Part of a series of changes that will end with prohibiting use of sync/atomic
(u)int32 functions. See cl/440484071 for more details.
PiperOrigin-RevId: 442673296
All atomic 64 bit ints are changed to atomicbitops.(Ui|I)nt64. A nogo checker
enforces that sync/atomic 64 bit functions are not called.
For reviewers: the interesting changes are in the atomicbitops and checkaligned
packages.
Why do this?
- It is very easy to accidentally use atomic values without sync/atomic funcs.
- We have checkatomics, but this is optional and is forgotten in several places.
- Using a type+checker to enforce this seems less error prone and simpler.
- We get NoCopy protection.
- Use of 64 bit atomics can break 32 bit builds. We have types to handle this
without any runtime cost, so we might as well use them.
PiperOrigin-RevId: 440473398
AlignedAtomicUint64 is 15 bytes and it takes 16 bytes in structures. On
32-bit systems, variables and structure fields is guaranteed to be
32-bit aligned and this means that we need only 12 bytes to find 8
contiguous bytes.
Ayush Ranjan
Kevin Krakauer
Brad Fitzpatrick
Andrei Vagin
Jamie Liu