Revert "[HLSL][RootSignature] Define and integrate HLSLRootSignatureAttr" (#134273)

Reverts #134124

The build is failing again to a linking error:
[here](#134124 (comment)).
Again the error was not present locally or any of the pre-merge builds
and must have been transitively linked in these build environments...

Author: inbelic

clang/include/clang/AST/Attr.h

@@ -26,7 +26,6 @@
 #include "clang/Basic/SourceLocation.h"
 #include "clang/Support/Compiler.h"
 #include "llvm/Frontend/HLSL/HLSLResource.h"
-#include "llvm/Frontend/HLSL/HLSLRootSignature.h"
 #include "llvm/Support/CodeGen.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/VersionTuple.h"

clang/include/clang/Basic/Attr.td

@@ -4710,25 +4710,6 @@ def Error : InheritableAttr {
   let Documentation = [ErrorAttrDocs];
 }
 
-def HLSLRootSignature : Attr {
-  /// [RootSignature(Signature)]
-  let Spellings = [Microsoft<"RootSignature">];
-  let Args = [StringArgument<"Signature">];
-  let Subjects = SubjectList<[Function],
-                             ErrorDiag, "'function'">;
-  let LangOpts = [HLSL];
-  let Documentation = [HLSLRootSignatureDocs];
-  let AdditionalMembers = [{
-private:
-  ArrayRef<llvm::hlsl::rootsig::RootElement> RootElements;
-public:
-  void setElements(ArrayRef<llvm::hlsl::rootsig::RootElement> Elements) {
-    RootElements = Elements;
-  }
-  auto getElements() const { return RootElements; }
-}];
-}
-
 def HLSLNumThreads: InheritableAttr {
   let Spellings = [Microsoft<"numthreads">];
   let Args = [IntArgument<"X">, IntArgument<"Y">, IntArgument<"Z">];

clang/include/clang/Basic/AttrDocs.td

@@ -8145,17 +8145,6 @@ and https://microsoft.github.io/hlsl-specs/proposals/0013-wave-size-range.html
   }];
 }
 
-def HLSLRootSignatureDocs : Documentation {
-  let Category = DocCatFunction;
-  let Content = [{
-The ``RootSignature`` attribute applies to HLSL entry functions to define what
-types of resources are bound to the graphics pipeline.
-
-For details about the use and specification of Root Signatures please see here:
-https://learn.microsoft.com/en-us/windows/win32/direct3d12/root-signatures
-  }];
-}
-
 def NumThreadsDocs : Documentation {
   let Category = DocCatFunction;
   let Content = [{

clang/include/clang/Sema/SemaHLSL.h

@@ -118,7 +118,6 @@ class SemaHLSL : public SemaBase {
                                        bool IsCompAssign);
   void emitLogicalOperatorFixIt(Expr *LHS, Expr *RHS, BinaryOperatorKind Opc);
 
-  void handleRootSignatureAttr(Decl *D, const ParsedAttr &AL);
   void handleNumThreadsAttr(Decl *D, const ParsedAttr &AL);
   void handleWaveSizeAttr(Decl *D, const ParsedAttr &AL);
   void handleSV_DispatchThreadIDAttr(Decl *D, const ParsedAttr &AL);

clang/lib/Sema/SemaDeclAttr.cpp

@@ -7498,9 +7498,6 @@ ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D, const ParsedAttr &AL,
     break;
 
   // HLSL attributes:
-  case ParsedAttr::AT_HLSLRootSignature:
-    S.HLSL().handleRootSignatureAttr(D, AL);
-    break;
   case ParsedAttr::AT_HLSLNumThreads:
     S.HLSL().handleNumThreadsAttr(D, AL);
     break;

clang/lib/Sema/SemaHLSL.cpp

@@ -28,7 +28,6 @@
 #include "clang/Basic/SourceLocation.h"
 #include "clang/Basic/Specifiers.h"
 #include "clang/Basic/TargetInfo.h"
-#include "clang/Parse/ParseHLSLRootSignature.h"
 #include "clang/Sema/Initialization.h"
 #include "clang/Sema/ParsedAttr.h"
 #include "clang/Sema/Sema.h"
@@ -942,40 +941,6 @@ void SemaHLSL::emitLogicalOperatorFixIt(Expr *LHS, Expr *RHS,
       << NewFnName << FixItHint::CreateReplacement(FullRange, OS.str());
 }
 
-void SemaHLSL::handleRootSignatureAttr(Decl *D, const ParsedAttr &AL) {
-  if (AL.getNumArgs() != 1) {
-    Diag(AL.getLoc(), diag::err_attribute_wrong_number_arguments) << AL << 1;
-    return;
-  }
-
-  StringRef Signature;
-  if (!SemaRef.checkStringLiteralArgumentAttr(AL, 0, Signature))
-    return;
-
-  SourceLocation Loc = AL.getArgAsExpr(0)->getExprLoc();
-  // TODO(#126565): pass down below to lexer when fp is supported
-  // llvm::RoundingMode RM = SemaRef.CurFPFeatures.getRoundingMode();
-  hlsl::RootSignatureLexer Lexer(Signature, Loc);
-  SmallVector<llvm::hlsl::rootsig::RootElement> Elements;
-  hlsl::RootSignatureParser Parser(Elements, Lexer, SemaRef.getPreprocessor());
-
-  if (Parser.parse())
-    return;
-
-  // Allocate elements onto AST context
-  unsigned N = Elements.size();
-  auto RootElements = MutableArrayRef<llvm::hlsl::rootsig::RootElement>(
-      ::new (getASTContext()) llvm::hlsl::rootsig::RootElement[N], N);
-  for (unsigned I = 0; I < N; ++I)
-    RootElements[I] = Elements[I];
-
-  // Set elements
-  auto *Result = ::new (getASTContext())
-      HLSLRootSignatureAttr(getASTContext(), AL, Signature);
-  Result->setElements(ArrayRef<llvm::hlsl::rootsig::RootElement>(RootElements));
-  D->addAttr(Result);
-}
-
 void SemaHLSL::handleNumThreadsAttr(Decl *D, const ParsedAttr &AL) {
   llvm::VersionTuple SMVersion =
       getASTContext().getTargetInfo().getTriple().getOSVersion();