Added Control Flow Protection Flag

Cf-protection is a target independent flag that instructs the back-end to instrument control flow mechanisms like: Branch, Return, etc.
For example in X86 this flag will be used to instrument Indirect Branch Tracking instructions.

Differential Revision: https://reviews.llvm.org/D40478

Change-Id: I5126e766c0e6b84118cae0ee8a20fe78cc373dea
llvm-svn: 322063

2 files changed, 16 insertions, 1 deletions

diff --git a/clang/lib/CodeGen/CodeGenFunction.cpp b/clang/lib/CodeGen/CodeGenFunction.cpp
index 0cbe071d1b9..4a45b5ac19c 100644
--- a/clang/lib/CodeGen/CodeGenFunction.cpp
+++ b/clang/lib/CodeGen/CodeGenFunction.cpp
@@ -887,7 +887,8 @@ void CodeGenFunction::StartFunction(GlobalDecl GD,
   }
 
   // Apply xray attributes to the function (as a string, for now)
-  if (D && ShouldXRayInstrumentFunction()) {
+  bool InstrumentXray = ShouldXRayInstrumentFunction();
+  if (D && InstrumentXray) {
     if (const auto *XRayAttr = D->getAttr<XRayInstrumentAttr>()) {
       if (XRayAttr->alwaysXRayInstrument())
         Fn->addFnAttr("function-instrument", "xray-always");
diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index 32c9b28124a..b08ead80c1c 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -502,6 +502,20 @@ void CodeGenModule::Release() {
     getModule().addModuleFlag(llvm::Module::Override, "Cross-DSO CFI", 1);
   }
 
+  if (CodeGenOpts.CFProtectionReturn &&
+      Target.checkCFProtectionReturnSupported(getDiags())) {
+    // Indicate that we want to instrument return control flow protection.
+    getModule().addModuleFlag(llvm::Module::Override, "cf-protection-return",
+                              1);
+  }
+
+  if (CodeGenOpts.CFProtectionBranch &&
+      Target.checkCFProtectionBranchSupported(getDiags())) {
+    // Indicate that we want to instrument branch control flow protection.
+    getModule().addModuleFlag(llvm::Module::Override, "cf-protection-branch",
+                              1);
+  }
+
   if (LangOpts.CUDAIsDevice && getTriple().isNVPTX()) {
     // Indicate whether __nvvm_reflect should be configured to flush denormal
     // floating point values to 0.  (This corresponds to its "__CUDA_FTZ"