Stream: git-wasmtime

Topic: wasmtime / PR #6167 Cranelift: remove non-egraphs optimiz...

Wasmtime GitHub notifications bot (Apr 06 2023 at 15:54):

cfallin opened PR #6167 from cfallin:remove-non-egraphs to bytecodealliance:main:

This PR removes the LICM, GVN, and preopt passes, and associated support pieces, from cranelift-codegen. Not to worry, we still have optimizations: the egraph framework subsumes all of these, and has been on by default since #5181.

A few decision points:

• Filetests for the legacy LICM, GVN and simple_preopt were removed too. As we built optimizations in the egraph framework we wrote new tests for the equivalent functionality, and many of the old tests were testing specific behaviors in the old implementations that may not be relevant anymore. However if folks prefer I could take a different approach here and try to port over all of the tests.

• The corresponding filetest modes (commands) were deleted too. The test alias_analysis mode remains, but no longer invokes a separate GVN first (since there is no separate GVN that will not also do alias analysis) so the tests were tweaked slightly to work with that. The egrpah testsuite also covers alias analysis.

• The divconst_magic_numbers module is removed since it's unused without simple_preopt, though this is the one remaining optimization we still need to build in the egraphs framework, pending #5908. The magic numbers will live forever in git history so removing this in the meantime is not a major issue IMHO.

• The use_egraphs setting itself was removed at both the Cranelift and Wasmtime levels. It has been marked deprecated for a few releases now (Wasmtime 6.0, 7.0, upcoming 8.0, and corresponding Cranelift versions) so I think this is probably OK. As an alternative if anyone feels strongly, we could leave the setting and make it a no-op.

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Wasmtime GitHub notifications bot (Apr 06 2023 at 15:54):

cfallin requested elliottt for a review on PR #6167.

Wasmtime GitHub notifications bot (Apr 06 2023 at 15:54):

cfallin requested wasmtime-compiler-reviewers for a review on PR #6167.

Wasmtime GitHub notifications bot (Apr 06 2023 at 15:54):

cfallin requested alexcrichton for a review on PR #6167.

Wasmtime GitHub notifications bot (Apr 06 2023 at 15:54):

cfallin requested wasmtime-core-reviewers for a review on PR #6167.

Wasmtime GitHub notifications bot (Apr 06 2023 at 15:56):

cfallin requested fitzgen for a review on PR #6167.

Wasmtime GitHub notifications bot (Apr 06 2023 at 15:57):

cfallin requested jameysharp for a review on PR #6167.

Wasmtime GitHub notifications bot (Apr 06 2023 at 15:58):

fitzgen submitted PR review.

Wasmtime GitHub notifications bot (Apr 06 2023 at 16:13):

alexcrichton submitted PR review.

Wasmtime GitHub notifications bot (Apr 06 2023 at 16:16):

elliottt submitted PR review.

Wasmtime GitHub notifications bot (Apr 06 2023 at 16:16):

elliottt created PR review comment:

I think we're still unable to port this optimization to egraphs. That shouldn't block this PR, but it would be nice to optimize control flow in the future as well :)

Wasmtime GitHub notifications bot (Apr 06 2023 at 16:17):

elliottt submitted PR review.

Wasmtime GitHub notifications bot (Apr 06 2023 at 16:22):

cfallin updated PR #6167.

Wasmtime GitHub notifications bot (Apr 06 2023 at 16:32):

cfallin submitted PR review.

Wasmtime GitHub notifications bot (Apr 06 2023 at 16:32):

cfallin created PR review comment:

Ah, yes, it looks like this is doing (brif (icmp eq a 0) ...) -> (brif a ...) and the equivalent for ne -- that would indeed be useful to have someday!

Wasmtime GitHub notifications bot (Apr 06 2023 at 17:44):

jameysharp submitted PR review.

Wasmtime GitHub notifications bot (Apr 06 2023 at 17:44):

jameysharp created PR review comment:

Specifically, that issue is tracked in #6106.

Wasmtime GitHub notifications bot (Apr 06 2023 at 18:51):

cfallin merged PR #6167.

Last updated: Dec 23 2024 at 13:07 UTC