identify volatile declaration in debug information / disassembly

Question

I'm looking for a creative solution for making sure that variables delivered to a specific macro are declared with type volatile in C language, with TMS470 compiler. meaning:

good method:

volatile int   *_p_reg;
VOLATILE_MACRO(_p_reg);

compilation failure:

int   *_p_reg;
VOLATILE_MACRO(_p_reg);

I wish to perform the verification after the compilation, meaning going over the disassembly or the debug information and identify those calls. I can't seem to find any evidence for the volatile in the debug info.

any ideas?

thanks!

Answer 1

Two possible solutions using gcc extensions. The run-time version uses __builtin_types_compatible_p and an assert. The compile-time version is similar but uses a hack to get a static assert which fires at compile-time (albeit with a rather cryptic error message):

Run-time

#include <stdio.h>
#include <assert.h>

#define VOLATILE_MACRO(p) \
    assert (__builtin_types_compatible_p(typeof(p), typeof(volatile int *)))

int main()
{
    volatile int * x;
    int * y;

    VOLATILE_MACRO(x);  // <<< OK
    VOLATILE_MACRO(y);  // <<< run-time error

    return 0;
}

Compile-time

#include <stdio.h>
#include <assert.h>

#define A                      BUILD_NAME(__LINE__)
#define BUILD_NAME(line)       BUILD_NAME2(line)
#define BUILD_NAME2(line)      assert_ ## line
#define STATIC_ASSERT(test)    typedef char A[(test) ? 1 : -1]

#define VOLATILE_MACRO(p) \
    STATIC_ASSERT (__builtin_types_compatible_p(typeof(p), typeof(volatile int *)))

int main()
{
    volatile int * x;
    int * y;

    VOLATILE_MACRO(x);  // <<< OK
    VOLATILE_MACRO(y);  // <<< compile error

    return 0;
}

Note that if you need to support other volatile types then the macro can simply be extended with multiple chained __builtin_types_compatible_p tests, e.g.

#define VOLATILE_MACRO(p) \
    assert (__builtin_types_compatible_p(typeof(p), typeof(volatile int *)) ||
            __builtin_types_compatible_p(typeof(p), typeof(volatile short *)))