This commit implements the [wide-arithmetic] proposal which has recently
reached phase 2 in the WebAssembly proposals process. The goal here is
to implement support in LLVM for emitting these instructions which are
gated behind a new feature flag by default. A new `wide-arithmetic`
feature flag is introduced which gates these four new instructions from
being emitted.
Emission of each instruction itself is relatively simple given LLVM's
preexisting lowering rules and infrastructure. The main gotcha is that
due to the multi-result nature of all of these instructions it needed
the lowerings to be implemented in C++ rather than in TableGen.
[wide-arithmetic]: https://github.com/WebAssembly/wide-arithmetic
I'm not entirely sure what the criteria for 'bleeding-edge' used to be,
but at this point it seems to be the set of all added features in LLVM.
This adds remaining features to bleeding-edge config.
#80923 newly enabled multivalue and reference-types in the generic CPU.
But enabling reference-types ended up breaking up Wasm's Chromium CI
(https://chromium-review.googlesource.com/c/emscripten-releases/+/5500231)
because the way the table index is encoded is different from MVP (u32)
vs. reference-types (LEB), which caused different encodings for
`call_indirect`.
And Chromium CI's and Emscripten's minimum required node version is v16,
which does not yet support reference-types, which does not recognize
that table index encoding. reference-types is first supported in node
v17.2.
We knew the current minimum required node for Emscripten (v16) did not
support reference-types, but thought it was fine because unless you
explicitly use `__funcref` or `__externref` things would be fine, and if
you want to use them explicitly, you would have a newer node. But it
turned out it also affected the encoding of `call_indirect`.
While we are discussing the potential solutions, I will disable
reference-types to unblock the rolls.
We are currently using `PREFIX-DAG` and `PREFIX-NOT` within a single
`PREFIX` test in a mixed way, but `-DAG` and `-NOT` do not work that
way. For example:
Result:
```
1
2
3
```
Test file:
```c
// CHECK-DAG: 3
// CHECK-DAG: 1
// CHECK-NOT: 2
```
This does not work. The last line `CHECK-NOT: 2` does not trigger any
error, because we've already covered all three lines (1~3) while
matching `CHECK-DAG: 3` and `CHECK-DAG: 1`, and FileCheck tries to check
the line `CHECK-NOT: 2` _after_ the line `3`.
Actually, we have
```c
// BLEEDING-EDGE-NOT:#define __wasm_reference_types__ 1{{$}}
```
even though reference-types is enabled in 'bleeding-edge' config, and
this has not triggered any error.
This section
(https://llvm.org/docs/CommandGuide/FileCheck.html#the-check-dag-directive)
explains the interactions between `CHECK-DAG` and `CHECK-NOT`s:
> As a result, the surrounding `CHECK-DAG:` directives cannot be
reordered, i.e. all occurrences matching `CHECK-DAG:` before
`CHECK-NOT:` must not fall behind occurrences matching `CHECK-DAG:`
after `CHECK-NOT:`.
So in order to test the 'include' lists and 'not-include' lists, we have
to run the tests twice with different prefixes. This splits `GENERIC`
and `BLEEDING-EDGE` tests in two configs (`***-INCLUDE` and `***`) to
test them correctly.
This also adds some spaces after colons, sorts the feature lists, and
adds `1{{$}}` to the `MVP` tests to make them consistent with `GENERIC`
and `BLEEDING-EDGE` tests.
Adding to allow users to get this flag into the target features section for
future use cases.
Reviewed By: tlively, aheejin
Differential Revision: https://reviews.llvm.org/D158409
Now that the WebAssembly SIMD specification is finalized and engines are
generally up-to-date, there is no need for a separate target feature for gating
SIMD instructions that engines have not implemented. With this change,
v128.const is now enabled by default with the simd128 target feature.
Differential Revision: https://reviews.llvm.org/D98457
Summary:
This adds the reference types target feature. This does not enable any
more functionality in LLVM/clang for now, but this is necessary to embed
the info in the target features section, which is used by Binaryen and
Emscripten. It turned out that after D69832 `-fwasm-exceptions` crashed
because we didn't have the reference types target feature.
Reviewers: tlively
Subscribers: dschuff, sbc100, jgravelle-google, hiraditya, sunfish, cfe-commits, llvm-commits
Tags: #clang, #llvm
Differential Revision: https://reviews.llvm.org/D73320
Summary:
These features will both be implemented soon, so I thought I would
save time by adding the boilerplate for both of them at the same time.
Reviewers: aheejin
Subscribers: dschuff, sbc100, jgravelle-google, hiraditya, sunfish, cfe-commits, llvm-commits
Tags: #clang, #llvm
Differential Revision: https://reviews.llvm.org/D62047
llvm-svn: 361516
Summary:
This feature is not actually used for anything in the WebAssembly
backend, but adding it allows users to get it into the target features
sections of their objects, which makes these objects
future-compatible.
Reviewers: aheejin, dschuff
Subscribers: sbc100, jgravelle-google, hiraditya, sunfish, jdoerfert, cfe-commits, llvm-commits
Tags: #clang, #llvm
Differential Revision: https://reviews.llvm.org/D60013
llvm-svn: 357321
Summary:
To prevent the instability of bulk-memory in the wasm backend from
blocking separate pthread testing, temporarily remove the logic that
adds -mbulk-memory in the presence of -pthread. Since browsers will
ship bulk memory before or alongside threads, this change will be
reverted as soon as bulk memory has stabilized in the backend.
Reviewers: sbc100
Subscribers: dschuff, jgravelle-google, aheejin, sunfish, jfb, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D58854
llvm-svn: 355248
Summary:
In the clang UI, replaces -mthread-model posix with -matomics as the
source of truth on threading. In the backend, replaces
-thread-model=posix with the atomics target feature, which is now
collected on the WebAssemblyTargetMachine along with all other used
features. These collected features will also be used to emit the
target features section in the future.
The default configuration for the backend is thread-model=posix and no
atomics, which was previously an invalid configuration. This change
makes the default valid because the thread model is ignored.
A side effect of this change is that objects are never emitted with
passive segments. It will instead be up to the linker to decide
whether sections should be active or passive based on whether atomics
are used in the final link.
Reviewers: aheejin, sbc100, dschuff
Subscribers: mehdi_amini, jgravelle-google, hiraditya, sunfish, steven_wu, dexonsmith, rupprecht, jfb, jdoerfert, cfe-commits, llvm-commits
Tags: #clang, #llvm
Differential Revision: https://reviews.llvm.org/D58742
llvm-svn: 355112
Summary:
There have been three options related to threads and users had to set
all three of them separately to get the correct compilation results.
This makes sure the relationship between the options makes sense and
sets necessary options for users if only part of the necessary options
are specified. This does:
- Remove `-matomics`; this option alone does not enable anything, so
removed it to not confuse users.
- `-mthread-model posix` sets `-target-feature +atomics`
- `-pthread` sets both `-target-feature +atomics` and
`-mthread-model posix`
Also errors out when explicitly given options don't match, such as
`-pthread` is given with `-mthread-model single`.
Reviewers: dschuff, sbc100, tlively, sunfish
Subscribers: jgravelle-google, jfb, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D57874
llvm-svn: 353761
This implements basic support for compiling (though not yet assembling
or linking) for a WebAssembly target. Note that ABI details are not yet
finalized, and may change.
Differential Revision: http://reviews.llvm.org/D12002
llvm-svn: 246814
