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

   1 /*
   2  * llvm C frontend for perf. Support dynamically compile C file
   3  *
   4  * Inspired by clang example code:
   5  * http://llvm.org/svn/llvm-project/cfe/trunk/examples/clang-interpreter/main.cpp
   6  *
   7  * Copyright (C) 2016 Wang Nan <wangnan0@huawei.com>
   8  * Copyright (C) 2016 Huawei Inc.
   9  */
  10
  11 #include "clang/CodeGen/CodeGenAction.h"
  12 #include "clang/Frontend/CompilerInvocation.h"
  13 #include "clang/Frontend/CompilerInstance.h"
  14 #include "clang/Frontend/TextDiagnosticPrinter.h"
  15 #include "clang/Tooling/Tooling.h"
  16 #include "llvm/IR/Module.h"
  17 #include "llvm/Option/Option.h"
  18 #include "llvm/Support/ManagedStatic.h"
  19 #include <memory>
  20
  21 #include "clang.h"
  22 #include "clang-c.h"
  23
  24 namespace perf {
  25
  26 static std::unique_ptr<llvm::LLVMContext> LLVMCtx;
  27
  28 using namespace clang;
  29
  30 static vfs::InMemoryFileSystem *
  31 buildVFS(StringRef& Name, StringRef& Content)
  32 {
  33         vfs::InMemoryFileSystem *VFS = new vfs::InMemoryFileSystem(true);
  34         VFS->addFile(Twine(Name), 0, llvm::MemoryBuffer::getMemBuffer(Content));
  35         return VFS;
  36 }
  37
  38 static CompilerInvocation *
  39 createCompilerInvocation(StringRef& Path, DiagnosticsEngine& Diags)
  40 {
  41         llvm::opt::ArgStringList CCArgs {
  42                 "-cc1",
  43                 "-triple", "bpf-pc-linux",
  44                 "-fsyntax-only",
  45                 "-ferror-limit", "19",
  46                 "-fmessage-length", "127",
  47                 "-O2",
  48                 "-nostdsysteminc",
  49                 "-nobuiltininc",
  50                 "-vectorize-loops",
  51                 "-vectorize-slp",
  52                 "-Wno-unused-value",
  53                 "-Wno-pointer-sign",
  54                 "-x", "c"};
  55         CompilerInvocation *CI = tooling::newInvocation(&Diags, CCArgs);
  56
  57         FrontendOptions& Opts = CI->getFrontendOpts();
  58         Opts.Inputs.clear();
  59         Opts.Inputs.emplace_back(Path, IK_C);
  60         return CI;
  61 }
  62
  63 std::unique_ptr<llvm::Module>
  64 getModuleFromSource(StringRef Name, StringRef Content)
  65 {
  66         CompilerInstance Clang;
  67         Clang.createDiagnostics();
  68
  69         IntrusiveRefCntPtr<vfs::FileSystem> VFS = buildVFS(Name, Content);
  70         Clang.setVirtualFileSystem(&*VFS);
  71
  72         IntrusiveRefCntPtr<CompilerInvocation> CI =
  73                 createCompilerInvocation(Name, Clang.getDiagnostics());
  74         Clang.setInvocation(&*CI);
  75
  76         std::unique_ptr<CodeGenAction> Act(new EmitLLVMOnlyAction(&*LLVMCtx));
  77         if (!Clang.ExecuteAction(*Act))
  78                 return std::unique_ptr<llvm::Module>(nullptr);
  79
  80         return Act->takeModule();
  81 }
  82
  83 }
  84
  85 extern "C" {
  86 void perf_clang__init(void)
  87 {
  88         perf::LLVMCtx.reset(new llvm::LLVMContext());
  89 }
  90
  91 void perf_clang__cleanup(void)
  92 {
  93         perf::LLVMCtx.reset(nullptr);
  94         llvm::llvm_shutdown();
  95 }
  96 }