With the old backends, this would log the lowered+legalized clif, but the log is
useles now with the new backends. Logging the disasm is the new moral
equivalent.
Fixes#3468.
If a program has many instances of the pattern "goto next; next:" in a
row (i.e., no-op branches to the fallthrough address), the branch
simplification in `MachBuffer` would remove them all, as expected.
However, in order to work correctly, the algorithm needs to track all
labels that alias the current buffer tail, so that they can be adjusted
later if another branch chomp occurs.
When many thousands of this branch-to-next pattern occur, many thousands
of labels will reference the current buffer tail, and this list of
thousands of labels will be shuffled between the branch metadata struct
and the "labels at tail" struct as branches are appended and then
chomped immediately.
It's possible that with smarter data structure design, we could somehow
share the list of labels -- e.g., a single array of all labels, in order
they are bound, with ranges of indices in this array used to represent
lists of labels (actually, that seems like a better design in general);
but let's leave that to future optimization work.
For now, we can avoid the quadratic behavior by just "giving up" if the
list is too long; it's always valid to not optimize a branch. It is very
unlikely that the "normal" case will have more than 100 "goto next"
branches in a row, so this should not have any perf impact; if it does,
we will leave 1 out of every 100 such branches un-optimized in a long
sequence of thousands.
This takes total compilation time down on my machine from ~300ms to
~72ms for the `foo.wasm` case in #3441. For reference, the old backend
(now removed), built from arbitrarily-chosen-1-year-old commit
`c7fcc344`, takes 158ms, so we're ~twice as fast, which is what I would
expect.
It appears that some allocation heuristics have changed slightly since
0.0.31, so some of the golden-output filetests are updated as well.
Ideally we would rely more on runtests rather than golden-compilation
tests; but for now this is sufficient. (I'm not sure exactly what in
regalloc.rs changed to alter these heuristics; it's actually been almost
a year since the 0.0.31 release with several refactorings and tweaks
merged since then.)
Fixes#3441.
When there is a linking error caused by an undefined instance, list all
the instances exports in the error message. This will clarify errors for
undefined two-level imports that get desugared to one-level instance
imports under the module-linking proposal.
This commit fixes an issue in Cranelift where legalization of
`heap_addr` instructions (used by wasm to represent heap accesses) could
be off-by-two where loads that should be valid were actually treated as
invalid. The bug here happened in an optimization where tests against
odd constants were being altered to tests against even constants by
subtracting one from the limit instead of adding one to the limit. The
comment around this area has been updated in accordance with a little
more math-stuff as well to help future readers.
Before this commit we actually have two builders checking for security
advisories on CI, one is `cargo audit` and one is `cargo deny`. The
`cargo deny` builder is slightly different in that it checks a few other
things about our dependency tree such as licenses, duplicates, etc. This
commit removes the advisory check from `cargo deny` on CI and then moves
the `cargo audit` check to a separate workflow.
The `cargo audit` check will now run nightly and will open an issue on
the Wasmtime repository when an advisory is found. This should help make
it such that our CI is never broken by the publication of an advisory
but we're still promptly notified whenever an advisory is made. I've
updated the release process notes to indicate that the open issues
should be double-checked to ensure that there are no open advisories
that we need to take care of.
