Fix floats on Wasm #2041
Open
Fix floats on Wasm #2041
Conversation
This file contains hidden or 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
bettio
requested changes
Dec 19, 2025
jgonet
force-pushed
the
jgonet/fix-floats-upstream
branch
from
d288f4c to
086c903
Compare
Contributor
Author
|
Back from holiday break! I added section for Xtensa and updated comment. |
On wasm32, terms are aligned by 4 bytes. `memory_heap_allocation` returns a pointer for `n` terms. We used float_term_t to create an union between a term and float. However, floats are aligned to 8 bytes which made casting between union and term pointers unsafe. We replaced union usage to `memcpy` which allows unaligned memory access. The true solution would be to return correctly aligned memory from memory_heap_alloc but fix for that would need a lot more testing. Signed-off-by: Jakub Gonet <[email protected]>
jgonet
force-pushed
the
jgonet/fix-floats-upstream
branch
from
086c903 to
da5a126
Compare
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
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Outdated suggestions cannot be applied.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.
On wasm32, terms are aligned by 4 bytes.
memory_heap_allocationreturns a pointer fornterms. We used float_term_t to create an union between a term and float. However, floats are aligned to 8 bytes which made casting between union and term pointers unsafe.We replaced union usage to
memcpywhich allows unaligned memory access. The true solution would be to return correctly aligned memory frommemory_heap_allocbut fix for that would need a lot more testing.These changes are made under both the "Apache 2.0" and the "GNU Lesser General
Public License 2.1 or later" license terms (dual license).
SPDX-License-Identifier: Apache-2.0 OR LGPL-2.1-or-later