[llvm-branch-commits] [llvm] [DXIL] Add support for root signature flag element in DXContainer (PR #123147)

[Finn Plummer via llvm-branch-commits]

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@@ -0,0 +1,157 @@
+//===- DXILRootSignature.cpp - DXIL 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 and APIs for working with DXIL
+///       Root Signatures.
+///
+//===----------------------------------------------------------------------===//
+#include "DXILRootSignature.h"
+#include "DirectX.h"
+#include "llvm/ADT/StringSwitch.h"
+#include "llvm/ADT/Twine.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/Module.h"
+#include <cstdint>
+
+using namespace llvm;
+using namespace llvm::dxil;
+
+static bool reportError(Twine Message) {
+  report_fatal_error(Message, false);
+  return true;
+}
+
+static bool parseRootFlags(ModuleRootSignature *MRS, MDNode *RootFlagNode) {
+
+  if (RootFlagNode->getNumOperands() != 2)
+    return reportError("Invalid format for RootFlag Element");
+
+  auto *Flag = mdconst::extract<ConstantInt>(RootFlagNode->getOperand(1));
+  uint32_t Value = Flag->getZExtValue();
+
+  // Root Element validation, as specified:
+  // https://github.com/llvm/wg-hlsl/blob/main/proposals/0002-root-signature-in-clang.md#validations-during-dxil-generation
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inbelic wrote:

I wonder if it is beneficial to decouple the parsing and validation logic?

On one hand it means that the generated structures might be in an invalid state. But then we would have an isolated pass to verify the `MRS` struct. If there is a case that we will generate the `MRS` another way then we could re-use the validation.

https://github.com/llvm/llvm-project/pull/123147