================
@@ -433,6 +433,26 @@ Attribute Changes in Clang
- Fix a bug where clang doesn't automatically apply the ``[[gsl::Owner]]`` or
``[[gsl::Pointer]]`` to STL explicit template specialization decls.
(#GH109442)
+- Introduced ``__attribute__((wraps))`` which can be added to type or variable
+ declarations. Using an attributed type or variable in an arithmetic
+ expression will define the overflow behavior for that expression as having
+ two's complement wrap-around. These expressions will not be instrumented by
+ overflow sanitizers nor will they cause integer overflow warnings. They also
+ cannot be optimized away by some eager UB optimizations as the behavior of
+ the arithmetic is no longer "undefined".
+
+ There is also ``__attribute__((no_wraps))`` which can be added to types or
+ variable declarations. Types or variables with this attribute may be
+ instrumented by overflow sanitizers, if enabled. Note that this matches the
+ default behavior of integer types. So, in most cases, ``no_wraps`` serves
----------------
JustinStitt wrote:
When used alongside very strict SSCLs there is great utility to be gained from
`no_wraps`.
In the kernel we want to use an SSCL ignorelist like this:
```
[{signed-integer-overflow,unsigned-integer-overflow}]
type:*
```
then annotate specific types like `size_t` in source:
``` cpp
typedef __kernel_size_t size_t __attribute__((no_wraps));
```
https://github.com/llvm/llvm-project/pull/115094
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