[clang][RISCV] Accept -fcf-protection=branch when Zicfilp extension is on

-fcf-protection=branch turns on indirect branching protection on RISC-V targets
with Zicfilp extension.

Author: mylai-mtk

clang/lib/Basic/Targets/RISCV.h

@@ -131,6 +131,13 @@ class RISCVTargetInfo : public TargetInfo {
   bool supportsCpuInit() const override { return getTriple().isOSLinux(); }
   bool validateCpuSupports(StringRef Feature) const override;
   bool isValidFeatureName(StringRef Name) const override;
+
+  bool
+  checkCFProtectionBranchSupported(DiagnosticsEngine &Diags) const override {
+    if (ISAInfo->hasExtension("zicfilp"))
+      return true;
+    return TargetInfo::checkCFProtectionBranchSupported(Diags);
+  }
 };
 class LLVM_LIBRARY_VISIBILITY RISCV32TargetInfo : public RISCVTargetInfo {
 public: