The following derived type definition generates the warning: warning #6379: The structure contains one or more misaligned fields
type table_format sequence real(kind=dp), dimension(:), ALLOCATABLE :: array_data real(kind=dp) :: aa real(kind=dp) :: bb real(kind=dp) :: cc integer(kind=i4) :: nn integer(kind=i4) :: kk integer(kind=i4) :: jj character(len=52) :: title end type table_format
Can someone explain how to align the fields of this derived type? Does the use of the keyword "sequence" provide a performance benefit by storing all the derived type elements in adjacent memory location or do I not understand how to use sequence? In other words, should I not be using sequence?
The problem here is that the descriptor for the allocatable array isn't a multiple of 8 bytes, so it causes the real(dp) components to be misaligned when compiled for 32-bits.
Move that component to after the real and integer components.
Don't use SEQUENCE - it hurts performance in some cases by preventing the compiler from naturally aligning the components.