unsigned int __ldrex(volatile void *ptr)

where:

The __ldrex intrinsic returns the data loaded from the memory address pointed to by ptr.

The compiler does not recognize the __ldrex intrinsic when compiling for a target that does not support the LDREX instruction. The compiler generates either a warning or an error in this case.

The __ldrex intrinsic does not support access to doubleword data. The compiler generates an error if you specify an access width that is not supported.

int foo(void)
{
    int loc = 0xff;
    return __ldrex((volatile char *)loc);
}

Compiling this code with the command-line option --cpu=6k produces

||foo|| PROC
    MOV      r0,#0xff
    LDREXB   r0,[r0]
    BX       lr
    ENDP