[compiler-rt][CMake] Fix configuration on PowerPC with sanitizers

[Hahnfeld]

Summary

TEST_BIG_ENDIAN() performs compile tests that will fail with
-nodefaultlibs when building under LLVM_USE_SANITIZER.

[alekseyshl]

I wonder what's the error message?

cmake/base-config-ix.cmake

153

cmake_push_check_state()

157

cmake_pop_check_state()

[Hahnfeld]

The error with -DLLVM_USE_SANITIZER=Address is

-- Check if the system is big endian
-- Searching 16 bit integer
-- Looking for stddef.h
-- Looking for stddef.h - not found
-- Check size of unsigned short
-- Check size of unsigned short - failed
-- Check size of unsigned int
-- Check size of unsigned int - failed
-- Check size of unsigned long
-- Check size of unsigned long - failed
CMake Error at <...>/cmake/share/cmake-3.5/Modules/TestBigEndian.cmake:51 (message):
  no suitable type found
Call Stack (most recent call first):
  projects/compiler-rt/cmake/base-config-ix.cmake:151 (TEST_BIG_ENDIAN)
  projects/compiler-rt/cmake/config-ix.cmake:138 (test_targets)
  projects/compiler-rt/CMakeLists.txt:99 (include)

The reason is that the compile tests are performed with -fsanitize=address -nodefaultlibs. This gives a lot of undefined references because the runtime dependencies aren't linked in.

[alekseyshl]

http://lab.llvm.org:8011/builders/sanitizer-ppc64be-linux/builds/4004 is broken by this change

[alekseyshl]

compiler-rt/trunk/cmake/base-config-ix.cmake

154 ↗

(On Diff #117132)

Oh, right, it should be:

string(REPLACE "-nodefaultlibs" "" CMAKE_REQUIRED_FLAGS ${CMAKE_REQUIRED_FLAGS})

[Hahnfeld]

compiler-rt/trunk/cmake/base-config-ix.cmake

154 ↗

(On Diff #117132)

Sorry! Thanks for fixing it so fast, my git-svn just told me that I'm out of sync!

cmake/base-config-ix.cmake

elseif("${COMPILER_RT_DEFAULT_TARGET_ARCH}" MATCHES "i[2-6]86|x86|amd64")
       else()
         if (CMAKE_SIZEOF_VOID_P EQUAL 4)
           test_target_arch(i386 "" "")
         else()
           test_target_arch(x86_64 "" "")
         endif()
       endif()
     elseif("${COMPILER_RT_DEFAULT_TARGET_ARCH}" MATCHES "powerpc")
+      # Strip out -nodefaultlibs when calling TEST_BIG_ENDIAN. Configuration
+      # will fail with this option when building with a sanitizer.
+      set(OLD_CMAKE_REQUIRED_FLAGS ${CMAKE_REQUIRED_FLAGS})
+      string(REPLACE "-nodefaultlibs" "" CMAKE_REQUIRED_FLAGS ${OLD_CMAKE_REQUIRED_FLAGS})
       TEST_BIG_ENDIAN(HOST_IS_BIG_ENDIAN)
+      # Undo the change.
+      set(CMAKE_REQUIRED_FLAGS "${OLD_CMAKE_REQUIRED_FLAGS}")
+
       if(HOST_IS_BIG_ENDIAN)
         test_target_arch(powerpc64 "" "-m64")
       else()
         test_target_arch(powerpc64le "" "-m64")
       endif()
     elseif("${COMPILER_RT_DEFAULT_TARGET_ARCH}" MATCHES "s390x")
       test_target_arch(s390x "" "")
     elseif("${COMPILER_RT_DEFAULT_TARGET_ARCH}" MATCHES "mipsel|mips64el")