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

[Damyan Pepper via llvm-branch-commits]

================
@@ -0,0 +1,134 @@
+//===- 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/IR/Constants.h"
+#include "llvm/IR/Metadata.h"
+#include "llvm/IR/Module.h"
+
+using namespace llvm;
+using namespace llvm::dxil;
+
+static bool parseRootFlags(ModuleRootSignature *MRS, MDNode *RootFlagNode) {
+
+  assert(RootFlagNode->getNumOperands() == 2 &&
+         "Invalid format for RootFlag Element");
+  auto *Flag = mdconst::extract<ConstantInt>(RootFlagNode->getOperand(1));
+  auto 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
+  assert((Value & ~0x80000fff) == 0 && "Invalid flag for RootFlag Element");
+
+  MRS->Flags = Value;
+  return false;
+}
+
+static bool parseRootSignatureElement(ModuleRootSignature *MRS,
+                                      MDNode *Element) {
+  MDString *ElementText = cast<MDString>(Element->getOperand(0));
+  assert(ElementText != nullptr &&
+         "First preoperty of element is not a string");
+
+  RootSignatureElementKind ElementKind =
+      StringSwitch<RootSignatureElementKind>(ElementText->getString())
+          .Case("RootFlags", RootSignatureElementKind::RootFlags)
+          .Case("RootConstants", RootSignatureElementKind::RootConstants)
+          .Case("RootCBV", RootSignatureElementKind::RootDescriptor)
+          .Case("RootSRV", RootSignatureElementKind::RootDescriptor)
+          .Case("RootUAV", RootSignatureElementKind::RootDescriptor)
+          .Case("Sampler", RootSignatureElementKind::RootDescriptor)
+          .Case("DescriptorTable", RootSignatureElementKind::DescriptorTable)
+          .Case("StaticSampler", RootSignatureElementKind::StaticSampler)
+          .Default(RootSignatureElementKind::None);
+
+  switch (ElementKind) {
+
+  case RootSignatureElementKind::RootFlags: {
+    return parseRootFlags(MRS, Element);
+    break;
+  }
+
+  case RootSignatureElementKind::RootConstants:
+  case RootSignatureElementKind::RootDescriptor:
+  case RootSignatureElementKind::DescriptorTable:
+  case RootSignatureElementKind::StaticSampler:
+  case RootSignatureElementKind::None:
+    llvm_unreachable("Not Implemented yet");
+    break;
+  }
+
+  return true;
+}
+
+bool ModuleRootSignature::parse(int32_t Version, NamedMDNode *Root) {
+  this->Version = Version;
+  bool HasError = false;
+
+  for (unsigned int Sid = 0; Sid < Root->getNumOperands(); Sid++) {
+    // This should be an if, for error handling
----------------
damyanp wrote:

```
    // This should be an if, for error handling
```

It probably should...so why isn't it?

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