define the fdx-rootsignature-define option

Author: inbelic

clang/include/clang/Basic/LangOptions.h

@@ -552,6 +552,10 @@ class LangOptions : public LangOptionsBase {
   llvm::dxbc::RootSignatureVersion HLSLRootSigVer =
       llvm::dxbc::RootSignatureVersion::V1_1;
 
+  /// The HLSL root signature that will be used to overide the root signature
+  /// used for the shader entry point.
+  std::string HLSLRootSigOverride;
+
   // Indicates if the wasm-opt binary must be ignored in the case of a
   // WebAssembly target.
   bool NoWasmOpt = false;

clang/include/clang/Driver/Options.td

@@ -9436,6 +9436,13 @@ def dxc_rootsig_ver :
   Alias<fdx_rootsignature_version>,
   Group<dxc_Group>,
   Visibility<[DXCOption]>;
+def fdx_rootsignature_define :
+  Joined<["-"], "fdx-rootsignature-define=">,
+  Group<dxc_Group>,
+  Visibility<[ClangOption, CC1Option]>,
+  MarshallingInfoString<LangOpts<"HLSLRootSigOverride">, "\"\"">,
+  HelpText<"Override entry function root signature with root signature at "
+           "given macro name.">;
 def hlsl_entrypoint : Option<["-"], "hlsl-entry", KIND_SEPARATE>,
                       Group<dxc_Group>,
                       Visibility<[ClangOption, CC1Option]>,

clang/lib/Frontend/CompilerInvocation.cpp

@@ -640,6 +640,10 @@ static bool FixupInvocation(CompilerInvocation &Invocation,
     Diags.Report(diag::err_drv_argument_not_allowed_with)
         << "-fdx-rootsignature-version" << GetInputKindName(IK);
 
+  if (Args.hasArg(OPT_fdx_rootsignature_define) && !LangOpts.HLSL)
+    Diags.Report(diag::err_drv_argument_not_allowed_with)
+        << "-fdx-rootsignature-define" << GetInputKindName(IK);
+
   if (Args.hasArg(OPT_fgpu_allow_device_init) && !LangOpts.HIP)
     Diags.Report(diag::warn_ignored_hip_only_option)
         << Args.getLastArg(OPT_fgpu_allow_device_init)->getAsString(Args);