[HLSL] Add the Qstrip-rootsignature DXC driver option

Author: inbelic

clang/include/clang/Basic/CodeGenOptions.def

@@ -479,6 +479,9 @@ CODEGENOPT(StaticClosure, 1, 0, Benign)
 /// Assume that UAVs/SRVs may alias
 CODEGENOPT(ResMayAlias, 1, 0, Benign)
 
+/// Omit the root signature from produced DXContainer
+CODEGENOPT(HLSLRootSigStrip, 1, 0, Benign)
+
 /// Controls how unwind v2 (epilog) information should be generated for x64
 /// Windows.
 ENUM_CODEGENOPT(WinX64EHUnwindV2, WinX64EHUnwindV2Mode,

clang/include/clang/Driver/Options.td

@@ -9404,6 +9404,12 @@ def res_may_alias : Option<["/", "-"], "res-may-alias", KIND_FLAG>,
   Visibility<[DXCOption, ClangOption, CC1Option]>,
   HelpText<"Assume that UAVs/SRVs may alias">,
   MarshallingInfoFlag<CodeGenOpts<"ResMayAlias">>;
+def dxc_strip_rootsignature :
+  Option<["/", "-"], "Qstrip-rootsignature", KIND_FLAG>,
+  Group<dxc_Group>,
+  Visibility<[DXCOption]>,
+  HelpText<"Omit the root signature from produced DXContainer">,
+  MarshallingInfoFlag<CodeGenOpts<"HLSLRootSigStrip">>;
 def target_profile : DXCJoinedOrSeparate<"T">, MetaVarName<"<profile>">,
   HelpText<"Set target profile">,
   Values<"ps_6_0, ps_6_1, ps_6_2, ps_6_3, ps_6_4, ps_6_5, ps_6_6, ps_6_7,"

clang/lib/Driver/Driver.cpp

@@ -4662,6 +4662,16 @@ void Driver::BuildDefaultActions(Compilation &C, DerivedArgList &Args,
         Actions.push_back(C.MakeAction<BinaryTranslatorJobAction>(
             LastAction, types::TY_DX_CONTAINER));
     }
+    if (TC.requiresObjcopy(Args)) {
+      Action *LastAction = Actions.back();
+      // llvm-objcopy expects a DXIL container, which can either be
+      // validated (in which case they are TY_DX_CONTAINER), or unvalidated
+      // (TY_OBJECT).
+      if (LastAction->getType() == types::TY_DX_CONTAINER ||
+          LastAction->getType() == types::TY_Object)
+        Actions.push_back(C.MakeAction<BinaryModifyJobAction>(
+            LastAction, types::TY_DX_CONTAINER));
+    }
   }
 
   // Claim ignored clang-cl options.

clang/lib/Driver/ToolChains/HLSL.cpp

@@ -295,6 +295,30 @@ void tools::hlsl::MetalConverter::ConstructJob(
                                          Exec, CmdArgs, Inputs, Input));
 }
 
+void tools::hlsl::LLVMObjcopy::ConstructJob(Compilation &C, const JobAction &JA,
+                                            const InputInfo &Output,
+                                            const InputInfoList &Inputs,
+                                            const ArgList &Args,
+                                            const char *LinkingOutput) const {
+
+  std::string ObjcopyPath = getToolChain().GetProgramPath("llvm-objcopy");
+  const char *Exec = Args.MakeArgString(ObjcopyPath);
+
+  ArgStringList CmdArgs;
+  assert(Inputs.size() == 1 && "Unable to handle multiple inputs.");
+  const InputInfo &Input = Inputs[0];
+  CmdArgs.push_back(Input.getFilename());
+  CmdArgs.push_back(Output.getFilename());
+
+  if (Args.hasArg(options::OPT_dxc_strip_rootsignature)) {
+    const char *Frs = Args.MakeArgString("--remove-section=RTS0");
+    CmdArgs.push_back(Frs);
+  }
+
+  C.addCommand(std::make_unique<Command>(JA, *this, ResponseFileSupport::None(),
+                                         Exec, CmdArgs, Inputs, Input));
+}
+
 /// DirectX Toolchain
 HLSLToolChain::HLSLToolChain(const Driver &D, const llvm::Triple &Triple,
                              const ArgList &Args)
@@ -315,6 +339,10 @@ Tool *clang::driver::toolchains::HLSLToolChain::getTool(
     if (!MetalConverter)
       MetalConverter.reset(new tools::hlsl::MetalConverter(*this));
     return MetalConverter.get();
+  case Action::BinaryModifyJobClass:
+    if (!LLVMObjcopy)
+      LLVMObjcopy.reset(new tools::hlsl::LLVMObjcopy(*this));
+    return LLVMObjcopy.get();
   default:
     return ToolChain::getTool(AC);
   }
@@ -452,16 +480,25 @@ bool HLSLToolChain::requiresBinaryTranslation(DerivedArgList &Args) const {
   return Args.hasArg(options::OPT_metal) && Args.hasArg(options::OPT_dxc_Fo);
 }
 
+bool HLSLToolChain::requiresObjcopy(DerivedArgList &Args) const {
+  return Args.hasArg(options::OPT_dxc_Fo) &&
+         Args.hasArg(options::OPT_dxc_strip_rootsignature);
+}
+
 bool HLSLToolChain::isLastJob(DerivedArgList &Args,
                               Action::ActionClass AC) const {
   bool HasTranslation = requiresBinaryTranslation(Args);
   bool HasValidation = requiresValidation(Args);
+  bool HasObjcopy = requiresObjcopy(Args);
   // If translation and validation are not required, we should only have one
   // action.
-  if (!HasTranslation && !HasValidation)
+  if (!HasTranslation && !HasValidation && !HasObjcopy)
     return true;
   if ((HasTranslation && AC == Action::BinaryTranslatorJobClass) ||
-      (!HasTranslation && HasValidation && AC == Action::BinaryAnalyzeJobClass))
+      (!HasTranslation && HasValidation &&
+       AC == Action::BinaryAnalyzeJobClass) ||
+      (!HasTranslation && !HasValidation && HasObjcopy &&
+       AC == Action::BinaryModifyJobClass))
     return true;
   return false;
 }

clang/lib/Driver/ToolChains/HLSL.h

@@ -42,6 +42,19 @@ class LLVM_LIBRARY_VISIBILITY MetalConverter : public Tool {
                     const llvm::opt::ArgList &TCArgs,
                     const char *LinkingOutput) const override;
 };
+
+class LLVM_LIBRARY_VISIBILITY LLVMObjcopy : public Tool {
+public:
+  LLVMObjcopy(const ToolChain &TC)
+      : Tool("hlsl::LLVMObjcopy", "llvm-objcopy", TC) {}
+
+  bool hasIntegratedCPP() const override { return false; }
+
+  void ConstructJob(Compilation &C, const JobAction &JA,
+                    const InputInfo &Output, const InputInfoList &Inputs,
+                    const llvm::opt::ArgList &TCArgs,
+                    const char *LinkingOutput) const override;
+};
 } // namespace hlsl
 } // namespace tools
 
@@ -65,6 +78,7 @@ class LLVM_LIBRARY_VISIBILITY HLSLToolChain : public ToolChain {
   static std::optional<std::string> parseTargetProfile(StringRef TargetProfile);
   bool requiresValidation(llvm::opt::DerivedArgList &Args) const;
   bool requiresBinaryTranslation(llvm::opt::DerivedArgList &Args) const;
+  bool requiresObjcopy(llvm::opt::DerivedArgList &Args) const;
   bool isLastJob(llvm::opt::DerivedArgList &Args, Action::ActionClass AC) const;
 
   // Set default DWARF version to 4 for DXIL uses version 4.
@@ -73,6 +87,7 @@ class LLVM_LIBRARY_VISIBILITY HLSLToolChain : public ToolChain {
 private:
   mutable std::unique_ptr<tools::hlsl::Validator> Validator;
   mutable std::unique_ptr<tools::hlsl::MetalConverter> MetalConverter;
+  mutable std::unique_ptr<tools::hlsl::LLVMObjcopy> LLVMObjcopy;
 };
 
 } // end namespace toolchains

clang/test/Driver/dxc_strip_rootsignature.hlsl

@@ -0,0 +1,10 @@
+// RUN: %clang_dxc -Qstrip-rootsignature -T cs_6_0 /Fo %t -### %s 2>&1 | FileCheck %s
+
+// Test to demonstrate that we specify to the root signature with the
+// -Qstrip-rootsignature option
+
+// CHECK: "{{.*}}llvm-objcopy{{.*}}" "{{.*}}" "{{.*}}" "--remove-section=RTS0"
+
+[shader("compute"), RootSignature("")]
+[numthreads(1,1,1)]
+void EmptyEntry() {}