[llvm] [lldb] [lld] [libc] [clang] [libcxx] [flang] [CMAKE] Enable FatLTO as a build option for LLVM (PR #80480)

[Petr Hosek via llvm-commits]

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@@ -1251,6 +1253,10 @@ elseif(LLVM_ENABLE_LTO)
   endif()
 endif()
 
+if(LLVM_ENABLE_FATLTO AND (FUCHSIA OR UNIX))
+    append("-ffat-lto-objects" CMAKE_EXE_LINKER_FLAGS CMAKE_SHARED_LINKER_FLAGS)
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petrhosek wrote:

I think you also need to append this flag to `CMAKE_C_FLAGS` and `CMAKE_CXX_FLAGS` just like we do for `-flto` above.

https://github.com/llvm/llvm-project/pull/80480