[libunwind] a59165b - [runtimes] Don't try passing --target flags to GCC

Louis Dionne via cfe-commits cfe-commits at lists.llvm.org
Thu Jul 15 13:52:25 PDT 2021


Author: Louis Dionne
Date: 2021-07-15T16:52:02-04:00
New Revision: a59165b01778a3b02c510a96951d115d39babd86

URL: https://github.com/llvm/llvm-project/commit/a59165b01778a3b02c510a96951d115d39babd86
DIFF: https://github.com/llvm/llvm-project/commit/a59165b01778a3b02c510a96951d115d39babd86.diff

LOG: [runtimes] Don't try passing --target flags to GCC

When a target triple is specified in CMake via XXX_TARGET_TRIPLE, we tried
passing the --target=<...> flag to the compiler. However, not all compilers
support that flag (e.g. GCC, which is not a cross-compiler). As a result,
setting e.g. LIBCXX_TARGET_TRIPLE=<host-triple> would end up trying to
pass --target=<host-triple> to GCC, which breaks everything because the
flag isn't even supported.

This commit only adds `--target=<...>` & friends to the flags if it is
supported by the compiler.

One could argue that it's confusing to pass LIBCXX_TARGET_TRIPLE=<...>
and have it be ignored. That's correct, and one possibility would be
to assert that the requested triple is the same as the host triple when
we know the compiler is unable to cross-compile. However, note that this
is a pre-existing issue (setting the TARGET_TRIPLE variable never had an
influence on the flags passed to the compiler), and also fixing that is
starting to look like reimplementing a lot of CMake logic that is already
handled with CMAKE_CXX_COMPILER_TARGET.

Differential Revision: https://reviews.llvm.org/D106082

Added: 
    

Modified: 
    libcxx/CMakeLists.txt
    libcxx/cmake/Modules/HandleLibcxxFlags.cmake
    libcxxabi/CMakeLists.txt
    libcxxabi/cmake/Modules/HandleLibcxxabiFlags.cmake
    libunwind/CMakeLists.txt
    libunwind/cmake/Modules/HandleLibunwindFlags.cmake

Removed: 
    


################################################################################
diff  --git a/libcxx/CMakeLists.txt b/libcxx/CMakeLists.txt
index 10caf0f8e3025..3025b6c4f37b5 100644
--- a/libcxx/CMakeLists.txt
+++ b/libcxx/CMakeLists.txt
@@ -465,17 +465,17 @@ include(HandleLibcxxFlags)
 add_target_flags_if(LIBCXX_BUILD_32_BITS "-m32")
 
 if(LIBCXX_TARGET_TRIPLE)
-  add_target_flags("--target=${LIBCXX_TARGET_TRIPLE}")
+  add_target_flags_if_supported("--target=${LIBCXX_TARGET_TRIPLE}")
 elseif(CMAKE_CXX_COMPILER_TARGET)
   set(LIBCXX_TARGET_TRIPLE "${CMAKE_CXX_COMPILER_TARGET}")
 endif()
 if(LIBCXX_SYSROOT)
-  add_target_flags("--sysroot=${LIBCXX_SYSROOT}")
+  add_target_flags_if_supported("--sysroot=${LIBCXX_SYSROOT}")
 elseif(CMAKE_SYSROOT)
   set(LIBCXX_SYSROOT "${CMAKE_SYSROOT}")
 endif()
 if(LIBCXX_GCC_TOOLCHAIN)
-  add_target_flags("--gcc-toolchain=${LIBCXX_GCC_TOOLCHAIN}")
+  add_target_flags_if_supported("--gcc-toolchain=${LIBCXX_GCC_TOOLCHAIN}")
 elseif(CMAKE_CXX_COMPILER_EXTERNAL_TOOLCHAIN)
   set(LIBCXX_GCC_TOOLCHAIN "${CMAKE_CXX_COMPILER_EXTERNAL_TOOLCHAIN}")
 endif()

diff  --git a/libcxx/cmake/Modules/HandleLibcxxFlags.cmake b/libcxx/cmake/Modules/HandleLibcxxFlags.cmake
index a5b4df6600ee3..859cfc4a51559 100644
--- a/libcxx/cmake/Modules/HandleLibcxxFlags.cmake
+++ b/libcxx/cmake/Modules/HandleLibcxxFlags.cmake
@@ -121,6 +121,17 @@ macro(add_target_flags_if condition)
   endif()
 endmacro()
 
+# Add all the flags supported by the compiler to all of
+# 'CMAKE_CXX_FLAGS', 'CMAKE_C_FLAGS', 'LIBCXX_COMPILE_FLAGS'
+# and 'LIBCXX_LINK_FLAGS'.
+macro(add_target_flags_if_supported)
+  foreach(flag ${ARGN})
+    mangle_name("${flag}" flagname)
+    check_cxx_compiler_flag("${flag}" "LIBCXX_SUPPORTS_${flagname}_FLAG")
+    add_target_flags_if(LIBCXX_SUPPORTS_${flagname}_FLAG ${flag})
+  endforeach()
+endmacro()
+
 # Add a specified list of flags to both 'LIBCXX_COMPILE_FLAGS' and
 # 'LIBCXX_LINK_FLAGS'.
 macro(add_flags)

diff  --git a/libcxxabi/CMakeLists.txt b/libcxxabi/CMakeLists.txt
index 584bcbd2adde6..8c21fc39d1857 100644
--- a/libcxxabi/CMakeLists.txt
+++ b/libcxxabi/CMakeLists.txt
@@ -258,17 +258,17 @@ include(HandleLibcxxabiFlags)
 add_target_flags_if(LIBCXXABI_BUILD_32_BITS "-m32")
 
 if(LIBCXXABI_TARGET_TRIPLE)
-  add_target_flags("--target=${LIBCXXABI_TARGET_TRIPLE}")
+  add_target_flags_if_supported("--target=${LIBCXXABI_TARGET_TRIPLE}")
 elseif(CMAKE_CXX_COMPILER_TARGET)
   set(LIBCXXABI_TARGET_TRIPLE "${CMAKE_CXX_COMPILER_TARGET}")
 endif()
 if(LIBCXX_GCC_TOOLCHAIN)
-  add_target_flags("--gcc-toolchain=${LIBCXXABI_GCC_TOOLCHAIN}")
+  add_target_flags_if_supported("--gcc-toolchain=${LIBCXXABI_GCC_TOOLCHAIN}")
 elseif(CMAKE_CXX_COMPILER_EXTERNAL_TOOLCHAIN)
   set(LIBCXXABI_GCC_TOOLCHAIN "${CMAKE_CXX_COMPILER_EXTERNAL_TOOLCHAIN}")
 endif()
 if(LIBCXXABI_SYSROOT)
-  add_target_flags("--sysroot=${LIBCXXABI_SYSROOT}")
+  add_target_flags_if_supported("--sysroot=${LIBCXXABI_SYSROOT}")
 elseif(CMAKE_SYSROOT)
   set(LIBCXXABI_SYSROOT "${CMAKE_SYSROOT}")
 endif()

diff  --git a/libcxxabi/cmake/Modules/HandleLibcxxabiFlags.cmake b/libcxxabi/cmake/Modules/HandleLibcxxabiFlags.cmake
index 19d6e93b20b02..512e71a6a7805 100644
--- a/libcxxabi/cmake/Modules/HandleLibcxxabiFlags.cmake
+++ b/libcxxabi/cmake/Modules/HandleLibcxxabiFlags.cmake
@@ -123,6 +123,17 @@ macro(add_target_flags_if condition)
   endif()
 endmacro()
 
+# Add all the flags supported by the compiler to all of
+# 'CMAKE_CXX_FLAGS', 'CMAKE_C_FLAGS', 'LIBCXXABI_COMPILE_FLAGS'
+# and 'LIBCXXABI_LINK_FLAGS'.
+macro(add_target_flags_if_supported)
+  foreach(flag ${ARGN})
+    mangle_name("${flag}" flagname)
+    check_cxx_compiler_flag("${flag}" "LIBCXXABI_SUPPORTS_${flagname}_FLAG")
+    add_target_flags_if(LIBCXXABI_SUPPORTS_${flagname}_FLAG ${flag})
+  endforeach()
+endmacro()
+
 # Add a specified list of flags to both 'LIBCXXABI_COMPILE_FLAGS' and
 # 'LIBCXXABI_LINK_FLAGS'.
 macro(add_flags)

diff  --git a/libunwind/CMakeLists.txt b/libunwind/CMakeLists.txt
index 9eada6895e009..9563328896676 100644
--- a/libunwind/CMakeLists.txt
+++ b/libunwind/CMakeLists.txt
@@ -152,17 +152,17 @@ include(HandleLibunwindFlags)
 add_target_flags_if(LIBUNWIND_BUILD_32_BITS "-m32")
 
 if(LIBUNWIND_TARGET_TRIPLE)
-  add_target_flags("--target=${LIBUNWIND_TARGET_TRIPLE}")
+  add_target_flags_if_supported("--target=${LIBUNWIND_TARGET_TRIPLE}")
 elseif(CMAKE_CXX_COMPILER_TARGET)
   set(LIBUNWIND_TARGET_TRIPLE "${CMAKE_CXX_COMPILER_TARGET}")
 endif()
 if(LIBUNWIND_GCC_TOOLCHAIN)
-  add_target_flags("--gcc-toolchain=${LIBUNWIND_GCC_TOOLCHAIN}")
+  add_target_flags_if_supported("--gcc-toolchain=${LIBUNWIND_GCC_TOOLCHAIN}")
 elseif(CMAKE_CXX_COMPILER_EXTERNAL_TOOLCHAIN)
   set(LIBUNWIND_GCC_TOOLCHAIN "${CMAKE_CXX_COMPILER_EXTERNAL_TOOLCHAIN}")
 endif()
 if(LIBUNWIND_SYSROOT)
-  add_target_flags("--sysroot=${LIBUNWIND_SYSROOT}")
+  add_target_flags_if_supported("--sysroot=${LIBUNWIND_SYSROOT}")
 elseif(CMAKE_SYSROOT)
   set(LIBUNWIND_SYSROOT "${CMAKE_SYSROOT}")
 endif()

diff  --git a/libunwind/cmake/Modules/HandleLibunwindFlags.cmake b/libunwind/cmake/Modules/HandleLibunwindFlags.cmake
index 57ba0b8cf7cd9..675071f9433fe 100644
--- a/libunwind/cmake/Modules/HandleLibunwindFlags.cmake
+++ b/libunwind/cmake/Modules/HandleLibunwindFlags.cmake
@@ -124,6 +124,17 @@ macro(add_target_flags_if condition)
   endif()
 endmacro()
 
+# Add all the flags supported by the compiler to all of
+# 'CMAKE_CXX_FLAGS', 'CMAKE_C_FLAGS', 'LIBUNWIND_COMPILE_FLAGS'
+# and 'LIBUNWIND_LINK_FLAGS'.
+macro(add_target_flags_if_supported)
+  foreach(flag ${ARGN})
+    mangle_name("${flag}" flagname)
+    check_cxx_compiler_flag("${flag}" "LIBUNWIND_SUPPORTS_${flagname}_FLAG")
+    add_target_flags_if(LIBUNWIND_SUPPORTS_${flagname}_FLAG ${flag})
+  endforeach()
+endmacro()
+
 # Add a specified list of flags to both 'LIBUNWIND_COMPILE_FLAGS' and
 # 'LIBUNWIND_LINK_FLAGS'.
 macro(add_flags)


        


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