[HLSL][RootSiganture] Add parsing of new number params in StaticSampler

[inbelic]

• defines in-memory reprsentation of maxAnisotropy, minLOD and maxLOD
• integrates parsing of these number parameters with their respective, parseUInt and parseFloat respectively
• adds basic unit tests to demonstrate setting functionality

Part 3 of #126574

[llvmbot]

@llvm/pr-subscribers-hlsl

@llvm/pr-subscribers-clang

Author: Finn Plummer (inbelic)

Changes

• defines in-memory reprsentation of maxAnisotropy, minLOD and maxLOD
• integrates parsing of these number parameters with their respective, parseUInt and parseFloat respectively
• adds basic unit tests to demonstrate setting functionality

Part 3 of #126574

---

Full diff: https://github.com/llvm/llvm-project/pull/140291.diff

6 Files Affected:

• (modified) clang/include/clang/Lex/HLSLRootSignatureTokenKinds.def (+3)
• (modified) clang/include/clang/Parse/ParseHLSLRootSignature.h (+3)
• (modified) clang/lib/Parse/ParseHLSLRootSignature.cpp (+60)
• (modified) clang/unittests/Lex/LexHLSLRootSignatureTest.cpp (+1-1)
• (modified) clang/unittests/Parse/ParseHLSLRootSignatureTest.cpp (+20-2)
• (modified) llvm/include/llvm/Frontend/HLSL/HLSLRootSignature.h (+3)

diff --git a/clang/include/clang/Lex/HLSLRootSignatureTokenKinds.def b/clang/include/clang/Lex/HLSLRootSignatureTokenKinds.def
index 5d16eaa5b72f6..7ca131349fed4 100644
--- a/clang/include/clang/Lex/HLSLRootSignatureTokenKinds.def
+++ b/clang/include/clang/Lex/HLSLRootSignatureTokenKinds.def
@@ -102,6 +102,9 @@ KEYWORD(offset)
 
 // StaticSampler Keywords:
 KEYWORD(mipLODBias)
+KEYWORD(maxAnisotropy)
+KEYWORD(minLOD)
+KEYWORD(maxLOD)
 
 // Unbounded Enum:
 UNBOUNDED_ENUM(unbounded, "unbounded")
diff --git a/clang/include/clang/Parse/ParseHLSLRootSignature.h b/clang/include/clang/Parse/ParseHLSLRootSignature.h
index c12b022a030ef..e62d5de948a44 100644
--- a/clang/include/clang/Parse/ParseHLSLRootSignature.h
+++ b/clang/include/clang/Parse/ParseHLSLRootSignature.h
@@ -112,6 +112,9 @@ class RootSignatureParser {
   struct ParsedStaticSamplerParams {
     std::optional<llvm::hlsl::rootsig::Register> Reg;
     std::optional<float> MipLODBias;
+    std::optional<uint32_t> MaxAnisotropy;
+    std::optional<float> MinLOD;
+    std::optional<float> MaxLOD;
   };
   std::optional<ParsedStaticSamplerParams> parseStaticSamplerParams();
 
diff --git a/clang/lib/Parse/ParseHLSLRootSignature.cpp b/clang/lib/Parse/ParseHLSLRootSignature.cpp
index db2e922160062..04fe8d00f25cd 100644
--- a/clang/lib/Parse/ParseHLSLRootSignature.cpp
+++ b/clang/lib/Parse/ParseHLSLRootSignature.cpp
@@ -384,6 +384,15 @@ std::optional<StaticSampler> RootSignatureParser::parseStaticSampler() {
   if (Params->MipLODBias.has_value())
     Sampler.MipLODBias = Params->MipLODBias.value();
 
+  if (Params->MaxAnisotropy.has_value())
+    Sampler.MaxAnisotropy = Params->MaxAnisotropy.value();
+
+  if (Params->MinLOD.has_value())
+    Sampler.MinLOD = Params->MinLOD.value();
+
+  if (Params->MaxLOD.has_value())
+    Sampler.MaxLOD = Params->MaxLOD.value();
+
   if (consumeExpectedToken(TokenKind::pu_r_paren,
                            diag::err_hlsl_unexpected_end_of_params,
                            /*param of=*/TokenKind::kw_StaticSampler))
@@ -686,6 +695,57 @@ RootSignatureParser::parseStaticSamplerParams() {
         return std::nullopt;
       Params.MipLODBias = (float)*MipLODBias;
     }
+
+    // `maxAnisotropy` `=` POS_INT
+    if (tryConsumeExpectedToken(TokenKind::kw_maxAnisotropy)) {
+      if (Params.MaxAnisotropy.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 MaxAnisotropy = parseUIntParam();
+      if (!MaxAnisotropy.has_value())
+        return std::nullopt;
+      Params.MaxAnisotropy = MaxAnisotropy;
+    }
+
+    // `minLOD` `=` NUMBER
+    if (tryConsumeExpectedToken(TokenKind::kw_minLOD)) {
+      if (Params.MinLOD.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 MinLOD = parseFloatParam();
+      if (!MinLOD.has_value())
+        return std::nullopt;
+      Params.MinLOD = MinLOD;
+    }
+
+    // `maxLOD` `=` NUMBER
+    if (tryConsumeExpectedToken(TokenKind::kw_maxLOD)) {
+      if (Params.MaxLOD.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 MaxLOD = parseFloatParam();
+      if (!MaxLOD.has_value())
+        return std::nullopt;
+      Params.MaxLOD = MaxLOD;
+    }
   } while (tryConsumeExpectedToken(TokenKind::pu_comma));
 
   return Params;
diff --git a/clang/unittests/Lex/LexHLSLRootSignatureTest.cpp b/clang/unittests/Lex/LexHLSLRootSignatureTest.cpp
index b610b8f10f8da..575a97e75a05d 100644
--- a/clang/unittests/Lex/LexHLSLRootSignatureTest.cpp
+++ b/clang/unittests/Lex/LexHLSLRootSignatureTest.cpp
@@ -136,7 +136,7 @@ TEST_F(LexHLSLRootSignatureTest, ValidLexAllTokensTest) {
     space visibility flags
     numDescriptors offset
 
-    mipLODBias
+    mipLODBias maxAnisotropy minLOD maxLOD
 
     unbounded
     DESCRIPTOR_RANGE_OFFSET_APPEND
diff --git a/clang/unittests/Parse/ParseHLSLRootSignatureTest.cpp b/clang/unittests/Parse/ParseHLSLRootSignatureTest.cpp
index 539232e0bf2c2..94e0464ddf03b 100644
--- a/clang/unittests/Parse/ParseHLSLRootSignatureTest.cpp
+++ b/clang/unittests/Parse/ParseHLSLRootSignatureTest.cpp
@@ -225,7 +225,11 @@ TEST_F(ParseHLSLRootSignatureTest, ValidParseDTClausesTest) {
 
 TEST_F(ParseHLSLRootSignatureTest, ValidParseStaticSamplerTest) {
   const llvm::StringLiteral Source = R"cc(
-    StaticSampler(s0, mipLODBias = 0)
+    StaticSampler(s0),
+    StaticSampler(s0, maxAnisotropy = 3,
+      minLOD = 4.2f, mipLODBias = 0.23e+3,
+      maxLOD = 9000,
+    )
   )cc";
 
   TrivialModuleLoader ModLoader;
@@ -241,13 +245,27 @@ TEST_F(ParseHLSLRootSignatureTest, ValidParseStaticSamplerTest) {
 
   ASSERT_FALSE(Parser.parse());
 
-  ASSERT_EQ(Elements.size(), 1u);
+  ASSERT_EQ(Elements.size(), 2u);
 
+  // Check default values are as expected
   RootElement Elem = Elements[0];
   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, 0.f);
+  ASSERT_EQ(std::get<StaticSampler>(Elem).MaxAnisotropy, 16u);
+  ASSERT_EQ(std::get<StaticSampler>(Elem).MinLOD, 0.f);
+  ASSERT_EQ(std::get<StaticSampler>(Elem).MaxLOD, 3.402823466e+38f);
+
+  // Check values can be set as expected
+  Elem = Elements[1];
+  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, 230.f);
+  ASSERT_EQ(std::get<StaticSampler>(Elem).MaxAnisotropy, 3u);
+  ASSERT_EQ(std::get<StaticSampler>(Elem).MinLOD, 4.2f);
+  ASSERT_EQ(std::get<StaticSampler>(Elem).MaxLOD, 9000.f);
 
   ASSERT_TRUE(Consumer->isSatisfied());
 }
diff --git a/llvm/include/llvm/Frontend/HLSL/HLSLRootSignature.h b/llvm/include/llvm/Frontend/HLSL/HLSLRootSignature.h
index 6b4da48a302bc..8ee58b87f5e49 100644
--- a/llvm/include/llvm/Frontend/HLSL/HLSLRootSignature.h
+++ b/llvm/include/llvm/Frontend/HLSL/HLSLRootSignature.h
@@ -161,6 +161,9 @@ struct DescriptorTableClause {
 struct StaticSampler {
   Register Reg;
   float MipLODBias = 0.f;
+  uint32_t MaxAnisotropy = 16;
+  float MinLOD = 0.f;
+  float MaxLOD = 3.402823466e+38f; // FLT_MAX
 };
 
 /// Models RootElement : RootFlags | RootConstants | RootParam