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