[builtins] Enable building of the builtins library for MIPS targets.

[vkalintiris]

Ping.

[samsonov]

LGTM

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

elseif("${COMPILER_RT_DEFAULT_TARGET_ARCH}" MATCHES "powerpc")
     endif()
   elseif("${COMPILER_RT_DEFAULT_TARGET_ARCH}" MATCHES "mipsel|mips64el")
     # Gcc doesn't accept -m32/-m64 so we do the next best thing and use
     # -mips32r2/-mips64r2. We don't use -mips1/-mips3 because we want to match
     # clang's default CPU's. In the 64-bit case, we must also specify the ABI
     # since the default ABI differs between gcc and clang.
     # FIXME: Ideally, we would build the N32 library too.
     test_target_arch(mipsel "" "-mips32r2" "--target=mipsel-linux-gnu")
-    test_target_arch(mips64el "" "-mips64r2" "-mabi=n64")
+    test_target_arch(mips64el "" "-mips64r2" "--target=mips64el-linux-gnu" "-mabi=n64")
   elseif("${COMPILER_RT_DEFAULT_TARGET_ARCH}" MATCHES "mips")
     test_target_arch(mips "" "-mips32r2" "--target=mips-linux-gnu")
-    test_target_arch(mips64 "" "-mips64r2" "-mabi=n64")
+    test_target_arch(mips64 "" "-mips64r2" "--target=mips64-linux-gnu" "-mabi=n64")
   elseif("${COMPILER_RT_DEFAULT_TARGET_ARCH}" MATCHES "arm")
     test_target_arch(arm "" "-march=armv7-a" "-mfloat-abi=soft")
     test_target_arch(armhf "" "-march=armv7-a" "-mfloat-abi=hard")
   elseif("${COMPILER_RT_DEFAULT_TARGET_ARCH}" MATCHES "aarch32")
     test_target_arch(aarch32 "" "-march=armv8-a")
   elseif("${COMPILER_RT_DEFAULT_TARGET_ARCH}" MATCHES "aarch64")
     test_target_arch(aarch64 "" "-march=armv8-a")
   endif()

 set(PPC64 powerpc64 powerpc64le)
 
 if(APPLE)
   set(ARM64 arm64)
   set(ARM32 armv7 armv7s)
   set(X86_64 x86_64 x86_64h)
 endif()
 
-set(ALL_BUILTIN_SUPPORTED_ARCH ${X86} ${X86_64} ${ARM32} ${ARM64})
+set(ALL_BUILTIN_SUPPORTED_ARCH ${X86} ${X86_64} ${ARM32} ${ARM64}
+    ${MIPS32} ${MIPS64})
 set(ALL_SANITIZER_COMMON_SUPPORTED_ARCH ${X86} ${X86_64} ${PPC64}
     ${ARM32} ${ARM64} ${MIPS32} ${MIPS64})
 set(ALL_ASAN_SUPPORTED_ARCH ${X86} ${X86_64} ${ARM32} ${ARM64}
     ${MIPS32} ${MIPS64} ${PPC64})
 set(ALL_DFSAN_SUPPORTED_ARCH ${X86_64} ${MIPS64} ${ARM64})
 set(ALL_LSAN_SUPPORTED_ARCH ${X86_64} ${MIPS64} ${ARM64})
 set(ALL_MSAN_SUPPORTED_ARCH ${X86_64} ${MIPS64} ${ARM64})
 set(ALL_PROFILE_SUPPORTED_ARCH ${X86} ${X86_64} ${ARM32} ${ARM64} ${PPC64}

compiler-rt/trunk/lib/builtins/CMakeLists.txt

 set(armv7s_SOURCES ${arm_SOURCES})
 set(arm64_SOURCES ${aarch64_SOURCES})
 
 # macho_embedded archs
 set(armv6m_SOURCES ${GENERIC_SOURCES})
 set(armv7m_SOURCES ${arm_SOURCES})
 set(armv7em_SOURCES ${arm_SOURCES})
 
+set(mips_SOURCES ${GENERIC_SOURCES})
+set(mipsel_SOURCES ${mips_SOURCES})
+set(mips64_SOURCES ${mips_SOURCES})
+set(mips64el_SOURCES ${mips_SOURCES})
+
 add_custom_target(builtins)
 
 if (APPLE)
   add_subdirectory(Darwin-excludes)
   add_subdirectory(macho_embedded)
   darwin_add_builtin_libraries(${BUILTIN_SUPPORTED_OS})
 elseif (NOT WIN32 OR MINGW)
   foreach (arch ${BUILTIN_SUPPORTED_ARCH})