perf clang: Use real file system for #include

Utilize clang's OverlayFileSystem facility, allow CompilerInstance to
access real file system.

With this patch the '#include' directive can be used.

Add a new getModuleFromSource for real file.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: Alexei Starovoitov <ast@fb.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Joe Stringer <joe@ovn.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/20161126070354.141764-12-wangnan0@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 32 insertions, 12 deletions

diff --git a/tools/perf/util/c++/clang.cpp b/tools/perf/util/c++/clang.cpp
index c17b1176e25d..cf96199b4b6f 100644
--- a/tools/perf/util/c++/clang.cpp
+++ b/tools/perf/util/c++/clang.cpp
@@ -15,6 +15,7 @@
 #include "clang/Tooling/Tooling.h"
 #include "llvm/IR/Module.h"
 #include "llvm/Option/Option.h"
+#include "llvm/Support/FileSystem.h"
 #include "llvm/Support/ManagedStatic.h"
 #include <memory>
 
@@ -27,14 +28,6 @@ static std::unique_ptr<llvm::LLVMContext> LLVMCtx;
 
 using namespace clang;
 
-static vfs::InMemoryFileSystem *
-buildVFS(StringRef& Name, StringRef& Content)
-{
-        vfs::InMemoryFileSystem *VFS = new vfs::InMemoryFileSystem(true);
-        VFS->addFile(Twine(Name), 0, llvm::MemoryBuffer::getMemBuffer(Content));
-        return VFS;
-}
-
 static CompilerInvocation *
 createCompilerInvocation(StringRef& Path, DiagnosticsEngine& Diags)
 {
@@ -60,17 +53,17 @@ createCompilerInvocation(StringRef& Path, DiagnosticsEngine& Diags)
         return CI;
 }
 
-std::unique_ptr<llvm::Module>
-getModuleFromSource(StringRef Name, StringRef Content)
+static std::unique_ptr<llvm::Module>
+getModuleFromSource(StringRef Path,
+                    IntrusiveRefCntPtr<vfs::FileSystem> VFS)
 {
         CompilerInstance Clang;
         Clang.createDiagnostics();
 
-        IntrusiveRefCntPtr<vfs::FileSystem> VFS = buildVFS(Name, Content);
         Clang.setVirtualFileSystem(&*VFS);
 
         IntrusiveRefCntPtr<CompilerInvocation> CI =
-                createCompilerInvocation(Name, Clang.getDiagnostics());
+                createCompilerInvocation(Path, Clang.getDiagnostics());
         Clang.setInvocation(&*CI);
 
         std::unique_ptr<CodeGenAction> Act(new EmitLLVMOnlyAction(&*LLVMCtx));
@@ -80,6 +73,33 @@ getModuleFromSource(StringRef Name, StringRef Content)
         return Act->takeModule();
 }
 
+std::unique_ptr<llvm::Module>
+getModuleFromSource(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(Name, OverlayFS);
+}
+
+std::unique_ptr<llvm::Module>
+getModuleFromSource(StringRef Path)
+{
+        IntrusiveRefCntPtr<vfs::FileSystem> VFS(vfs::getRealFileSystem());
+        return getModuleFromSource(Path, VFS);
+}
+
 }
 
 extern "C" {