The placement new operator enables the programmer to specify the memory in which the object being instantiated will be allocated. A problem may arise when such a pointer is misaligned with the underlying architecture alignment restrictions. On several RISC architectures such as PowerPC or on IA64 (Itanium) or Intel (IA32) CPUs which were configured to fault on unaligned access, access to unaligned objects might cause the program to terminate abnormally. Noncompliant
Noncompliant Code Example
In this non compliant code a struct of type A is allocated on the memory region of s.B. The problem is that A has a member of type unsigned long which on IA32 systems is required to be aligned to 4. However B is an array of unsigned chars inside S and is not aligned to 4. After the call to new, the pointer a is pointing to an unaligned memory address. Writing val into a->i can cause the program to terminate abnormally.
...