1 | //===-- Common internal contructs -------------------------------*- C++ -*-===// |
2 | // |
3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
4 | // See https://llvm.org/LICENSE.txt for license information. |
5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
6 | // |
7 | //===----------------------------------------------------------------------===// |
8 | |
9 | #ifndef LLVM_LIBC_SRC___SUPPORT_COMMON_H |
10 | #define LLVM_LIBC_SRC___SUPPORT_COMMON_H |
11 | |
12 | #ifndef LIBC_NAMESPACE |
13 | #error "LIBC_NAMESPACE macro is not defined." |
14 | #endif |
15 | |
16 | #include "src/__support/macros/attributes.h" |
17 | #include "src/__support/macros/properties/architectures.h" |
18 | |
19 | #ifndef LLVM_LIBC_FUNCTION_ATTR |
20 | #define LLVM_LIBC_FUNCTION_ATTR |
21 | #endif |
22 | |
23 | // MacOS needs to be excluded because it does not support aliasing. |
24 | #if defined(LIBC_COPT_PUBLIC_PACKAGING) && (!defined(__APPLE__)) |
25 | #define LLVM_LIBC_FUNCTION_IMPL(type, name, arglist) \ |
26 | LLVM_LIBC_FUNCTION_ATTR decltype(LIBC_NAMESPACE::name) \ |
27 | __##name##_impl__ __asm__(#name); \ |
28 | decltype(LIBC_NAMESPACE::name) name [[gnu::alias(#name)]]; \ |
29 | type __##name##_impl__ arglist |
30 | #else |
31 | #define LLVM_LIBC_FUNCTION_IMPL(type, name, arglist) type name arglist |
32 | #endif |
33 | |
34 | // This extra layer of macro allows `name` to be a macro to rename a function. |
35 | #define LLVM_LIBC_FUNCTION(type, name, arglist) \ |
36 | LLVM_LIBC_FUNCTION_IMPL(type, name, arglist) |
37 | |
38 | namespace LIBC_NAMESPACE { |
39 | namespace internal { |
40 | LIBC_INLINE constexpr bool same_string(char const *lhs, char const *rhs) { |
41 | for (; *lhs || *rhs; ++lhs, ++rhs) |
42 | if (*lhs != *rhs) |
43 | return false; |
44 | return true; |
45 | } |
46 | } // namespace internal |
47 | } // namespace LIBC_NAMESPACE |
48 | |
49 | #define __LIBC_MACRO_TO_STRING(str) #str |
50 | #define LIBC_MACRO_TO_STRING(str) __LIBC_MACRO_TO_STRING(str) |
51 | |
52 | // LLVM_LIBC_IS_DEFINED checks whether a particular macro is defined. |
53 | // Usage: constexpr bool kUseAvx = LLVM_LIBC_IS_DEFINED(__AVX__); |
54 | // |
55 | // This works by comparing the stringified version of the macro with and without |
56 | // evaluation. If FOO is not undefined both stringifications yield "FOO". If FOO |
57 | // is defined, one stringification yields "FOO" while the other yields its |
58 | // stringified value "1". |
59 | #define LLVM_LIBC_IS_DEFINED(macro) \ |
60 | !LIBC_NAMESPACE::internal::same_string( \ |
61 | LLVM_LIBC_IS_DEFINED__EVAL_AND_STRINGIZE(macro), #macro) |
62 | #define LLVM_LIBC_IS_DEFINED__EVAL_AND_STRINGIZE(s) #s |
63 | |
64 | #endif // LLVM_LIBC_SRC___SUPPORT_COMMON_H |
65 | |