.gitignore

*.exe
*.dll
*.lib

bar.c

#include <windows.h>
#include <stdio.h>

int main() {
  HMODULE hFoo = LoadLibrary("foo.dll");
  DWORD *dwData = (DWORD *)GetProcAddress(hFoo, "dwData");
  fprintf(stderr, "dwData = %p\n", dwData);
  fprintf(stderr, "*dwData = %lld\n", *dwData);
  return 0;
}

baz.c

#include <windows.h>
#include <stdio.h>

__declspec(dllimport) DWORD dwData;

int main() {
  fprintf(stderr, "&dwData = %p\n", &dwData);
  fprintf(stderr, "dwData = %lld\n", dwData);
  return 0;
}

foo.s

.data
.globl dwData
dwData:
        .long 1234

log.txt

$ wine bar.exe
dwData = 000000006AE83000
*dwData = 1234
$ wine baz.exe
&dwData = 000000006AE83000
dwData = 1234

Makefile

all: bar.exe baz.exe

clean:
	rm *.exe *.dll *.lib

.PHONY: all clean

foo.dll foo.lib: foo.s
	x86_64-w64-mingw32-gcc -shared $^ -o foo.dll -Wl,--out-implib,foo.lib

bar.exe: bar.c foo.dll
	x86_64-w64-mingw32-gcc $(filter %.c,$^) -o $@

baz.exe: baz.c foo.lib
	x86_64-w64-mingw32-gcc $(filter %.c,$^) -L. -lfoo -o $@