Wasmtime GitHub notifications bot (Aug 10 2022 at 19:35): Wasmtime GitHub notifications bot (Aug 10 2022 at 19:35):uweigand opened PR #4682 from s390x-lane-order to main:
This implements the s390x back-end portion of the solution for
https://github.com/bytecodealliance/wasmtime/issues/4566We now support both big- and little-endian vector lane order
in code generation. The order used for a function is determined
by the function's ABI: if it uses a Wasmtime ABI, it will use
little-endian lane order, and big-endian lane order otherwise.
(This ensures that all raw_bitcast instructions generated by
both wasmtime and other cranelift frontends can always be
implemented as a no-op.)Lane order affects the implementation of a number of operations:
- Vector immediates
- Vector memory load / store (in big- and little-endian variants)
Operations explicitly using lane numbers
(insertlane, extractlane, shuffle, swizzle)Operations implicitly using lane numbers
(iadd_pairwise, narrow/widen, promote/demote, fcvt_low, vhigh_bits)In addition, when calling a function using a different lane order,
we need to lane-swap all vector values passed or returned in registers.A small number of changes to common code were also needed:
Ensure we always select a Wasmtime calling convention on s390x
in crates/cranelift (func_signature).Fix vector immediates for filetests/runtests. In PR #4427,
I attempted to fix this by byte-swapping the V128 value, but
with the new scheme, we'd instead need to perform a per-lane
byte swap. Since we do not know the actual type in write_to_slice
and read_from_slice, this isn't easily possible.Revert this part of PR #4427 again, and instead just mark the
memory buffer as little-endian when emitting the trampoline;
the back-end will then emit correct code to load the constant.Change a runtest in simd-bitselect-to-vselect.clif to no longer
make little-endian lane order assumptions.Remove runtests in simd-swizzle.clif that make little-endian
lane order assumptions by relying on implicit type conversion
when using a non-i16x8 swizzle result type (this feature should
probably be removed anyway).Tested with both wasmtime and cg_clif.
FYI - @cfallin
<!--
Please ensure that the following steps are all taken care of before submitting
the PR.
[ ] This has been discussed in issue #..., or if not, please tell us why
here.[ ] A short description of what this does, why it is needed; if the
description becomes long, the matter should probably be discussed in an issue
first.[ ] This PR contains test cases, if meaningful.
- [ ] A reviewer from the core maintainer team has been assigned for this PR.
If you don't know who could review this, please indicate so. The list of
suggested reviewers on the right can help you.Please ensure all communication adheres to the code of conduct.
-->
Wasmtime GitHub notifications bot (Aug 10 2022 at 20:19):uweigand updated PR #4682 from s390x-lane-order to main.
Wasmtime GitHub notifications bot (Aug 10 2022 at 21:58):uweigand updated PR #4682 from s390x-lane-order to main.
Wasmtime GitHub notifications bot (Aug 11 2022 at 19:10):cfallin submitted PR review.
Wasmtime GitHub notifications bot (Aug 11 2022 at 19:10):cfallin merged PR #4682.
Last updated: Nov 22 2024 at 16:03 UTC