[clang] [llvm] [HLSL][RootSignature] Implement parsing of a DescriptorTable with empty clauses (PR #133302)

[via llvm-commits]

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@@ -0,0 +1,44 @@
+//===- HLSLRootSignature.h - HLSL Root Signature helper objects -----------===//
+//
+// 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 objects for working with HLSL Root
+/// Signatures.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_FRONTEND_HLSL_HLSLROOTSIGNATURE_H
+#define LLVM_FRONTEND_HLSL_HLSLROOTSIGNATURE_H
+
+#include "llvm/Support/DXILABI.h"
+#include <variant>
+
+namespace llvm {
+namespace hlsl {
+namespace rootsig {
+
+// Definitions of the in-memory data layout structures
+
+// Models the end of a descriptor table and stores its visibility
+struct DescriptorTable {
+  uint32_t NumClauses = 0; // The number of clauses in the table
+};
+
+// Models DTClause : CBV | SRV | UAV | Sampler, by collecting like parameters
+using ClauseType = llvm::dxil::ResourceClass;
+struct DescriptorTableClause {
+  ClauseType Type;
+};
+
+// Models RootElement : DescriptorTable | DescriptorTableClause
+using RootElement = std::variant<DescriptorTable, DescriptorTableClause>;
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joaosaffran wrote:

I feel like the `DescriptorTableClause` should be a member of `DescriptorTable` and not a RootElement, since those are connected in the metadata representation, it should be easier that way, IMHO.

https://github.com/llvm/llvm-project/pull/133302