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[Clang][OpenMP][NVPTX] Replace libomptarget-nvptx-path with `libomp…
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…target-nvptx-bc-path`

D94700 removed the static library so we no longer need to pass
`-llibomptarget-nvptx` to `nvlink`. Since the bitcode library is the only device
runtime for now, instead of emitting a warning when it is not found, an error
should be raised. We also set a new option `libomptarget-nvptx-bc-path` to let
user choose which bitcode library is being used.

Reviewed By: JonChesterfield

Differential Revision: https://reviews.llvm.org/D95161
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@shiltian
shiltian committed Jan 23, 2021
1 parent e4847a7 commit 5ad038a
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Showing 6 changed files with 52 additions and 51 deletions.
4 changes: 2 additions & 2 deletions clang/docs/ClangCommandLineReference.rst
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Expand Up @@ -1143,9 +1143,9 @@ Set directory to include search path with prefix

Add directory to SYSTEM include search path, absolute paths are relative to -isysroot

.. option:: --libomptarget-nvptx-path=<arg>
.. option:: --libomptarget-nvptx-bc-path=<arg>

Path to libomptarget-nvptx libraries
Path to libomptarget-nvptx bitcode library

.. option:: --ptxas-path=<arg>

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6 changes: 3 additions & 3 deletions clang/include/clang/Basic/DiagnosticDriverKinds.td
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Expand Up @@ -263,12 +263,12 @@ def err_drv_omp_host_target_not_supported : Error<
"The target '%0' is not a supported OpenMP host target.">;
def err_drv_expecting_fopenmp_with_fopenmp_targets : Error<
"The option -fopenmp-targets must be used in conjunction with a -fopenmp option compatible with offloading, please use -fopenmp=libomp or -fopenmp=libiomp5.">;
def err_drv_omp_offload_target_missingbcruntime : Error<
"No library '%0' found in the default clang lib directory or in LIBRARY_PATH. Please use --libomptarget-nvptx-bc-path to specify nvptx bitcode library.">;
def err_drv_omp_offload_target_bcruntime_not_found : Error<"Bitcode library '%0' does not exist.">;
def warn_drv_omp_offload_target_duplicate : Warning<
"The OpenMP offloading target '%0' is similar to target '%1' already specified - will be ignored.">,
InGroup<OpenMPTarget>;
def warn_drv_omp_offload_target_missingbcruntime : Warning<
"No library '%0' found in the default clang lib directory or in LIBRARY_PATH. Expect degraded performance due to no inlining of runtime functions on target devices.">,
InGroup<OpenMPTarget>;
def err_drv_unsupported_embed_bitcode
: Error<"%0 is not supported with -fembed-bitcode">;
def err_drv_bitcode_unsupported_on_toolchain : Error<
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4 changes: 2 additions & 2 deletions clang/include/clang/Driver/Options.td
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Expand Up @@ -992,8 +992,8 @@ def gpu_max_threads_per_block_EQ : Joined<["--"], "gpu-max-threads-per-block=">,
def gpu_instrument_lib_EQ : Joined<["--"], "gpu-instrument-lib=">,
HelpText<"Instrument device library for HIP, which is a LLVM bitcode containing "
"__cyg_profile_func_enter and __cyg_profile_func_exit">;
def libomptarget_nvptx_path_EQ : Joined<["--"], "libomptarget-nvptx-path=">, Group<i_Group>,
HelpText<"Path to libomptarget-nvptx libraries">;
def libomptarget_nvptx_bc_path_EQ : Joined<["--"], "libomptarget-nvptx-bc-path=">, Group<i_Group>,
HelpText<"Path to libomptarget-nvptx bitcode library">;
def dD : Flag<["-"], "dD">, Group<d_Group>, Flags<[CC1Option]>,
HelpText<"Print macro definitions in -E mode in addition to normal output">;
def dI : Flag<["-"], "dI">, Group<d_Group>, Flags<[CC1Option]>,
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52 changes: 28 additions & 24 deletions clang/lib/Driver/ToolChains/Cuda.cpp
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Expand Up @@ -600,11 +600,6 @@ void NVPTX::OpenMPLinker::ConstructJob(Compilation &C, const JobAction &JA,
CmdArgs.push_back("-arch");
CmdArgs.push_back(Args.MakeArgString(GPUArch));

// Assume that the directory specified with --libomptarget_nvptx_path
// contains the static library libomptarget-nvptx.a.
if (const Arg *A = Args.getLastArg(options::OPT_libomptarget_nvptx_path_EQ))
CmdArgs.push_back(Args.MakeArgString(Twine("-L") + A->getValue()));

// Add paths specified in LIBRARY_PATH environment variable as -L options.
addDirectoryList(Args, CmdArgs, "-L", "LIBRARY_PATH");

Expand All @@ -614,9 +609,6 @@ void NVPTX::OpenMPLinker::ConstructJob(Compilation &C, const JobAction &JA,
llvm::sys::path::append(DefaultLibPath, "lib" CLANG_LIBDIR_SUFFIX);
CmdArgs.push_back(Args.MakeArgString(Twine("-L") + DefaultLibPath));

// Add linking against library implementing OpenMP calls on NVPTX target.
CmdArgs.push_back("-lomptarget-nvptx");

for (const auto &II : Inputs) {
if (II.getType() == types::TY_LLVM_IR ||
II.getType() == types::TY_LTO_IR ||
Expand Down Expand Up @@ -761,9 +753,6 @@ void CudaToolChain::addClangTargetOptions(

if (DeviceOffloadingKind == Action::OFK_OpenMP) {
SmallVector<StringRef, 8> LibraryPaths;
if (const Arg *A = DriverArgs.getLastArg(options::OPT_libomptarget_nvptx_path_EQ))
LibraryPaths.push_back(A->getValue());

// Add user defined library paths from LIBRARY_PATH.
llvm::Optional<std::string> LibPath =
llvm::sys::Process::GetEnv("LIBRARY_PATH");
Expand All @@ -781,22 +770,37 @@ void CudaToolChain::addClangTargetOptions(
llvm::sys::path::append(DefaultLibPath, Twine("lib") + CLANG_LIBDIR_SUFFIX);
LibraryPaths.emplace_back(DefaultLibPath.c_str());

std::string LibOmpTargetName =
"libomptarget-nvptx-" + GpuArch.str() + ".bc";
bool FoundBCLibrary = false;
for (StringRef LibraryPath : LibraryPaths) {
SmallString<128> LibOmpTargetFile(LibraryPath);
llvm::sys::path::append(LibOmpTargetFile, LibOmpTargetName);
if (llvm::sys::fs::exists(LibOmpTargetFile)) {
// First check whether user specifies bc library
if (const Arg *A =
DriverArgs.getLastArg(options::OPT_libomptarget_nvptx_bc_path_EQ)) {
std::string LibOmpTargetName(A->getValue());
if (llvm::sys::fs::exists(LibOmpTargetName)) {
CC1Args.push_back("-mlink-builtin-bitcode");
CC1Args.push_back(DriverArgs.MakeArgString(LibOmpTargetFile));
FoundBCLibrary = true;
break;
CC1Args.push_back(DriverArgs.MakeArgString(LibOmpTargetName));
} else {
getDriver().Diag(diag::err_drv_omp_offload_target_bcruntime_not_found)
<< LibOmpTargetName;
}
} else {
bool FoundBCLibrary = false;

std::string LibOmpTargetName =
"libomptarget-nvptx-" + GpuArch.str() + ".bc";

for (StringRef LibraryPath : LibraryPaths) {
SmallString<128> LibOmpTargetFile(LibraryPath);
llvm::sys::path::append(LibOmpTargetFile, LibOmpTargetName);
if (llvm::sys::fs::exists(LibOmpTargetFile)) {
CC1Args.push_back("-mlink-builtin-bitcode");
CC1Args.push_back(DriverArgs.MakeArgString(LibOmpTargetFile));
FoundBCLibrary = true;
break;
}
}
if (!FoundBCLibrary)
getDriver().Diag(diag::err_drv_omp_offload_target_missingbcruntime)
<< LibOmpTargetName;
}
if (!FoundBCLibrary)
getDriver().Diag(diag::warn_drv_omp_offload_target_missingbcruntime)
<< LibOmpTargetName;
}
}

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Empty file added clang/test/Driver/Inputs/libomptarget/libomptarget-nvptx-test.bc
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Empty file.
37 changes: 17 additions & 20 deletions clang/test/Driver/openmp-offload-gpu.c
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Expand Up @@ -34,22 +34,6 @@

/// ###########################################################################

/// Check that -lomptarget-nvptx is passed to nvlink.
// RUN: %clang -### -no-canonical-prefixes -fopenmp=libomp \
// RUN: -fopenmp-targets=nvptx64-nvidia-cuda %s 2>&1 \
// RUN: | FileCheck -check-prefix=CHK-NVLINK %s
/// Check that the value of --libomptarget-nvptx-path is forwarded to nvlink.
// RUN: %clang -### -no-canonical-prefixes -fopenmp=libomp \
// RUN: --libomptarget-nvptx-path=/path/to/libomptarget/ \
// RUN: -fopenmp-targets=nvptx64-nvidia-cuda %s 2>&1 \
// RUN: | FileCheck -check-prefixes=CHK-NVLINK,CHK-LIBOMPTARGET-NVPTX-PATH %s

// CHK-NVLINK: nvlink
// CHK-LIBOMPTARGET-NVPTX-PATH-SAME: "-L/path/to/libomptarget/"
// CHK-NVLINK-SAME: "-lomptarget-nvptx"

/// ###########################################################################

/// Check cubin file generation and usage by nvlink
// RUN: %clang -### -no-canonical-prefixes -target powerpc64le-unknown-linux-gnu -fopenmp=libomp \
// RUN: -fopenmp-targets=nvptx64-nvidia-cuda -save-temps %s 2>&1 \
Expand Down Expand Up @@ -173,13 +157,15 @@
// RUN: -Xopenmp-target -march=sm_20 --cuda-path=%S/Inputs/CUDA_80/usr/local/cuda \
// RUN: -fopenmp-relocatable-target -save-temps -no-canonical-prefixes %s 2>&1 \
// RUN: | FileCheck -check-prefix=CHK-BCLIB %s
/// The user can override default detection using --libomptarget-nvptx-path=.
// RUN: %clang -### -fopenmp=libomp -fopenmp-targets=nvptx64-nvidia-cuda --libomptarget-nvptx-path=%S/Inputs/libomptarget \
/// The user can override default detection using --libomptarget-nvptx-bc-path=.
// RUN: %clang -### -fopenmp=libomp -fopenmp-targets=nvptx64-nvidia-cuda \
// RUN: --libomptarget-nvptx-bc-path=%S/Inputs/libomptarget/libomptarget-nvptx-test.bc \
// RUN: -Xopenmp-target -march=sm_20 --cuda-path=%S/Inputs/CUDA_80/usr/local/cuda \
// RUN: -fopenmp-relocatable-target -save-temps -no-canonical-prefixes %s 2>&1 \
// RUN: | FileCheck -check-prefix=CHK-BCLIB %s
// RUN: | FileCheck -check-prefix=CHK-BCLIB-USER %s

// CHK-BCLIB: clang{{.*}}-triple{{.*}}nvptx64-nvidia-cuda{{.*}}-mlink-builtin-bitcode{{.*}}libomptarget-nvptx-sm_20.bc
// CHK-BCLIB-USER: clang{{.*}}-triple{{.*}}nvptx64-nvidia-cuda{{.*}}-mlink-builtin-bitcode{{.*}}libomptarget-nvptx-test.bc
// CHK-BCLIB-NOT: {{error:|warning:}}

/// ###########################################################################
Expand All @@ -191,7 +177,18 @@
// RUN: -fopenmp-relocatable-target -save-temps -no-canonical-prefixes %s 2>&1 \
// RUN: | FileCheck -check-prefix=CHK-BCLIB-WARN %s

// CHK-BCLIB-WARN: No library 'libomptarget-nvptx-sm_20.bc' found in the default clang lib directory or in LIBRARY_PATH. Expect degraded performance due to no inlining of runtime functions on target devices.
// CHK-BCLIB-WARN: No library 'libomptarget-nvptx-sm_20.bc' found in the default clang lib directory or in LIBRARY_PATH. Please use --libomptarget-nvptx-bc-path to specify nvptx bitcode library.

/// ###########################################################################

/// Check that the error is thrown when the libomptarget bitcode library does not exist.
// RUN: %clang -### -fopenmp=libomp -fopenmp-targets=nvptx64-nvidia-cuda \
// RUN: -Xopenmp-target -march=sm_20 --cuda-path=%S/Inputs/CUDA_80/usr/local/cuda \
// RUN: --libomptarget-nvptx-bc-path=not-exist.bc \
// RUN: -fopenmp-relocatable-target -save-temps -no-canonical-prefixes %s 2>&1 \
// RUN: | FileCheck -check-prefix=CHK-BCLIB-ERROR %s

// CHK-BCLIB-ERROR: Bitcode library 'not-exist.bc' does not exist.

/// Check that debug info is emitted in dwarf-2
// RUN: %clang -### -no-canonical-prefixes -fopenmp=libomp -fopenmp-targets=nvptx64-nvidia-cuda -Xopenmp-target -march=sm_60 %s -g -O1 --no-cuda-noopt-device-debug 2>&1 \
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