do more processing in clang-fuzzer (use EmitAssemblyAction)

[kcc]

Summary

use EmitAssemblyAction in clang-fuzzer

[kcc]

ignore this for now. I've found how to make it even more interesting (by using llvm::InitializeAllTargets, etc), will send an update later.

[kcc]

Use EmitObjAction; also link and initialize the targets so
that we actually call the optimizer.

[klimek]

lg

tools/clang-fuzzer/CMakeLists.txt

 if( LLVM_USE_SANITIZE_COVERAGE )
   set(LLVM_LINK_COMPONENTS support)
 
   add_clang_executable(clang-fuzzer
     EXCLUDE_FROM_ALL
     ClangFuzzer.cpp
     )
 
   target_link_libraries(clang-fuzzer
     ${CLANG_FORMAT_LIB_DEPS}
     clangAST
+    clangCodeGen
     clangBasic
     clangDriver
     clangFrontend
     clangRewriteFrontend
     clangStaticAnalyzerFrontend
     clangTooling
     LLVMFuzzer
     )
 endif()

tools/clang-fuzzer/ClangFuzzer.cpp

 /// \file
 /// \brief This file implements a function that runs Clang on a single
 ///  input. This function is then linked into the Fuzzer library.
 ///
 //===----------------------------------------------------------------------===//
 
 #include "clang/Tooling/Tooling.h"
 #include "clang/Frontend/FrontendActions.h"
+#include "clang/CodeGen/CodeGenAction.h"
 #include "clang/Frontend/CompilerInstance.h"
 #include "clang/Lex/PreprocessorOptions.h"
 #include "llvm/Option/Option.h"
 
 using namespace clang;
 
 extern "C" int LLVMFuzzerTestOneInput(uint8_t *data, size_t size) {
   std::string s((const char *)data, size);
   llvm::opt::ArgStringList CC1Args;
   CC1Args.push_back("-cc1");
   CC1Args.push_back("./test.cc");
   llvm::IntrusiveRefCntPtr<FileManager> Files(
       new FileManager(FileSystemOptions()));
   IgnoringDiagConsumer Diags;
   IntrusiveRefCntPtr<DiagnosticOptions> DiagOpts = new DiagnosticOptions();
   DiagnosticsEngine Diagnostics(
       IntrusiveRefCntPtr<clang::DiagnosticIDs>(new DiagnosticIDs()), &*DiagOpts,
       &Diags, false);
   std::unique_ptr<clang::CompilerInvocation> Invocation(
       tooling::newInvocation(&Diagnostics, CC1Args));
   std::unique_ptr<llvm::MemoryBuffer> Input =
       llvm::MemoryBuffer::getMemBuffer(s);
   Invocation->getPreprocessorOpts().addRemappedFile("./test.cc", Input.release());
   std::unique_ptr<tooling::ToolAction> action(
-      tooling::newFrontendActionFactory<clang::SyntaxOnlyAction>());
+      tooling::newFrontendActionFactory<clang::EmitAssemblyAction>());
   std::shared_ptr<PCHContainerOperations> PCHContainerOps =
       std::make_shared<PCHContainerOperations>();
   action->runInvocation(std::move(Invocation), Files.get(), PCHContainerOps,
                         &Diags);
   return 0;
 }