MPIGetaddressvoid

MPI_Get_address is a function in the Message Passing Interface (MPI) used to obtain the memory address of a local object as a value in the MPI address space. It is primarily employed when constructing derived datatypes, such as structures, where portable displacements are required across processes.

In C, the function typically has the signature: int MPI_Get_address(void *location, MPI_Aint *address). The location parameter is a pointer to the object whose address is requested, and address is an output parameter that receives the address as an MPI_Aint, an MPI-defined integer type large enough to hold a pointer. The returned address is expressed in the process’s address space and is suitable for computing offsets used in datatype constructors.

Common usage involves computing displacements for derived datatypes. A typical pattern is to call MPI_Get_address for a base object and for each member, then subtract the base address from each member’s address to obtain relative displacements. These displacements are used in MPI_Type_create_struct and related routines to ensure portable memory layouts when sending structured data between processes.

Return values indicate success (MPI_SUCCESS) or an error code, in which case the MPI error handler is invoked. MPI_Get_address complements older, deprecated bindings such as MPI_Address and is the preferred C binding for obtaining addresses in modern MPI programs. It is essential for creating portable, architecture-independent datatype layouts and for accurate data packing and unpacking in heterogeneous environments. See also MPI_Aint, MPI_Type_create_struct, and related datatype construction routines.