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[clang] Add the ability to link libclc OpenCL libraries #146503

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Merged
merged 8 commits into from
Aug 4, 2025
Merged

[clang] Add the ability to link libclc OpenCL libraries #146503

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a511265
[libclc] Place libclc files in clang's resource dir
frasercrmck Jun 30, 2025
2e38758
[clang] Add the ability to link libclc OpenCL libraries
frasercrmck Jul 1, 2025
dc2a825
adjust LIBRARY_PATH usage in tests
frasercrmck Jul 1, 2025
30b4c4f
fix path checks
frasercrmck Jul 1, 2025
314818f
consume_front
frasercrmck Jul 7, 2025
c70cfaf
remove logic for LIBRARY_PATH
frasercrmck Jul 7, 2025
ff537a9
fix diagnostic; add error test
frasercrmck Jul 7, 2025
a6df4ee
only when not offloading
frasercrmck Aug 4, 2025
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2 changes: 2 additions & 0 deletions clang/include/clang/Basic/DiagnosticDriverKinds.td
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Expand Up @@ -394,6 +394,8 @@ def warn_drv_fraw_string_literals_in_cxx11 : Warning<
"ignoring '-f%select{no-|}0raw-string-literals', which is only valid for C and C++ standards before C++11">,
InGroup<UnusedCommandLineArgument>;

def err_drv_libclc_not_found : Error<"no libclc library '%0' found in the clang resource directory">;

def err_drv_invalid_malign_branch_EQ : Error<
"invalid argument '%0' to -malign-branch=; each element must be one of: %1">;

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3 changes: 3 additions & 0 deletions clang/include/clang/Driver/CommonArgs.h
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Expand Up @@ -215,6 +215,9 @@ void addOpenMPDeviceRTL(const Driver &D, const llvm::opt::ArgList &DriverArgs,
StringRef BitcodeSuffix, const llvm::Triple &Triple,
const ToolChain &HostTC);

void addOpenCLBuiltinsLib(const Driver &D, const llvm::opt::ArgList &DriverArgs,
llvm::opt::ArgStringList &CC1Args);

void addOutlineAtomicsArgs(const Driver &D, const ToolChain &TC,
const llvm::opt::ArgList &Args,
llvm::opt::ArgStringList &CmdArgs,
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15 changes: 15 additions & 0 deletions clang/include/clang/Driver/Options.td
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Expand Up @@ -1422,6 +1422,21 @@ def fno_hip_emit_relocatable : Flag<["-"], "fno-hip-emit-relocatable">,
HelpText<"Do not override toolchain to compile HIP source to relocatable">;
}

// Clang specific/exclusive options for OpenACC.
def openacc_macro_override
: Separate<["-"], "fexperimental-openacc-macro-override">,
Visibility<[ClangOption, CC1Option]>,
Group<f_Group>,
HelpText<"Overrides the _OPENACC macro value for experimental testing "
"during OpenACC support development">;
def openacc_macro_override_EQ
: Joined<["-"], "fexperimental-openacc-macro-override=">,
Alias<openacc_macro_override>;

// End Clang specific/exclusive options for OpenACC.

def libclc_lib_EQ : Joined<["--"], "libclc-lib=">, Group<opencl_Group>,
HelpText<"Namespec of libclc OpenCL bitcode library to link">;
def libomptarget_amdgpu_bc_path_EQ : Joined<["--"], "libomptarget-amdgpu-bc-path=">, Group<i_Group>,
HelpText<"Path to libomptarget-amdgcn bitcode library">;
def libomptarget_amdgcn_bc_path_EQ : Joined<["--"], "libomptarget-amdgcn-bc-path=">, Group<i_Group>,
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3 changes: 3 additions & 0 deletions clang/lib/Driver/ToolChains/AMDGPU.cpp
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Expand Up @@ -857,6 +857,9 @@ void AMDGPUToolChain::addClangTargetOptions(
CC1Args.push_back("-fvisibility=hidden");
CC1Args.push_back("-fapply-global-visibility-to-externs");
}

if (DeviceOffloadingKind == Action::OFK_None)
addOpenCLBuiltinsLib(getDriver(), DriverArgs, CC1Args);
}

void AMDGPUToolChain::addClangWarningOptions(ArgStringList &CC1Args) const {
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37 changes: 37 additions & 0 deletions clang/lib/Driver/ToolChains/CommonArgs.cpp
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Expand Up @@ -2985,6 +2985,43 @@ void tools::addHIPRuntimeLibArgs(const ToolChain &TC, Compilation &C,
}
}

void tools::addOpenCLBuiltinsLib(const Driver &D,
const llvm::opt::ArgList &DriverArgs,
llvm::opt::ArgStringList &CC1Args) {
// Check whether user specifies a libclc bytecode library
const Arg *A = DriverArgs.getLastArg(options::OPT_libclc_lib_EQ);
if (!A)
return;

// Find device libraries in <LLVM_DIR>/lib/clang/<ver>/lib/libclc/
SmallString<128> LibclcPath(D.ResourceDir);
llvm::sys::path::append(LibclcPath, "lib", "libclc");

// If the namespec is of the form :filename, search for that file.
StringRef LibclcNamespec(A->getValue());
bool FilenameSearch = LibclcNamespec.consume_front(":");
SmallString<128> LibclcTargetFile(LibclcNamespec);

if (FilenameSearch && llvm::sys::fs::exists(LibclcTargetFile)) {
CC1Args.push_back("-mlink-builtin-bitcode");
CC1Args.push_back(DriverArgs.MakeArgString(LibclcTargetFile));
} else {
// Search the library paths for the file
if (!FilenameSearch)
LibclcTargetFile += ".bc";

llvm::sys::path::append(LibclcPath, LibclcTargetFile);
if (llvm::sys::fs::exists(LibclcPath)) {
CC1Args.push_back("-mlink-builtin-bitcode");
CC1Args.push_back(DriverArgs.MakeArgString(LibclcPath));
} else {
// Since the user requested a library, if we haven't one then report an
// error.
D.Diag(diag::err_drv_libclc_not_found) << LibclcTargetFile;
}
}
}

void tools::addOutlineAtomicsArgs(const Driver &D, const ToolChain &TC,
const llvm::opt::ArgList &Args,
llvm::opt::ArgStringList &CmdArgs,
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Empty file added clang/test/Driver/Inputs/libclc/libclc.bc
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Empty file added clang/test/Driver/Inputs/libclc/subdir/libclc.bc
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9 changes: 9 additions & 0 deletions clang/test/Driver/opencl-libclc.cl
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@@ -0,0 +1,9 @@
// RUN: %clang -### -target amdgcn-amd-amdhsa --no-offloadlib --libclc-lib=:%S/Inputs/libclc/libclc.bc %s 2>&1 | FileCheck %s
// RUN: %clang -### -target amdgcn-amd-amdhsa --no-offloadlib --libclc-lib=:%S/Inputs/libclc/subdir/libclc.bc %s 2>&1 | FileCheck %s --check-prefix CHECK-SUBDIR

// RUN: not %clang -### -target amdgcn-amd-amdhsa --no-offloadlib --libclc-lib=:%S/Inputs/libclc/subdir/not-here.bc %s 2>&1 | FileCheck %s --check-prefix CHECK-ERROR

// CHECK: -mlink-builtin-bitcode{{.*}}Inputs{{/|\\\\}}libclc{{/|\\\\}}libclc.bc
// CHECK-SUBDIR: -mlink-builtin-bitcode{{.*}}Inputs{{/|\\\\}}libclc{{/|\\\\}}subdir{{/|\\\\}}libclc.bc

// CHECK-ERROR: no libclc library{{.*}}not-here.bc' found in the clang resource directory
13 changes: 10 additions & 3 deletions libclc/CMakeLists.txt
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Expand Up @@ -73,6 +73,9 @@ if( LIBCLC_STANDALONE_BUILD OR CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DI
set( ${tool}_target )
endforeach()
endif()

# Setup the paths where libclc runtimes should be stored.
set( LIBCLC_OUTPUT_LIBRARY_DIR ${CMAKE_CURRENT_BINARY_DIR} )
else()
# In-tree configuration
set( LIBCLC_STANDALONE_BUILD FALSE )
Expand All @@ -92,10 +95,14 @@ else()
get_host_tool_path( llvm-link LLVM_LINK llvm-link_exe llvm-link_target )
get_host_tool_path( opt OPT opt_exe opt_target )
endif()
endif()

# Setup the paths where libclc runtimes should be stored.
set( LIBCLC_OUTPUT_LIBRARY_DIR ${CMAKE_CURRENT_BINARY_DIR} )
# Setup the paths where libclc runtimes should be stored. By default, in an
# in-tree build we place the libraries in clang's resource driectory.
get_clang_resource_dir( LIBCLC_OUTPUT_DIR PREFIX ${LLVM_LIBRARY_OUTPUT_INTDIR}/.. )

# Note we do not adhere to LLVM_ENABLE_PER_TARGET_RUNTIME_DIR.
set( LIBCLC_OUTPUT_LIBRARY_DIR ${LIBCLC_OUTPUT_DIR}/lib/libclc )
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@wenju-he wenju-he Aug 8, 2025 •
edited
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When configuring on windows using cmake msvc generator

cmake -G "Visual Studio 17 2022" -A x64 -Thost=x64 -DLLVM_ENABLE_PROJECTS="llvm;clang;clang-tools-extra;libclc" -DLLVM_INCLUDE_TESTS=OFF -DLLVM_BUILD_TESTS=OFF -DLLVM_ENABLE_ASSERTIONS=ON -DLLVM_TARGETS_TO_BUILD="X86;AMDGPU" -DCMAKE_INSTALL_PREFIX=install -DCMAKE_BUILD_TYPE=Release -DLIBCLC_TARGETS_TO_BUILD="amdgcn--amdhsa" ../llvm

install command in tools\libclc\cmake_install.cmake is not correctly configured as there is a unresolved $(Configuration):

if(CMAKE_INSTALL_COMPONENT STREQUAL "Unspecified" OR NOT CMAKE_INSTALL_COMPONENT)
  file(INSTALL DESTINATION "${CMAKE_INSTALL_PREFIX}/share/clc" TYPE FILE FILES "D:/wenjuhe/llvm-project/build/$(Configuration)/lib/../lib/clang/22/lib/libclc/amdgcn--amdhsa.bc")
endif()

It causes install error in our downstream project and the error is reproducible in llvm-project:

cmake --build . --config Release --target install -j40

  CMake Error at tools/libclc/cmake_install.cmake:45 (file):
    file INSTALL cannot find
    "D:/wenjuhe/llvm-project/build/$(Configuration)/lib/../lib/clang/22/lib/libclc/amdgcn--amdhsa.bc":
    File exists.

@frasercrmck do you have suggestion about why $(Configuration) is unresolved?
cmake jinja generator doesn't seem to have the issue because I can build llvm-project and install with ninja.

If I enable libclc in LLVM_ENABLE_RUNTIMES, there is another build error:

cmake -G "Visual Studio 17 2022" -A x64 -Thost=x64 -DLLVM_ENABLE_PROJECTS="llvm;clang;clang-tools-extra" -DLLVM_ENABLE_RUNTIMES=libclc -DLLVM_INCLUDE_TESTS=OFF -DLLVM_BUILD_TESTS=OFF -DLLVM_ENABLE_ASSERTIONS=ON -DLLVM_TARGETS_TO_BUILD="X86;AMDGPU" -DCMAKE_INSTALL_PREFIX=install -DCMAKE_BUILD_TYPE=Release -DLIBCLC_TARGETS_TO_BUILD="amdgcn--amdhsa" ../llvm

Unknown CMake command "get_clang_resource_dir".

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@wenju-he wenju-he Aug 8, 2025

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will be fixed by #152703

endif()

if( EXISTS ${LIBCLC_CUSTOM_LLVM_TOOLS_BINARY_DIR} )
message( WARNING "Using custom LLVM tools to build libclc: "
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