[CMake] Drop libLTO and switch to PIE for Fuchsia toolchain

[phosek]

Summary

All our users have migrated to ld64.lld so we no longer need libLTO.

[abrachet]

Nice thats 71mb saved :)

clang/cmake/caches/Fuchsia-stage2.cmake

 # This file sets up a CMakeCache for the second stage of a Fuchsia toolchain build.
 
 set(LLVM_TARGETS_TO_BUILD X86;ARM;AArch64;RISCV CACHE STRING "")
 
 set(PACKAGE_VENDOR Fuchsia CACHE STRING "")
 
 set(LLVM_ENABLE_PROJECTS "bolt;clang;clang-tools-extra;lld;llvm;polly" CACHE STRING "")
 set(LLVM_ENABLE_RUNTIMES "compiler-rt;libcxx;libcxxabi;libunwind" CACHE STRING "")
 
 set(LLVM_ENABLE_BACKTRACES OFF CACHE BOOL "")
 set(LLVM_ENABLE_DIA_SDK OFF CACHE BOOL "")
 set(LLVM_ENABLE_LIBCXX ON CACHE BOOL "")
 set(LLVM_ENABLE_LIBEDIT OFF CACHE BOOL "")
 set(LLVM_ENABLE_LLD ON CACHE BOOL "")
 set(LLVM_ENABLE_LTO ON CACHE BOOL "")
 set(LLVM_ENABLE_PER_TARGET_RUNTIME_DIR ON CACHE BOOL "")
+set(LLVM_ENABLE_PIC OFF CACHE BOOL "")
 set(LLVM_ENABLE_PLUGINS OFF CACHE BOOL "")
 set(LLVM_ENABLE_TERMINFO OFF CACHE BOOL "")
 set(LLVM_ENABLE_UNWIND_TABLES OFF CACHE BOOL "")
 set(LLVM_ENABLE_Z3_SOLVER OFF CACHE BOOL "")
 set(LLVM_ENABLE_ZLIB ON CACHE BOOL "")
 set(LLVM_INCLUDE_DOCS OFF CACHE BOOL "")
 set(LLVM_INCLUDE_EXAMPLES OFF CACHE BOOL "")
 set(LLVM_STATIC_LINK_CXX_STDLIB ON CACHE BOOL "")

 endif()
 
 foreach(target aarch64-unknown-linux-gnu;armv7-unknown-linux-gnueabihf;i386-unknown-linux-gnu;x86_64-unknown-linux-gnu)
   if(LINUX_${target}_SYSROOT)
     # Set the per-target builtins options.
     list(APPEND BUILTIN_TARGETS "${target}")
     set(BUILTINS_${target}_CMAKE_SYSTEM_NAME Linux CACHE STRING "")
     set(BUILTINS_${target}_CMAKE_BUILD_TYPE RelWithDebInfo CACHE STRING "")
+    set(BUILTINS_${target}_CMAKE_POSITION_INDEPENDENT_CODE ON CACHE BOOL "")
     set(BUILTINS_${target}_CMAKE_C_FLAGS "--target=${target}" CACHE STRING "")
     set(BUILTINS_${target}_CMAKE_CXX_FLAGS "--target=${target}" CACHE STRING "")
     set(BUILTINS_${target}_CMAKE_ASM_FLAGS "--target=${target}" CACHE STRING "")
     set(BUILTINS_${target}_CMAKE_SYSROOT ${LINUX_${target}_SYSROOT} CACHE STRING "")
     set(BUILTINS_${target}_CMAKE_SHARED_LINKER_FLAGS "-fuse-ld=lld" CACHE STRING "")
     set(BUILTINS_${target}_CMAKE_MODULE_LINKER_FLAGS "-fuse-ld=lld" CACHE STRING "")
     set(BUILTINS_${target}_CMAKE_EXE_LINKER_FLAG "-fuse-ld=lld" CACHE STRING "")
 
     # Set the per-target runtimes options.
     list(APPEND RUNTIME_TARGETS "${target}")
     set(RUNTIMES_${target}_CMAKE_SYSTEM_NAME Linux CACHE STRING "")
     set(RUNTIMES_${target}_CMAKE_BUILD_TYPE RelWithDebInfo CACHE STRING "")
+    set(RUNTIMES_${target}_CMAKE_POSITION_INDEPENDENT_CODE ON CACHE BOOL "")
     set(RUNTIMES_${target}_CMAKE_C_FLAGS "--target=${target}" CACHE STRING "")
     set(RUNTIMES_${target}_CMAKE_CXX_FLAGS "--target=${target}" CACHE STRING "")
     set(RUNTIMES_${target}_CMAKE_ASM_FLAGS "--target=${target}" CACHE STRING "")
     set(RUNTIMES_${target}_CMAKE_SYSROOT ${LINUX_${target}_SYSROOT} CACHE STRING "")
     set(RUNTIMES_${target}_CMAKE_SHARED_LINKER_FLAGS "-fuse-ld=lld" CACHE STRING "")
     set(RUNTIMES_${target}_CMAKE_MODULE_LINKER_FLAGS "-fuse-ld=lld" CACHE STRING "")
     set(RUNTIMES_${target}_CMAKE_EXE_LINKER_FLAGS "-fuse-ld=lld" CACHE STRING "")
     set(RUNTIMES_${target}_COMPILER_RT_CXX_LIBRARY "libcxx" CACHE STRING "")
foreach(target i386-unknown-fuchsia;x86_64-unknown-fuchsia;aarch64-unknown-fuchsia;riscv64-unknown-fuchsia)
     set(FUCHSIA_${target}_SYSROOT "${FUCHSIA_SDK}/arch/${FUCHSIA_${target}_NAME}/sysroot")
   endforeach()
 
   foreach(target i386-unknown-fuchsia;x86_64-unknown-fuchsia;aarch64-unknown-fuchsia;riscv64-unknown-fuchsia)
     # Set the per-target builtins options.
     list(APPEND BUILTIN_TARGETS "${target}")
     set(BUILTINS_${target}_CMAKE_SYSTEM_NAME Fuchsia CACHE STRING "")
     set(BUILTINS_${target}_CMAKE_BUILD_TYPE RelWithDebInfo CACHE STRING "")
+    set(BUILTINS_${target}_CMAKE_POSITION_INDEPENDENT_CODE ON CACHE BOOL "")
     set(BUILTINS_${target}_CMAKE_ASM_FLAGS ${FUCHSIA_${target}_COMPILER_FLAGS} CACHE STRING "")
     set(BUILTINS_${target}_CMAKE_C_FLAGS ${FUCHSIA_${target}_COMPILER_FLAGS} CACHE STRING "")
     set(BUILTINS_${target}_CMAKE_CXX_FLAGS ${FUCHSIA_${target}_COMPILER_FLAGS} CACHE STRING "")
     set(BUILTINS_${target}_CMAKE_SHARED_LINKER_FLAGS ${FUCHSIA_${target}_LINKER_FLAGS} CACHE STRING "")
     set(BUILTINS_${target}_CMAKE_MODULE_LINKER_FLAGS ${FUCHSIA_${target}_LINKER_FLAGS} CACHE STRING "")
     set(BUILTINS_${target}_CMAKE_EXE_LINKER_FLAGS ${FUCHSIA_${target}_LINKER_FLAGS} CACHE STRING "")
     set(BUILTINS_${target}_CMAKE_SYSROOT ${FUCHSIA_${target}_SYSROOT} CACHE PATH "")
   endforeach()
 
   foreach(target x86_64-unknown-fuchsia;aarch64-unknown-fuchsia)
     # Set the per-target runtimes options.
     list(APPEND RUNTIME_TARGETS "${target}")
     set(RUNTIMES_${target}_CMAKE_SYSTEM_NAME Fuchsia CACHE STRING "")
     set(RUNTIMES_${target}_CMAKE_BUILD_TYPE RelWithDebInfo CACHE STRING "")
     set(RUNTIMES_${target}_CMAKE_BUILD_WITH_INSTALL_RPATH ON CACHE BOOL "")
+    set(RUNTIMES_${target}_CMAKE_POSITION_INDEPENDENT_CODE ON CACHE BOOL "")
     set(RUNTIMES_${target}_CMAKE_ASM_FLAGS ${FUCHSIA_${target}_COMPILER_FLAGS} CACHE STRING "")
     set(RUNTIMES_${target}_CMAKE_C_FLAGS ${FUCHSIA_${target}_COMPILER_FLAGS} CACHE STRING "")
     set(RUNTIMES_${target}_CMAKE_CXX_FLAGS ${FUCHSIA_${target}_COMPILER_FLAGS} CACHE STRING "")
     set(RUNTIMES_${target}_CMAKE_SHARED_LINKER_FLAGS ${FUCHSIA_${target}_LINKER_FLAGS} CACHE STRING "")
     set(RUNTIMES_${target}_CMAKE_MODULE_LINKER_FLAGS ${FUCHSIA_${target}_LINKER_FLAGS} CACHE STRING "")
     set(RUNTIMES_${target}_CMAKE_EXE_LINKER_FLAGS ${FUCHSIA_${target}_LINKER_FLAGS} CACHE STRING "")
     set(RUNTIMES_${target}_CMAKE_SYSROOT ${FUCHSIA_${target}_SYSROOT} CACHE PATH "")
     set(RUNTIMES_${target}_COMPILER_RT_CXX_LIBRARY "libcxx" CACHE STRING "")
set(LLVM_TOOLCHAIN_TOOLS
   llvm-xray
   sancov
   scan-build-py
   CACHE STRING "")
 
 set(LLVM_DISTRIBUTION_COMPONENTS
   clang
   lld
-  LTO
   clang-apply-replacements
   clang-doc
   clang-format
   clang-resource-headers
   clang-include-fixer
   clang-refactor
   clang-scan-deps
   clang-tidy
   clangd
   find-all-symbols
   builtins
   runtimes
   ${LLVM_TOOLCHAIN_TOOLS}
   CACHE STRING "")