in overall
instantiation time and performance, as compared to either eager init
with pure-mmap memory or user-mode pagefault handling with uffd,
remain).
Following up on #3696, use the new is-terminal crate to test for a tty
rather than having platform-specific logic in Wasmtime. The is-terminal
crate has a platform-independent API which takes a handle.
This also updates the tree to cap-std 0.24 etc., to avoid depending on
multiple versions of io-lifetimes at once, as enforced by the cargo deny
check.
With the addition of `sock_accept()` in `wasi-0.11.0`, wasmtime can now
implement basic networking for pre-opened sockets.
For Windows `AsHandle` was replaced with `AsRawHandleOrSocket` to cope
with the duality of Handles and Sockets.
For Unix a `wasi_cap_std_sync::net::Socket` enum was created to handle
the {Tcp,Unix}{Listener,Stream} more efficiently in
`WasiCtxBuilder::preopened_socket()`.
The addition of that many `WasiFile` implementors was mainly necessary,
because of the difference in the `num_ready_bytes()` function.
A known issue is Windows now busy polling on sockets, because except
for `stdin`, nothing is querying the status of windows handles/sockets.
Another know issue on Windows, is that there is no crate providing
support for `fcntl(fd, F_GETFL, 0)` on a socket.
Signed-off-by: Harald Hoyer <harald@profian.com>
As first suggested by Jan on the Zulip here [1], a cheap and effective
way to obtain copy-on-write semantics of a "backing image" for a Wasm
memory is to mmap a file with `MAP_PRIVATE`. The `memfd` mechanism
provided by the Linux kernel allows us to create anonymous,
in-memory-only files that we can use for this mapping, so we can
construct the image contents on-the-fly then effectively create a CoW
overlay. Furthermore, and importantly, `madvise(MADV_DONTNEED, ...)`
will discard the CoW overlay, returning the mapping to its original
state.
By itself this is almost enough for a very fast
instantiation-termination loop of the same image over and over,
without changing the address space mapping at all (which is
expensive). The only missing bit is how to implement
heap *growth*. But here memfds can help us again: if we create another
anonymous file and map it where the extended parts of the heap would
go, we can take advantage of the fact that a `mmap()` mapping can
be *larger than the file itself*, with accesses beyond the end
generating a `SIGBUS`, and the fact that we can cheaply resize the
file with `ftruncate`, even after a mapping exists. So we can map the
"heap extension" file once with the maximum memory-slot size and grow
the memfd itself as `memory.grow` operations occur.
The above CoW technique and heap-growth technique together allow us a
fastpath of `madvise()` and `ftruncate()` only when we re-instantiate
the same module over and over, as long as we can reuse the same
slot. This fastpath avoids all whole-process address-space locks in
the Linux kernel, which should mean it is highly scalable. It also
avoids the cost of copying data on read, as the `uffd` heap backend
does when servicing pagefaults; the kernel's own optimized CoW
logic (same as used by all file mmaps) is used instead.
[1] https://bytecodealliance.zulipchat.com/#narrow/stream/206238-general/topic/Copy.20on.20write.20based.20instance.20reuse/near/266657772
WASI doesn't have an `isatty` ioctl or syscall, so wasi-libc's `isatty`
implementation uses the file descriptor type and rights to determine if
the file descriptor is likely to be a tty. The real fix here will be to
add an `isatty` call to WASI. But for now, have Wasmtime set the
filetype and rights for file descriptors so that wasi-libc's `isatty`
works as expected.
* Provide helpers for demangling function names
* Profile trampolines in vtune too
* get rid of mapping
* avoid code duplication with jitdump_linux
* maintain previous default display name for wasm functions
* no dash, grrr
* Remove unused profiling error type
Before this PR, each profiler (perf/vtune, at the moment) had to have a
demangler for each of the programming languages that could have been
compiled to wasm and fed into wasmtime. With this, wasmtime now
demangles names before even forwarding them to the underlying profiler,
which makes for a unified representation in profilers, and avoids
incorrect demangling in profilers.
* fuzz: Refactor Wasmtime's fuzz targets
A recent fuzz bug found is related to timing out when compiling a
module. This timeout, however, is predominately because Cranelift's
debug verifier is enabled and taking up over half the compilation time.
I wanted to fix this by disabling the verifier when input modules might
have a lot of functions, but this was pretty difficult to implement.
Over time we've grown a number of various fuzzers. Most are
`wasm-smith`-based at this point but there's various entry points for
configuring the wasm-smith module, the wasmtime configuration, etc. I've
historically gotten quite lost in trying to change defaults and feeling
like I have to touch a lot of different places. This is the motivation
for this commit, simplifying fuzzer default configuration.
This commit removes the ability to create a default `Config` for
fuzzing, instead only supporting generating a configuration via
`Arbitrary`. This then involved refactoring all targets and fuzzers to
ensure that configuration is generated through `Arbitrary`. This should
actually expand the coverage of some existing fuzz targets since
`Arbitrary for Config` will tweak options that don't affect runtime,
such as memory configuration or jump veneers.
All existing fuzz targets are refactored to use this new method of
configuration. Some fuzz targets were also shuffled around or
reimplemented:
* `compile` - this now directly calls `Module::new` to skip all the
fuzzing infrastructure. This is mostly done because this fuzz target
isn't too interesting and is largely just seeing what happens when
things are thrown at the wall for Wasmtime.
* `instantiate-maybe-invalid` - this fuzz target now skips instantiation
and instead simply goes into `Module::new` like the `compile` target.
The rationale behind this is that most modules won't instantiate
anyway and this fuzz target is primarily fuzzing the compiler. This
skips having to generate arbitrary configuration since
wasm-smith-generated-modules (or valid ones at least) aren't used
here.
* `instantiate` - this fuzz target was removed. In general this fuzz
target isn't too interesting in isolation. Almost everything it deals
with likely won't pass compilation and is covered by the `compile`
fuzz target, and otherwise interesting modules being instantiated can
all theoretically be created by `wasm-smith` anyway.
* `instantiate-wasm-smith` and `instantiate-swarm` - these were both merged
into a new `instantiate` target (replacing the old one from above).
There wasn't really much need to keep these separate since they really
only differed at this point in methods of timeout. Otherwise we much
more heavily use `SwarmConfig` than wasm-smith's built-in options.
The intention is that we should still have basically the same coverage
of fuzzing as before, if not better because configuration is now
possible on some targets. Additionally there is one centralized point of
configuration for fuzzing for wasmtime, `Arbitrary for ModuleConfig`.
This internally creates an arbitrary `SwarmConfig` from `wasm-smith` and
then further tweaks it for Wasmtime's needs, such as enabling various
wasm proposals by default. In the future enabling a wasm proposal on
fuzzing should largely just be modifying this one trait implementation.
* fuzz: Sometimes disable the cranelift debug verifier
This commit disables the cranelift debug verifier if the input wasm
module might be "large" for the definition of "more than 10 functions".
While fuzzing we disable threads (set them to 1) and enable the
cranelift debug verifier. Coupled with a 20-30x slowdown this means that
a module with the maximum number of functions, 100, gives:
60x / 100 functions / 30x slowdown = 20ms
With only 20 milliseconds per function this is even further halved by
the `differential` fuzz target compiling a module twice, which means
that, when compiling with a normal release mode Wasmtime, if any
function takes more than 10ms to compile then it's a candidate for
timing out while fuzzing. Given that the cranelift debug verifier can
more than double compilation time in fuzzing mode this actually means
that the real time budget for function compilation is more like 4ms.
The `wasm-smith` crate can pretty easily generate a large function that
takes 4ms to compile, and then when that function is multiplied 100x in
the `differential` fuzz target we trivially time out the fuzz target.
The hope of this commit is to buy back half our budget by disabling the
debug verifier for modules that may have many functions. Further
refinements can be implemented in the future such as limiting functions
for just the differential target as well.
* Fix the single-function-module fuzz configuration
* Tweak how features work in differential fuzzing
* Disable everything for baseline differential fuzzing
* Enable selectively for each engine afterwards
* Also forcibly enable reference types and bulk memory for spec tests
* Log wasms when compiling
* Add reference types support to v8 fuzzer
* Fix timeouts via fuel
The default store has "infinite" fuel so that needs to be consumed
before fuel is added back in.
* Remove fuzzing-specific tests
These no longer compile and also haven't been added to in a long time.
Most of the time a reduced form of original the fuzz test case is added
when a fuzz bug is fixed.
This update is no real change in functionality but brings in several of
the latest changes to the `ittapi-rs` library: minor fixes to the C
library, a new license expression for the Cargo crate, better
documentation, updated Rust bindings, and the removal of `cmake` as a
dependency (uses `cc` directly instead).
