rdrand: Avoid assuming usize is the native word size.
#442
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newpavlov
reviewed
May 31, 2024
newpavlov
approved these changes
May 31, 2024
josephlr
approved these changes
May 31, 2024
`x86_64-unknown-linux-gnux32` has target_pointer_width = "32", so usize is 32-bits. In this case, we were throwing away half of each RDRAND result and doing twice as many RDRAND invocations as necessary. This wasn't noticed because `as` silently does a lossy conversion.
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I removed the CI changes because we don't have a way of testing this on an x32 target, and the code built and ran correctly (but suboptimally) before and after this change on all these targets |
Merged
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x86_64-unknown-linux-gnux32has target_pointer_width = "32", so usize is 32-bits. In this case, we were throwing away half of each RDRAND result and doing twice as many RDRAND invocations as necessary. This wasn't noticed becauseassilently does a lossy conversion.Add x86_64-unknown-linux-gnux32 to the test matrix.[Edit: Ubuntu doesn't support x32 by policy; see https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1994516/comments/21].