Switch to gold linker on android x86, x86_64, arm

[tberghammer]

Summary

Switch to gold linker on android x86, x86_64, arm

These architectures already using the gold linker for the android framework and switching to gold gives us the opportunity to enable ICF.
Safe ICF (identical code folding) reduces the size of an optimized and striped binary by ~5%

[labath]

looks good

[ovyalov]

LGTM

cmake/platforms/Android.cmake

124 ↗

(On Diff #42295)

Just out of curiosity - you haven't included arm64, it's not supported by gold?

[tberghammer]

cmake/platforms/Android.cmake

124 ↗

(On Diff #42295)

There were some issues when we tried to change the android framework over to using gold on arm64 so we went back to the default linker util it can get fixed. Most likely it wouldn't affect lldb-server but better to be safe.

lldb/trunk/cmake/platforms/Android.cmake

if( index EQUAL -1 )
   set( LLDB_SYSTEM_LIBS ${LLDB_SYSTEM_LIBS} CACHE INTERNAL "" FORCE )
  endif()
  if( LLVM_BUILD_STATIC )
   # Temporary workaround for static linking with the latest API.
   set( ANDROID_CXX_FLAGS "${ANDROID_CXX_FLAGS} -DANDROID_MIPS_BUILD_STATIC" )
  endif()
 endif()
 
+# Use gold linker and enable safe ICF in case of x86, x86_64 and arm
+if ( ANDROID_ABI STREQUAL "x86"    OR
+     ANDROID_ABI STREQUAL "x86_64" OR
+     ANDROID_ABI STREQUAL "armeabi")
+ set( ANDROID_LINKER_FLAGS "${ANDROID_LINKER_FLAGS} -fuse-ld=gold -Wl,--icf=safe" )
+endif()
+
 if( NOT LLVM_BUILD_STATIC )
  # PIE is required for API 21+ so we enable it if we're not statically linking
  # unfortunately, it is not supported before API 16 so we need to do something
  # else there see http://llvm.org/pr23457
  set( ANDROID_CXX_FLAGS "${ANDROID_CXX_FLAGS} -pie -fPIE" )
 endif()
 
 # linker flags