pre-req: add parsing of MipLODBias as an uint

- defines a float data member of StaticSampler that will be used to test
functionality of parsing a float

Author: inbelic

clang/include/clang/Parse/ParseHLSLRootSignature.h

@@ -111,6 +111,7 @@ class RootSignatureParser {
 
   struct ParsedStaticSamplerParams {
     std::optional<llvm::hlsl::rootsig::Register> Reg;
+    std::optional<float> MipLODBias;
   };
   std::optional<ParsedStaticSamplerParams> parseStaticSamplerParams();
 

clang/lib/Parse/ParseHLSLRootSignature.cpp

@@ -376,6 +376,10 @@ std::optional<StaticSampler> RootSignatureParser::parseStaticSampler() {
 
   Sampler.Reg = Params->Reg.value();
 
+  // Fill in optional values
+  if (Params->MipLODBias.has_value())
+    Sampler.MipLODBias = Params->MipLODBias.value();
+
   if (consumeExpectedToken(TokenKind::pu_r_paren,
                            diag::err_hlsl_unexpected_end_of_params,
                            /*param of=*/TokenKind::kw_StaticSampler))
@@ -661,6 +665,23 @@ RootSignatureParser::parseStaticSamplerParams() {
         return std::nullopt;
       Params.Reg = Reg;
     }
+
+    // `mipLODBias` `=` NUMBER
+    if (tryConsumeExpectedToken(TokenKind::kw_mipLODBias)) {
+      if (Params.MipLODBias.has_value()) {
+        getDiags().Report(CurToken.TokLoc, diag::err_hlsl_rootsig_repeat_param)
+            << CurToken.TokKind;
+        return std::nullopt;
+      }
+
+      if (consumeExpectedToken(TokenKind::pu_equal))
+        return std::nullopt;
+
+      auto MipLODBias = parseUIntParam();
+      if (!MipLODBias.has_value())
+        return std::nullopt;
+      Params.MipLODBias = (float)*MipLODBias;
+    }
   } while (tryConsumeExpectedToken(TokenKind::pu_comma));
 
   return Params;

clang/unittests/Parse/ParseHLSLRootSignatureTest.cpp

@@ -225,7 +225,7 @@ TEST_F(ParseHLSLRootSignatureTest, ValidParseDTClausesTest) {
 
 TEST_F(ParseHLSLRootSignatureTest, ValidParseStaticSamplerTest) {
   const llvm::StringLiteral Source = R"cc(
-    StaticSampler(s0)
+    StaticSampler(s0, mipLODBias = 0)
   )cc";
 
   TrivialModuleLoader ModLoader;
@@ -247,6 +247,7 @@ TEST_F(ParseHLSLRootSignatureTest, ValidParseStaticSamplerTest) {
   ASSERT_TRUE(std::holds_alternative<StaticSampler>(Elem));
   ASSERT_EQ(std::get<StaticSampler>(Elem).Reg.ViewType, RegisterType::SReg);
   ASSERT_EQ(std::get<StaticSampler>(Elem).Reg.Number, 0u);
+  ASSERT_EQ(std::get<StaticSampler>(Elem).MipLODBias, 0u);
 
   ASSERT_TRUE(Consumer->isSatisfied());
 }

llvm/include/llvm/Frontend/HLSL/HLSLRootSignature.h

@@ -157,6 +157,7 @@ raw_ostream &operator<<(raw_ostream &OS, const DescriptorTableClause &Clause);
 
 struct StaticSampler {
   Register Reg;
+  float MipLODBias = 0.f;
 };
 
 /// Models RootElement : RootFlags | RootConstants | RootParam