Due to SIMD's v128 operations, vectors that may have had an explicit type (e.g. f32x4) before a v128 operation will subsequently have CLIF's v128 stand-in type: i8x16. In order for follow-on operations (that may be more stricly typed, e.g. f32x4.add) to avoid CLIF errors, we must bitcast them back to the operation type. The raw_bitcast operation used to do this emits no machine code but does incur some small compile-time cost; it would be nice to avoid this in the future.
The failure crate invents its own traits that don't use
std::error::Error (because failure predates certain features added to
Error); this prevents using ? on an error from failure in a function
using Error. The thiserror crate integrates with the standard Error
trait instead.
We weren't previously keeping track of quite the right information for whether
an `if .. else .. end`'s following block was reachable or not. It should be
reachable if the head is reachable and either the consequent or alternative end
reachable (and therefore fall through to the following block) or do an early
`br_if` to it.
This commit rejiggers `ControlStackFrame::If` to keep track of reachability at
the end of the consequent (we don't need to keep track of it at the end of the
alternative, since that is simply `state.reachable`) and adds Wasm tests for
every reachability situation we can encounter with `if .. else .. end`.
Fixes#1132
* cranelift-wasm: replace `WasmTypesMap` with `ModuleTranslationState`
The `ModuleTranslationState` contains information decoded from the Wasm module
that must be referenced during each Wasm function's translation.
This is only for data that is maintained by `cranelift-wasm` itself, as opposed
to being maintained by the embedder. Data that is maintained by the embedder is
represented with `ModuleEnvironment`.
A `ModuleTranslationState` is returned by `translate_module`, and can then be
used when translating functions from that module.
* cranelift-wasm: rename `TranslationState` to `FuncTranslationState`
To disambiguate a bit with the new `ModuleTranslationState`.
* cranelift-wasm: Reorganize the internal `state` module into submodules
One module for the `ModuleTranslationState` and another for the
`FuncTranslationState`.
* cranelift-wasm: replace `FuncTranslator` with methods on `ModuleTranslationState`
`FuncTranslator` was two methods that always took ownership of `self`, so it
didn't really make sense as an object as opposed to two different functions, or
in this case methods on the object that actually persists for a longer time.
I think this improves ergonomics nicely.
Before:
```rust
let module_translation = translate_module(...)?;
for body in func_bodies {
let mut translator = FuncTranslator::new();
translator.translate(body, ...)?;
}
```
After:
```rust
let module_translation = translate_module(...)?;
for body in func_bodies {
module_translation.translate_func(body, ...)?;
}
```
Note that this commit does not remove `FuncTranslator`. It still exists, but is
just a wrapper over the `ModuleTranslationState` methods, and it is marked
deprecated, so that downstream users get a heads up. This should make the
transition easier.
* Revert "cranelift-wasm: replace `FuncTranslator` with methods on `ModuleTranslationState`"
This reverts commit 075f9ae933bcaae39348b61287c8f78a4009340d.
This commit fixes a bug where at the end of an `if..else..end`'s consequent
block, we would sometimes erroneously jump to the `else` block instead of to the
following destination block. Not good!
This commit introduces initial support for multi-value Wasm. Wasm blocks and
calls can now take and return an arbitrary number of values.
The encoding for multi-value blocks means that we need to keep the contents of
the "Types" section around when translating function bodies. To do this, we
introduce a `WasmTypesMap` type that maps the type indices to their parameters
and returns, construct it when parsing the "Types" section, and shepherd it
through a bunch of functions and methods when translating function bodies.
Only i16x8 and i32x4 are encoded in this commit mainly because i8x16 and i64x2 do not have simple encodings in x86. i64x2 is not required by the SIMD spec and there is discussion (https://github.com/WebAssembly/simd/pull/98#issuecomment-530092217) about removing i8x16.
`VisibleTranslationState` was a wrapper around a `TranslationState` that was
meant to public API consumers outside of this crate. However, the internal
`TranslationState` and all its methods were still publicly exposed! This commit
simplifies and remedies the situation by combining them into a single
`TranslationState` type. Most of its methods are only `pub(crate)` now, not
visible to the entire world. The only methods that are `pub` are the ones that
`VisibleTranslationState` exposed.
