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# Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
# SPDX-License-Identifier: Apache-2.0.
include(CheckCCompilerFlag)
include(CheckIncludeFile)
include(CheckSymbolExists)
include(CMakeParseArguments) # needed for CMake v3.4 and lower
option(AWS_ENABLE_LTO "Enables LTO on libraries. Ensure this is set on all consumed targets, or linking will fail" OFF)
option(LEGACY_COMPILER_SUPPORT "This enables builds with compiler versions such as gcc 4.1.2. This is not a 'supported' feature; it's just a best effort." OFF)
option(AWS_SUPPORT_WIN7 "Restricts WINAPI calls to Win7 and older (This will have implications in downstream libraries that use TLS especially)" OFF)
option(AWS_WARNINGS_ARE_ERRORS "Compiler warning is treated as an error. Try turning this off when observing errors on a new or uncommon compiler" OFF)
option(AWS_ENABLE_TRACING "Enable tracing macros" OFF)
option(AWS_STATIC_MSVC_RUNTIME_LIBRARY "Windows-only. Turn ON to use the statically-linked MSVC runtime lib, instead of the DLL" OFF)
option(STATIC_CRT "Deprecated. Use AWS_STATIC_MSVC_RUNTIME_LIBRARY instead" OFF)
# Check for Posix Large Files Support (LFS).
# On most 64bit systems, LFS is enabled by default.
# On some 32bit systems, LFS must be enabled by via defines before headers are included.
# For more info, see docs:
# https://www.gnu.org/software/libc/manual/html_node/File-Position-Primitive.html
# https://www.gnu.org/software/libc/manual/html_node/Feature-Test-Macros.html
function(aws_check_posix_lfs extra_flags variable)
list(APPEND CMAKE_REQUIRED_FLAGS ${extra_flags})
check_c_source_compiles("
#include <stdio.h>
/* fails to compile if off_t smaller than 64bits */
typedef char array[sizeof(off_t) >= 8 ? 1 : -1];
int main() {
return 0;
}"
HAS_64BIT_FILE_OFFSET_${variable})
if (HAS_64BIT_FILE_OFFSET_${variable})
# sometimes off_t is 64bit, but fseeko() is missing (ex: Android API < 24)
check_symbol_exists(fseeko "stdio.h" HAS_FSEEKO_${variable})
if (HAS_FSEEKO_${variable})
set(${variable} 1 PARENT_SCOPE)
endif()
endif()
endfunction()
# This function will set all common flags on a target
# Options:
# NO_WGNU: Disable -Wgnu
# NO_WEXTRA: Disable -Wextra
# NO_PEDANTIC: Disable -pedantic
function(aws_set_common_properties target)
set(options NO_WGNU NO_WEXTRA NO_PEDANTIC NO_LTO)
cmake_parse_arguments(SET_PROPERTIES "${options}" "" "" ${ARGN})
if(MSVC)
# Remove other /W flags
if(CMAKE_C_FLAGS MATCHES "/W[0-4]")
string(REGEX REPLACE "/W[0-4]" "" CMAKE_C_FLAGS "${CMAKE_C_FLAGS}")
set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS}" PARENT_SCOPE)
endif()
list(APPEND AWS_C_FLAGS /W4 /MP)
if(AWS_WARNINGS_ARE_ERRORS)
list(APPEND AWS_C_FLAGS /WX)
endif()
# /volatile:iso relaxes some implicit memory barriers that MSVC normally applies for volatile accesses
# Since we want to be compatible with user builds using /volatile:iso, use it for the tests.
list(APPEND AWS_C_FLAGS /volatile:iso)
# disable non-constant initializer warning, it's not non-standard, just for Microsoft
list(APPEND AWS_C_FLAGS /wd4204)
# disable passing the address of a local warning. Again, not non-standard, just for Microsoft
list(APPEND AWS_C_FLAGS /wd4221)
if (AWS_SUPPORT_WIN7)
# Use only APIs available in Win7 and later
message(STATUS "Windows 7 support requested, forcing WINVER and _WIN32_WINNT to 0x0601")
list(APPEND AWS_C_FLAGS /DWINVER=0x0601)
list(APPEND AWS_C_FLAGS /D_WIN32_WINNT=0x0601)
list(APPEND AWS_C_FLAGS /DAWS_SUPPORT_WIN7=1)
endif()
# Set MSVC runtime libary.
# Note: there are other ways of doing this if we bump our CMake minimum to 3.14+
# See: https://cmake.org/cmake/help/latest/policy/CMP0091.html
if (AWS_STATIC_MSVC_RUNTIME_LIBRARY OR STATIC_CRT)
list(APPEND AWS_C_FLAGS "/MT$<$<CONFIG:Debug>:d>")
else()
list(APPEND AWS_C_FLAGS "/MD$<$<CONFIG:Debug>:d>")
endif()
else()
list(APPEND AWS_C_FLAGS -Wall -Wstrict-prototypes)
list(APPEND AWS_C_FLAGS $<$<NOT:$<CONFIG:Release>>:-fno-omit-frame-pointer>)
if(AWS_WARNINGS_ARE_ERRORS)
list(APPEND AWS_C_FLAGS -Werror)
endif()
if(NOT SET_PROPERTIES_NO_WEXTRA)
list(APPEND AWS_C_FLAGS -Wextra)
endif()
if(NOT SET_PROPERTIES_NO_PEDANTIC)
list(APPEND AWS_C_FLAGS -pedantic)
endif()
# Warning disables always go last to avoid future flags re-enabling them
list(APPEND AWS_C_FLAGS -Wno-long-long)
# Always enable position independent code, since this code will always end up in a shared lib
check_c_compiler_flag("-fPIC -Werror" HAS_FPIC_FLAG)
if (HAS_FPIC_FLAG)
list(APPEND AWS_C_FLAGS -fPIC)
endif()
if (LEGACY_COMPILER_SUPPORT)
list(APPEND AWS_C_FLAGS -Wno-strict-aliasing)
endif()
# -moutline-atomics generates code for both older load/store exclusive atomics and also
# Arm's Large System Extensions (LSE) which scale substantially better on large core count systems.
#
# Test by compiling a program that actually uses atomics.
# Previously we'd simply used check_c_compiler_flag() but that wasn't detecting
# some real-world problems (see https://github.com/awslabs/aws-c-common/issues/902).
if (AWS_ARCH_ARM64)
set(old_flags "${CMAKE_REQUIRED_FLAGS}")
set(CMAKE_REQUIRED_FLAGS "-moutline-atomics -Werror")
check_c_source_compiles("
int main() {
int x = 1;
__atomic_fetch_add(&x, -1, __ATOMIC_SEQ_CST);
return x;
}" HAS_MOUTLINE_ATOMICS)
set(CMAKE_REQUIRED_FLAGS "${old_flags}")
if (HAS_MOUTLINE_ATOMICS)
list(APPEND AWS_C_FLAGS -moutline-atomics)
endif()
endif()
# Check for Posix Large File Support (LFS).
# Doing this check here, instead of AwsFeatureTests.cmake,
# because we might need to modify AWS_C_FLAGS to enable it.
set(HAS_LFS FALSE)
aws_check_posix_lfs("" BY_DEFAULT)
if (BY_DEFAULT)
set(HAS_LFS TRUE)
else()
aws_check_posix_lfs("-D_FILE_OFFSET_BITS=64" VIA_DEFINES)
if (VIA_DEFINES)
list(APPEND AWS_C_FLAGS "-D_FILE_OFFSET_BITS=64")
set(HAS_LFS TRUE)
endif()
endif()
# This becomes a define in config.h
set(AWS_HAVE_POSIX_LARGE_FILE_SUPPORT ${HAS_LFS} CACHE BOOL "Posix Large File Support")
# Hide symbols from libcrypto.a
# This avoids problems when an application ends up using both libcrypto.a and libcrypto.so.
#
# An example of this happening is the aws-c-io tests.
# All the C libs are compiled statically, but then a PKCS#11 library is
# loaded at runtime which happens to use libcrypto.so from OpenSSL.
# If the symbols from libcrypto.a aren't hidden, then SOME function calls use the libcrypto.a implementation
# and SOME function calls use the libcrypto.so implementation, and this mismatch leads to weird crashes.
if (UNIX AND NOT APPLE)
# If we used target_link_options() (CMake 3.13+) we could make these flags PUBLIC
set_property(TARGET ${target} APPEND_STRING PROPERTY LINK_FLAGS " -Wl,--exclude-libs,libcrypto.a")
endif()
endif()
check_include_file(stdint.h HAS_STDINT)
check_include_file(stdbool.h HAS_STDBOOL)
if (NOT HAS_STDINT)
list(APPEND AWS_C_FLAGS -DNO_STDINT)
endif()
if (NOT HAS_STDBOOL)
list(APPEND AWS_C_FLAGS -DNO_STDBOOL)
endif()
if(NOT SET_PROPERTIES_NO_WGNU)
check_c_compiler_flag("-Wgnu -Werror" HAS_WGNU)
if(HAS_WGNU)
# -Wgnu-zero-variadic-macro-arguments results in a lot of false positives
list(APPEND AWS_C_FLAGS -Wgnu -Wno-gnu-zero-variadic-macro-arguments)
# some platforms implement htonl family of functions via GNU statement expressions (https://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html)
# which generates -Wgnu-statement-expression warning.
set(old_flags "${CMAKE_REQUIRED_FLAGS}")
set(CMAKE_REQUIRED_FLAGS "-Wgnu -Werror")
check_c_source_compiles("
#include <netinet/in.h>
int main() {
uint32_t x = 0;
x = htonl(x);
return (int)x;
}" NO_GNU_EXPR)
set(CMAKE_REQUIRED_FLAGS "${old_flags}")
if (NOT NO_GNU_EXPR)
list(APPEND AWS_C_FLAGS -Wno-gnu-statement-expression)
endif()
endif()
endif()
# some platforms (especially when cross-compiling) do not have the sysconf API in their toolchain files.
check_c_source_compiles("
#include <unistd.h>
int main() {
sysconf(_SC_NPROCESSORS_ONLN);
}" HAVE_SYSCONF)
if (HAVE_SYSCONF)
list(APPEND AWS_C_DEFINES_PRIVATE -DHAVE_SYSCONF)
endif()
list(APPEND AWS_C_DEFINES_PRIVATE $<$<CONFIG:Debug>:DEBUG_BUILD>)
if ((NOT SET_PROPERTIES_NO_LTO) AND AWS_ENABLE_LTO)
# enable except in Debug builds
set(_ENABLE_LTO_EXPR $<NOT:$<CONFIG:Debug>>)
# try to check whether compiler supports LTO/IPO
if (POLICY CMP0069)
cmake_policy(SET CMP0069 NEW)
include(CheckIPOSupported OPTIONAL RESULT_VARIABLE ipo_check_exists)
if (ipo_check_exists)
check_ipo_supported(RESULT ipo_supported)
if (ipo_supported)
message(STATUS "Enabling IPO/LTO for Release builds")
else()
message(STATUS "AWS_ENABLE_LTO is enabled, but cmake/compiler does not support it, disabling")
set(_ENABLE_LTO_EXPR OFF)
endif()
endif()
endif()
else()
set(_ENABLE_LTO_EXPR OFF)
endif()
if(BUILD_SHARED_LIBS)
if (NOT MSVC)
# this should only be set when building shared libs.
list(APPEND AWS_C_FLAGS "-fvisibility=hidden")
endif()
endif()
if(AWS_ENABLE_TRACING)
target_link_libraries(${target} PRIVATE ittnotify)
else()
# Disable intel notify api if tracing is not enabled
list(APPEND AWS_C_DEFINES_PRIVATE -DINTEL_NO_ITTNOTIFY_API)
endif()
target_compile_options(${target} PRIVATE ${AWS_C_FLAGS})
target_compile_definitions(${target} PRIVATE ${AWS_C_DEFINES_PRIVATE} PUBLIC ${AWS_C_DEFINES_PUBLIC})
set_target_properties(${target} PROPERTIES LINKER_LANGUAGE C C_STANDARD 99 C_STANDARD_REQUIRED ON)
set_target_properties(${target} PROPERTIES INTERPROCEDURAL_OPTIMIZATION ${_ENABLE_LTO_EXPR}>)
endfunction()
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