[OpenMP] OpenMP device offloading code generation produces a cubin file which is then integrated in the host binary using the host linker.
Diff: D29654
llvm-svn: 310362
diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index aea36cd..1273b7a 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -1025,3 +1025,128 @@
break;
}
}
+
+/// Add OpenMP linker script arguments at the end of the argument list so that
+/// the fat binary is built by embedding each of the device images into the
+/// host. The linker script also defines a few symbols required by the code
+/// generation so that the images can be easily retrieved at runtime by the
+/// offloading library. This should be used only in tool chains that support
+/// linker scripts.
+void tools::AddOpenMPLinkerScript(const ToolChain &TC, Compilation &C,
+ const InputInfo &Output,
+ const InputInfoList &Inputs,
+ const ArgList &Args, ArgStringList &CmdArgs,
+ const JobAction &JA) {
+
+ // If this is not an OpenMP host toolchain, we don't need to do anything.
+ if (!JA.isHostOffloading(Action::OFK_OpenMP))
+ return;
+
+ // Create temporary linker script. Keep it if save-temps is enabled.
+ const char *LKS;
+ SmallString<256> Name = llvm::sys::path::filename(Output.getFilename());
+ if (C.getDriver().isSaveTempsEnabled()) {
+ llvm::sys::path::replace_extension(Name, "lk");
+ LKS = C.getArgs().MakeArgString(Name.c_str());
+ } else {
+ llvm::sys::path::replace_extension(Name, "");
+ Name = C.getDriver().GetTemporaryPath(Name, "lk");
+ LKS = C.addTempFile(C.getArgs().MakeArgString(Name.c_str()));
+ }
+
+ // Add linker script option to the command.
+ CmdArgs.push_back("-T");
+ CmdArgs.push_back(LKS);
+
+ // Create a buffer to write the contents of the linker script.
+ std::string LksBuffer;
+ llvm::raw_string_ostream LksStream(LksBuffer);
+
+ // Get the OpenMP offload tool chains so that we can extract the triple
+ // associated with each device input.
+ auto OpenMPToolChains = C.getOffloadToolChains<Action::OFK_OpenMP>();
+ assert(OpenMPToolChains.first != OpenMPToolChains.second &&
+ "No OpenMP toolchains??");
+
+ // Track the input file name and device triple in order to build the script,
+ // inserting binaries in the designated sections.
+ SmallVector<std::pair<std::string, const char *>, 8> InputBinaryInfo;
+
+ // Add commands to embed target binaries. We ensure that each section and
+ // image is 16-byte aligned. This is not mandatory, but increases the
+ // likelihood of data to be aligned with a cache block in several main host
+ // machines.
+ LksStream << "/*\n";
+ LksStream << " OpenMP Offload Linker Script\n";
+ LksStream << " *** Automatically generated by Clang ***\n";
+ LksStream << "*/\n";
+ LksStream << "TARGET(binary)\n";
+ auto DTC = OpenMPToolChains.first;
+ for (auto &II : Inputs) {
+ const Action *A = II.getAction();
+ // Is this a device linking action?
+ if (A && isa<LinkJobAction>(A) &&
+ A->isDeviceOffloading(Action::OFK_OpenMP)) {
+ assert(DTC != OpenMPToolChains.second &&
+ "More device inputs than device toolchains??");
+ InputBinaryInfo.push_back(std::make_pair(
+ DTC->second->getTriple().normalize(), II.getFilename()));
+ ++DTC;
+ LksStream << "INPUT(" << II.getFilename() << ")\n";
+ }
+ }
+
+ assert(DTC == OpenMPToolChains.second &&
+ "Less device inputs than device toolchains??");
+
+ LksStream << "SECTIONS\n";
+ LksStream << "{\n";
+
+ // Put each target binary into a separate section.
+ for (const auto &BI : InputBinaryInfo) {
+ LksStream << " .omp_offloading." << BI.first << " :\n";
+ LksStream << " ALIGN(0x10)\n";
+ LksStream << " {\n";
+ LksStream << " PROVIDE_HIDDEN(.omp_offloading.img_start." << BI.first
+ << " = .);\n";
+ LksStream << " " << BI.second << "\n";
+ LksStream << " PROVIDE_HIDDEN(.omp_offloading.img_end." << BI.first
+ << " = .);\n";
+ LksStream << " }\n";
+ }
+
+ // Add commands to define host entries begin and end. We use 1-byte subalign
+ // so that the linker does not add any padding and the elements in this
+ // section form an array.
+ LksStream << " .omp_offloading.entries :\n";
+ LksStream << " ALIGN(0x10)\n";
+ LksStream << " SUBALIGN(0x01)\n";
+ LksStream << " {\n";
+ LksStream << " PROVIDE_HIDDEN(.omp_offloading.entries_begin = .);\n";
+ LksStream << " *(.omp_offloading.entries)\n";
+ LksStream << " PROVIDE_HIDDEN(.omp_offloading.entries_end = .);\n";
+ LksStream << " }\n";
+ LksStream << "}\n";
+ LksStream << "INSERT BEFORE .data\n";
+ LksStream.flush();
+
+ // Dump the contents of the linker script if the user requested that. We
+ // support this option to enable testing of behavior with -###.
+ if (C.getArgs().hasArg(options::OPT_fopenmp_dump_offload_linker_script))
+ llvm::errs() << LksBuffer;
+
+ // If this is a dry run, do not create the linker script file.
+ if (C.getArgs().hasArg(options::OPT__HASH_HASH_HASH))
+ return;
+
+ // Open script file and write the contents.
+ std::error_code EC;
+ llvm::raw_fd_ostream Lksf(LKS, EC, llvm::sys::fs::F_None);
+
+ if (EC) {
+ C.getDriver().Diag(clang::diag::err_unable_to_make_temp) << EC.message();
+ return;
+ }
+
+ Lksf << LksBuffer;
+}