The VFPASSERT SCALAR directive informs the assembler that the following VFP instructions are in scalar mode. This forces the instruction syntax to be scalar.
Use the VFPASSERT SCALAR directive to mark the end of any block of code where the VFP mode is VECTOR.
Place the VFPASSERT SCALAR directive immediately after the instruction where the change occurs. This is usually an FMXR instruction, but might be a BL instruction.
If a function expects VFP to be in vector mode on exit, place a VFPASSERT SCALAR directive immediately after the last instruction. Such a function would not be AAPCS compliant.
This directive does not generate any code. It is only an assertion by the programmer. The assembler produces error messages if any such assertions are inconsistent with each other, or with any vector notation in VFP data processing instructions.
The assembler faults vector notation in VFP data processing instructions following a VFPASSERT SCALAR directive, even if the vector length is 1.
VFPASSERT SCALAR ; scalar mode faddd d4, d4, d0 ; okay fadds s4<3>, s8<3>, s0 ; ERROR, vectors in scalar mode fabss s24<1>, s28<1> ; ERROR, vectors in scalar mode ; (even though length==1)