C66x DSP CPU and Instruction Set Reference Guide (SPRUGH7 Nov 2010) section 3.8.12 (and subsections) has a long list of instructions that may not go in parallel, such as "DINT||NOP 5". The assembler does not detect some of these erroneous sequences and so therefore will not emit an error if such a sequence occurs in assembly. The C/C++ compiler does not produce these sequences when compiling C or C+, so the user of the compiler can safely assume these sequences won't occur if only compiling C or C+ code.

For example, the assembler does not detect the following erroneous sequences:

 ; asm does not detect erroneous sequence
   IDLE
||  NOP 2

 ; asm does not detect erroneous sequence
    NOP 3
||  SWE

 ; asm does not detect erroneous sequence
    RINT
||  MVC.S2 B0, TSR