Wasmtime has a few representations of `Val` and `ValType` across the
internal crates, the `wasmtime` crate, and the C API. These were
previously sometimes mentioned in different orders which means that
converting between the two took a little extra code than before. This
commit is a micro-optimization to align the types across the various
places we define these to help reduce the codegen burden when converting
between these types.
This is not expected to have a major impact on performance, rather it's
a small cleanup which should be easy-ish to preserve I've noticed while
staring at assembly.
Implemented `SaddSat` and `SsubSat` to add and subtract signed vector
values, saturating at the type boundaries rather than overflowing.
Changed the parser to allow signed `i8` immediates in vectors as part of
this work; fixes#3276.
Copyright (c) 2021, Arm Limited.
- Fixed CI tests for AArch64 and old x86.
- Rename `simd-umulhi.clif` to `umulhi.clif`.
- Rename `simd-umulhi-aarch64.clif` to `simd-umulhi.clif`.
Copyright (c) 2021, Arm Limited.
The `()` type accidentally wasn't getting its trivial type conversions
inlined because it doesn't actually have any type parameters. This
commit adds `#[inline]` to the relevant functions to ensure that these
get inlined across crates.
Currently wasm-calls work with `Result<T, Trap>` internally but `Trap`
is an enum defined in `wasmtime-runtime` which is actually quite large.
Since traps are supposed to be rare this commit changes these functions
to return a `Box<Trap>` which is un-boxed later up in the `wasmtime`
crate within a `#[cold]` function.
Implemented `Umulhi` for the Cranelift interpreter, performing unsigned
integer multiplication and producing the high half of a double-length
result.
Fixed `ExtractUpper` conversion behaviour as part of this change, which
was extracting from a 128-bit value regardless of the size of the
original value.
Copyright (c) 2021, Arm Limited.
which is more expressive than the former.
Instead of just configuring Module::deserialize to ignore version
information, we can configure Module::serialize to emit a custom version
string, and Module::deserialize to check for that string. A new enum
ModuleVersionStrategy is declared, and
Config::deserialize_check_wasmtime_version:bool is replaced with
Config::module_version:ModuleVersionStrategy.
* Use relative `call` instructions between wasm functions
This commit is a relatively major change to the way that Wasmtime
generates code for Wasm modules and how functions call each other.
Prior to this commit all function calls between functions, even if they
were defined in the same module, were done indirectly through a
register. To implement this the backend would emit an absolute 8-byte
relocation near all function calls, load that address into a register,
and then call it. While this technique is simple to implement and easy
to get right, it has two primary downsides associated with it:
* Function calls are always indirect which means they are more difficult
to predict, resulting in worse performance.
* Generating a relocation-per-function call requires expensive
relocation resolution at module-load time, which can be a large
contributing factor to how long it takes to load a precompiled module.
To fix these issues, while also somewhat compromising on the previously
simple implementation technique, this commit switches wasm calls within
a module to using the `colocated` flag enabled in Cranelift-speak, which
basically means that a relative call instruction is used with a
relocation that's resolved relative to the pc of the call instruction
itself.
When switching the `colocated` flag to `true` this commit is also then
able to move much of the relocation resolution from `wasmtime_jit::link`
into `wasmtime_cranelift::obj` during object-construction time. This
frontloads all relocation work which means that there's actually no
relocations related to function calls in the final image, solving both
of our points above.
The main gotcha in implementing this technique is that there are
hardware limitations to relative function calls which mean we can't
simply blindly use them. AArch64, for example, can only go +/- 64 MB
from the `bl` instruction to the target, which means that if the
function we're calling is a greater distance away then we would fail to
resolve that relocation. On x86_64 the limits are +/- 2GB which are much
larger, but theoretically still feasible to hit. Consequently the main
increase in implementation complexity is fixing this issue.
This issue is actually already present in Cranelift itself, and is
internally one of the invariants handled by the `MachBuffer` type. When
generating a function relative jumps between basic blocks have similar
restrictions. This commit adds new methods for the `MachBackend` trait
and updates the implementation of `MachBuffer` to account for all these
new branches. Specifically the changes to `MachBuffer` are:
* For AAarch64 the `LabelUse::Branch26` value now supports veneers, and
AArch64 calls use this to resolve relocations.
* The `emit_island` function has been rewritten internally to handle
some cases which previously didn't come up before, such as:
* When emitting an island the deadline is now recalculated, where
previously it was always set to infinitely in the future. This was ok
prior since only a `Branch19` supported veneers and once it was
promoted no veneers were supported, so without multiple layers of
promotion the lack of a new deadline was ok.
* When emitting an island all pending fixups had veneers forced if
their branch target wasn't known yet. This was generally ok for
19-bit fixups since the only kind getting a veneer was a 19-bit
fixup, but with mixed kinds it's a bit odd to force veneers for a
26-bit fixup just because a nearby 19-bit fixup needed a veneer.
Instead fixups are now re-enqueued unless they're known to be
out-of-bounds. This may run the risk of generating more islands for
19-bit branches but it should also reduce the number of islands for
between-function calls.
* Otherwise the internal logic was tweaked to ideally be a bit more
simple, but that's a pretty subjective criteria in compilers...
I've added some simple testing of this for now. A synthetic compiler
option was create to simply add padded 0s between functions and test
cases implement various forms of calls that at least need veneers. A
test is also included for x86_64, but it is unfortunately pretty slow
because it requires generating 2GB of output. I'm hoping for now it's
not too bad, but we can disable the test if it's prohibitive and
otherwise just comment the necessary portions to be sure to run the
ignored test if these parts of the code have changed.
The final end-result of this commit is that for a large module I'm
working with the number of relocations dropped to zero, meaning that
nothing actually needs to be done to the text section when it's loaded
into memory (yay!). I haven't run final benchmarks yet but this is the
last remaining source of significant slowdown when loading modules,
after I land a number of other PRs both active and ones that I only have
locally for now.
* Fix arm32
* Review comments
* Finished the Markdown Parser Example for Wasmtime
* Made requested changes
* Tiny change to explanation of `--dir` CLI arg
* Add `bash` annotations to shell script code blocks
* Trying to fix the markdown example bug
* Figured out rustdoc, and what needed to be done
* Made requested changes
Co-authored-by: Till Schneidereit <till@tillschneidereit.net>
Implemented `Insertlane` to insert a value in the lane specified by the
immediate value, overwriting the existing value in that lane.
Added `TernaryImm8` support for the `imm_value` function.
Copyright (c) 2021, Arm Limited.
Almost all the tests in the interpreter are already in the runtests
folder so that we can reuse them for the backends. The distinction
between interpreter tests and runtests is no longer very clear, since
they should both support the same clif code, and produce the same results.
We only have two test files:
* `add.clif` tests the add and jump instruction, both of which are
already covered in other test files, so we remove that file.
* `fibonacci.clif` does a recursive call which is currently not supported
in the filetest environment, so we keep this test interpreter only for now.
Implemented `IaddPairwise` for the Cranelift interpreter, to add pairs
of adjacent values in two SIMD vectors, concatenating them at the end
(preserving both lane size and number of lanes).
Copyright (c) 2021, Arm Limited
Perform a search over block predecessors trying to find loops of
unreachable predecessors. We do this by iterating on predecessors and
marking them as visited, stopping if we find a previously visited block
or if we find a block with multiple predecessors.
This issue was found by the CLIF fuzzer in #3094.
This makes Cranelift use the Rust `alloc` API its allocations,
rather than directly calling into `libc`, which makes it respect
the `#[global_allocator]` configuration.
Also, use `region::page::ceil` instead of having our own copies of
that logic.
- Fixes for compiling on OpenBSD
- io-lifetimes 0.3.0 has an option (io_lifetimes_use_std, which is off
by default) for testing the `io_safety` feature in Rust nightly.
* Add a `Module::deserialize_file` method
This commit adds a new method to the `wasmtime::Module` type,
`deserialize_file`. This is intended to be the same as the `deserialize`
method except for the serialized module is present as an on-disk file.
This enables Wasmtime to internally use `mmap` to avoid copying bytes
around and generally makes loading a module much faster.
A C API is added in this commit as well for various bindings to use this
accelerated path now as well. Another option perhaps for a Rust-based
API is to have an API taking a `File` itself to allow for a custom file
descriptor in one way or another, but for now that's left for a possible
future refactoring if we find a use case.
* Fix compat with main - handle readdonly mmap
* wip
* Try to fix Windows support
* Implement `IaddCin`, `IaddCout`, and `IaddCarry` for Cranelift interpreter
Implemented the following Opcodes for the Cranelift interpreter:
- `IaddCin` to add two scalar integers with an input carry flag.
- `IaddCout` to add two scalar integers and report overflow with the carry flag.
- `IaddCarry` to add two scalar integers with an input carry flag, reporting overflow with the output carry flag.
Copyright (c) 2021, Arm Limited
* Simplify carry check + add i64 `IaddCarry` tests
Copyright (c) 2021, Arm Limited
* Move tests to `runtests`
Copyright (c) 2021, Arm Limited
* Add differential fuzzing against V8
This commit adds a differential fuzzing target to Wasmtime along the
lines of the wasmi and spec interpreters we already have, but with V8
instead. The intention here is that wasmi is unlikely to receive updates
over time (e.g. for SIMD), and the spec interpreter is not suitable for
fuzzing against in general due to its performance characteristics. The
hope is that V8 is indeed appropriate to fuzz against because it's
naturally receiving updates and it also is expected to have good
performance.
Here the `rusty_v8` crate is used which provides bindings to V8 as well
as precompiled binaries by default. This matches exactly the use case we
need and at least for now I think the `rusty_v8` crate will be
maintained by the Deno folks as they continue to develop it. If it
becomes an issue though maintaining we can evaluate other options to
have differential fuzzing against.
For now this commit enables the SIMD and bulk-memory feature of
fuzz-target-generation which should enable them to get
differentially-fuzzed with V8 in addition to the compilation fuzzing
we're already getting.
* Use weak linkage for GDB jit helpers
This should help us deduplicate our symbol with other JIT runtimes, if
any. For now this leans on some C helpers to define the weak linkage
since Rust doesn't support that on stable yet.
* Don't use rusty_v8 on MinGW
They don't have precompiled libraries there.
* Fix msvc build
* Comment about execution
