improve diagnostics for root descriptors

Author: inbelic

clang/include/clang/Parse/ParseHLSLRootSignature.h

@@ -100,7 +100,8 @@ class RootSignatureParser {
     std::optional<llvm::dxbc::RootDescriptorFlags> Flags;
   };
   std::optional<ParsedRootDescriptorParams>
-  parseRootDescriptorParams(RootSignatureToken::Kind RegType);
+  parseRootDescriptorParams(RootSignatureToken::Kind DescType,
+                            RootSignatureToken::Kind RegType);
 
   struct ParsedClauseParams {
     std::optional<llvm::hlsl::rootsig::Register> Reg;

clang/lib/Parse/ParseHLSLRootSignature.cpp

@@ -209,10 +209,13 @@ std::optional<RootDescriptor> RootSignatureParser::parseRootDescriptor() {
   }
   Descriptor.setDefaultFlags(Version);
 
-  auto Params = parseRootDescriptorParams(ExpectedReg);
+  auto Params = parseRootDescriptorParams(DescriptorKind, ExpectedReg);
   if (!Params.has_value())
     return std::nullopt;
 
+  if (consumeExpectedToken(TokenKind::pu_r_paren))
+    return std::nullopt;
+
   // Check mandatory parameters were provided
   if (!Params->Reg.has_value()) {
     reportDiag(diag::err_hlsl_rootsig_missing_param) << ExpectedReg;
@@ -231,9 +234,6 @@ std::optional<RootDescriptor> RootSignatureParser::parseRootDescriptor() {
   if (Params->Flags.has_value())
     Descriptor.Flags = Params->Flags.value();
 
-  if (consumeExpectedToken(TokenKind::pu_r_paren))
-    return std::nullopt;
-
   return Descriptor;
 }
 
@@ -503,14 +503,15 @@ RootSignatureParser::parseRootConstantParams() {
 }
 
 std::optional<RootSignatureParser::ParsedRootDescriptorParams>
-RootSignatureParser::parseRootDescriptorParams(TokenKind RegType) {
+RootSignatureParser::parseRootDescriptorParams(TokenKind DescType,
+                                               TokenKind RegType) {
   assert(CurToken.TokKind == TokenKind::pu_l_paren &&
          "Expects to only be invoked starting at given token");
 
   ParsedRootDescriptorParams Params;
-  do {
-    // ( `b` | `t` | `u`) POS_INT
+  while (!peekExpectedToken(TokenKind::pu_r_paren)) {
     if (tryConsumeExpectedToken(RegType)) {
+      // ( `b` | `t` | `u`) POS_INT
       if (Params.Reg.has_value()) {
         reportDiag(diag::err_hlsl_rootsig_repeat_param) << CurToken.TokKind;
         return std::nullopt;
@@ -519,10 +520,8 @@ RootSignatureParser::parseRootDescriptorParams(TokenKind RegType) {
       if (!Reg.has_value())
         return std::nullopt;
       Params.Reg = Reg;
-    }
-
-    // `space` `=` POS_INT
-    if (tryConsumeExpectedToken(TokenKind::kw_space)) {
+    } else if (tryConsumeExpectedToken(TokenKind::kw_space)) {
+      // `space` `=` POS_INT
       if (Params.Space.has_value()) {
         reportDiag(diag::err_hlsl_rootsig_repeat_param) << CurToken.TokKind;
         return std::nullopt;
@@ -535,10 +534,8 @@ RootSignatureParser::parseRootDescriptorParams(TokenKind RegType) {
       if (!Space.has_value())
         return std::nullopt;
       Params.Space = Space;
-    }
-
-    // `visibility` `=` SHADER_VISIBILITY
-    if (tryConsumeExpectedToken(TokenKind::kw_visibility)) {
+    } else if (tryConsumeExpectedToken(TokenKind::kw_visibility)) {
+      // `visibility` `=` SHADER_VISIBILITY
       if (Params.Visibility.has_value()) {
         reportDiag(diag::err_hlsl_rootsig_repeat_param) << CurToken.TokKind;
         return std::nullopt;
@@ -551,10 +548,8 @@ RootSignatureParser::parseRootDescriptorParams(TokenKind RegType) {
       if (!Visibility.has_value())
         return std::nullopt;
       Params.Visibility = Visibility;
-    }
-
-    // `flags` `=` ROOT_DESCRIPTOR_FLAGS
-    if (tryConsumeExpectedToken(TokenKind::kw_flags)) {
+    } else if (tryConsumeExpectedToken(TokenKind::kw_flags)) {
+      // `flags` `=` ROOT_DESCRIPTOR_FLAGS
       if (Params.Flags.has_value()) {
         reportDiag(diag::err_hlsl_rootsig_repeat_param) << CurToken.TokKind;
         return std::nullopt;
@@ -567,8 +562,16 @@ RootSignatureParser::parseRootDescriptorParams(TokenKind RegType) {
       if (!Flags.has_value())
         return std::nullopt;
       Params.Flags = Flags;
+    } else {
+      consumeNextToken(); // position to start of invalid token
+      reportDiag(diag::err_hlsl_rootsig_invalid_param) << /*param of=*/DescType;
+      return std::nullopt;
     }
-  } while (tryConsumeExpectedToken(TokenKind::pu_comma));
+
+    // ',' denotes another element, otherwise, expected to be at ')'
+    if (!tryConsumeExpectedToken(TokenKind::pu_comma))
+      break;
+  }
 
   return Params;
 }

clang/test/SemaHLSL/RootSignature-err.hlsl

@@ -34,3 +34,7 @@ void bad_root_signature_5() {}
 // expected-error@+1 {{invalid parameter of RootConstants}}
 [RootSignature(MultiLineRootSignature)]
 void bad_root_signature_6() {}
+
+// expected-error@+1 {{invalid parameter of SRV}}
+[RootSignature("SRV(invalid)")]
+void bad_root_signature_7() {}

clang/unittests/Parse/ParseHLSLRootSignatureTest.cpp

@@ -1318,4 +1318,31 @@ TEST_F(ParseHLSLRootSignatureTest, InvalidRootConstantParamsCommaTest) {
   ASSERT_TRUE(Consumer->isSatisfied());
 }
 
+TEST_F(ParseHLSLRootSignatureTest, InvalidRootDescriptorParamsCommaTest) {
+  // This test will check that an error is produced when there is a missing
+  // comma between parameters
+  const llvm::StringLiteral Source = R"cc(
+    CBV(
+      b0
+      flags = 0
+    )
+  )cc";
+
+  auto Ctx = createMinimalASTContext();
+  StringLiteral *Signature = wrapSource(Ctx, Source);
+
+  TrivialModuleLoader ModLoader;
+  auto PP = createPP(Source, ModLoader);
+
+  SmallVector<RootSignatureElement> Elements;
+  hlsl::RootSignatureParser Parser(RootSignatureVersion::V1_1, Elements,
+                                   Signature, *PP);
+
+  // Test correct diagnostic produced
+  Consumer->setExpected(diag::err_expected);
+  ASSERT_TRUE(Parser.parse());
+
+  ASSERT_TRUE(Consumer->isSatisfied());
+}
+
 } // anonymous namespace