builtin-align-cxx.cpp
14.4 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
// C++-specific checks for the alignment builtins
// RUN: %clang_cc1 -triple=x86_64-unknown-unknown -std=c++11 -o - %s -fsyntax-only -verify
// Check that we don't crash when using dependent types in __builtin_align:
template <typename a, a b>
void *c(void *d) { // expected-note{{candidate template ignored}}
return __builtin_align_down(d, b);
}
struct x {};
x foo;
void test(void *value) {
c<int, 16>(value);
c<struct x, foo>(value); // expected-error{{no matching function for call to 'c'}}
}
template <typename T, long Alignment, long ArraySize = 16>
void test_templated_arguments() {
T array[ArraySize]; // expected-error{{variable has incomplete type 'fwddecl'}}
static_assert(__is_same(decltype(__builtin_align_up(array, Alignment)), T *), // expected-error{{requested alignment is not a power of 2}}
"return type should be the decayed array type");
static_assert(__is_same(decltype(__builtin_align_down(array, Alignment)), T *),
"return type should be the decayed array type");
static_assert(__is_same(decltype(__builtin_is_aligned(array, Alignment)), bool),
"return type should be bool");
T *x1 = __builtin_align_up(array, Alignment);
T *x2 = __builtin_align_down(array, Alignment);
bool x3 = __builtin_align_up(array, Alignment);
}
void test() {
test_templated_arguments<int, 32>(); // fine
test_templated_arguments<struct fwddecl, 16>();
// expected-note@-1{{in instantiation of function template specialization 'test_templated_arguments<fwddecl, 16, 16>'}}
// expected-note@-2{{forward declaration of 'fwddecl'}}
test_templated_arguments<int, 7>(); // invalid alignment value
// expected-note@-1{{in instantiation of function template specialization 'test_templated_arguments<int, 7, 16>'}}
}
template <typename T, long ArraySize>
void test_incorrect_alignment_without_instatiation(T value) {
int array[32];
static_assert(__is_same(decltype(__builtin_align_up(array, 31)), int *), // expected-error{{requested alignment is not a power of 2}}
"return type should be the decayed array type");
static_assert(__is_same(decltype(__builtin_align_down(array, 7)), int *), // expected-error{{requested alignment is not a power of 2}}
"return type should be the decayed array type");
static_assert(__is_same(decltype(__builtin_is_aligned(array, -1)), bool), // expected-error{{requested alignment must be 1 or greater}}
"return type should be bool");
__builtin_align_up(array); // expected-error{{too few arguments to function call, expected 2, have 1}}
__builtin_align_up(array, 31); // expected-error{{requested alignment is not a power of 2}}
__builtin_align_down(array, 31); // expected-error{{requested alignment is not a power of 2}}
__builtin_align_up(array, 31); // expected-error{{requested alignment is not a power of 2}}
__builtin_align_up(value, 31); // This shouldn't want since the type is dependent
__builtin_align_up(value); // Same here
__builtin_align_up(array, sizeof(sizeof(value)) - 1); // expected-error{{requested alignment is not a power of 2}}
__builtin_align_up(array, value); // no diagnostic as the alignment is value dependent.
(void)__builtin_align_up(array, ArraySize); // The same above here
}
// The original fix for the issue above broke some legitimate code.
// Here is a regression test:
typedef __SIZE_TYPE__ size_t;
void *allocate_impl(size_t size);
template <typename T>
T *allocate() {
constexpr size_t allocation_size =
__builtin_align_up(sizeof(T), sizeof(void *));
return static_cast<T *>(
__builtin_assume_aligned(allocate_impl(allocation_size), sizeof(void *)));
}
struct Foo {
int value;
};
void *test2() {
return allocate<struct Foo>();
}
// Check that pointers-to-members cannot be used:
class MemPtr {
public:
int data;
void func();
virtual void vfunc();
};
void test_member_ptr() {
__builtin_align_up(&MemPtr::data, 64); // expected-error{{operand of type 'int MemPtr::*' where arithmetic or pointer type is required}}
__builtin_align_down(&MemPtr::func, 64); // expected-error{{operand of type 'void (MemPtr::*)()' where arithmetic or pointer type is required}}
__builtin_is_aligned(&MemPtr::vfunc, 64); // expected-error{{operand of type 'void (MemPtr::*)()' where arithmetic or pointer type is required}}
}
void test_references(Foo &i) {
// Check that the builtins look at the referenced type rather than the reference itself.
(void)__builtin_align_up(i, 64); // expected-error{{operand of type 'Foo' where arithmetic or pointer type is required}}
(void)__builtin_align_up(static_cast<Foo &>(i), 64); // expected-error{{operand of type 'Foo' where arithmetic or pointer type is required}}
(void)__builtin_align_up(static_cast<const Foo &>(i), 64); // expected-error{{operand of type 'const Foo' where arithmetic or pointer type is required}}
(void)__builtin_align_up(static_cast<Foo &&>(i), 64); // expected-error{{operand of type 'Foo' where arithmetic or pointer type is required}}
(void)__builtin_align_up(static_cast<const Foo &&>(i), 64); // expected-error{{operand of type 'const Foo' where arithmetic or pointer type is required}}
(void)__builtin_align_up(&i, 64);
}
// Check that constexpr wrapper functions can be constant-evaluated.
template <typename T>
constexpr bool wrap_is_aligned(T ptr, long align) {
return __builtin_is_aligned(ptr, align);
// expected-note@-1{{requested alignment -3 is not a positive power of two}}
// expected-note@-2{{requested alignment 19 is not a positive power of two}}
// expected-note@-3{{requested alignment must be 128 or less for type 'char'; 4194304 is invalid}}
}
template <typename T>
constexpr T wrap_align_up(T ptr, long align) {
return __builtin_align_up(ptr, align);
// expected-note@-1{{requested alignment -2 is not a positive power of two}}
// expected-note@-2{{requested alignment 18 is not a positive power of two}}
// expected-note@-3{{requested alignment must be 2147483648 or less for type 'int'; 8589934592 is invalid}}
// expected-error@-4{{operand of type 'bool' where arithmetic or pointer type is required}}
}
template <typename T>
constexpr T wrap_align_down(T ptr, long align) {
return __builtin_align_down(ptr, align);
// expected-note@-1{{requested alignment -1 is not a positive power of two}}
// expected-note@-2{{requested alignment 17 is not a positive power of two}}
// expected-note@-3{{requested alignment must be 32768 or less for type 'short'; 1048576 is invalid}}
}
constexpr int a1 = wrap_align_up(22, 32);
static_assert(a1 == 32, "");
constexpr int a2 = wrap_align_down(22, 16);
static_assert(a2 == 16, "");
constexpr bool a3 = wrap_is_aligned(22, 32);
static_assert(!a3, "");
static_assert(wrap_align_down(wrap_align_up(22, 16), 32) == 32, "");
static_assert(wrap_is_aligned(wrap_align_down(wrap_align_up(22, 16), 32), 32), "");
static_assert(!wrap_is_aligned(wrap_align_down(wrap_align_up(22, 16), 32), 64), "");
constexpr long const_value(long l) { return l; }
// Check some invalid values during constant-evaluation
static_assert(wrap_align_down(1, const_value(-1)), ""); // expected-error{{not an integral constant expression}}
// expected-note@-1{{in call to 'wrap_align_down(1, -1)'}}
static_assert(wrap_align_up(1, const_value(-2)), ""); // expected-error{{not an integral constant expression}}
// expected-note@-1{{in call to 'wrap_align_up(1, -2)'}}
static_assert(wrap_is_aligned(1, const_value(-3)), ""); // expected-error{{not an integral constant expression}}
// expected-note@-1{{in call to 'wrap_is_aligned(1, -3)'}}
static_assert(wrap_align_down(1, const_value(17)), ""); // expected-error{{not an integral constant expression}}
// expected-note@-1{{in call to 'wrap_align_down(1, 17)'}}
static_assert(wrap_align_up(1, const_value(18)), ""); // expected-error{{not an integral constant expression}}
// expected-note@-1{{in call to 'wrap_align_up(1, 18)'}}
static_assert(wrap_is_aligned(1, const_value(19)), ""); // expected-error{{not an integral constant expression}}
// expected-note@-1{{in call to 'wrap_is_aligned(1, 19)'}}
// Check invalid values for smaller types:
static_assert(wrap_align_down(static_cast<short>(1), const_value(1 << 20)), ""); // expected-error{{not an integral constant expression}}
// expected-note@-1{{in call to 'wrap_align_down(1, 1048576)'}}
// Check invalid boolean type
static_assert(wrap_align_up(static_cast<int>(1), const_value(1ull << 33)), ""); // expected-error{{not an integral constant expression}}
// expected-note@-1{{in call to 'wrap_align_up(1, 8589934592)'}}
static_assert(wrap_is_aligned(static_cast<char>(1), const_value(1 << 22)), ""); // expected-error{{not an integral constant expression}}
// expected-note@-1{{in call to 'wrap_is_aligned(1, 4194304)'}}
// Check invalid boolean type
static_assert(wrap_align_up(static_cast<bool>(1), const_value(1 << 21)), ""); // expected-error{{not an integral constant expression}}
// expected-note@-1{{in instantiation of function template specialization 'wrap_align_up<bool>' requested here}}
// Check constant evaluation for pointers:
_Alignas(32) char align32array[128];
static_assert(&align32array[0] == &align32array[0], "");
// __builtin_align_up/down can be constant evaluated as a no-op for values
// that are known to have greater alignment:
static_assert(__builtin_align_up(&align32array[0], 32) == &align32array[0], "");
static_assert(__builtin_align_up(&align32array[0], 4) == &align32array[0], "");
static_assert(__builtin_align_down(&align32array[0], 4) == __builtin_align_up(&align32array[0], 8), "");
// But it can not be evaluated if the alignment is greater than the minimum
// known alignment, since in that case the value might be the same if it happens
// to actually be aligned to 64 bytes at run time.
static_assert(&align32array[0] == __builtin_align_up(&align32array[0], 64), ""); // expected-error{{not an integral constant expression}}
// expected-note@-1{{cannot constant evaluate the result of adjusting alignment to 64}}
static_assert(__builtin_align_up(&align32array[0], 64) == __builtin_align_up(&align32array[0], 64), ""); // expected-error{{not an integral constant expression}}
// expected-note@-1{{cannot constant evaluate the result of adjusting alignment to 64}}
// However, we can compute in case the requested alignment is less than the
// base alignment:
static_assert(__builtin_align_up(&align32array[0], 4) == &align32array[0], "");
static_assert(__builtin_align_up(&align32array[1], 4) == &align32array[4], "");
static_assert(__builtin_align_up(&align32array[2], 4) == &align32array[4], "");
static_assert(__builtin_align_up(&align32array[3], 4) == &align32array[4], "");
static_assert(__builtin_align_up(&align32array[4], 4) == &align32array[4], "");
static_assert(__builtin_align_up(&align32array[5], 4) == &align32array[8], "");
static_assert(__builtin_align_up(&align32array[6], 4) == &align32array[8], "");
static_assert(__builtin_align_up(&align32array[7], 4) == &align32array[8], "");
static_assert(__builtin_align_up(&align32array[8], 4) == &align32array[8], "");
static_assert(__builtin_align_down(&align32array[0], 4) == &align32array[0], "");
static_assert(__builtin_align_down(&align32array[1], 4) == &align32array[0], "");
static_assert(__builtin_align_down(&align32array[2], 4) == &align32array[0], "");
static_assert(__builtin_align_down(&align32array[3], 4) == &align32array[0], "");
static_assert(__builtin_align_down(&align32array[4], 4) == &align32array[4], "");
static_assert(__builtin_align_down(&align32array[5], 4) == &align32array[4], "");
static_assert(__builtin_align_down(&align32array[6], 4) == &align32array[4], "");
static_assert(__builtin_align_down(&align32array[7], 4) == &align32array[4], "");
static_assert(__builtin_align_down(&align32array[8], 4) == &align32array[8], "");
// Achiving the same thing using casts to uintptr_t is not allowed:
static_assert((char *)((__UINTPTR_TYPE__)&align32array[7] & ~3) == &align32array[4], ""); // expected-error{{not an integral constant expression}}
static_assert(__builtin_align_down(&align32array[1], 4) == &align32array[0], "");
static_assert(__builtin_align_down(&align32array[1], 64) == &align32array[0], ""); // expected-error{{not an integral constant expression}}
// expected-note@-1{{cannot constant evaluate the result of adjusting alignment to 64}}
// Add some checks for __builtin_is_aligned:
static_assert(__builtin_is_aligned(&align32array[0], 32), "");
static_assert(__builtin_is_aligned(&align32array[4], 4), "");
// We cannot constant evaluate whether the array is aligned to > 32 since this
// may well be true at run time.
static_assert(!__builtin_is_aligned(&align32array[0], 64), ""); // expected-error{{not an integral constant expression}}
// expected-note@-1{{cannot constant evaluate whether run-time alignment is at least 64}}
// However, if the alignment being checked is less than the minimum alignment of
// the base object we can check the low bits of the alignment:
static_assert(__builtin_is_aligned(&align32array[0], 4), "");
static_assert(!__builtin_is_aligned(&align32array[1], 4), "");
static_assert(!__builtin_is_aligned(&align32array[2], 4), "");
static_assert(!__builtin_is_aligned(&align32array[3], 4), "");
static_assert(__builtin_is_aligned(&align32array[4], 4), "");
// TODO: this should evaluate to true even though we can't evaluate the result
// of __builtin_align_up() to a concrete value
static_assert(__builtin_is_aligned(__builtin_align_up(&align32array[0], 64), 64), ""); // expected-error{{not an integral constant expression}}
// expected-note@-1{{cannot constant evaluate the result of adjusting alignment to 64}}
// Check different source and alignment type widths are handled correctly.
static_assert(!__builtin_is_aligned(static_cast<signed long>(7), static_cast<signed short>(4)), "");
static_assert(!__builtin_is_aligned(static_cast<signed short>(7), static_cast<signed long>(4)), "");
// Also check signed -- unsigned mismatch.
static_assert(!__builtin_is_aligned(static_cast<signed long>(7), static_cast<signed long>(4)), "");
static_assert(!__builtin_is_aligned(static_cast<unsigned long>(7), static_cast<unsigned long>(4)), "");
static_assert(!__builtin_is_aligned(static_cast<signed long>(7), static_cast<unsigned long>(4)), "");
static_assert(!__builtin_is_aligned(static_cast<unsigned long>(7), static_cast<signed long>(4)), "");
static_assert(!__builtin_is_aligned(static_cast<signed long>(7), static_cast<unsigned short>(4)), "");
static_assert(!__builtin_is_aligned(static_cast<unsigned short>(7), static_cast<signed long>(4)), "");