2016-11-26 15:03:34 +08:00
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/*
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* llvm C frontend for perf. Support dynamically compile C file
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*
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* Inspired by clang example code:
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* http://llvm.org/svn/llvm-project/cfe/trunk/examples/clang-interpreter/main.cpp
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*
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* Copyright (C) 2016 Wang Nan <wangnan0@huawei.com>
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* Copyright (C) 2016 Huawei Inc.
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*/
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#include "clang/CodeGen/CodeGenAction.h"
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#include "clang/Frontend/CompilerInvocation.h"
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#include "clang/Frontend/CompilerInstance.h"
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#include "clang/Frontend/TextDiagnosticPrinter.h"
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#include "clang/Tooling/Tooling.h"
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2016-11-26 15:03:38 +08:00
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#include "llvm/IR/LegacyPassManager.h"
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2016-11-26 15:03:34 +08:00
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#include "llvm/IR/Module.h"
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#include "llvm/Option/Option.h"
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2016-11-26 15:03:35 +08:00
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#include "llvm/Support/FileSystem.h"
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2016-11-26 15:03:34 +08:00
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#include "llvm/Support/ManagedStatic.h"
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2016-11-26 15:03:38 +08:00
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#include "llvm/Support/TargetRegistry.h"
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#include "llvm/Support/TargetSelect.h"
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#include "llvm/Target/TargetMachine.h"
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#include "llvm/Target/TargetOptions.h"
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2016-11-26 15:03:34 +08:00
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#include <memory>
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#include "clang.h"
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#include "clang-c.h"
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namespace perf {
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static std::unique_ptr<llvm::LLVMContext> LLVMCtx;
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using namespace clang;
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static CompilerInvocation *
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createCompilerInvocation(llvm::opt::ArgStringList CFlags, StringRef& Path,
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DiagnosticsEngine& Diags)
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2016-11-26 15:03:34 +08:00
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{
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llvm::opt::ArgStringList CCArgs {
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"-cc1",
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"-triple", "bpf-pc-linux",
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"-fsyntax-only",
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"-ferror-limit", "19",
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"-fmessage-length", "127",
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"-O2",
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"-nostdsysteminc",
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"-nobuiltininc",
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"-vectorize-loops",
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"-vectorize-slp",
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"-Wno-unused-value",
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"-Wno-pointer-sign",
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"-x", "c"};
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CCArgs.append(CFlags.begin(), CFlags.end());
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2016-11-26 15:03:34 +08:00
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CompilerInvocation *CI = tooling::newInvocation(&Diags, CCArgs);
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FrontendOptions& Opts = CI->getFrontendOpts();
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Opts.Inputs.clear();
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Opts.Inputs.emplace_back(Path, IK_C);
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return CI;
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}
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static std::unique_ptr<llvm::Module>
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getModuleFromSource(llvm::opt::ArgStringList CFlags,
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StringRef Path, IntrusiveRefCntPtr<vfs::FileSystem> VFS)
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{
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CompilerInstance Clang;
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Clang.createDiagnostics();
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Clang.setVirtualFileSystem(&*VFS);
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IntrusiveRefCntPtr<CompilerInvocation> CI =
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createCompilerInvocation(std::move(CFlags), Path,
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Clang.getDiagnostics());
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Clang.setInvocation(&*CI);
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std::unique_ptr<CodeGenAction> Act(new EmitLLVMOnlyAction(&*LLVMCtx));
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if (!Clang.ExecuteAction(*Act))
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return std::unique_ptr<llvm::Module>(nullptr);
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return Act->takeModule();
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}
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std::unique_ptr<llvm::Module>
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getModuleFromSource(llvm::opt::ArgStringList CFlags,
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StringRef Name, StringRef Content)
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{
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using namespace vfs;
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llvm::IntrusiveRefCntPtr<OverlayFileSystem> OverlayFS(
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new OverlayFileSystem(getRealFileSystem()));
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llvm::IntrusiveRefCntPtr<InMemoryFileSystem> MemFS(
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new InMemoryFileSystem(true));
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/*
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* pushOverlay helps setting working dir for MemFS. Must call
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* before addFile.
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*/
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OverlayFS->pushOverlay(MemFS);
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MemFS->addFile(Twine(Name), 0, llvm::MemoryBuffer::getMemBuffer(Content));
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return getModuleFromSource(std::move(CFlags), Name, OverlayFS);
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}
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std::unique_ptr<llvm::Module>
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getModuleFromSource(llvm::opt::ArgStringList CFlags, StringRef Path)
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{
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IntrusiveRefCntPtr<vfs::FileSystem> VFS(vfs::getRealFileSystem());
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return getModuleFromSource(std::move(CFlags), Path, VFS);
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2016-11-26 15:03:35 +08:00
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}
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2016-11-26 15:03:38 +08:00
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std::unique_ptr<llvm::SmallVectorImpl<char>>
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getBPFObjectFromModule(llvm::Module *Module)
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{
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using namespace llvm;
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std::string TargetTriple("bpf-pc-linux");
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std::string Error;
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const Target* Target = TargetRegistry::lookupTarget(TargetTriple, Error);
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if (!Target) {
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llvm::errs() << Error;
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return std::unique_ptr<llvm::SmallVectorImpl<char>>(nullptr);
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}
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llvm::TargetOptions Opt;
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TargetMachine *TargetMachine =
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Target->createTargetMachine(TargetTriple,
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"generic", "",
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Opt, Reloc::Static);
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Module->setDataLayout(TargetMachine->createDataLayout());
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Module->setTargetTriple(TargetTriple);
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std::unique_ptr<SmallVectorImpl<char>> Buffer(new SmallVector<char, 0>());
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raw_svector_ostream ostream(*Buffer);
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legacy::PassManager PM;
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if (TargetMachine->addPassesToEmitFile(PM, ostream,
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TargetMachine::CGFT_ObjectFile)) {
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llvm::errs() << "TargetMachine can't emit a file of this type\n";
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return std::unique_ptr<llvm::SmallVectorImpl<char>>(nullptr);;
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}
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PM.run(*Module);
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return std::move(Buffer);
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}
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2016-11-26 15:03:34 +08:00
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}
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extern "C" {
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void perf_clang__init(void)
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{
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perf::LLVMCtx.reset(new llvm::LLVMContext());
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LLVMInitializeBPFTargetInfo();
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LLVMInitializeBPFTarget();
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LLVMInitializeBPFTargetMC();
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LLVMInitializeBPFAsmPrinter();
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}
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void perf_clang__cleanup(void)
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{
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perf::LLVMCtx.reset(nullptr);
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llvm::llvm_shutdown();
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}
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2016-11-26 15:03:39 +08:00
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int perf_clang__compile_bpf(const char *filename,
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void **p_obj_buf,
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size_t *p_obj_buf_sz)
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{
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using namespace perf;
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if (!p_obj_buf || !p_obj_buf_sz)
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return -EINVAL;
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llvm::opt::ArgStringList CFlags;
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auto M = getModuleFromSource(std::move(CFlags), filename);
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if (!M)
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return -EINVAL;
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auto O = getBPFObjectFromModule(&*M);
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if (!O)
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return -EINVAL;
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size_t size = O->size_in_bytes();
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void *buffer;
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buffer = malloc(size);
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if (!buffer)
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return -ENOMEM;
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memcpy(buffer, O->data(), size);
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*p_obj_buf = buffer;
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*p_obj_buf_sz = size;
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return 0;
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}
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2016-11-26 15:03:34 +08:00
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}
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