michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: /* this code contributed by Bert Driehuis <bert_driehuis@nl.compuware.com> */
michael@0: 
michael@0: #include <stdio.h>
michael@0: 
michael@0: // Try to determine the vtable layout generated by G++
michael@0: // Produces the offset at which the first vtable entry can be
michael@0: // found, and the factor to apply for subsequent entries on stdout.
michael@0: // Example output:
michael@0: //    #define GCC_VTABLE_START        0xc
michael@0: //    #define GCC_VTABLE_FACTOR       0x8
michael@0: 
michael@0: class test {
michael@0: public:
michael@0:       virtual int     t1(void);
michael@0:       virtual int     t2(void);
michael@0:       int             x;
michael@0: };
michael@0: 
michael@0: test::test() { this->x = 0x12121212; };
michael@0: 
michael@0: int test::t1(void) { return 1; }
michael@0: int test::t2(void) { return 2; }
michael@0: 
michael@0: void die(char *x) {
michael@0:       fprintf(stderr, "%s\n", x);
michael@0:       exit(1);
michael@0: }
michael@0: 
michael@0: int 
michael@0: main()
michael@0: {
michael@0:       int             i;
michael@0:       test           *t = new test();
michael@0:       int            *tp = (int *) t;
michael@0:       int             off1 = -1;
michael@0:       int             off2 = -1;
michael@0:       int             factor;
michael@0:       int             factorshift;
michael@0: 
michael@0:       if (*tp++ != 0x12121212)
michael@0:               die("Integer element test::x not found!");
michael@0:       tp = (int *) *tp;
michael@0:       for (i = 0; i < 10; i++) {
michael@0:               if (tp[i] == (int) t->t1)
michael@0:                       off1 = i;
michael@0:               if (tp[i] == (int) t->t2)
michael@0:                       off2 = i;
michael@0:       }
michael@0:       if (off1 == -1 || off2 == -1)
michael@0:               die("Could not determine offset into vtable!");
michael@0:       factor = (off2 - off1) * 4;
michael@0:       factorshift = -1;
michael@0:       while (factor) {
michael@0:               factorshift++;
michael@0:               factor >>= 1;
michael@0:       }
michael@0:       printf("/* Automatically generated by vtable_layout_x86.cpp */\n");
michael@0:       printf("#define GCC_VTABLE_START\t0x%x\n", off1 * 4);
michael@0:       printf("#define GCC_VTABLE_FACTOR\t0x%x\n", (off2 - off1) * 4);
michael@0:       printf("#define GCC_VTABLE_SHIFT\t0x%x\n", factorshift);
michael@0:       exit(0);
michael@0: }