[Tooling] Allow -flto flags and filter out -Wa, flags

This change fixes the problem in https://bugs.llvm.org/show_bug.cgi?id=38332
by allowing driver::Action::BackendJobClass to run with the analyzer.
Otherwise, such jobs will look up the non-existing compilation database
and then run without flags.
Also filter out the -Wa,* flags that could be passed to and ignored
by the clang compiler.  Clang-tidy gives warnings about unused -Wa,* flags.

Differential Revision: http://reviews.llvm.org/D51002

llvm-svn: 340421

clang/lib/Tooling/CompilationDatabase.cpp

@@ -218,6 +218,15 @@ struct MatchesAny {
   ArrayRef<std::string> Arr;
 };
 
+// Filter of tools unused flags such as -no-integrated-as and -Wa,*.
+// They are not used for syntax checking, and could confuse targets
+// which don't support these options.
+struct FilterUnusedFlags {
+  bool operator() (StringRef S) {
+    return (S == "-no-integrated-as") || S.startswith("-Wa,");
+  }
+};
+
 } // namespace
 
 /// Strips any positional args and possible argv[0] from a command-line
@@ -275,10 +284,7 @@ static bool stripPositionalArgs(std::vector<const char *> Args,
   // up with no jobs but then this is the user's fault.
   Args.push_back("placeholder.cpp");
 
-  // Remove -no-integrated-as; it's not used for syntax checking,
-  // and it confuses targets which don't support this option.
-  Args.erase(std::remove_if(Args.begin(), Args.end(),
-                            MatchesAny(std::string("-no-integrated-as"))),
+  Args.erase(std::remove_if(Args.begin(), Args.end(), FilterUnusedFlags()),
              Args.end());
 
   const std::unique_ptr<driver::Compilation> Compilation(
@@ -291,9 +297,11 @@ static bool stripPositionalArgs(std::vector<const char *> Args,
   CompileJobAnalyzer CompileAnalyzer;
 
   for (const auto &Cmd : Jobs) {
-    // Collect only for Assemble and Compile jobs. If we do all jobs we get
-    // duplicates since Link jobs point to Assemble jobs as inputs.
+    // Collect only for Assemble, Backend, and Compile jobs. If we do all jobs
+    // we get duplicates since Link jobs point to Assemble jobs as inputs.
+    // -flto* flags make the BackendJobClass, which still needs analyzer.
     if (Cmd.getSource().getKind() == driver::Action::AssembleJobClass ||
+        Cmd.getSource().getKind() == driver::Action::BackendJobClass ||
         Cmd.getSource().getKind() == driver::Action::CompileJobClass) {
       CompileAnalyzer.run(&Cmd.getSource());
     }

clang/test/Tooling/clang-check-analyzer.cpp

@@ -1,4 +1,7 @@
 // RUN: clang-check -analyze "%s" -- -c 2>&1 | FileCheck %s
+// RUN: clang-check -analyze "%s" -- -c -flto -Wa,--noexecstack 2>&1 | FileCheck %s
+// RUN: clang-check -analyze "%s" -- -c -no-integrated-as -flto=thin 2>&1 | FileCheck %s
+// RUN: clang-check -analyze "%s" -- -c -flto=full 2>&1 | FileCheck %s
 
 // CHECK: Dereference of null pointer
 void a(int *x) { if(x){} *x = 47; }