Quite the contrary. If printf wasn't an instrinsic, the compiler couldn't even give you warnings that you're risking getting garbage or causing segfaults.

• Implicit coercion from int to pointer: %p expects a pointer, but you pass it an ptrdiff_t. (twice)
• Data doesn't match format specifier: %x expects (a pointer to) an int or unsigned int, but you pass it (a pointer to) a ptrdiff_t (thrice).

The other warning is for void main. I guess that's no longer kosher?

So the minimal change is:

• Add casts to the parameters of printf to they match the format string.
• Adjust the return value of main.
• Avoid MS-specific extensions.

#include <stdint.h>
#include <stdio.h>

#define ALIGN_BITS  ( sizeof(void*) >> 1 )
#define BIT_BITS     3
#define BYTE_BITS   14

int check_new( uintptr_t p ) {
    uintptr_t slot = ( p >> (BYTE_BITS + BIT_BITS + ALIGN_BITS) );
    uintptr_t byte = ( p >> (ALIGN_BITS + BIT_BITS)) & 0x00003fffULL;
    uintptr_t bit  = ( p >> ALIGN_BITS)               & 0x00000007ULL;
    uintptr_t nop  =   p                              & 0x3ULL;

    printf(
        "address: %p slot: %p byte: %4x bit: %4x nop:%x\n",
        (void*)p, (void*)slot, (unsigned)byte, (unsigned)bit, (unsigne
+d)nop
    );
    return 1;
}

int main( void ) {
    uintptr_t p;

    for( p = 123456ULL; p < ( 1ULL << 31 ); p += ( 1ULL << 29 ) ) {
        check_new( p );
    }

    return 0;
}
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