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aligned_alloc requirements update. #681
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@bsdjhb and @jrtc27 is this change acceptable to you.
So this seems reasonable to check.
I do wonder if there should be a mitigations feature enforce libc spec, so that uses know when they are violating the spec, but for performance sensitive use cases, we do not need to take the instructions for checking these conditions. E.g. add something to: snmalloc/src/snmalloc/ds_core/mitigations.h Lines 68 to 211 in fb776da
@nwf do you have thoughts on this. |
No objection to enforcing that. The OpenZFS case that motivated removing the overly-strict requirement does |
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LGTM
So I dug a bit deeper into this. We did use to have this assertion and removed it here: It seems that the spec was loosened by This seems to be in the the N2310 draft for C17. So the spec does not require an allocator to fail on this case. I would sooner leave the check out as it will be faster. @devnexen did you have a strong reason for wanting this? |
Looking at a C23 draft there (N3220) there is no restriction given for size, even (inheriting the same behaviour for 0 as malloc as that's hoisted out into the section introduction). So yeah whilst this restriction is fine for C11 it is wrong for newer standards. |
I would not mind then to enable this additional check only for C11 ? |
You have no idea what C standard the caller is compiled for. |
true true ... ok gonna drop this check then. |
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in addition, specs requires size to be a multiple of alignment.