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CMake: Change __attribute__((__ifunc__())) detection.

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This renames ALLOW_ATTR_IFUNC to USE_ATTR_IFUNC and applies the ifunc
detection changes that were made to the Autotools build.

Fixes: https://github.com/tukaani-project/xz/issues/70
This commit is contained in:
Jia Tan 2023-11-22 20:33:36 +08:00
parent 20ecee40a0
commit d4af167570
1 changed files with 45 additions and 8 deletions
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53
CMakeLists.txt
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@ -796,13 +796,46 @@ endif()
# Check for __attribute__((__ifunc__())) support.
option(ALLOW_ATTR_IFUNC "Allow use of __attribute__((__ifunc__())) if \
supported by the system" ON)
# Supported values for USE_ATTR_IFUNC:
#
# auto (default) - Detect ifunc support with a compile test.
# ON - Always enable ifunc.
# OFF - Disable ifunc usage.
set(USE_ATTR_IFUNC "auto" CACHE STRING "Use __attribute__((__ifunc__())).")
if(ALLOW_ATTR_IFUNC)
set(SUPPORTED_USE_ATTR_IFUNC auto ON OFF)
if(NOT USE_ATTR_IFUNC IN_LIST SUPPORTED_USE_ATTR_IFUNC)
message(FATAL_ERROR "'${USE_ATTR_IFUNC}' is not a supported value for"
"USE_ATTR_IFUNC")
endif()
# When USE_ATTR_IFUNC is 'auto', allow the use of __attribute__((__ifunc__()))
# if compiler support is detected and we are building for GNU/Linux (glibc)
# or FreeBSD. uClibc and musl don't support ifunc in their dynamic linkers
# but some compilers still accept the attribute when compiling for these
# C libraries, which results in broken binaries. That's why we need to
# check which libc is being used.
if(USE_ATTR_IFUNC STREQUAL "auto")
cmake_push_check_state()
set(CMAKE_REQUIRED_FLAGS "-Werror")
check_c_source_compiles("
/*
* Force a compilation error when not using glibc on Linux
* or if we are not using FreeBSD. uClibc will define
* __GLIBC__ but does not support ifunc, so we must have
* an extra check to disable with uClibc.
*/
#if defined(__linux__)
# include <features.h>
# if !defined(__GLIBC__) || defined(__UCLIBC__)
compile error
# endif
#elif !defined(__FreeBSD__)
compile error
#endif
static void func(void) { return; }
static void (*resolve_func(void)) (void) { return func; }
void func_ifunc(void)
@ -817,15 +850,19 @@ if(ALLOW_ATTR_IFUNC)
void make_clang_quiet(void);
void make_clang_quiet(void) { resolve_func()(); }
"
HAVE_FUNC_ATTRIBUTE_IFUNC)
cmake_pop_check_state()
tuklib_add_definition_if(liblzma HAVE_FUNC_ATTRIBUTE_IFUNC)
SYSTEM_SUPPORTS_IFUNC)
if(HAVE_FUNC_ATTRIBUTE_IFUNC AND CMAKE_C_FLAGS MATCHES "-fsanitize=")
cmake_pop_check_state()
endif()
if(USE_ATTR_IFUNC STREQUAL "ON" OR SYSTEM_SUPPORTS_IFUNC)
tuklib_add_definitions(liblzma HAVE_FUNC_ATTRIBUTE_IFUNC)
if(CMAKE_C_FLAGS MATCHES "-fsanitize=")
message(SEND_ERROR
"CMAKE_C_FLAGS or the environment variable CFLAGS "
"contains '-fsanitize=' which is incompatible "
"with ifunc. Use -DALLOW_ATTR_IFUNC=OFF "
"with ifunc. Use -DUSE_ATTR_IFUNC=OFF "
"as an argument to 'cmake' when using '-fsanitize'.")
endif()
endif()