Intel® Fortran Compiler 18.0 Developer Guide and Reference
General Compiler Directive:Specifies the byte alignment for a loop.
!DIR$ CODE_ALIGN [:n]
n |
(Optional) A positive integer constant expression indicating the number of bytes for the minimum alignment boundary. Its value must be a power of 2 between 1 and 4096, such as 1, 2, 4, 8, 16, 32, 64, 128, and so on. If you specify 1 for n, no alignment is performed. If you do not specify n, the default alignment is 16 bytes. |
This directive must precede the loop or block of code to be aligned.
If code is compiled with the -falign-loops=m (Linux* and macOS*) or /Qalign-loops:m (Windows*) option and a “CODE_ALIGN:n” directive precedes a loop, the loop is aligned on a MAX (m, n) byte boundary. If a procedure has the “CODE_ALIGN:k” attribute and a “CODE_ALIGN:n” directive precedes a loop, then both the procedure and the loop are aligned on a MAX (k, n) byte boundary.
Consider the following code fragment in file test_code_align.f90:
!DIR$ CODE_ALIGN
DO J = 1, N
…
END DOCompiling test_code_align.f90 aligns the code that begins the DO J loop on a (default) 16-byte boundary. If you do not specify the CODE_ALIGN directive, the alignment of the loop is implementation-dependent and may change from compilation to compilation.