[llvm-branch-commits] [clang] [llvm] [HLSL][RootSignature] Implement Parsing of Descriptor Tables (PR #122982)

Finn Plummer via llvm-branch-commits llvm-branch-commits at lists.llvm.org
Fri Jan 17 16:12:05 PST 2025


https://github.com/inbelic updated https://github.com/llvm/llvm-project/pull/122982

>From 58ef8ad2d3d9bfa008745b35f1514222c13b773a Mon Sep 17 00:00:00 2001
From: Finn Plummer <canadienfinn at gmail.com>
Date: Tue, 14 Jan 2025 22:23:22 +0000
Subject: [PATCH 1/3] [HLSL][RootSignature] Implement Parsing of Descriptor
 Tables

- Defines the in-memory data layout for the Descriptor Table Clauses,
its dependent flags/enums and parent RootElement in HLSLRootSignature.h
- Implements a Parser and its required Parsing methods in
ParseHLSLRootSignature
---
 .../clang/Parse/ParseHLSLRootSignature.h      |  68 ++++
 clang/lib/Parse/ParseHLSLRootSignature.cpp    | 327 ++++++++++++++++++
 .../Parse/ParseHLSLRootSignatureTest.cpp      |  85 +++++
 .../llvm/Frontend/HLSL/HLSLRootSignature.h    | 140 ++++++++
 4 files changed, 620 insertions(+)
 create mode 100644 llvm/include/llvm/Frontend/HLSL/HLSLRootSignature.h

diff --git a/clang/include/clang/Parse/ParseHLSLRootSignature.h b/clang/include/clang/Parse/ParseHLSLRootSignature.h
index 6c534411e754a0..9464bd8f2f9e0f 100644
--- a/clang/include/clang/Parse/ParseHLSLRootSignature.h
+++ b/clang/include/clang/Parse/ParseHLSLRootSignature.h
@@ -21,6 +21,8 @@
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/StringSwitch.h"
 
+#include "llvm/Frontend/HLSL/HLSLRootSignature.h"
+
 namespace llvm {
 namespace hlsl {
 namespace root_signature {
@@ -89,6 +91,72 @@ class RootSignatureLexer {
   }
 };
 
+class RootSignatureParser {
+public:
+  RootSignatureParser(SmallVector<RootElement> &Elements,
+                      const SmallVector<RootSignatureToken> &Tokens);
+
+  // Iterates over the provided tokens and constructs the in-memory
+  // representations of the RootElements.
+  //
+  // The return value denotes if there was a failure and the method will
+  // return on the first encountered failure, or, return false if it
+  // can sucessfully reach the end of the tokens.
+  bool Parse();
+
+private:
+  bool ReportError(); // TODO: Implement this to report error through Diags
+
+  // Root Element helpers
+  bool ParseRootElement();
+  bool ParseDescriptorTable();
+  bool ParseDescriptorTableClause();
+
+  // Common parsing helpers
+  bool ParseRegister(Register &Register);
+
+  // Various flags/enum parsing helpers
+  bool ParseDescriptorRangeFlags(DescriptorRangeFlags &Flags);
+  bool ParseShaderVisibility(ShaderVisibility &Flag);
+
+  // Increment the token iterator if we have not reached the end.
+  // Return value denotes if we were already at the last token.
+  bool ConsumeNextToken();
+
+  // Attempt to retrieve the next token, if TokenKind is invalid then there was
+  // no next token.
+  RootSignatureToken PeekNextToken();
+
+  // Peek if the next token is of the expected kind.
+  //
+  // Return value denotes if it failed to match the expected kind, either it is
+  // the end of the stream or it didn't match any of the expected kinds.
+  bool PeekExpectedToken(TokenKind Expected);
+  bool PeekExpectedToken(ArrayRef<TokenKind> AnyExpected);
+
+  // Consume the next token and report an error if it is not of the expected
+  // kind.
+  //
+  // Return value denotes if it failed to match the expected kind, either it is
+  // the end of the stream or it didn't match any of the expected kinds.
+  bool ConsumeExpectedToken(TokenKind Expected);
+  bool ConsumeExpectedToken(ArrayRef<TokenKind> AnyExpected);
+
+  // Peek if the next token is of the expected kind and if it is then consume
+  // it.
+  //
+  // Return value denotes if it failed to match the expected kind, either it is
+  // the end of the stream or it didn't match any of the expected kinds. It will
+  // not report an error if there isn't a match.
+  bool TryConsumeExpectedToken(TokenKind Expected);
+  bool TryConsumeExpectedToken(ArrayRef<TokenKind> Expected);
+
+private:
+  SmallVector<RootElement> &Elements;
+  SmallVector<RootSignatureToken>::const_iterator CurTok;
+  SmallVector<RootSignatureToken>::const_iterator LastTok;
+};
+
 } // namespace root_signature
 } // namespace hlsl
 } // namespace llvm
diff --git a/clang/lib/Parse/ParseHLSLRootSignature.cpp b/clang/lib/Parse/ParseHLSLRootSignature.cpp
index fac4a92f1920be..c5e6dd112c6fae 100644
--- a/clang/lib/Parse/ParseHLSLRootSignature.cpp
+++ b/clang/lib/Parse/ParseHLSLRootSignature.cpp
@@ -148,6 +148,333 @@ bool RootSignatureLexer::LexToken(RootSignatureToken &Result) {
   return false;
 }
 
+// Parser Definitions
+
+RootSignatureParser::RootSignatureParser(
+    SmallVector<RootElement> &Elements,
+    const SmallVector<RootSignatureToken> &Tokens)
+    : Elements(Elements) {
+  CurTok = Tokens.begin();
+  LastTok = Tokens.end();
+}
+
+bool RootSignatureParser::ReportError() { return true; }
+
+bool RootSignatureParser::Parse() {
+  CurTok--; // Decrement once here so we can use the ...ExpectedToken api
+
+  // Iterate as many RootElements as possible
+  bool HasComma = true;
+  while (HasComma &&
+         !TryConsumeExpectedToken(ArrayRef{TokenKind::kw_DescriptorTable})) {
+    if (ParseRootElement())
+      return true;
+    HasComma = !TryConsumeExpectedToken(TokenKind::pu_comma);
+  }
+  if (HasComma)
+    return ReportError(); // report 'comma' denotes a required extra item
+
+  // Ensure that we are at the end of the tokens
+  CurTok++;
+  if (CurTok != LastTok)
+    return ReportError(); // report expected end of input but got more
+  return false;
+}
+
+bool RootSignatureParser::ParseRootElement() {
+  // Dispatch onto the correct parse method
+  switch (CurTok->Kind) {
+  case TokenKind::kw_DescriptorTable:
+    return ParseDescriptorTable();
+  default:
+    llvm_unreachable("Switch for an expected token was not provided");
+    return true;
+  }
+}
+
+bool RootSignatureParser::ParseDescriptorTable() {
+  DescriptorTable Table;
+
+  if (ConsumeExpectedToken(TokenKind::pu_l_paren))
+    return true;
+
+  // Iterate as many DescriptorTableClaues as possible
+  bool HasComma = true;
+  while (!TryConsumeExpectedToken({TokenKind::kw_CBV, TokenKind::kw_SRV,
+                                   TokenKind::kw_UAV, TokenKind::kw_Sampler})) {
+    if (ParseDescriptorTableClause())
+      return true;
+    Table.NumClauses++;
+    HasComma = !TryConsumeExpectedToken(TokenKind::pu_comma);
+  }
+
+  // Consume optional 'visibility' paramater
+  if (HasComma && !TryConsumeExpectedToken(TokenKind::kw_visibility)) {
+    if (ConsumeExpectedToken(TokenKind::pu_equal))
+      return true;
+
+    if (ParseShaderVisibility(Table.Visibility))
+      return true;
+
+    HasComma = !TryConsumeExpectedToken(TokenKind::pu_comma);
+  }
+
+  if (HasComma)
+    return ReportError(); // report 'comma' denotes a required extra item
+
+  if (ConsumeExpectedToken(TokenKind::pu_r_paren))
+    return true;
+
+  Elements.push_back(RootElement(Table));
+  return false;
+}
+
+bool RootSignatureParser::ParseDescriptorTableClause() {
+  // Determine the type of Clause first so we can initialize the struct with
+  // the correct default flags
+  ClauseType CT;
+  switch (CurTok->Kind) {
+  case TokenKind::kw_CBV:
+    CT = ClauseType::CBV;
+    break;
+  case TokenKind::kw_SRV:
+    CT = ClauseType::SRV;
+    break;
+  case TokenKind::kw_UAV:
+    CT = ClauseType::UAV;
+    break;
+  case TokenKind::kw_Sampler:
+    CT = ClauseType::Sampler;
+    break;
+  default:
+    llvm_unreachable("Switch for an expected token was not provided");
+    return true;
+  }
+  DescriptorTableClause Clause(CT);
+
+  if (ConsumeExpectedToken(TokenKind::pu_l_paren))
+    return true;
+
+  // Consume mandatory Register paramater
+  if (ConsumeExpectedToken(
+          {TokenKind::bReg, TokenKind::tReg, TokenKind::uReg, TokenKind::sReg}))
+    return true;
+  if (ParseRegister(Clause.Register))
+    return true;
+
+  // Start parsing the optional parameters
+  bool HasComma = !TryConsumeExpectedToken(TokenKind::pu_comma);
+
+  // Consume optional 'numDescriptors' paramater
+  if (HasComma && !TryConsumeExpectedToken(TokenKind::kw_numDescriptors)) {
+    if (ConsumeExpectedToken(TokenKind::pu_equal))
+      return true;
+    if (ConsumeExpectedToken(TokenKind::int_literal))
+      return true;
+
+    Clause.NumDescriptors = CurTok->IntLiteral;
+
+    HasComma = !TryConsumeExpectedToken(TokenKind::pu_comma);
+  }
+
+  // Consume optional 'space' paramater
+  if (HasComma && !TryConsumeExpectedToken(TokenKind::kw_space)) {
+    if (ConsumeExpectedToken(TokenKind::pu_equal))
+      return true;
+    if (ConsumeExpectedToken(TokenKind::int_literal))
+      return true;
+
+    Clause.Space = CurTok->IntLiteral;
+
+    HasComma = !TryConsumeExpectedToken(TokenKind::pu_comma);
+  }
+
+  // Consume optional 'offset' paramater
+  if (HasComma && !TryConsumeExpectedToken(TokenKind::kw_offset)) {
+    if (ConsumeExpectedToken(TokenKind::pu_equal))
+      return true;
+    if (ConsumeExpectedToken(ArrayRef{
+            TokenKind::int_literal, TokenKind::en_DescriptorRangeOffsetAppend}))
+      return true;
+
+    // Offset defaults to DescriptorTableOffsetAppend so only change if we have
+    // an int arg
+    if (CurTok->Kind == TokenKind::int_literal)
+      Clause.Offset = CurTok->IntLiteral;
+
+    HasComma = !TryConsumeExpectedToken(TokenKind::pu_comma);
+  }
+
+  // Consume optional 'flags' paramater
+  if (HasComma && !TryConsumeExpectedToken(TokenKind::kw_flags)) {
+    if (ConsumeExpectedToken(TokenKind::pu_equal))
+      return true;
+    if (ParseDescriptorRangeFlags(Clause.Flags))
+      return true;
+
+    HasComma = !TryConsumeExpectedToken(TokenKind::pu_comma);
+  }
+
+  if (HasComma)
+    return ReportError(); // report 'comma' denotes a required extra item
+  if (ConsumeExpectedToken(TokenKind::pu_r_paren))
+    return true;
+
+  Elements.push_back(Clause);
+  return false;
+}
+
+bool RootSignatureParser::ParseRegister(Register &Register) {
+  switch (CurTok->Kind) {
+  case TokenKind::bReg:
+    Register.ViewType = RegisterType::BReg;
+    break;
+  case TokenKind::tReg:
+    Register.ViewType = RegisterType::TReg;
+    break;
+  case TokenKind::uReg:
+    Register.ViewType = RegisterType::UReg;
+    break;
+  case TokenKind::sReg:
+    Register.ViewType = RegisterType::SReg;
+    break;
+  default:
+    llvm_unreachable("Switch for an expected token was not provided");
+    return true;
+  }
+
+  Register.Number = CurTok->IntLiteral;
+
+  return false;
+}
+
+bool RootSignatureParser::ParseDescriptorRangeFlags(
+    DescriptorRangeFlags &Flags) {
+
+  // Define the possible flag kinds
+  SmallVector<TokenKind> FlagToks = {
+      TokenKind::int_literal, // This is used to capture the possible '0'
+#define DESCRIPTOR_RANGE_FLAG_ENUM(NAME, LIT, ON) TokenKind::en_##NAME,
+#include "clang/Parse/HLSLRootSignatureTokenKinds.def"
+  };
+
+  if (PeekExpectedToken(FlagToks))
+    return ReportError(); // report there must be at least one flag specified
+
+  // Since there is at least one flag specified then reset the default flag
+  Flags = DescriptorRangeFlags::None;
+
+  // Iterate over the given list of flags
+  bool HasOr = true;
+  while (HasOr && !TryConsumeExpectedToken(FlagToks)) {
+    switch (CurTok->Kind) {
+    case TokenKind::int_literal: {
+      if (CurTok->IntLiteral != 0)
+        return ReportError(); // report invalid flag value error
+      // No need to 'or' with 0 so just break
+      break;
+    }
+    // Set each specified flag set in the flags
+#define DESCRIPTOR_RANGE_FLAG_ENUM(NAME, LIT, ON)                              \
+  case TokenKind::en_##NAME: {                                                 \
+    Flags |= DescriptorRangeFlags::NAME;                                       \
+    break;                                                                     \
+  }
+#include "clang/Parse/HLSLRootSignatureTokenKinds.def"
+    default:
+      llvm_unreachable("Switch for an expected token was not provided");
+      return true;
+    }
+    HasOr = !TryConsumeExpectedToken(TokenKind::pu_or);
+  }
+  if (HasOr)
+    return ReportError(); // report 'or' denotes a required extra item
+
+  return false;
+}
+
+bool RootSignatureParser::ParseShaderVisibility(ShaderVisibility &Flag) {
+
+  // Define the possible flag kinds
+  SmallVector<TokenKind> FlagToks = {
+#define SHADER_VISIBILITY_ENUM(NAME, LIT) TokenKind::en_##NAME,
+#include "clang/Parse/HLSLRootSignatureTokenKinds.def"
+  };
+
+  // Required mandatory flag argument
+  if (ConsumeExpectedToken(FlagToks))
+    return true;
+
+  switch (CurTok->Kind) {
+#define SHADER_VISIBILITY_ENUM(NAME, LIT)                                      \
+  case TokenKind::en_##NAME: {                                                 \
+    Flag = ShaderVisibility::NAME;                                             \
+    break;                                                                     \
+  }
+#include "clang/Parse/HLSLRootSignatureTokenKinds.def"
+  default:
+    llvm_unreachable("Switch for an expected token was not provided");
+    return true;
+  }
+
+  return false;
+}
+
+RootSignatureToken RootSignatureParser::PeekNextToken() {
+  RootSignatureToken Token; // Defaults to invalid kind
+  if (CurTok != LastTok)
+    Token = *(CurTok + 1);
+  return Token;
+}
+
+bool RootSignatureParser::ConsumeNextToken() {
+  if (CurTok == LastTok)
+    return ReportError(); // Report unexpected end of tokens error
+  CurTok++;
+  return false;
+}
+
+bool RootSignatureParser::PeekExpectedToken(TokenKind Expected) {
+  return PeekExpectedToken(ArrayRef{Expected});
+}
+
+bool RootSignatureParser::PeekExpectedToken(ArrayRef<TokenKind> AnyExpected) {
+  RootSignatureToken Token = PeekNextToken();
+  if (Token.Kind == TokenKind::invalid)
+    return true;
+  for (auto Expected : AnyExpected) {
+    if (Token.Kind == Expected)
+      return false;
+  }
+  return true;
+}
+
+bool RootSignatureParser::ConsumeExpectedToken(TokenKind Expected) {
+  return ConsumeExpectedToken(ArrayRef{Expected});
+}
+
+bool RootSignatureParser::ConsumeExpectedToken(
+    ArrayRef<TokenKind> AnyExpected) {
+  if (ConsumeNextToken())
+    return true;
+  for (auto Expected : AnyExpected) {
+    if (CurTok->Kind == Expected)
+      return false;
+  }
+  return ReportError(); // Report unexpected token kind error
+}
+
+bool RootSignatureParser::TryConsumeExpectedToken(TokenKind Expected) {
+  return TryConsumeExpectedToken(ArrayRef{Expected});
+}
+
+bool RootSignatureParser::TryConsumeExpectedToken(
+    ArrayRef<TokenKind> AnyExpected) {
+  if (PeekExpectedToken(AnyExpected))
+    return true;
+  return ConsumeNextToken();
+}
+
 } // namespace root_signature
 } // namespace hlsl
 } // namespace llvm
diff --git a/clang/unittests/Parse/ParseHLSLRootSignatureTest.cpp b/clang/unittests/Parse/ParseHLSLRootSignatureTest.cpp
index 42c57731ddb804..6a2ab179edae33 100644
--- a/clang/unittests/Parse/ParseHLSLRootSignatureTest.cpp
+++ b/clang/unittests/Parse/ParseHLSLRootSignatureTest.cpp
@@ -130,4 +130,89 @@ TEST_F(ParseHLSLRootSignatureTest, LexValidTokensTest) {
   CheckTokens(Tokens, Expected);
 }
 
+TEST_F(ParseHLSLRootSignatureTest, ParseValidDTClausesTest) {
+  const llvm::StringLiteral Source = R"cc(
+    DescriptorTable(
+      CBV(b0),
+      SRV(t42, numDescriptors = 4, offset = 32),
+      Sampler(s987, space = 2, flags = 0),
+      UAV(u987234,
+        flags = Descriptors_Volatile | Data_Volatile
+              | Data_Static_While_Set_At_Execute | Data_Static
+              | Descriptors_Static_Keeping_Buffer_Bounds_Checks
+      ),
+      visibility = Shader_Visibility_Pixel
+    )
+  )cc";
+
+  TrivialModuleLoader ModLoader;
+  Preprocessor *PP = CreatePP(Source, ModLoader);
+  auto TokLoc = SourceLocation();
+
+  RootSignatureLexer Lexer(Source, TokLoc, *PP);
+
+  SmallVector<RootSignatureToken> Tokens;
+  ASSERT_FALSE(Lexer.Lex(Tokens));
+
+  SmallVector<RootElement> Elements;
+  RootSignatureParser Parser(Elements, Tokens);
+
+  ASSERT_FALSE(Parser.Parse());
+  ASSERT_EQ((int)Elements.size(), 5);
+
+  // Test default values are set correctly
+  RootElement Elem = Elements[0];
+  ASSERT_EQ(Elem.Tag, RootElement::ElementType::DescriptorTableClause);
+  ASSERT_EQ(Elem.Clause.Type, ClauseType::CBV);
+  ASSERT_EQ(Elem.Clause.Register.ViewType, RegisterType::BReg);
+  ASSERT_EQ(Elem.Clause.Register.Number, (uint32_t)0);
+  ASSERT_EQ(Elem.Clause.NumDescriptors, (uint32_t)1);
+  ASSERT_EQ(Elem.Clause.Space, (uint32_t)0);
+  ASSERT_EQ(Elem.Clause.Offset, (uint32_t)DescriptorTableOffsetAppend);
+  ASSERT_EQ(Elem.Clause.Flags,
+            DescriptorRangeFlags::DataStaticWhileSetAtExecute);
+
+  // Test optionally specified 'numDescriptors' and 'offset' parameters
+  Elem = Elements[1];
+  ASSERT_EQ(Elem.Tag, RootElement::ElementType::DescriptorTableClause);
+  ASSERT_EQ(Elem.Clause.Type, ClauseType::SRV);
+  ASSERT_EQ(Elem.Clause.Register.ViewType, RegisterType::TReg);
+  ASSERT_EQ(Elem.Clause.Register.Number, (uint32_t)42);
+  ASSERT_EQ(Elem.Clause.NumDescriptors, (uint32_t)4);
+  ASSERT_EQ(Elem.Clause.Space, (uint32_t)0);
+  ASSERT_EQ(Elem.Clause.Offset, (uint32_t)32);
+  ASSERT_EQ(Elem.Clause.Flags,
+            DescriptorRangeFlags::DataStaticWhileSetAtExecute);
+
+  // Test specified 'space' and the '0' flag in 'flags'
+  Elem = Elements[2];
+  ASSERT_EQ(Elem.Tag, RootElement::ElementType::DescriptorTableClause);
+  ASSERT_EQ(Elem.Clause.Type, ClauseType::Sampler);
+  ASSERT_EQ(Elem.Clause.Register.ViewType, RegisterType::SReg);
+  ASSERT_EQ(Elem.Clause.Register.Number, (uint32_t)987);
+  ASSERT_EQ(Elem.Clause.NumDescriptors, (uint32_t)1);
+  ASSERT_EQ(Elem.Clause.Space, (uint32_t)2);
+  ASSERT_EQ(Elem.Clause.Offset, (uint32_t)DescriptorTableOffsetAppend);
+  ASSERT_EQ(Elem.Clause.Flags, DescriptorRangeFlags::None);
+
+  // Test that we can specify all valid flags
+  Elem = Elements[3];
+  ASSERT_EQ(Elem.Tag, RootElement::ElementType::DescriptorTableClause);
+  ASSERT_EQ(Elem.Clause.Type, ClauseType::UAV);
+  ASSERT_EQ(Elem.Clause.Register.ViewType, RegisterType::UReg);
+  ASSERT_EQ(Elem.Clause.Register.Number, (uint32_t)987234);
+  ASSERT_EQ(Elem.Clause.NumDescriptors, (uint32_t)1);
+  ASSERT_EQ(Elem.Clause.Space, (uint32_t)0);
+  ASSERT_EQ(Elem.Clause.Offset, (uint32_t)DescriptorTableOffsetAppend);
+  ASSERT_EQ(Elem.Clause.Flags, DescriptorRangeFlags::ValidFlags);
+
+  // Test generated DescriptorTable start has correct values
+  Elem = Elements[4];
+  ASSERT_EQ(Elem.Tag, RootElement::ElementType::DescriptorTable);
+  ASSERT_EQ(Elem.Table.NumClauses, (uint32_t)4);
+  ASSERT_EQ(Elem.Table.Visibility, ShaderVisibility::Pixel);
+
+  delete PP;
+}
+
 } // anonymous namespace
diff --git a/llvm/include/llvm/Frontend/HLSL/HLSLRootSignature.h b/llvm/include/llvm/Frontend/HLSL/HLSLRootSignature.h
new file mode 100644
index 00000000000000..7707180f8a4942
--- /dev/null
+++ b/llvm/include/llvm/Frontend/HLSL/HLSLRootSignature.h
@@ -0,0 +1,140 @@
+//===- 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 <stdint.h>
+
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/Support/Endian.h"
+
+namespace llvm {
+namespace hlsl {
+namespace root_signature {
+
+// This is a copy from DebugInfo/CodeView/CodeView.h
+#define RS_DEFINE_ENUM_CLASS_FLAGS_OPERATORS(Class)                            \
+  inline Class operator|(Class a, Class b) {                                   \
+    return static_cast<Class>(llvm::to_underlying(a) |                         \
+                              llvm::to_underlying(b));                         \
+  }                                                                            \
+  inline Class operator&(Class a, Class b) {                                   \
+    return static_cast<Class>(llvm::to_underlying(a) &                         \
+                              llvm::to_underlying(b));                         \
+  }                                                                            \
+  inline Class operator~(Class a) {                                            \
+    return static_cast<Class>(~llvm::to_underlying(a));                        \
+  }                                                                            \
+  inline Class &operator|=(Class &a, Class b) {                                \
+    a = a | b;                                                                 \
+    return a;                                                                  \
+  }                                                                            \
+  inline Class &operator&=(Class &a, Class b) {                                \
+    a = a & b;                                                                 \
+    return a;                                                                  \
+  }
+
+// Definition of the various enumerations and flags
+enum class DescriptorRangeFlags : unsigned {
+  None = 0,
+  DescriptorsVolatile = 0x1,
+  DataVolatile = 0x2,
+  DataStaticWhileSetAtExecute = 0x4,
+  DataStatic = 0x8,
+  DescriptorsStaticKeepingBufferBoundsChecks = 0x10000,
+  ValidFlags = 0x1000f,
+  ValidSamplerFlags = DescriptorsVolatile,
+};
+RS_DEFINE_ENUM_CLASS_FLAGS_OPERATORS(DescriptorRangeFlags)
+
+enum class ShaderVisibility {
+  All = 0,
+  Vertex = 1,
+  Hull = 2,
+  Domain = 3,
+  Geometry = 4,
+  Pixel = 5,
+  Amplification = 6,
+  Mesh = 7,
+};
+
+// Definitions of the in-memory data layout structures
+
+// Models the different registers: bReg | tReg | uReg | sReg
+enum class RegisterType { BReg, TReg, UReg, SReg };
+struct Register {
+  RegisterType ViewType;
+  uint32_t Number;
+};
+
+static const uint32_t DescriptorTableOffsetAppend = 0xffffffff;
+// Models DTClause : CBV | SRV | UAV | Sampler by collecting like parameters
+enum class ClauseType { CBV, SRV, UAV, Sampler };
+struct DescriptorTableClause {
+  ClauseType Type;
+  Register Register;
+  uint32_t NumDescriptors = 1;
+  uint32_t Space = 0;
+  uint32_t Offset = DescriptorTableOffsetAppend;
+  DescriptorRangeFlags Flags;
+
+  DescriptorTableClause(ClauseType Type) : Type(Type) {
+    switch (Type) {
+    case ClauseType::CBV:
+      Flags = DescriptorRangeFlags::DataStaticWhileSetAtExecute;
+      break;
+    case ClauseType::SRV:
+      Flags = DescriptorRangeFlags::DataStaticWhileSetAtExecute;
+      break;
+    case ClauseType::UAV:
+      Flags = DescriptorRangeFlags::DataVolatile;
+      break;
+    case ClauseType::Sampler:
+      Flags = DescriptorRangeFlags::None;
+      break;
+    }
+  }
+};
+
+// Models the end of a descriptor table and stores its visibility
+struct DescriptorTable {
+  ShaderVisibility Visibility = ShaderVisibility::All;
+  uint32_t NumClauses = 0; // The number of clauses in the table
+};
+
+// Models RootElement : DescriptorTable | DescriptorTableClause
+struct RootElement {
+  enum class ElementType {
+    DescriptorTable,
+    DescriptorTableClause,
+  };
+
+  ElementType Tag;
+  union {
+    DescriptorTable Table;
+    DescriptorTableClause Clause;
+  };
+
+  // Constructors
+  RootElement(DescriptorTable Table)
+      : Tag(ElementType::DescriptorTable), Table(Table) {}
+  RootElement(DescriptorTableClause Clause)
+      : Tag(ElementType::DescriptorTableClause), Clause(Clause) {}
+};
+
+} // namespace root_signature
+} // namespace hlsl
+} // namespace llvm
+
+#endif // LLVM_FRONTEND_HLSL_HLSLROOTSIGNATURE_H

>From 5efadf0390d3fbb33ea41b2bf2335d6c1b078333 Mon Sep 17 00:00:00 2001
From: Finn Plummer <canadienfinn at gmail.com>
Date: Tue, 14 Jan 2025 23:21:02 +0000
Subject: [PATCH 2/3] add extra default visibility testcase

- also catches a small error for no clauses edge case
---
 clang/lib/Parse/ParseHLSLRootSignature.cpp           |  2 +-
 clang/unittests/Parse/ParseHLSLRootSignatureTest.cpp | 11 +++++++++--
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/clang/lib/Parse/ParseHLSLRootSignature.cpp b/clang/lib/Parse/ParseHLSLRootSignature.cpp
index c5e6dd112c6fae..ce62526c6d88bc 100644
--- a/clang/lib/Parse/ParseHLSLRootSignature.cpp
+++ b/clang/lib/Parse/ParseHLSLRootSignature.cpp
@@ -219,7 +219,7 @@ bool RootSignatureParser::ParseDescriptorTable() {
     HasComma = !TryConsumeExpectedToken(TokenKind::pu_comma);
   }
 
-  if (HasComma)
+  if (HasComma && Table.NumClauses != 0)
     return ReportError(); // report 'comma' denotes a required extra item
 
   if (ConsumeExpectedToken(TokenKind::pu_r_paren))
diff --git a/clang/unittests/Parse/ParseHLSLRootSignatureTest.cpp b/clang/unittests/Parse/ParseHLSLRootSignatureTest.cpp
index 6a2ab179edae33..d13b70d9428078 100644
--- a/clang/unittests/Parse/ParseHLSLRootSignatureTest.cpp
+++ b/clang/unittests/Parse/ParseHLSLRootSignatureTest.cpp
@@ -142,7 +142,8 @@ TEST_F(ParseHLSLRootSignatureTest, ParseValidDTClausesTest) {
               | Descriptors_Static_Keeping_Buffer_Bounds_Checks
       ),
       visibility = Shader_Visibility_Pixel
-    )
+    ),
+    DescriptorTable()
   )cc";
 
   TrivialModuleLoader ModLoader;
@@ -158,7 +159,7 @@ TEST_F(ParseHLSLRootSignatureTest, ParseValidDTClausesTest) {
   RootSignatureParser Parser(Elements, Tokens);
 
   ASSERT_FALSE(Parser.Parse());
-  ASSERT_EQ((int)Elements.size(), 5);
+  ASSERT_EQ((int)Elements.size(), 6);
 
   // Test default values are set correctly
   RootElement Elem = Elements[0];
@@ -212,6 +213,12 @@ TEST_F(ParseHLSLRootSignatureTest, ParseValidDTClausesTest) {
   ASSERT_EQ(Elem.Table.NumClauses, (uint32_t)4);
   ASSERT_EQ(Elem.Table.Visibility, ShaderVisibility::Pixel);
 
+  // Test generated DescriptorTable start has correct default values
+  Elem = Elements[5];
+  ASSERT_EQ(Elem.Tag, RootElement::ElementType::DescriptorTable);
+  ASSERT_EQ(Elem.Table.NumClauses, (uint32_t)0);
+  ASSERT_EQ(Elem.Table.Visibility, ShaderVisibility::All);
+
   delete PP;
 }
 

>From cac95d10450c3dc4976d83ff8015b25a6718c3ec Mon Sep 17 00:00:00 2001
From: Finn Plummer <canadienfinn at gmail.com>
Date: Sat, 18 Jan 2025 00:11:40 +0000
Subject: [PATCH 3/3] rebase onto unique_ptr change

---
 clang/unittests/Parse/ParseHLSLRootSignatureTest.cpp | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/clang/unittests/Parse/ParseHLSLRootSignatureTest.cpp b/clang/unittests/Parse/ParseHLSLRootSignatureTest.cpp
index d13b70d9428078..68446b88e977dc 100644
--- a/clang/unittests/Parse/ParseHLSLRootSignatureTest.cpp
+++ b/clang/unittests/Parse/ParseHLSLRootSignatureTest.cpp
@@ -147,7 +147,7 @@ TEST_F(ParseHLSLRootSignatureTest, ParseValidDTClausesTest) {
   )cc";
 
   TrivialModuleLoader ModLoader;
-  Preprocessor *PP = CreatePP(Source, ModLoader);
+  auto PP = CreatePP(Source, ModLoader);
   auto TokLoc = SourceLocation();
 
   RootSignatureLexer Lexer(Source, TokLoc, *PP);
@@ -218,8 +218,6 @@ TEST_F(ParseHLSLRootSignatureTest, ParseValidDTClausesTest) {
   ASSERT_EQ(Elem.Tag, RootElement::ElementType::DescriptorTable);
   ASSERT_EQ(Elem.Table.NumClauses, (uint32_t)0);
   ASSERT_EQ(Elem.Table.Visibility, ShaderVisibility::All);
-
-  delete PP;
 }
 
 } // anonymous namespace



More information about the llvm-branch-commits mailing list