[NFC][RootSignature] Move RootSignature util functions (#142491)

`HLSLRootSignature.h` was originally created to hold the struct
definitions of an `llvm::hlsl::rootsig::RootElement` and some helper
functions for it.

However, there many users of the structs that don't require any of the
helper methods. This requires us to link the `FrontendHLSL` library,
where we otherwise wouldn't need to.

For instance:
- This [revert](https://github.com/llvm/llvm-project/pull/142005) was
required as it requires linking to the unrequired `FrontendHLSL` library
- As part of the change required here:
https://github.com/llvm/llvm-project/issues/126557. We will want to add
an `HLSLRootSignatureVersion` enum. Ideally this could live with the
root signature struct defs, but we don't want to link the helper objects
into `clang/Basic/TargetOptions.h`

This change allows the struct definitions to be kept in a single header
file and to then have the `FrontendHLSL` library only be linked when
required.

clang/lib/AST/TextNodeDumper.cpp

@@ -24,7 +24,7 @@
 #include "clang/Basic/Specifiers.h"
 #include "clang/Basic/TypeTraits.h"
 #include "llvm/ADT/StringExtras.h"
-#include "llvm/Frontend/HLSL/HLSLRootSignature.h"
+#include "llvm/Frontend/HLSL/HLSLRootSignatureUtils.h"
 
 #include <algorithm>
 #include <utility>

clang/lib/CodeGen/CGHLSLRuntime.cpp

@@ -23,6 +23,7 @@
 #include "clang/AST/Type.h"
 #include "clang/Basic/TargetOptions.h"
 #include "llvm/ADT/SmallVector.h"
+#include "llvm/Frontend/HLSL/HLSLRootSignatureUtils.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/DerivedTypes.h"
 #include "llvm/IR/GlobalVariable.h"

llvm/include/llvm/Frontend/HLSL/HLSLRootSignature.h

@@ -6,25 +6,19 @@
 //
 //===----------------------------------------------------------------------===//
 ///
-/// \file This file contains helper objects for working with HLSL Root
-/// Signatures.
+/// \file This file contains structure definitions of HLSL Root Signature
+/// objects.
 ///
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_FRONTEND_HLSL_HLSLROOTSIGNATURE_H
 #define LLVM_FRONTEND_HLSL_HLSLROOTSIGNATURE_H
 
-#include "llvm/ADT/ArrayRef.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/DXILABI.h"
-#include "llvm/Support/raw_ostream.h"
 #include <variant>
 
 namespace llvm {
-class LLVMContext;
-class MDNode;
-class Metadata;
-
 namespace hlsl {
 namespace rootsig {
 
@@ -195,8 +189,6 @@ struct DescriptorTable {
   uint32_t NumClauses = 0;
 };
 
-LLVM_ABI raw_ostream &operator<<(raw_ostream &OS, const DescriptorTable &Table);
-
 static const uint32_t NumDescriptorsUnbounded = 0xffffffff;
 static const uint32_t DescriptorTableOffsetAppend = 0xffffffff;
 // Models DTClause : CBV | SRV | UAV | Sampler, by collecting like parameters
@@ -225,9 +217,6 @@ struct DescriptorTableClause {
   }
 };
 
-LLVM_ABI raw_ostream &operator<<(raw_ostream &OS,
-                                 const DescriptorTableClause &Clause);
-
 struct StaticSampler {
   Register Reg;
   SamplerFilter Filter = SamplerFilter::Anisotropic;
@@ -264,32 +253,6 @@ using RootElement =
     std::variant<RootFlags, RootConstants, RootDescriptor, DescriptorTable,
                  DescriptorTableClause, StaticSampler>;
 
-LLVM_ABI void dumpRootElements(raw_ostream &OS, ArrayRef<RootElement> Elements);
-
-class MetadataBuilder {
-public:
-  MetadataBuilder(llvm::LLVMContext &Ctx, ArrayRef<RootElement> Elements)
-      : Ctx(Ctx), Elements(Elements) {}
-
-  /// Iterates through the elements and dispatches onto the correct Build method
-  ///
-  /// Accumulates the root signature and returns the Metadata node that is just
-  /// a list of all the elements
-  LLVM_ABI MDNode *BuildRootSignature();
-
-private:
-  /// Define the various builders for the different metadata types
-  MDNode *BuildRootFlags(const RootFlags &Flags);
-  MDNode *BuildRootConstants(const RootConstants &Constants);
-  MDNode *BuildRootDescriptor(const RootDescriptor &Descriptor);
-  MDNode *BuildDescriptorTable(const DescriptorTable &Table);
-  MDNode *BuildDescriptorTableClause(const DescriptorTableClause &Clause);
-
-  llvm::LLVMContext &Ctx;
-  ArrayRef<RootElement> Elements;
-  SmallVector<Metadata *> GeneratedMetadata;
-};
-
 } // namespace rootsig
 } // namespace hlsl
 } // namespace llvm

llvm/include/llvm/Frontend/HLSL/HLSLRootSignatureUtils.h

@@ -0,0 +1,65 @@
+//===- HLSLRootSignatureUtils.h - HLSL Root Signature helpers -------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file This file contains helper obejcts for working with HLSL Root
+/// Signatures.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_FRONTEND_HLSL_HLSLROOTSIGNATUREUTILS_H
+#define LLVM_FRONTEND_HLSL_HLSLROOTSIGNATUREUTILS_H
+
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/Frontend/HLSL/HLSLRootSignature.h"
+#include "llvm/Support/Compiler.h"
+#include "llvm/Support/raw_ostream.h"
+
+namespace llvm {
+class LLVMContext;
+class MDNode;
+class Metadata;
+
+namespace hlsl {
+namespace rootsig {
+
+LLVM_ABI raw_ostream &operator<<(raw_ostream &OS,
+                                 const DescriptorTableClause &Clause);
+
+LLVM_ABI raw_ostream &operator<<(raw_ostream &OS, const DescriptorTable &Table);
+
+LLVM_ABI void dumpRootElements(raw_ostream &OS, ArrayRef<RootElement> Elements);
+
+class MetadataBuilder {
+public:
+  MetadataBuilder(llvm::LLVMContext &Ctx, ArrayRef<RootElement> Elements)
+      : Ctx(Ctx), Elements(Elements) {}
+
+  /// Iterates through the elements and dispatches onto the correct Build method
+  ///
+  /// Accumulates the root signature and returns the Metadata node that is just
+  /// a list of all the elements
+  LLVM_ABI MDNode *BuildRootSignature();
+
+private:
+  /// Define the various builders for the different metadata types
+  MDNode *BuildRootFlags(const RootFlags &Flags);
+  MDNode *BuildRootConstants(const RootConstants &Constants);
+  MDNode *BuildRootDescriptor(const RootDescriptor &Descriptor);
+  MDNode *BuildDescriptorTable(const DescriptorTable &Table);
+  MDNode *BuildDescriptorTableClause(const DescriptorTableClause &Clause);
+
+  llvm::LLVMContext &Ctx;
+  ArrayRef<RootElement> Elements;
+  SmallVector<Metadata *> GeneratedMetadata;
+};
+
+} // namespace rootsig
+} // namespace hlsl
+} // namespace llvm
+
+#endif // LLVM_FRONTEND_HLSL_HLSLROOTSIGNATUREUTILS_H

llvm/lib/Frontend/HLSL/CMakeLists.txt

@@ -1,7 +1,7 @@
 add_llvm_component_library(LLVMFrontendHLSL
   CBuffer.cpp
   HLSLResource.cpp
-  HLSLRootSignature.cpp
+  HLSLRootSignatureUtils.cpp
 
   ADDITIONAL_HEADER_DIRS
   ${LLVM_MAIN_INCLUDE_DIR}/llvm/Frontend

llvm/lib/Frontend/HLSL/HLSLRootSignatureUtils.cpp

@@ -1,4 +1,4 @@
-//===- HLSLRootSignature.cpp - HLSL Root Signature helper objects ---------===//
+//===- HLSLRootSignatureUtils.cpp - HLSL Root Signature helpers -----------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
@@ -10,7 +10,7 @@
 ///
 //===----------------------------------------------------------------------===//
 
-#include "llvm/Frontend/HLSL/HLSLRootSignature.h"
+#include "llvm/Frontend/HLSL/HLSLRootSignatureUtils.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/bit.h"
 #include "llvm/IR/IRBuilder.h"

llvm/unittests/Frontend/HLSLRootSignatureDumpTest.cpp

@@ -6,7 +6,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "llvm/Frontend/HLSL/HLSLRootSignature.h"
+#include "llvm/Frontend/HLSL/HLSLRootSignatureUtils.h"
 #include "gtest/gtest.h"
 
 using namespace llvm::hlsl::rootsig;