PR https://github.com/bytecodealliance/wasmtime/pull/3187 introduced a
change to the write_to_slice and read_from_slice routines in
data_value.rs that switched byte order on big-endian systems:
the code used to use native byte order, and now hard-codes
little-endian byte order.
Fix by using native byte order again.
Implemented `UwidenLow` and `UwidenHigh` for the Cranelift interpreter,
doubling the width and halving the number of lanes preserving the low
and high halves respectively. Conversions are performed using unsigned
zero extension.
Copyright (c) 2021, Arm Limited
Implemented `Shuffle` for the Cranelift interpreter, to shuffle two SIMD
vectors together based on an immediate mask of 16 bytes.
Copyright (c) 2021, Arm Limited
Implemented for the Cranelift interpreter:
- `Bitrev` to reverse the order of the bits in an integer.
- `Cls` to count the leading bits which are the same as the sign bit in
an integer, yielding one less than the size of the integer for 0 and -1.
- `Clz` to count the number of leading zeros in the bitwise representation of the
integer.
- `Ctz` to count the number of trailing zeros in the bitwise representation of the
integer.
- `Popcnt` to count the number of ones in the bitwise representation of the
integer.
Copyright (c) 2021, Arm Limited
* Implement `Swizzle` and `Splat` for interpreter
Implemented for the Cranelift interpreter:
- `Swizzle` to shuffle an `i8x16` SIMD vector based
on the indices specified in another vector of the same size.
- `Splat` to create a SIMD vector with all lanes having the same value.
Copyright (c) 2021, Arm Limited
* Fix old x86 backend failing test
Copyright (c) 2021, Arm Limited
* Represent i16x8 and above as hex
Copyright (c) 2021, Arm Limited
* cranelift: Implement ZeroExtend for a bunch of types in interpreter
* cranelift: Implement VConst on interpreter
* cranelift: Implement VallTrue on interpreter
* cranelift: Implement VanyTrue on interpreter
* cranelift: Mark `v{all,any}_true` tests as machinst only
* cranelift: Disable `vany_true` tests on aarch64
The `b64x2` case produces an illegal instruction. See #3305
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.
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.
* 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
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.
* 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
