1 +
#
2 +
# SRT - Secure, Reliable, Transport
3 +
# Copyright (c) 2021 Haivision Systems Inc.
4 +
#
5 +
# This Source Code Form is subject to the terms of the Mozilla Public
6 +
# License, v. 2.0. If a copy of the MPL was not distributed with this
7 +
# file, You can obtain one at http://mozilla.org/MPL/2.0/.
8 +
#
9 + 10 +
# Check for GCC Atomic Intrinsics and whether libatomic is required.
11 +
#
12 +
# Sets:
13 +
# HAVE_LIBATOMIC
14 +
# HAVE_GCCATOMIC_INTRINSICS
15 +
# HAVE_GCCATOMIC_INTRINSICS_REQUIRES_LIBATOMIC
16 +
# HAVE_GCCATOMIC_INTRINSICS_STATIC
17 +
# HAVE_GCCATOMIC_INTRINSICS_STATIC_REQUIRES_LIBATOMIC
18 +
#
19 +
# See
20 +
# https://gcc.gnu.org/onlinedocs/gcc/_005f_005fatomic-Builtins.html
21 +
# https://gcc.gnu.org/wiki/Atomic/GCCMM/AtomicSync
22 + 23 +
include(CheckCSourceCompiles)
24 +
include(CheckLibraryExists)
25 + 26 +
function(CheckGCCAtomicIntrinsics)
27 + 28 +
unset(HAVE_LIBATOMIC)
29 +
unset(HAVE_LIBATOMIC PARENT_SCOPE)
30 +
unset(HAVE_LIBATOMIC CACHE)
31 + 32 +
unset(HAVE_GCCATOMIC_INTRINSICS)
33 +
unset(HAVE_GCCATOMIC_INTRINSICS PARENT_SCOPE)
34 +
unset(HAVE_GCCATOMIC_INTRINSICS CACHE)
35 + 36 +
unset(HAVE_GCCATOMIC_INTRINSICS_REQUIRES_LIBATOMIC)
37 +
unset(HAVE_GCCATOMIC_INTRINSICS_REQUIRES_LIBATOMIC PARENT_SCOPE)
38 +
unset(HAVE_GCCATOMIC_INTRINSICS_REQUIRES_LIBATOMIC CACHE)
39 + 40 +
unset(HAVE_GCCATOMIC_INTRINSICS_STATIC)
41 +
unset(HAVE_GCCATOMIC_INTRINSICS_STATIC PARENT_SCOPE)
42 +
unset(HAVE_GCCATOMIC_INTRINSICS_STATIC CACHE)
43 + 44 +
unset(HAVE_GCCATOMIC_INTRINSICS_STATIC_REQUIRES_LIBATOMIC)
45 +
unset(HAVE_GCCATOMIC_INTRINSICS_STATIC_REQUIRES_LIBATOMIC PARENT_SCOPE)
46 +
unset(HAVE_GCCATOMIC_INTRINSICS_STATIC_REQUIRES_LIBATOMIC CACHE)
47 + 48 +
unset(CMAKE_REQUIRED_FLAGS)
49 +
unset(CMAKE_REQUIRED_LIBRARIES)
50 +
unset(CMAKE_REQUIRED_LINK_OPTIONS)
51 + 52 +
set(CheckGCCAtomicIntrinsics_CODE
53 +
"
54 +
#include<stddef.h>
55 +
#include<stdint.h>
56 +
int main(void)
57 +
{
58 +
ptrdiff_t x = 0;
59 +
intmax_t y = 0;
60 +
__atomic_add_fetch(&x, 1, __ATOMIC_SEQ_CST);
61 +
__atomic_add_fetch(&y, 1, __ATOMIC_SEQ_CST);
62 +
return __atomic_sub_fetch(&x, 1, __ATOMIC_SEQ_CST)
63 +
+ __atomic_sub_fetch(&y, 1, __ATOMIC_SEQ_CST);
64 +
}
65 +
")
66 + 67 +
check_library_exists(
68 +
atomic __atomic_fetch_add_8 "" HAVE_LIBATOMIC)
69 + 70 +
check_c_source_compiles(
71 +
"${CheckGCCAtomicIntrinsics_CODE}"
72 +
HAVE_GCCATOMIC_INTRINSICS)
73 + 74 +
if (NOT HAVE_GCCATOMIC_INTRINSICS
75 +
AND HAVE_LIBATOMIC)
76 +
set(CMAKE_REQUIRED_LIBRARIES "atomic")
77 +
check_c_source_compiles(
78 +
"${CheckGCCAtomicIntrinsics_CODE}"
79 +
HAVE_GCCATOMIC_INTRINSICS_REQUIRES_LIBATOMIC)
80 +
if (HAVE_GCCATOMIC_INTRINSICS_REQUIRES_LIBATOMIC)
81 +
set(HAVE_GCCATOMIC_INTRINSICS TRUE PARENT_SCOPE)
82 +
endif()
83 +
endif()
84 + 85 +
unset(CMAKE_REQUIRED_FLAGS)
86 +
unset(CMAKE_REQUIRED_LIBRARIES)
87 +
unset(CMAKE_REQUIRED_LINK_OPTIONS)
88 + 89 +
if (HAVE_GCCATOMIC_INTRINSICS)
90 +
set(CMAKE_REQUIRED_LINK_OPTIONS "-static")
91 +
check_c_source_compiles(
92 +
"${CheckGCCAtomicIntrinsics_CODE}"
93 +
HAVE_GCCATOMIC_INTRINSICS_STATIC)
94 +
if (NOT HAVE_GCCATOMIC_INTRINSICS_STATIC
95 +
AND HAVE_LIBATOMIC)
96 +
set(CMAKE_REQUIRED_LIBRARIES "atomic")
97 +
check_c_source_compiles(
98 +
"${CheckGCCAtomicIntrinsics_CODE}"
99 +
HAVE_GCCATOMIC_INTRINSICS_STATIC)
100 +
if (HAVE_GCCATOMIC_INTRINSICS_STATIC)
101 +
set(HAVE_GCCATOMIC_INTRINSICS_STATIC_REQUIRES_LIBATOMIC TRUE PARENT_SCOPE)
102 +
endif()
103 +
endif()
104 +
endif()
105 + 106 +
unset(CMAKE_REQUIRED_FLAGS)
107 +
unset(CMAKE_REQUIRED_LIBRARIES)
108 +
unset(CMAKE_REQUIRED_LINK_OPTIONS)
109 + 110 +
endfunction(CheckGCCAtomicIntrinsics)
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