2 files changed, 34 insertions, 19 deletions

diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index ae12465d3f8..c60dc76ae1b 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -5975,26 +5975,19 @@ void Clang::AddClangCLArgs(const ArgList &Args, types::ID InputType,
   }
 
   if (Arg *A = Args.getLastArg(options::OPT__SLASH_guard)) {
-    SmallVector<StringRef, 1> SplitArgs;
-    StringRef(A->getValue()).split(SplitArgs, ",");
-    bool Instrument = false;
-    bool NoChecks = false;
-    for (StringRef Arg : SplitArgs) {
-      if (Arg.equals_lower("cf"))
-        Instrument = true;
-      else if (Arg.equals_lower("cf-"))
-        Instrument = false;
-      else if (Arg.equals_lower("nochecks"))
-        NoChecks = true;
-      else if (Arg.equals_lower("nochecks-"))
-        NoChecks = false;
-      else
-        D.Diag(diag::err_drv_invalid_value) << A->getSpelling() << Arg;
-    }
-    // Currently there's no support emitting CFG instrumentation; the flag only
-    // emits the table of address-taken functions.
-    if (Instrument || NoChecks)
+    StringRef GuardArgs = A->getValue();
+    // The only valid options are "cf", "cf,nochecks", and "cf-".
+    if (GuardArgs.equals_lower("cf")) {
+      // Emit CFG instrumentation and the table of address-taken functions.
       CmdArgs.push_back("-cfguard");
+    } else if (GuardArgs.equals_lower("cf,nochecks")) {
+      // Emit only the table of address-taken functions.
+      CmdArgs.push_back("-cfguard-no-checks");
+    } else if (GuardArgs.equals_lower("cf-")) {
+      // Do nothing, but we might want to emit a security warning in future.
+    } else {
+      D.Diag(diag::err_drv_invalid_value) << A->getSpelling() << GuardArgs;
+    }
   }
 }
 
diff --git a/clang/lib/Driver/ToolChains/MSVC.cpp b/clang/lib/Driver/ToolChains/MSVC.cpp
index 1d31844bfcc..4e143f6a5d3 100644
--- a/clang/lib/Driver/ToolChains/MSVC.cpp
+++ b/clang/lib/Driver/ToolChains/MSVC.cpp
@@ -422,6 +422,17 @@ void visualstudio::Linker::ConstructJob(Compilation &C, const JobAction &JA,
 
   Args.AddAllArgValues(CmdArgs, options::OPT__SLASH_link);
 
+  // Control Flow Guard checks
+  if (Arg *A = Args.getLastArg(options::OPT__SLASH_guard)) {
+    StringRef GuardArgs = A->getValue();
+    if (GuardArgs.equals_lower("cf") || GuardArgs.equals_lower("cf,nochecks")) {
+      // MSVC doesn't yet support the "nochecks" modifier.
+      CmdArgs.push_back("-guard:cf");
+    } else if (GuardArgs.equals_lower("cf-")) {
+      CmdArgs.push_back("-guard:cf-");
+    }
+  }
+
   if (Args.hasFlag(options::OPT_fopenmp, options::OPT_fopenmp_EQ,
                    options::OPT_fno_openmp, false)) {
     CmdArgs.push_back("-nodefaultlib:vcomp.lib");
@@ -679,6 +690,17 @@ std::unique_ptr<Command> visualstudio::Compiler::GetCommand(
                           : "/Zc:threadSafeInit-");
   }
 
+  // Control Flow Guard checks
+  if (Arg *A = Args.getLastArg(options::OPT__SLASH_guard)) {
+    StringRef GuardArgs = A->getValue();
+    if (GuardArgs.equals_lower("cf") || GuardArgs.equals_lower("cf,nochecks")) {
+      // MSVC doesn't yet support the "nochecks" modifier.
+      CmdArgs.push_back("/guard:cf");
+    } else if (GuardArgs.equals_lower("cf-")) {
+      CmdArgs.push_back("/guard:cf-");
+    }
+  }
+
   // Pass through all unknown arguments so that the fallback command can see
   // them too.
   Args.AddAllArgs(CmdArgs, options::OPT_UNKNOWN);