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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 <jakub.gonet@swmansion.com>
mat-hek
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Dec 17, 2025
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Upstream here: atomvm/AtomVM#2041 |
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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 from memory_heap_alloc but fix for that would need a lot more testing.