westonpace commented on code in PR #35565:
URL: https://github.com/apache/arrow/pull/35565#discussion_r1205260531
##########
cpp/src/arrow/util/align_util.cc:
##########
@@ -94,12 +135,17 @@ bool CheckAlignment(const Table& table, int64_t alignment,
return all_aligned;
}
+// Most allocators require a minimum of 8-byte alignment.
+constexpr int64_t kMinimumAlignment = 8;
Review Comment:
At the end of the day we end up with:
```
const int result =
posix_memalign(reinterpret_cast<void**>(out),
static_cast<size_t>(alignment),
static_cast<size_t>(size));
if (result == ENOMEM) {
return Status::OutOfMemory("malloc of size ", size, " failed");
}
if (result == EINVAL) {
return Status::Invalid("invalid alignment parameter: ",
static_cast<size_t>(alignment));
}
```
The docs for `posix_memalign` state:
```
The address of the
allocated memory will be a multiple of alignment, which must be a
power of two and a multiple of sizeof(void *)
```
`sizeof(void*)` is 8 and so when I pass 4 I get:
```
'_error_or_value28.status()' failed with Invalid: invalid alignment
parameter: 4
```
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