docs: don't disallow lowering to stack pop

Author: LuigiPiucco

library/core/src/ptr/mod.rs

@@ -1763,10 +1763,11 @@ pub const unsafe fn write_unaligned<T>(dst: *mut T, src: T) {
 /// - When a volatile operation is used for memory inside an [allocation], it behaves exactly like
 ///   [`read`], except for the additional guarantee that it won't be elided or reordered (see
 ///   above). This implies that the operation will actually access memory and not e.g. be lowered to
-///   a register access or stack pop. Other than that, all the usual rules for memory accesses apply
-///   (including provenance). In particular, just like in C, whether an operation is volatile has no
-///   bearing whatsoever on questions involving concurrent access from multiple threads. Volatile
-///   accesses behave exactly like non-atomic accesses in that regard.
+///   reusing data from a previous read, such as a register that performed a previous load on that
+///   memory. Other than that, all the usual rules for memory accesses apply (including provenance).
+///   In particular, just like in C, whether an operation is volatile has no bearing whatsoever on
+///   questions involving concurrent access from multiple threads. Volatile accesses behave exactly
+///   like non-atomic accesses in that regard.
 ///
 /// - Volatile operations, however, may also be used to access memory that is _outside_ of any Rust
 ///   allocation. In this use-case, the pointer does *not* have to be [valid] for reads. This is