[llvm-branch-commits] [clang] [llvm] [HLSL][RootSignature] Add Metadata generation of Root Signatures for Attr (PR #125131)

[Joshua Batista via llvm-branch-commits]

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+//===- HLSLRootSignature.cpp - 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 helpers for working with HLSL Root Signatures.
+///
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Frontend/HLSL/HLSLRootSignature.h"
+#include "llvm/IR/IRBuilder.h"
+#include "llvm/IR/Metadata.h"
+#include "llvm/IR/Module.h"
+
+namespace llvm {
+namespace hlsl {
+namespace rootsig {
+
+// Static helper functions
+
+static MDString *ClauseTypeToName(LLVMContext &Ctx, ClauseType Type) {
+  StringRef Name;
+  switch (Type) {
+  case ClauseType::CBuffer:
+    Name = "CBV";
+    break;
+  case ClauseType::SRV:
+    Name = "SRV";
+    break;
+  case ClauseType::UAV:
+    Name = "UAV";
+    break;
+  case ClauseType::Sampler:
+    Name = "Sampler";
+    break;
+  }
+  return MDString::get(Ctx, Name);
+}
+
+// Helper struct so that we can use the overloaded notation of std::visit
+template <class... Ts> struct OverloadBuilds : Ts... {
+  using Ts::operator()...;
+};
+template <class... Ts> OverloadBuilds(Ts...) -> OverloadBuilds<Ts...>;
+
+MDNode *MetadataBuilder::BuildRootSignature() {
+  for (const RootElement &Element : Elements) {
+    MDNode *ElementMD =
+        std::visit(OverloadBuilds{
+                       [&](DescriptorTable Table) -> MDNode * {
+                         return BuildDescriptorTable(Table);
+                       },
+                       [&](DescriptorTableClause Clause) -> MDNode * {
+                         return BuildDescriptorTableClause(Clause);
+                       },
+                   },
+                   Element);
+    GeneratedMetadata.push_back(ElementMD);
+  }
+
+  return MDNode::get(Ctx, GeneratedMetadata);
+}
+
+MDNode *MetadataBuilder::BuildDescriptorTable(const DescriptorTable &Table) {
+  IRBuilder<> B(Ctx);
+  SmallVector<Metadata *> TableOperands;
+  // Set the mandatory arguments
+  TableOperands.push_back(MDString::get(Ctx, "DescriptorTable"));
+  TableOperands.push_back(ConstantAsMetadata::get(
+      B.getInt32(llvm::to_underlying(Table.Visibility))));
+
+  // Remaining operands are references to the table's clauses. The in-memory
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bob80905 wrote:

Very helpful 👍

https://github.com/llvm/llvm-project/pull/125131