Hello, On 6/19/19 12:25 AM, Nick Radcliffe via discuss wrote:

I recently noticed that a parameter check in MPII_Win_get_attr looks a bit off:

            /* A common user error is to pass the address of a 4-byte              * int when the address of a pointer (or an address-sized int)              * should have been used.  We can test for this specific              * case.  Note that this code assumes sizeof(intptr_t) is              * a power of 2. */             if ((intptr_t) attribute_val & (sizeof(intptr_t) - 1)) {                 MPIR_ERR_SETANDSTMT(mpi_errno, MPI_ERR_ARG, goto fn_fail, "**attrnotptr");             }

The comment indicates that the check is testing "attribute_val" to see if a pointer to int was passed in, rather than a double pointer or pointer to an integer that can store an address. But the check seems to only be testing for 8 byte alignment (and failing if not aligned). Am I missing something here?

There is more to be discussed here: * you are correct to observe that the test is only for alignment to sizeof(intptr_t) (which on LP64 machines would typically be 8) but also: * the code assumes sizeof(intptr_t) == sizeof(any *) which might not be true on systems implementing the additional correctness checks of llvm SoftBound + CETS * intptr_t might not even exist (although I assume mpich would not build on such platforms for other reasons anyway). * int might indeed be address-sized, i.e. the check adds nothing of value on 32-bit platforms. From my point-of-view this is exactly the kind of quick hack that riddles "modern" software. Thomas