Remove incomplete/unmaintained ARM32 backend (for now). #3799
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
github-actions
bot
added
cranelift
akirilov-arm
approved these changes
Feb 14, 2022
In bytecodealliance#3721, we have been discussing what to do about the ARM32 backend in Cranelift. Currently, this backend supports only 32-bit types, which is insufficient for full Wasm-MVP; it's missing other critical bits, like floating-point support; and it has only ever been exercised, AFAIK, via the filetests for the individual CLIF instructions that are implemented. We were very very thankful for the original contribution of this backend, even in its partial state, and we had hoped at the time that we could eventually mature it in-tree until it supported e.g. Wasm and other use-cases. But that hasn't yet happened -- to the blame of no-one, to be clear, we just haven't had a contributor with sufficient time. Unfortunately, the existence of the backend and lack of active maintainer now potentially pose a bit of a burden as we hope to make continuing changes to the backend framework. For example, the ISLE migration, and the use of regalloc2 that it will allow, would need all of the existing lowering patterns in the hand-written ARM32 backend to be rewritten as ISLE rules. Given that we don't currently have the resources to do this, we think it's probably best if we, sadly, for now remove this partial backend. This is not in any way a statement of what we might accept in the future, though. If, in the future, an ARM32 backend updated to our latest codebase with an active maintainer were to appear, we'd be happy to merge it (and likewise for any other architecture!). But for now, this is probably the best path. Thanks again to the original contributor @jmkrauz and we hope that this work can eventually be brought back and reused if someone has the time to do so!
cfallin
force-pushed
the
remove-arm32
branch
from
3dda608
to
b9928ba
Compare
mpardesh
pushed a commit
to avanhatt/wasmtime
that referenced
this pull request
Mar 17, 2022
…ance#3799) In bytecodealliance#3721, we have been discussing what to do about the ARM32 backend in Cranelift. Currently, this backend supports only 32-bit types, which is insufficient for full Wasm-MVP; it's missing other critical bits, like floating-point support; and it has only ever been exercised, AFAIK, via the filetests for the individual CLIF instructions that are implemented. We were very very thankful for the original contribution of this backend, even in its partial state, and we had hoped at the time that we could eventually mature it in-tree until it supported e.g. Wasm and other use-cases. But that hasn't yet happened -- to the blame of no-one, to be clear, we just haven't had a contributor with sufficient time. Unfortunately, the existence of the backend and lack of active maintainer now potentially pose a bit of a burden as we hope to make continuing changes to the backend framework. For example, the ISLE migration, and the use of regalloc2 that it will allow, would need all of the existing lowering patterns in the hand-written ARM32 backend to be rewritten as ISLE rules. Given that we don't currently have the resources to do this, we think it's probably best if we, sadly, for now remove this partial backend. This is not in any way a statement of what we might accept in the future, though. If, in the future, an ARM32 backend updated to our latest codebase with an active maintainer were to appear, we'd be happy to merge it (and likewise for any other architecture!). But for now, this is probably the best path. Thanks again to the original contributor @jmkrauz and we hope that this work can eventually be brought back and reused if someone has the time to do so!
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
In #3721, we have been discussing what to do about the ARM32 backend in
Cranelift. Currently, this backend supports only 32-bit types, which is
insufficient for full Wasm-MVP; it's missing other critical bits, like
floating-point support; and it has only ever been exercised, AFAIK, via
the filetests for the individual CLIF instructions that are implemented.
We were very very thankful for the original contribution of this
backend, even in its partial state, and we had hoped at the time that we
could eventually mature it in-tree until it supported e.g. Wasm and
other use-cases. But that hasn't yet happened -- to the blame of no-one,
to be clear, we just haven't had a contributor with sufficient time.
Unfortunately, the existence of the backend and lack of active
maintainer now potentially pose a bit of a burden as we hope to make
continuing changes to the backend framework. For example, the ISLE
migration, and the use of regalloc2 that it will allow, would need all
of the existing lowering patterns in the hand-written ARM32 backend to
be rewritten as ISLE rules.
Given that we don't currently have the resources to do this, we think
it's probably best if we, sadly, for now remove this partial backend.
This is not in any way a statement of what we might accept in the
future, though. If, in the future, an ARM32 backend updated to our
latest codebase with an active maintainer were to appear, we'd be happy
to merge it (and likewise for any other architecture!). But for now,
this is probably the best path. Thanks again to the original contributor
@jmkrauz and we hope that this work can eventually be brought back and
reused if someone has the time to do so!
Closes #3721.