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.
This patch restricts the `Err(..)` return from `blocktype_to_type` to be
`Err(..)` only in the case where it really is an error to continue. The three
use points of `blocktype_to_type` are changed to check for an `Err(..)` rather
than silently ignoring it. There are also cosmetic changes to `type_to_type`
and `tabletype_to_type`.
When compiling wasm_lua_binarytrees, this reduces the number of blocks
allocated by CL by 1.9%. Instruction count falls by 0.1%.
Details:
* `type_to_type` and `tabletype_to_type`:
- Added the function name in the failure message
- No functional change for non-error cases
- Push the `Ok(..)` to expression leaves, where it really applies. This
corrects the misleading impression that, in the case of an unsupported
type, the function returns `Ok` wrapped around whatever
`wasm_unsupported` returns. It doesn't do that, but it certainly reads
like that. This assumes that the LLVM backend will do tail merging, so
the generated code will be unchanged.
* `blocktype_to_type`:
- Change return type from `WasmResult<ir::Type>` to `WasmResult<Option<ir::Type>>`
- Manually inline the call to `type_to_type`, to make this function easier
to read.
- For the non-error case: map `TypeOrFuncType::Type(Type::EmptyBlockType)`
to `Ok(None)` rather than `Err(..)`, since that's what all the call sites
expect - For the error cases, add the function name in the failure
messages
* cranelift-wasm/src/code_translator.rs
- For the three uses of `blocktype_to_type`, use `?` to detect failures and
drop out immediately, meaning that the code will no longer silently ignore
errors.
This commit adds a hook to the `ModuleEnvironment` trait to learn when a
custom section in a wasm file is read. This hook can in theory be used
to parse and handle custom sections as they appear in the wasm file
without having to re-iterate over the wasm file after cranelift has
already parsed the wasm file.
The `translate_module` function is now less strict in that it doesn't
require sections to be in a particular order, but it's figured that the
wasm file is already validated elsewhere to verify the section order.
* the target-lexicon crate no longer has or needs the std feature
in cargo, so we can delete all default-features=false, any mentions
of its std feature, and the nostd configs in many lib.rs files
* the representation of arm architectures has changed, so some case
statements needed refactoring
By default, constants added by SIMD's v128.const will be typed as I8x16 in CLIF. This type must be changed to the appropriate vector type before use to satisfy cranelift's type checking. To do this, we track what SSA values are created by v128.const and convert them with a raw_bitcast immediately before use in the currently implemented SIMD instructions.
-Add resumable_trap, safepoint, isnull, and null instructions
-Add Stackmap struct and StackmapSink trait
Co-authored-by: Mir Ahmed <mirahmed753@gmail.com>
Co-authored-by: Dan Gohman <sunfish@mozilla.com>
* [wasm] return a WasmResult from `declare_table_elements`
This method in particular needs to accommodate failure because any table index other than zero is
currently invalid.
* [wasm] additional failure handling improvements
- Adds `WasmResult<()>` as the return type for most of the `ModuleEnvironment` methods that
previously returned nothing.
- Replaces some panics with `WasmError::Unsupported` now that the methods can return a result.
- Adds a `wasm_unsupported!()` macro for early returns with a formatted unsupported message.
