[🍒6.2]: [compiler-rt] Fix detecting _Float16 support for secondary targets #10446
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…lvm#117813) It turns out we were not passing -m32 to the check_c_source_compiles() invocation since CMAKE_REQUIRE_FLAGS needs to be string separated list and we were passing a ;-separated CMake list which appears to be parsed by CMake as 'ignore all arguments beyond the first'. Fix this by transforming the list to a command line first. With this change, Clang 17 no longer claims to support _Float16 for i386. (cherry picked from commit a4c8ef0) (cherry picked from commit 8b57579)
) The try-compile mechanism requires that `CMAKE_REQUIRED_FLAGS` is a space-separated string instead of a list of flags. The original code expanded `BUILTIN_FLAGS` into `CMAKE_REQUIRED_FLAGS` as a space-separated string and then would overwrite `CMAKE_REQUIRED_FLAGS` with `TARGET_${arch}_CFLAGS` prepended to the unexpanded `BUILTIN_CFLAGS_${arch}`. This resulted in the first two arguments being passed into the try-compile invocation, but dropping the other arguments listed in `BUILTIN_CFLAGS_${arch}`. This patch appends `TARGET_${arch}_CFLAGS` and `BUILTIN_CFLAGS_${arch}` to `CMAKE_REQUIRED_FLAGS` before expanding CMAKE_REQUIRED_FLAGS as a space-separated string. This passes any pre-set required flags, in addition to all of the builtin and target flags to the Float16 detection. (cherry picked from commit 0d3f5ec) (cherry picked from commit e958952)
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@swift-ci please test |
edymtt
approved these changes
Apr 9, 2025
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@swiftlang/llvm-project-branch-managers, can I get a review on this please? Thanks. |
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Cherry-picked from: #10366
Which is a cherry-pick of: llvm#117813 and llvm#133952
This fixes the float16 detection when building compiler-rt, which is required for building on FreeBSD.
This change fixes how arguments are passed into the try-compile used to determine whether the platform that compiler-rt is being built for has Float16 capabilities. This ensures that all of the required flags are actually passed into the try-compile instead of only passing the first.
This impacts how compiler-rt detects whether the platform has support for Float16 and BFloat16.
This affects how the build system detects Float16 support when compiling for the specified platform. If this is wrong, compiler-rt fails to compile.
LLVM Testing. Local verification that compiler-rt builds.
Verified that the compiler-rt build as part of the Swift build reports that the Float16/BFloat16 type check fails for arm64, arm64e, x86_64h, x86_64, and i386, as it does prior to this change. Given that the configuration is the same, this has no impact on the Apple builds.