[clang][ARM] Re-word PACBTI warning.

[amilendra]

Summary

The original warning added in D115501 when pacbti is used with an
incompatible architecture was not exactly correct because it was
not really ignored and can affect codegen.

Therefore reword to say that the pacbti option is incompatible with
the given architecture.

[chill]

clang/include/clang/Basic/DiagnosticCommonKinds.td

149

"is incompatible"

[amilendra]

[clang][ARM] Re-word PACBTI warning.

Fix grammar error.

clang/include/clang/Basic/DiagnosticCommonKinds.td

 def warn_conflicting_nullability_attr_overriding_param_types : Warning<
   "conflicting nullability specifier on parameter types, %0 "
   "conflicts with existing specifier %1">,
   InGroup<Nullability>;
 
 def err_nullability_conflicting : Error<
   "nullability specifier %0 conflicts with existing specifier %1">;
 
-def warn_target_unsupported_branch_protection_option: Warning <
-  "ignoring '-mbranch-protection=' option because the '%0' architecture does not support it">,
+def warn_incompatible_branch_protection_option: Warning <
+  "'-mbranch-protection=' option is incompatible with the '%0' architecture">,
   InGroup<BranchProtection>;
 
 def warn_target_unsupported_branch_protection_attribute: Warning <
   "ignoring the 'branch-protection' attribute because the '%0' architecture does not support it">,
   InGroup<BranchProtection>;
 }
 
 // OpenCL Section 6.8.g

clang/lib/Driver/ToolChains/Clang.cpp

const Arg *A = isAArch64
                                        options::OPT_mbranch_protection_EQ)
                      : Args.getLastArg(options::OPT_mbranch_protection_EQ);
   if (!A)
     return;
 
   const Driver &D = TC.getDriver();
   const llvm::Triple &Triple = TC.getEffectiveTriple();
   if (!(isAArch64 || (Triple.isArmT32() && Triple.isArmMClass())))
-    D.Diag(diag::warn_target_unsupported_branch_protection_option)
+    D.Diag(diag::warn_incompatible_branch_protection_option)
         << Triple.getArchName();
 
   StringRef Scope, Key;
   bool IndirectBranches;
 
   if (A->getOption().matches(options::OPT_msign_return_address_EQ)) {
     Scope = A->getValue();
     if (!Scope.equals("none") && !Scope.equals("non-leaf") &&

clang/test/Driver/arm-security-options.c

 // BTE-OFF-NOT: "-mbranch-target-enforce"
 // BTE-ON: "-mbranch-target-enforce"
 
 // BAD-BP-PROTECTION: invalid branch protection option 'bar' in '-mbranch-protection={{.*}}'
 
 // BAD-B-KEY-COMBINATION: invalid branch protection option 'b-key' in '-mbranch-protection={{.*}}'
 // BAD-LEAF-COMBINATION: invalid branch protection option 'leaf' in '-mbranch-protection={{.*}}'
 
-// INCOMPATIBLE-ARCH: ignoring '-mbranch-protection=' option because the '{{.*}}' architecture does not support it
+// INCOMPATIBLE-ARCH: '-mbranch-protection=' option is incompatible with the '{{.*}}' architecture