[clang] Don't force diagnosing when checking if -fcf-protection=branch is supported

This turns the target hook that checks if `-fcf-protection=branch` is supported
into a pure check function that is suitable to be used in more places.

Author: mylai-mtk

clang/include/clang/Basic/TargetInfo.h

@@ -1725,8 +1725,7 @@ class TargetInfo : public TransferrableTargetInfo,
   }
 
   /// Check if the target supports CFProtection branch.
-  virtual bool
-  checkCFProtectionBranchSupported(DiagnosticsEngine &Diags) const;
+  virtual bool checkCFProtectionBranchSupported() const;
 
   /// Get the target default CFBranchLabelScheme scheme
   virtual CFBranchLabelSchemeKind getDefaultCFBranchLabelScheme() const;

clang/lib/Basic/TargetInfo.cpp

@@ -192,11 +192,7 @@ void TargetInfo::resetDataLayout(StringRef DL, const char *ULP) {
   UserLabelPrefix = ULP;
 }
 
-bool
-TargetInfo::checkCFProtectionBranchSupported(DiagnosticsEngine &Diags) const {
-  Diags.Report(diag::err_opt_not_valid_on_target) << "cf-protection=branch";
-  return false;
-}
+bool TargetInfo::checkCFProtectionBranchSupported() const { return false; }
 
 CFBranchLabelSchemeKind TargetInfo::getDefaultCFBranchLabelScheme() const {
   // if this hook is called, the target should override it

clang/lib/Basic/Targets/RISCV.h

@@ -135,11 +135,8 @@ class RISCVTargetInfo : public TargetInfo {
   bool validateGlobalRegisterVariable(StringRef RegName, unsigned RegSize,
                                       bool &HasSizeMismatch) const override;
 
-  bool
-  checkCFProtectionBranchSupported(DiagnosticsEngine &Diags) const override {
-    if (ISAInfo->hasExtension("zicfilp"))
-      return true;
-    return TargetInfo::checkCFProtectionBranchSupported(Diags);
+  bool checkCFProtectionBranchSupported() const override {
+    return ISAInfo->hasExtension("zicfilp");
   }
 
   CFBranchLabelSchemeKind getDefaultCFBranchLabelScheme() const override {

clang/lib/Basic/Targets/X86.h

@@ -266,11 +266,8 @@ class LLVM_LIBRARY_VISIBILITY X86TargetInfo : public TargetInfo {
     return TargetInfo::checkCFProtectionReturnSupported(Diags);
   };
 
-  bool
-  checkCFProtectionBranchSupported(DiagnosticsEngine &Diags) const override {
-    if (CPU == llvm::X86::CK_None || CPU >= llvm::X86::CK_PentiumPro)
-      return true;
-    return TargetInfo::checkCFProtectionBranchSupported(Diags);
+  bool checkCFProtectionBranchSupported() const override {
+    return CPU == llvm::X86::CK_None || CPU >= llvm::X86::CK_PentiumPro;
   };
 
   virtual bool validateOperandSize(const llvm::StringMap<bool> &FeatureMap,

clang/lib/CodeGen/CodeGenModule.cpp

@@ -1159,11 +1159,13 @@ void CodeGenModule::Release() {
                               1);
   }
 
-  if (CodeGenOpts.CFProtectionBranch &&
-      Target.checkCFProtectionBranchSupported(getDiags())) {
-    // Indicate that we want to instrument branch control flow protection.
-    getModule().addModuleFlag(llvm::Module::Min, "cf-protection-branch",
-                              1);
+  if (CodeGenOpts.CFProtectionBranch) {
+    if (Target.checkCFProtectionBranchSupported())
+      // Indicate that we want to instrument branch control flow protection.
+      getModule().addModuleFlag(llvm::Module::Min, "cf-protection-branch", 1);
+    else
+      getDiags().Report(diag::err_opt_not_valid_on_target)
+          << "cf-protection=branch";
   }
 
   if (CodeGenOpts.FunctionReturnThunks)