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[Fuchsia][cmake] Allow using FatLTO when building runtimes #112277

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Merged
merged 16 commits into from
Dec 9, 2024
Merged

[Fuchsia][cmake] Allow using FatLTO when building runtimes #112277

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1dafa52
[𝘀𝗽𝗿] initial version
ilovepi Oct 14, 2024
350d75e
Rebase on main
ilovepi Oct 14, 2024
38851d2
Remove newline from diff
ilovepi Oct 14, 2024
3990524
Rebase on main
ilovepi Oct 14, 2024
535f2f2
Avoid unecessary changes to libc++ cmake
ilovepi Oct 16, 2024
2ad6038
[𝘀𝗽𝗿] changes introduced through rebase
ilovepi Nov 12, 2024
49ce824
rebase and enable FatLTO for Fuchsia targets
ilovepi Nov 12, 2024
9511215
[𝘀𝗽𝗿] changes introduced through rebase
ilovepi Nov 14, 2024
1b3c34f
Rebase
ilovepi Nov 14, 2024
86c376e
[𝘀𝗽𝗿] changes introduced through rebase
ilovepi Nov 14, 2024
13973d0
Move --as-needed into the correct patch
ilovepi Nov 14, 2024
4b7b3f9
[𝘀𝗽𝗿] changes introduced through rebase
ilovepi Nov 18, 2024
b5551cc
update base revision
ilovepi Nov 18, 2024
e0d6cbf
[𝘀𝗽𝗿] changes introduced through rebase
ilovepi Dec 9, 2024
52c567e
Rebase on main
ilovepi Dec 9, 2024
8118e04
Rebase
ilovepi Dec 9, 2024
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16 changes: 16 additions & 0 deletions clang/cmake/caches/Fuchsia-stage2.cmake
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Original file line number Diff line number Diff line change
Expand Up @@ -192,6 +192,10 @@ foreach(target aarch64-unknown-linux-gnu;armv7-unknown-linux-gnueabihf;i386-unkn
set(RUNTIMES_${target}_LLVM_TOOLS_DIR "${CMAKE_BINARY_DIR}/bin" CACHE BOOL "")
set(RUNTIMES_${target}_LLVM_ENABLE_RUNTIMES "compiler-rt;libcxx;libcxxabi;libunwind" CACHE STRING "")

# Enable FatLTO for Linux and baremetal runtimes
set(RUNTIMES_${target}_LLVM_ENABLE_LTO ON CACHE BOOL "")
set(RUNTIMES_${target}_LLVM_ENABLE_FATLTO ON CACHE BOOL "")

# Use .build-id link.
list(APPEND RUNTIME_BUILD_ID_LINK "${target}")
endif()
Expand Down Expand Up @@ -274,6 +278,10 @@ if(FUCHSIA_SDK)
set(RUNTIMES_${target}+asan+noexcept_LIBCXXABI_ENABLE_EXCEPTIONS OFF CACHE BOOL "")
set(RUNTIMES_${target}+asan+noexcept_LIBCXX_ENABLE_EXCEPTIONS OFF CACHE BOOL "")

# Enable FatLTO for Fuchsia runtimes
set(RUNTIMES_${target}_LLVM_ENABLE_LTO ON CACHE BOOL "")
set(RUNTIMES_${target}_LLVM_ENABLE_FATLTO ON CACHE BOOL "")

# Use .build-id link.
list(APPEND RUNTIME_BUILD_ID_LINK "${target}")
endforeach()
Expand Down Expand Up @@ -360,6 +368,10 @@ foreach(target armv6m-none-eabi;armv7m-none-eabi;armv8m.main-none-eabi)
set(RUNTIMES_${target}_LLVM_INCLUDE_TESTS OFF CACHE BOOL "")
set(RUNTIMES_${target}_LLVM_ENABLE_ASSERTIONS OFF CACHE BOOL "")
set(RUNTIMES_${target}_LLVM_ENABLE_RUNTIMES "libc;libcxx" CACHE STRING "")

# Enable FatLTO for baremetal runtimes
set(RUNTIMES_${target}_LLVM_ENABLE_LTO ON CACHE BOOL "")
set(RUNTIMES_${target}_LLVM_ENABLE_FATLTO ON CACHE BOOL "")
endforeach()

foreach(target riscv32-unknown-elf)
Expand Down Expand Up @@ -412,6 +424,10 @@ foreach(target riscv32-unknown-elf)
set(RUNTIMES_${target}_LLVM_INCLUDE_TESTS OFF CACHE BOOL "")
set(RUNTIMES_${target}_LLVM_ENABLE_ASSERTIONS OFF CACHE BOOL "")
set(RUNTIMES_${target}_LLVM_ENABLE_RUNTIMES "libc;libcxx" CACHE STRING "")

# Enable FatLTO for baremetal runtimes
set(RUNTIMES_${target}_LLVM_ENABLE_LTO ON CACHE BOOL "")
set(RUNTIMES_${target}_LLVM_ENABLE_FATLTO ON CACHE BOOL "")
endforeach()

set(LLVM_BUILTIN_TARGETS "${BUILTIN_TARGETS}" CACHE STRING "")
Expand Down
6 changes: 6 additions & 0 deletions libcxxabi/src/CMakeLists.txt
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Expand Up @@ -75,6 +75,12 @@ if (NOT APPLE) # On Apple platforms, we always use -nostdlib++ so we don't need
add_library_flags_if(LIBCXXABI_HAS_C_LIB c)
endif()

if (FUCHSIA)
# TODO use CMAKE_LINK_LIBRARY_USING_FEATURE once our minimum CMake is at least 3.24
# https://cmake.org/cmake/help/latest/variable/CMAKE_LINK_LIBRARY_USING_FEATURE.html
add_link_flags("-Wl,--push-state,--as-needed,-lzircon,--pop-state")
endif()

if (NOT LIBCXXABI_USE_COMPILER_RT)
add_library_flags_if(LIBCXXABI_HAS_GCC_LIB gcc)
endif()
Expand Down
2 changes: 1 addition & 1 deletion llvm/cmake/modules/HandleLLVMOptions.cmake
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Original file line number Diff line number Diff line change
Expand Up @@ -1285,7 +1285,7 @@ elseif(LLVM_ENABLE_LTO)
endif()
endif()

if(LLVM_ENABLE_FATLTO AND UNIX AND NOT APPLE)
if(LLVM_ENABLE_FATLTO AND ((UNIX AND NOT APPLE) OR FUCHSIA))
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@ldionne ldionne Nov 28, 2024

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I don't understand why that diff is required since you're setting it properly in your cache files.

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@ilovepi ilovepi Dec 2, 2024

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Because Fuchsia Targets aren't UNIX. Without this change -ffat-lto-objects won't be passed to clang through CMake. The additional logic is basically to restrict the flag to ELF targets, and it missed Fuchsia when we added it, since we weren't building our runtimes with FatLTO initially, just the toolchain + tests.

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@ldionne ldionne Dec 9, 2024

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Sorry, I think I initially read if (LLVM_ENABLE_FATLTO OR ((UNIX AND NOT APPLE) OR FUCHSIA)).

append("-ffat-lto-objects" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
if(NOT LINKER_IS_LLD_LINK)
append("-ffat-lto-objects" CMAKE_EXE_LINKER_FLAGS CMAKE_SHARED_LINKER_FLAGS CMAKE_MODULE_LINKER_FLAGS)
Expand Down