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

[Finn Plummer via cfe-commits]

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@@ -0,0 +1,417 @@
+#include "clang/Parse/ParseHLSLRootSignature.h"
+
+#include "clang/Lex/LiteralSupport.h"
+
+#include "llvm/Support/raw_ostream.h"
+
+using namespace llvm::hlsl::rootsig;
+
+namespace clang {
+namespace hlsl {
+
+static std::string FormatTokenKinds(ArrayRef<TokenKind> Kinds) {
+  std::string TokenString;
+  llvm::raw_string_ostream Out(TokenString);
+  bool First = true;
+  for (auto Kind : Kinds) {
+    if (!First)
+      Out << ", ";
+    switch (Kind) {
+#define TOK(X, SPELLING)                                                       \
+  case TokenKind::X:                                                           \
+    Out << SPELLING;                                                           \
+    break;
+#include "clang/Lex/HLSLRootSignatureTokenKinds.def"
+    }
+    First = false;
+  }
+
+  return TokenString;
+}
+
+// Parser Definitions
+
+RootSignatureParser::RootSignatureParser(SmallVector<RootElement> &Elements,
+                                         RootSignatureLexer &Lexer,
+                                         Preprocessor &PP)
+    : Elements(Elements), Lexer(Lexer), PP(PP), CurToken(SourceLocation()) {}
+
+bool RootSignatureParser::Parse() {
+  // Handle edge-case of empty RootSignature()
+  if (Lexer.EndOfBuffer())
+    return false;
+
+  // Iterate as many RootElements as possible
+  while (!ParseRootElement()) {
+    if (Lexer.EndOfBuffer())
+      return false;
+    if (ConsumeExpectedToken(TokenKind::pu_comma))
+      return true;
+  }
+
+  return true;
+}
+
+bool RootSignatureParser::ParseRootElement() {
+  if (ConsumeExpectedToken(TokenKind::kw_DescriptorTable))
+    return true;
+
+  // Dispatch onto the correct parse method
+  switch (CurToken.Kind) {
+  case TokenKind::kw_DescriptorTable:
+    return ParseDescriptorTable();
+  default:
+    break;
+  }
+  llvm_unreachable("Switch for an expected token was not provided");
+}
+
+bool RootSignatureParser::ParseDescriptorTable() {
+  DescriptorTable Table;
+
+  if (ConsumeExpectedToken(TokenKind::pu_l_paren))
+    return true;
+
+  // Empty case:
+  if (TryConsumeExpectedToken(TokenKind::pu_r_paren)) {
+    Elements.push_back(Table);
+    return false;
+  }
+
+  bool SeenVisibility = false;
+  // Iterate through all the defined clauses
+  do {
+    // Handle the visibility parameter
+    if (TryConsumeExpectedToken(TokenKind::kw_visibility)) {
+      if (SeenVisibility) {
+        Diags().Report(CurToken.TokLoc, diag::err_hlsl_rootsig_repeat_param)
+            << FormatTokenKinds(CurToken.Kind);
+        return true;
+      }
+      SeenVisibility = true;
+      if (ParseParam(&Table.Visibility))
+        return true;
+      continue;
+    }
+
+    // Otherwise, we expect a clause
+    if (ParseDescriptorTableClause())
+      return true;
+    Table.NumClauses++;
+  } while (TryConsumeExpectedToken(TokenKind::pu_comma));
+
+  if (ConsumeExpectedToken(TokenKind::pu_r_paren))
+    return true;
+
+  Elements.push_back(Table);
+  return false;
+}
+
+bool RootSignatureParser::ParseDescriptorTableClause() {
+  if (ConsumeExpectedToken({TokenKind::kw_CBV, TokenKind::kw_SRV,
+                            TokenKind::kw_UAV, TokenKind::kw_Sampler}))
+    return true;
+
+  DescriptorTableClause Clause;
+  switch (CurToken.Kind) {
+  case TokenKind::kw_CBV:
+    Clause.Type = ClauseType::CBuffer;
+    break;
+  case TokenKind::kw_SRV:
+    Clause.Type = ClauseType::SRV;
+    break;
+  case TokenKind::kw_UAV:
+    Clause.Type = ClauseType::UAV;
+    break;
+  case TokenKind::kw_Sampler:
+    Clause.Type = ClauseType::Sampler;
+    break;
+  default:
+    llvm_unreachable("Switch for an expected token was not provided");
----------------
inbelic wrote:

Forwarding this for visibility: https://github.com/llvm/llvm-project/pull/122982#discussion_r1953996279

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