1 files changed, 212 insertions, 0 deletions
diff --git a/tools/perf/util/c++/clang.cpp b/tools/perf/util/c++/clang.cpp
new file mode 100644
index 000000000..895125045
--- /dev/null
+++ b/tools/perf/util/c++/clang.cpp
@@ -0,0 +1,212 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * llvm C frontend for perf. Support dynamically compile C file
+ *
+ * Inspired by clang example code:
+ * http://llvm.org/svn/llvm-project/cfe/trunk/examples/clang-interpreter/main.cpp
+ *
+ * Copyright (C) 2016 Wang Nan <wangnan0@huawei.com>
+ * Copyright (C) 2016 Huawei Inc.
+ */
+
+#include "clang/Basic/Version.h"
+#include "clang/CodeGen/CodeGenAction.h"
+#include "clang/Frontend/CompilerInvocation.h"
+#include "clang/Frontend/CompilerInstance.h"
+#include "clang/Frontend/TextDiagnosticPrinter.h"
+#include "clang/Tooling/Tooling.h"
+#include "llvm/IR/LegacyPassManager.h"
+#include "llvm/IR/Module.h"
+#include "llvm/Option/Option.h"
+#include "llvm/Support/FileSystem.h"
+#include "llvm/Support/ManagedStatic.h"
+#include "llvm/Support/TargetRegistry.h"
+#include "llvm/Support/TargetSelect.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetOptions.h"
+#include <memory>
+
+#include "clang.h"
+#include "clang-c.h"
+
+namespace perf {
+
+static std::unique_ptr<llvm::LLVMContext> LLVMCtx;
+
+using namespace clang;
+
+static CompilerInvocation *
+createCompilerInvocation(llvm::opt::ArgStringList CFlags, StringRef& Path,
+			 DiagnosticsEngine& Diags)
+{
+	llvm::opt::ArgStringList CCArgs {
+		"-cc1",
+		"-triple", "bpf-pc-linux",
+		"-fsyntax-only",
+		"-ferror-limit", "19",
+		"-fmessage-length", "127",
+		"-O2",
+		"-nostdsysteminc",
+		"-nobuiltininc",
+		"-vectorize-loops",
+		"-vectorize-slp",
+		"-Wno-unused-value",
+		"-Wno-pointer-sign",
+		"-x", "c"};
+
+	CCArgs.append(CFlags.begin(), CFlags.end());
+	CompilerInvocation *CI = tooling::newInvocation(&Diags, CCArgs);
+
+	FrontendOptions& Opts = CI->getFrontendOpts();
+	Opts.Inputs.clear();
+	Opts.Inputs.emplace_back(Path,
+			FrontendOptions::getInputKindForExtension("c"));
+	return CI;
+}
+
+static std::unique_ptr<llvm::Module>
+getModuleFromSource(llvm::opt::ArgStringList CFlags,
+		    StringRef Path, IntrusiveRefCntPtr<vfs::FileSystem> VFS)
+{
+	CompilerInstance Clang;
+	Clang.createDiagnostics();
+
+	Clang.setVirtualFileSystem(&*VFS);
+
+#if CLANG_VERSION_MAJOR < 4
+	IntrusiveRefCntPtr<CompilerInvocation> CI =
+		createCompilerInvocation(std::move(CFlags), Path,
+					 Clang.getDiagnostics());
+	Clang.setInvocation(&*CI);
+#else
+	std::shared_ptr<CompilerInvocation> CI(
+		createCompilerInvocation(std::move(CFlags), Path,
+					 Clang.getDiagnostics()));
+	Clang.setInvocation(CI);
+#endif
+
+	std::unique_ptr<CodeGenAction> Act(new EmitLLVMOnlyAction(&*LLVMCtx));
+	if (!Clang.ExecuteAction(*Act))
+		return std::unique_ptr<llvm::Module>(nullptr);
+
+	return Act->takeModule();
+}
+
+std::unique_ptr<llvm::Module>
+getModuleFromSource(llvm::opt::ArgStringList CFlags,
+		    StringRef Name, StringRef Content)
+{
+	using namespace vfs;
+
+	llvm::IntrusiveRefCntPtr<OverlayFileSystem> OverlayFS(
+			new OverlayFileSystem(getRealFileSystem()));
+	llvm::IntrusiveRefCntPtr<InMemoryFileSystem> MemFS(
+			new InMemoryFileSystem(true));
+
+	/*
+	 * pushOverlay helps setting working dir for MemFS. Must call
+	 * before addFile.
+	 */
+	OverlayFS->pushOverlay(MemFS);
+	MemFS->addFile(Twine(Name), 0, llvm::MemoryBuffer::getMemBuffer(Content));
+
+	return getModuleFromSource(std::move(CFlags), Name, OverlayFS);
+}
+
+std::unique_ptr<llvm::Module>
+getModuleFromSource(llvm::opt::ArgStringList CFlags, StringRef Path)
+{
+	IntrusiveRefCntPtr<vfs::FileSystem> VFS(vfs::getRealFileSystem());
+	return getModuleFromSource(std::move(CFlags), Path, VFS);
+}
+
+std::unique_ptr<llvm::SmallVectorImpl<char>>
+getBPFObjectFromModule(llvm::Module *Module)
+{
+	using namespace llvm;
+
+	std::string TargetTriple("bpf-pc-linux");
+	std::string Error;
+	const Target* Target = TargetRegistry::lookupTarget(TargetTriple, Error);
+	if (!Target) {
+		llvm::errs() << Error;
+		return std::unique_ptr<llvm::SmallVectorImpl<char>>(nullptr);
+	}
+
+	llvm::TargetOptions Opt;
+	TargetMachine *TargetMachine =
+		Target->createTargetMachine(TargetTriple,
+					    "generic", "",
+					    Opt, Reloc::Static);
+
+	Module->setDataLayout(TargetMachine->createDataLayout());
+	Module->setTargetTriple(TargetTriple);
+
+	std::unique_ptr<SmallVectorImpl<char>> Buffer(new SmallVector<char, 0>());
+	raw_svector_ostream ostream(*Buffer);
+
+	legacy::PassManager PM;
+	bool NotAdded;
+#if CLANG_VERSION_MAJOR < 7
+	NotAdded = TargetMachine->addPassesToEmitFile(PM, ostream,
+						      TargetMachine::CGFT_ObjectFile);
+#else
+	NotAdded = TargetMachine->addPassesToEmitFile(PM, ostream, nullptr,
+						      TargetMachine::CGFT_ObjectFile);
+#endif
+	if (NotAdded) {
+		llvm::errs() << "TargetMachine can't emit a file of this type\n";
+		return std::unique_ptr<llvm::SmallVectorImpl<char>>(nullptr);;
+	}
+	PM.run(*Module);
+
+	return std::move(Buffer);
+}
+
+}
+
+extern "C" {
+void perf_clang__init(void)
+{
+	perf::LLVMCtx.reset(new llvm::LLVMContext());
+	LLVMInitializeBPFTargetInfo();
+	LLVMInitializeBPFTarget();
+	LLVMInitializeBPFTargetMC();
+	LLVMInitializeBPFAsmPrinter();
+}
+
+void perf_clang__cleanup(void)
+{
+	perf::LLVMCtx.reset(nullptr);
+	llvm::llvm_shutdown();
+}
+
+int perf_clang__compile_bpf(const char *filename,
+			    void **p_obj_buf,
+			    size_t *p_obj_buf_sz)
+{
+	using namespace perf;
+
+	if (!p_obj_buf || !p_obj_buf_sz)
+		return -EINVAL;
+
+	llvm::opt::ArgStringList CFlags;
+	auto M = getModuleFromSource(std::move(CFlags), filename);
+	if (!M)
+		return  -EINVAL;
+	auto O = getBPFObjectFromModule(&*M);
+	if (!O)
+		return -EINVAL;
+
+	size_t size = O->size_in_bytes();
+	void *buffer;
+
+	buffer = malloc(size);
+	if (!buffer)
+		return -ENOMEM;
+	memcpy(buffer, O->data(), size);
+	*p_obj_buf = buffer;
+	*p_obj_buf_sz = size;
+	return 0;
+}
+}