CC2652R: _restore_interrupts() in ti_compatibility.h causes "invalid operand for instruction"

Tool/software:

Hi all,

I'm using TI Arm Clang Compiler v3.2.2.LTS, CCS v12.4, CC2674R10 (Cortex M33, Armv8-M)

building a project based on project_zero example

trying to use code originally written for armcl

this code uses _disable_interrupts() and _restore_interrupts() intrinsics to protect critical sections:

    uint32_t savevar;
    savevar = _disable_interrupts(); // get current interrupt state and disable interrupts (TI ARM Compiler intrinsic)
    // critical code...
    _restore_interrupts(savevar);    // restore interrupt state (TI ARM Compiler intrinsic)

tiarmclang does not support these intrinsics, but provides the ti_compatibility.h header file that should convert them to a tiarmclang compatible form:

/******************************************************************************/
/* Disable interrupts                                                         */
/******************************************************************************/
static __inline__ uint32_t __attribute__((always_inline))
_disable_interrupts(void)
{
#if __ARM_ARCH_PROFILE == 'M' && __ARM_ARCH == 6
    return _disable_IRQ();
#elif __ARM_ARCH_PROFILE == 'M' && __ARM_ARCH == 7
    uint32_t res = 0;
    __asm volatile ("MRS %0, FAULTMASK" : "=r" (res) : : );
    __asm volatile ("CPSID F" : : : );
    return res;
#elif __ARM_ARCH >= 7
    uint32_t res = _get_CPSR();
     __asm volatile ("CPSID IF" : : : );
    return res;
#else
    return 0
#endif
}

/******************************************************************************/
/* Restore interrupts                                                         */
/******************************************************************************/
static __inline__ void __attribute__((always_inline))
_restore_interrupts(uint32_t x)
{
#if __ARM_ARCH_PROFILE == 'M' && __ARM_ARCH == 6
    __asm volatile ("MSR PRIMASK, %0" : : "r" (x) : );
#elif __ARM_ARCH_PROFILE == 'M' && __ARM_ARCH == 7
    __asm volatile ("MSR FAULTMASK, %0" : : "r" (x) : );
#elif __ARM_ARCH >= 7
    __asm volatile ("MSR CPSR_fc, %0" : : "r" (x) : );
#endif
}

The compiler takes the path "#elif __ARM_ARCH >= 7" and fails on _restore_interrupts() with "invalid operand for instruction":

C:\ti\ccs1240\ccs\tools\compiler\ti-cgt-armllvm_3.2.2.LTS\include\c\ti_compatibility.h:1529:21: error: invalid operand for instruction
    __asm volatile ("MSR CPSR_fc, %0" : : "r" (x) : );
                    ^
<inline asm>:1:5: note: instantiated into assembly here
MSR CPSR_fc, r0
    ^

Is this code (and with it the whole header file) applicabe to Arm v8-M at all?

Is there already a fix available for this problem?

Or is there an alternative with the same functionality?
I found CPUcpsid() in driverlib's cpu.h: it also returns the original interrupt enable state, but there is no function to restore it to that state.

Regards,

Wolfgang