tools/perf/util/c++/clang.cpp

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * llvm C frontend for perf. Support dynamically compile C file
   4  *
   5  * Inspired by clang example code:
   6  * http://llvm.org/svn/llvm-project/cfe/trunk/examples/clang-interpreter/main.cpp
   7  *
   8  * Copyright (C) 2016 Wang Nan <wangnan0@huawei.com>
   9  * Copyright (C) 2016 Huawei Inc.
  10  */
  11
  12 #include "clang/Basic/Version.h"
  13 #include "clang/CodeGen/CodeGenAction.h"
  14 #include "clang/Frontend/CompilerInvocation.h"
  15 #include "clang/Frontend/CompilerInstance.h"
  16 #include "clang/Frontend/TextDiagnosticPrinter.h"
  17 #include "clang/Tooling/Tooling.h"
  18 #include "llvm/IR/LegacyPassManager.h"
  19 #include "llvm/IR/Module.h"
  20 #include "llvm/Option/Option.h"
  21 #include "llvm/Support/FileSystem.h"
  22 #include "llvm/Support/ManagedStatic.h"
  23 #include "llvm/Support/TargetRegistry.h"
  24 #include "llvm/Support/TargetSelect.h"
  25 #include "llvm/Target/TargetMachine.h"
  26 #include "llvm/Target/TargetOptions.h"
  27 #include <memory>
  28
  29 #include "clang.h"
  30 #include "clang-c.h"
  31
  32 namespace perf {
  33
  34 static std::unique_ptr<llvm::LLVMContext> LLVMCtx;
  35
  36 using namespace clang;
  37
  38 static CompilerInvocation *
  39 createCompilerInvocation(llvm::opt::ArgStringList CFlags, StringRef& Path,
  40                          DiagnosticsEngine& Diags)
  41 {
  42         llvm::opt::ArgStringList CCArgs {
  43                 "-cc1",
  44                 "-triple", "bpf-pc-linux",
  45                 "-fsyntax-only",
  46                 "-ferror-limit", "19",
  47                 "-fmessage-length", "127",
  48                 "-O2",
  49                 "-nostdsysteminc",
  50                 "-nobuiltininc",
  51                 "-vectorize-loops",
  52                 "-vectorize-slp",
  53                 "-Wno-unused-value",
  54                 "-Wno-pointer-sign",
  55                 "-x", "c"};
  56
  57         CCArgs.append(CFlags.begin(), CFlags.end());
  58         CompilerInvocation *CI = tooling::newInvocation(&Diags, CCArgs);
  59
  60         FrontendOptions& Opts = CI->getFrontendOpts();
  61         Opts.Inputs.clear();
  62         Opts.Inputs.emplace_back(Path,
  63                         FrontendOptions::getInputKindForExtension("c"));
  64         return CI;
  65 }
  66
  67 static std::unique_ptr<llvm::Module>
  68 getModuleFromSource(llvm::opt::ArgStringList CFlags,
  69                     StringRef Path, IntrusiveRefCntPtr<vfs::FileSystem> VFS)
  70 {
  71         CompilerInstance Clang;
  72         Clang.createDiagnostics();
  73
  74         Clang.setVirtualFileSystem(&*VFS);
  75
  76 #if CLANG_VERSION_MAJOR < 4
  77         IntrusiveRefCntPtr<CompilerInvocation> CI =
  78                 createCompilerInvocation(std::move(CFlags), Path,
  79                                          Clang.getDiagnostics());
  80         Clang.setInvocation(&*CI);
  81 #else
  82         std::shared_ptr<CompilerInvocation> CI(
  83                 createCompilerInvocation(std::move(CFlags), Path,
  84                                          Clang.getDiagnostics()));
  85         Clang.setInvocation(CI);
  86 #endif
  87
  88         std::unique_ptr<CodeGenAction> Act(new EmitLLVMOnlyAction(&*LLVMCtx));
  89         if (!Clang.ExecuteAction(*Act))
  90                 return std::unique_ptr<llvm::Module>(nullptr);
  91
  92         return Act->takeModule();
  93 }
  94
  95 std::unique_ptr<llvm::Module>
  96 getModuleFromSource(llvm::opt::ArgStringList CFlags,
  97                     StringRef Name, StringRef Content)
  98 {
  99         using namespace vfs;
 100
 101         llvm::IntrusiveRefCntPtr<OverlayFileSystem> OverlayFS(
 102                         new OverlayFileSystem(getRealFileSystem()));
 103         llvm::IntrusiveRefCntPtr<InMemoryFileSystem> MemFS(
 104                         new InMemoryFileSystem(true));
 105
 106         /*
 107          * pushOverlay helps setting working dir for MemFS. Must call
 108          * before addFile.
 109          */
 110         OverlayFS->pushOverlay(MemFS);
 111         MemFS->addFile(Twine(Name), 0, llvm::MemoryBuffer::getMemBuffer(Content));
 112
 113         return getModuleFromSource(std::move(CFlags), Name, OverlayFS);
 114 }
 115
 116 std::unique_ptr<llvm::Module>
 117 getModuleFromSource(llvm::opt::ArgStringList CFlags, StringRef Path)
 118 {
 119         IntrusiveRefCntPtr<vfs::FileSystem> VFS(vfs::getRealFileSystem());
 120         return getModuleFromSource(std::move(CFlags), Path, VFS);
 121 }
 122
 123 std::unique_ptr<llvm::SmallVectorImpl<char>>
 124 getBPFObjectFromModule(llvm::Module *Module)
 125 {
 126         using namespace llvm;
 127
 128         std::string TargetTriple("bpf-pc-linux");
 129         std::string Error;
 130         const Target* Target = TargetRegistry::lookupTarget(TargetTriple, Error);
 131         if (!Target) {
 132                 llvm::errs() << Error;
 133                 return std::unique_ptr<llvm::SmallVectorImpl<char>>(nullptr);
 134         }
 135
 136         llvm::TargetOptions Opt;
 137         TargetMachine *TargetMachine =
 138                 Target->createTargetMachine(TargetTriple,
 139                                             "generic", "",
 140                                             Opt, Reloc::Static);
 141
 142         Module->setDataLayout(TargetMachine->createDataLayout());
 143         Module->setTargetTriple(TargetTriple);
 144
 145         std::unique_ptr<SmallVectorImpl<char>> Buffer(new SmallVector<char, 0>());
 146         raw_svector_ostream ostream(*Buffer);
 147
 148         legacy::PassManager PM;
 149         bool NotAdded;
 150 #if CLANG_VERSION_MAJOR < 7
 151         NotAdded = TargetMachine->addPassesToEmitFile(PM, ostream,
 152                                                       TargetMachine::CGFT_ObjectFile);
 153 #else
 154         NotAdded = TargetMachine->addPassesToEmitFile(PM, ostream, nullptr,
 155                                                       TargetMachine::CGFT_ObjectFile);
 156 #endif
 157         if (NotAdded) {
 158                 llvm::errs() << "TargetMachine can't emit a file of this type\n";
 159                 return std::unique_ptr<llvm::SmallVectorImpl<char>>(nullptr);;
 160         }
 161         PM.run(*Module);
 162
 163         return Buffer;
 164 }
 165
 166 }
 167
 168 extern "C" {
 169 void perf_clang__init(void)
 170 {
 171         perf::LLVMCtx.reset(new llvm::LLVMContext());
 172         LLVMInitializeBPFTargetInfo();
 173         LLVMInitializeBPFTarget();
 174         LLVMInitializeBPFTargetMC();
 175         LLVMInitializeBPFAsmPrinter();
 176 }
 177
 178 void perf_clang__cleanup(void)
 179 {
 180         perf::LLVMCtx.reset(nullptr);
 181         llvm::llvm_shutdown();
 182 }
 183
 184 int perf_clang__compile_bpf(const char *filename,
 185                             void **p_obj_buf,
 186                             size_t *p_obj_buf_sz)
 187 {
 188         using namespace perf;
 189
 190         if (!p_obj_buf || !p_obj_buf_sz)
 191                 return -EINVAL;
 192
 193         llvm::opt::ArgStringList CFlags;
 194         auto M = getModuleFromSource(std::move(CFlags), filename);
 195         if (!M)
 196                 return  -EINVAL;
 197         auto O = getBPFObjectFromModule(&*M);
 198         if (!O)
 199                 return -EINVAL;
 200
 201         size_t size = O->size_in_bytes();
 202         void *buffer;
 203
 204         buffer = malloc(size);
 205         if (!buffer)
 206                 return -ENOMEM;
 207         memcpy(buffer, O->data(), size);
 208         *p_obj_buf = buffer;
 209         *p_obj_buf_sz = size;
 210         return 0;
 211 }
 212 }