[clang][RISCV] Introduce command line options for RISC-V Zicfilp CFI

This patch enables the following command line flags for RISC-V targets:

+ `-fcf-protection=branch` turns on forward-edge control-flow integrity conditioning
+ `-mcf-branch-label-scheme=unlabeled|func-sig` selects the label scheme used in the forward-edge CFI conditioning

1 files changed, 40 insertions, 0 deletions

diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index efd8525..6c09843 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -1688,6 +1688,18 @@ void CompilerInvocationBase::GenerateCodeGenArgs(const CodeGenOptions &Opts,
   else if (Opts.CFProtectionBranch)
     GenerateArg(Consumer, OPT_fcf_protection_EQ, "branch");
 
+  if (Opts.CFProtectionBranch) {
+    switch (Opts.getCFBranchLabelScheme()) {
+    case CFBranchLabelSchemeKind::Default:
+      break;
+#define CF_BRANCH_LABEL_SCHEME(Kind, FlagVal)                                  \
+  case CFBranchLabelSchemeKind::Kind:                                          \
+    GenerateArg(Consumer, OPT_mcf_branch_label_scheme_EQ, #FlagVal);           \
+    break;
+#include "clang/Basic/CFProtectionOptions.def"
+    }
+  }
+
   if (Opts.FunctionReturnThunks)
     GenerateArg(Consumer, OPT_mfunction_return_EQ, "thunk-extern");
 
@@ -2022,6 +2034,22 @@ bool CompilerInvocation::ParseCodeGenArgs(CodeGenOptions &Opts, ArgList &Args,
       Diags.Report(diag::err_drv_invalid_value) << A->getAsString(Args) << Name;
   }
 
+  if (Opts.CFProtectionBranch && T.isRISCV()) {
+    if (const Arg *A = Args.getLastArg(OPT_mcf_branch_label_scheme_EQ)) {
+      const auto Scheme =
+          llvm::StringSwitch<CFBranchLabelSchemeKind>(A->getValue())
+#define CF_BRANCH_LABEL_SCHEME(Kind, FlagVal)                                  \
+  .Case(#FlagVal, CFBranchLabelSchemeKind::Kind)
+#include "clang/Basic/CFProtectionOptions.def"
+              .Default(CFBranchLabelSchemeKind::Default);
+      if (Scheme != CFBranchLabelSchemeKind::Default)
+        Opts.setCFBranchLabelScheme(Scheme);
+      else
+        Diags.Report(diag::err_drv_invalid_value)
+            << A->getAsString(Args) << A->getValue();
+    }
+  }
+
   if (const Arg *A = Args.getLastArg(OPT_mfunction_return_EQ)) {
     auto Val = llvm::StringSwitch<llvm::FunctionReturnThunksKind>(A->getValue())
                    .Case("keep", llvm::FunctionReturnThunksKind::Keep)
@@ -3952,6 +3980,18 @@ bool CompilerInvocation::ParseLangArgs(LangOptions &Opts, ArgList &Args,
     }
   }
 
+  if (Opts.CFProtectionBranch) {
+    if (const Arg *A = Args.getLastArg(OPT_mcf_branch_label_scheme_EQ)) {
+      const auto Scheme =
+          llvm::StringSwitch<CFBranchLabelSchemeKind>(A->getValue())
+#define CF_BRANCH_LABEL_SCHEME(Kind, FlagVal)                                  \
+  .Case(#FlagVal, CFBranchLabelSchemeKind::Kind)
+#include "clang/Basic/CFProtectionOptions.def"
+              .Default(CFBranchLabelSchemeKind::Default);
+      Opts.setCFBranchLabelScheme(Scheme);
+    }
+  }
+
   if ((Args.hasArg(OPT_fsycl_is_device) || Args.hasArg(OPT_fsycl_is_host)) &&
       !Args.hasArg(OPT_sycl_std_EQ)) {
     // If the user supplied -fsycl-is-device or -fsycl-is-host, but failed to