[Driver][DXC] add rootsig-define as an alias option

Author: inbelic

clang/include/clang/Driver/Options.td

@@ -9443,6 +9443,11 @@ def fdx_rootsignature_define :
   MarshallingInfoString<LangOpts<"HLSLRootSigOverride">, "\"\"">,
   HelpText<"Override entry function root signature with root signature at "
            "given macro name.">;
+def dxc_rootsig_define :
+  Separate<["-"], "rootsig-define">,
+  Alias<fdx_rootsignature_define>,
+  Group<dxc_Group>,
+  Visibility<[DXCOption]>;
 def hlsl_entrypoint : Option<["-"], "hlsl-entry", KIND_SEPARATE>,
                       Group<dxc_Group>,
                       Visibility<[ClangOption, CC1Option]>,

clang/lib/Driver/ToolChains/Clang.cpp

@@ -3801,6 +3801,7 @@ static void RenderHLSLOptions(const ArgList &Args, ArgStringList &CmdArgs,
       options::OPT_disable_llvm_passes,
       options::OPT_fnative_half_type,
       options::OPT_hlsl_entrypoint,
+      options::OPT_fdx_rootsignature_define,
       options::OPT_fdx_rootsignature_version};
   if (!types::isHLSL(InputType))
     return;

clang/lib/Driver/ToolChains/HLSL.cpp

@@ -304,6 +304,13 @@ HLSLToolChain::TranslateArgs(const DerivedArgList &Args, StringRef BoundArch,
       A->claim();
       continue;
     }
+    if (A->getOption().getID() == options::OPT_dxc_rootsig_define) {
+      DAL->AddJoinedArg(nullptr,
+                        Opts.getOption(options::OPT_fdx_rootsignature_define),
+                        A->getValue());
+      A->claim();
+      continue;
+    }
     if (A->getOption().getID() == options::OPT__SLASH_O) {
       StringRef OStr = A->getValue();
       if (OStr == "d") {

clang/test/Driver/dxc_rootsig-define.hlsl

@@ -0,0 +1,21 @@
+// RUN: %clang_dxc -T cs_6_0 -fcgl %s | FileCheck %s --check-prefixes=CHECK,REG
+// RUN: %clang_dxc -T cs_6_0 -fcgl -rootsig-define EmptyRS %s | FileCheck %s --check-prefixes=CHECK,EMPTY
+// RUN: %clang_dxc -T cs_6_0 -fcgl -rootsig-define CmdRS -D CmdRS='"SRV(t0)"' %s | FileCheck %s --check-prefixes=CHECK,CMD
+
+#define EmptyRS ""
+#define NotEmptyRS "CBV(b0)"
+
+// CHECK: !dx.rootsignatures = !{![[#ENTRY:]]}
+// CHECK: ![[#ENTRY]] = !{ptr @main, ![[#RS:]], i32 2}
+
+// REG: ![[#RS]] = !{![[#CBV:]]}
+// REG: ![[#CBV]] = !{!"RootCBV"
+
+// EMPTY: ![[#RS]] = !{}
+
+// CMD: ![[#RS]] = !{![[#SRV:]]}
+// CMD: ![[#SRV]] = !{!"RootSRV"
+
+[shader("compute"), RootSignature(NotEmptyRS)]
+[numthreads(1,1,1)]
+void main() {}