[llvm] [HLSL] Add in-memory representation of Semantic Signatures (PR #209907)

[Finn Plummer via llvm-commits]

================
@@ -0,0 +1,100 @@
+//===- SemanticSignatures.h - HLSL Semantic 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 structure definitions of HLSL Semantic Signature
+/// objects.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_FRONTEND_HLSL_SEMANTICSIGNATURES_H
+#define LLVM_FRONTEND_HLSL_SEMANTICSIGNATURES_H
+
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/BinaryFormat/DXContainer.h"
+#include "llvm/Support/Compiler.h"
+#include "llvm/Support/DXILABI.h"
+#include "llvm/Support/Error.h"
+#include <cstdint>
+
+namespace llvm {
+
+class LLVMContext;
+class MDNode;
+
+namespace hlsl {
+
+// Definitions of the in-memory data layout structures
+
+// Sentinel values denoting that an element is unallocated
+static constexpr uint32_t UnallocatedRow = ~0U;
+static constexpr uint8_t UnallocatedCol = 0xFF;
+
+// Models a single packed range of signature rows with its semantic name and
+// indices, register placement, component masks, and stage-specific attributes.
+struct SemanticSignatureElement {
+  uint32_t SigId;
+  StringRef SemanticName;
+  dxil::ElementType CompType = dxil::ElementType::Invalid;
+  dxbc::PSV::SemanticKind SemanticKind = dxbc::PSV::SemanticKind::Arbitrary;
+  SmallVector<uint32_t> SemanticIndices;
+  dxbc::PSV::InterpolationMode InterpMode =
+      dxbc::PSV::InterpolationMode::Undefined;
+  uint32_t Rows = 1;
+  uint8_t Cols = 1;
+  uint32_t StartRow = UnallocatedRow;
+  uint8_t StartCol = UnallocatedCol;
+  uint8_t UsageMask = 0;
+  uint8_t DynIndexMask = 0;
+  uint32_t GSStream = 0;
+
+  bool isAllocated() const {
+    return StartRow != UnallocatedRow && StartCol != UnallocatedCol;
+  }
+
+  uint8_t getDeclaredMask() const {
+    if (!isAllocated())
+      return 0;
+    return static_cast<uint8_t>(((1U << Cols) - 1U) << StartCol);
+  }
+
+  uint8_t getAlwaysReadsMask() const { return UsageMask; }
+
+  uint8_t getNeverWritesMask() const {
+    return static_cast<uint8_t>(~UsageMask & getDeclaredMask());
+  }
+
+  dxbc::SigMinPrecision getMinPrecision(bool UseMinPrecision) const {
+    if (!UseMinPrecision)
+      return dxbc::SigMinPrecision::Default;
+    switch (CompType) {
+    case dxil::ElementType::F16:
+      return dxbc::SigMinPrecision::Float16;
+    case dxil::ElementType::I16:
+    case dxil::ElementType::SNormF16:
+    case dxil::ElementType::UNormF16:
+      return dxbc::SigMinPrecision::SInt16;
----------------
inbelic wrote:

Good catch thanks

https://github.com/llvm/llvm-project/pull/209907