1 #ifndef UTILS_H
2 #define UTILS_H
3
break_optimization(void * arg)4 inline void break_optimization(void *arg) {
5 __asm__ __volatile__("" : : "r" (arg) : "memory");
6 }
7
8 // Tests will instantiate this class to pad out bit sets to test out the
9 // various ways we can represent the bit set (32-bit inline, 64-bit inline,
10 // memory). Instantiating this class will trigger the instantiation of I
11 // templates with I virtual tables for classes deriving from T, I-2 of which
12 // will be of size sizeof(void*) * 5, 1 of which will be of size sizeof(void*)
13 // * 3, and 1 of which will be of size sizeof(void*) * 9. (Under the MS ABI
14 // each virtual table will be sizeof(void*) bytes smaller). Each category
15 // of virtual tables is aligned to a different power of 2, precluding the
16 // all-ones optimization. As a result, the bit vector for the base class will
17 // need to contain at least I*2 entries to accommodate all the derived virtual
18 // tables.
19 template <typename T, unsigned I>
20 struct Deriver : T {
DeriverDeriver21 Deriver() {
22 break_optimization(new Deriver<T, I-1>);
23 }
fDeriver24 virtual void f() {}
gDeriver25 virtual void g() {}
hDeriver26 virtual void h() {}
27 };
28
29 template <typename T>
30 struct Deriver<T, 0> : T {
31 virtual void f() {}
32 void g() {}
33 };
34
35 template <typename T>
36 struct Deriver<T, 1> : T {
37 Deriver() {
38 break_optimization(new Deriver<T, 0>);
39 }
40 virtual void f() {}
41 virtual void g() {}
42 virtual void h() {}
43 virtual void i() {}
44 virtual void j() {}
45 virtual void k() {}
46 virtual void l() {}
47 };
48
49 // Instantiate enough classes to force CFI checks for type T to use bit
50 // vectors of size 32 (if B32 defined), 64 (if B64 defined) or >64 (if BM
51 // defined).
52 template <typename T>
53 void create_derivers() {
54 #ifdef B32
55 break_optimization(new Deriver<T, 10>);
56 #endif
57
58 #ifdef B64
59 break_optimization(new Deriver<T, 25>);
60 #endif
61
62 #ifdef BM
63 break_optimization(new Deriver<T, 40>);
64 #endif
65 }
66
67 #endif
68