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[libclc] Support LLVM_ENABLE_RUNTIMES when building #141574

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Merged
merged 2 commits into from
Jun 5, 2025
Merged

[libclc] Support LLVM_ENABLE_RUNTIMES when building #141574

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2889aa6
[libclc] Support LLVM_ENABLE_RUNTIMES when building
frasercrmck May 27, 2025
22e11c9
move libclc earlier in runtimes order
frasercrmck May 28, 2025
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2 changes: 1 addition & 1 deletion libclc/CMakeLists.txt
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Expand Up @@ -72,7 +72,7 @@ else()
# Note that we check this later (for both build types) but we can provide a
# more useful error message when built in-tree. We assume that LLVM tools are
# always available so don't warn here.
if( NOT clang IN_LIST LLVM_ENABLE_PROJECTS )
if( NOT LLVM_RUNTIMES_BUILD AND NOT clang IN_LIST LLVM_ENABLE_PROJECTS )
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I'd quite like to keep this check/error if possible. The error you get if you forget -LLVM_ENABLE_PROJECTS=clang is horrible. Do you think it would it acceptable to pass through LLVM_ENABLE_PROJECTS to the runtimes build, @jhuber6?

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The runtimes builds pass this USE_TOOLCHAIN argument which tells the external project utility to grab the clang from the build directory. If we don't have clang it might be more reasonable to just emit a warning there. @petrhosek Is there a reason we don't already emit a warning / error if the user does a runtimes build without clang to bootstrap?

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Thanks. Yes I suppose in the absence of a higher-level warning like you describe, we could probably use USE_TOOLCHAIN to accomplish the same thing in a runtimes build.

With any luck this is all temporary, and a runtimes build will allow us to just take the cmake c compiler.

message(FATAL_ERROR "Clang is not enabled, but is required to build libclc in-tree")
endif()

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9 changes: 8 additions & 1 deletion llvm/CMakeLists.txt
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Expand Up @@ -141,7 +141,7 @@ endforeach()
# As we migrate runtimes to using the bootstrapping build, the set of default runtimes
# should grow as we remove those runtimes from LLVM_ENABLE_PROJECTS above.
set(LLVM_DEFAULT_RUNTIMES "libcxx;libcxxabi;libunwind")
set(LLVM_SUPPORTED_RUNTIMES "libc;libunwind;libcxxabi;pstl;libcxx;compiler-rt;openmp;llvm-libgcc;offload;flang-rt")
set(LLVM_SUPPORTED_RUNTIMES "libc;libunwind;libcxxabi;pstl;libcxx;compiler-rt;openmp;llvm-libgcc;offload;flang-rt;libclc")
set(LLVM_ENABLE_RUNTIMES "" CACHE STRING
"Semicolon-separated list of runtimes to build, or \"all\" (${LLVM_DEFAULT_RUNTIMES}). Supported runtimes are ${LLVM_SUPPORTED_RUNTIMES}.")
if(LLVM_ENABLE_RUNTIMES STREQUAL "all")
Expand Down Expand Up @@ -204,6 +204,13 @@ if ("flang-rt" IN_LIST LLVM_ENABLE_RUNTIMES)
endif ()
endif ()

if ("libclc" IN_LIST LLVM_ENABLE_PROJECTS)
message(WARNING "Using LLVM_ENABLE_PROJECTS=libclc is deprecated now, and will "
"become a fatal error in the LLVM 21 release. Please use "
"-DLLVM_ENABLE_RUNTIMES=libclc or see the instructions at "
"https://libclc.llvm.org/ for building the runtimes.")
endif()

# Set a shorthand option to enable the GPU build of the 'libc' project.
option(LIBC_GPU_BUILD "Enable the 'libc' project targeting the GPU" OFF)
if(LIBC_GPU_BUILD)
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2 changes: 1 addition & 1 deletion llvm/runtimes/CMakeLists.txt
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Expand Up @@ -193,7 +193,7 @@ endif()

function(_get_runtime_name name out_var)
string(FIND ${name} "lib" idx)
if(idx EQUAL 0 AND NOT ${name} STREQUAL "libc")
if(idx EQUAL 0 AND NOT (${name} STREQUAL "libc" OR ${name} STREQUAL "libclc"))
string(SUBSTRING ${name} 3 -1 name)
endif()
set(${out_var} ${name} PARENT_SCOPE)
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2 changes: 1 addition & 1 deletion runtimes/CMakeLists.txt
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Expand Up @@ -35,7 +35,7 @@ list(INSERT CMAKE_MODULE_PATH 0

# We order libraries to mirror roughly how they are layered, except that compiler-rt can depend
# on libc++, so we put it after.
set(LLVM_DEFAULT_RUNTIMES "libc;libunwind;libcxxabi;pstl;libcxx;compiler-rt;openmp;offload")
set(LLVM_DEFAULT_RUNTIMES "libc;libunwind;libcxxabi;pstl;libcxx;compiler-rt;libclc;openmp;offload")
set(LLVM_SUPPORTED_RUNTIMES "${LLVM_DEFAULT_RUNTIMES};llvm-libgcc;flang-rt")
set(LLVM_ENABLE_RUNTIMES "" CACHE STRING
"Semicolon-separated list of runtimes to build, or \"all\" (${LLVM_DEFAULT_RUNTIMES}). Supported runtimes are ${LLVM_SUPPORTED_RUNTIMES}.")
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