Remove MCCAS options in Scanner if not emitting Obj

Remove the MCCAS options in the dependency scanner if the FrontendAction
is not EmitObj. MCCAS should only be turned on when the compiler is
emitting an object file.

Author: rastogishubham

clang/lib/Tooling/DependencyScanning/ScanAndUpdateArgs.cpp

@@ -26,11 +26,19 @@ void tooling::dependencies::configureInvocationForCaching(
   auto &FrontendOpts = CI.getFrontendOpts();
   FrontendOpts.CacheCompileJob = true;
   FrontendOpts.IncludeTimestamps = false;
+
   // Clear this otherwise it defeats the purpose of making the compilation key
   // independent of certain arguments.
-  CI.getCodeGenOpts().DwarfDebugFlags.clear();
+  auto &CodeGenOpts = CI.getCodeGenOpts();
+  if (CI.getFrontendOpts().ProgramAction != frontend::ActionKind::EmitObj) {
+    CodeGenOpts.UseCASBackend = false;
+    CodeGenOpts.EmitCASIDFile = false;
+    auto &LLVMArgs = FrontendOpts.LLVMArgs;
+    llvm::erase(LLVMArgs, "-cas-friendly-debug-info");
+  }
+  CodeGenOpts.DwarfDebugFlags.clear();
   resetBenignCodeGenOptions(FrontendOpts.ProgramAction, CI.getLangOpts(),
-                            CI.getCodeGenOpts());
+                            CodeGenOpts);
 
   HeaderSearchOptions &HSOpts = CI.getHeaderSearchOpts();
   // Avoid writing potentially volatile diagnostic options into pcms.
@@ -78,7 +86,7 @@ void tooling::dependencies::configureInvocationForCaching(
       // Disable `-gmodules` to avoid debug info referencing a non-existent PCH
       // filename.
       // FIXME: we should also allow -gmodules if there is no PCH involved.
-      CI.getCodeGenOpts().DebugTypeExtRefs = false;
+      CodeGenOpts.DebugTypeExtRefs = false;
       HSOpts.ModuleFormat = "raw";
     }
     // Clear APINotes options.

clang/test/CAS/depscan-update-mccas.c

@@ -0,0 +1,24 @@
+// RUN: %clang -cc1depscan -o - -cc1-args -cc1 -triple \
+// RUN:        x86_64-apple-darwin10 -debug-info-kind=standalone -dwarf-version=4 \
+// RUN:        -debugger-tuning=lldb -emit-obj -fcas-backend -fcas-path %t/cas \
+// RUN:        -fcas-emit-casid-file -mllvm -cas-friendly-debug-info %s | FileCheck %s --check-prefix=MCCAS_ON
+
+// MCCAS_ON: -mllvm
+// MCCAS_ON: -cas-friendly-debug-info
+// MCCAS_ON: -fcas-backend
+// MCCAS_ON: -fcas-emit-casid-file
+
+// RUN: %clang -cc1depscan -o - -cc1-args -cc1 -triple \
+// RUN:        x86_64-apple-darwin10 -debug-info-kind=standalone -dwarf-version=4 \
+// RUN:        -debugger-tuning=lldb -emit-llvm -fcas-backend -fcas-path %t/cas \
+// RUN:        -fcas-emit-casid-file -mllvm -cas-friendly-debug-info %s | FileCheck %s --check-prefix=MCCAS_OFF 
+
+// MCCAS_OFF-NOT: -mllvm
+// MCCAS_OFF-NOT: -cas-friendly-debug-info
+// MCCAS_OFF-NOT: -fcas-backend
+// MCCAS_OFF-NOT: -fcas-emit-casid-file
+
+
+int foo(int x) {
+    return x+1;
+}