maxtessfactor attribute should take a floating point value (#6289)

* maxtessfactor attribute should take a floating point value

* Support integer value on maxtessfactor

9 files changed, 106 insertions, 3 deletions

diff --git a/source/slang/slang-check-impl.h b/source/slang/slang-check-impl.h
index e6520cfd3..350362a0e 100644
--- a/source/slang/slang-check-impl.h
+++ b/source/slang/slang-check-impl.h
@@ -1678,6 +1678,7 @@ public:
 
     AttributeDecl* lookUpAttributeDecl(Name* attributeName, Scope* scope);
 
+    bool hasFloatArgs(Attribute* attr, int numArgs);
     bool hasIntArgs(Attribute* attr, int numArgs);
     bool hasStringArgs(Attribute* attr, int numArgs);
 
diff --git a/source/slang/slang-check-modifier.cpp b/source/slang/slang-check-modifier.cpp
index 6e451b5cf..741823a65 100644
--- a/source/slang/slang-check-modifier.cpp
+++ b/source/slang/slang-check-modifier.cpp
@@ -312,6 +312,22 @@ AttributeDecl* SemanticsVisitor::lookUpAttributeDecl(Name* attributeName, Scope*
     return attrDecl;
 }
 
+bool SemanticsVisitor::hasFloatArgs(Attribute* attr, int numArgs)
+{
+    if (int(attr->args.getCount()) != numArgs)
+    {
+        return false;
+    }
+    for (int i = 0; i < numArgs; ++i)
+    {
+        if (!as<FloatingPointLiteralExpr>(attr->args[i]) && !as<IntegerLiteralExpr>(attr->args[i]))
+        {
+            return false;
+        }
+    }
+    return true;
+}
+
 bool SemanticsVisitor::hasIntArgs(Attribute* attr, int numArgs)
 {
     if (int(attr->args.getCount()) != numArgs)
@@ -692,9 +708,8 @@ Modifier* SemanticsVisitor::validateAttribute(
         }
     }
     else if (
-        (as<DomainAttribute>(attr)) || (as<MaxTessFactorAttribute>(attr)) ||
-        (as<OutputTopologyAttribute>(attr)) || (as<PartitioningAttribute>(attr)) ||
-        (as<PatchConstantFuncAttribute>(attr)))
+        (as<DomainAttribute>(attr)) || (as<OutputTopologyAttribute>(attr)) ||
+        (as<PartitioningAttribute>(attr)) || (as<PatchConstantFuncAttribute>(attr)))
     {
         // Let it go thru iff single string attribute
         if (!hasStringArgs(attr, 1))
@@ -724,6 +739,13 @@ Modifier* SemanticsVisitor::validateAttribute(
             sink->diagnose(attr, Diagnostics::attributeExpectedStringArg, attr->keywordName, 1);
         }
     }
+    else if (as<MaxTessFactorAttribute>(attr))
+    {
+        if (!hasFloatArgs(attr, 1))
+        {
+            getSink()->diagnose(attr, Diagnostics::expectedSingleFloatArg, attr->keywordName);
+        }
+    }
     else if (as<OutputControlPointsAttribute>(attr))
     {
         // Let it go thru iff single integral attribute
diff --git a/source/slang/slang-diagnostic-defs.h b/source/slang/slang-diagnostic-defs.h
index 4d037b68e..a1768415e 100644
--- a/source/slang/slang-diagnostic-defs.h
+++ b/source/slang/slang-diagnostic-defs.h
@@ -1045,6 +1045,12 @@ DIAGNOSTIC(
     attributeExpectedStringArg,
     "attribute '$0' expects argument $1 to be string")
 
+DIAGNOSTIC(
+    31009,
+    Error,
+    expectedSingleFloatArg,
+    "attribute '$0' expects a single floating point argument")
+
 DIAGNOSTIC(31100, Error, unknownStageName, "unknown stage name '$0'")
 DIAGNOSTIC(31101, Error, unknownImageFormatName, "unknown image format '$0'")
 DIAGNOSTIC(31101, Error, unknownDiagnosticName, "unknown diagnostic '$0'")
diff --git a/source/slang/slang-emit-hlsl.cpp b/source/slang/slang-emit-hlsl.cpp
index 53545b31f..9ebec0893 100644
--- a/source/slang/slang-emit-hlsl.cpp
+++ b/source/slang/slang-emit-hlsl.cpp
@@ -60,6 +60,32 @@ void HLSLSourceEmitter::_emitHLSLDecorationSingleInt(
     m_writer->emit(")]\n");
 }
 
+void HLSLSourceEmitter::_emitHLSLDecorationSingleFloat(
+    const char* name,
+    IRFunc* entryPoint,
+    IRFloatLit* val)
+{
+    SLANG_UNUSED(entryPoint);
+    SLANG_ASSERT(val);
+
+    m_writer->emit("[");
+    m_writer->emit(name);
+    m_writer->emit("(");
+
+    switch (val->getOp())
+    {
+    default:
+        SLANG_UNEXPECTED("needed a known floating point value");
+        break;
+
+    case kIROp_FloatLit:
+        m_writer->emit(static_cast<IRConstant*>(val)->value.floatVal);
+        break;
+    }
+
+    m_writer->emit(")]\n");
+}
+
 void HLSLSourceEmitter::_emitHLSLRegisterSemantic(
     LayoutResourceKind kind,
     EmitVarChain* chain,
@@ -511,6 +537,12 @@ void HLSLSourceEmitter::emitEntryPointAttributesImpl(
                 _emitHLSLDecorationSingleString("outputtopology", irFunc, decor->getTopology());
             }
 
+            /* [maxtessfactor(16.0)] */
+            if (auto decor = irFunc->findDecoration<IRMaxTessFactorDecoration>())
+            {
+                _emitHLSLDecorationSingleFloat("maxtessfactor", irFunc, decor->getMaxTessFactor());
+            }
+
             /* [outputcontrolpoints(4)] */
             if (auto decor = irFunc->findDecoration<IROutputControlPointsDecoration>())
             {
diff --git a/source/slang/slang-emit-hlsl.h b/source/slang/slang-emit-hlsl.h
index 07c7af3d2..28319f93a 100644
--- a/source/slang/slang-emit-hlsl.h
+++ b/source/slang/slang-emit-hlsl.h
@@ -118,6 +118,7 @@ protected:
 
     void _emitHLSLDecorationSingleString(const char* name, IRFunc* entryPoint, IRStringLit* val);
     void _emitHLSLDecorationSingleInt(const char* name, IRFunc* entryPoint, IRIntLit* val);
+    void _emitHLSLDecorationSingleFloat(const char* name, IRFunc* entryPoint, IRFloatLit* val);
 
     void _emitStageAccessSemantic(IRStageAccessDecoration* decoration, const char* name);
 };
diff --git a/source/slang/slang-ir-inst-defs.h b/source/slang/slang-ir-inst-defs.h
index d9c543efa..59a6852b1 100644
--- a/source/slang/slang-ir-inst-defs.h
+++ b/source/slang/slang-ir-inst-defs.h
@@ -845,6 +845,7 @@ INST_RANGE(BindingQuery, GetRegisterIndex, GetRegisterSpace)
     INST(DownstreamModuleExportDecoration,  downstreamModuleExport, 0, 0)
     INST(DownstreamModuleImportDecoration,  downstreamModuleImport, 0, 0)
     INST(PatchConstantFuncDecoration,       patchConstantFunc,      1, 0)
+    INST(MaxTessFactorDecoration,           maxTessFactor,          1, 0)
     INST(OutputControlPointsDecoration,     outputControlPoints,    1, 0)
     INST(OutputTopologyDecoration,          outputTopology,         1, 0)
     INST(PartitioningDecoration,            partioning,             1, 0)
diff --git a/source/slang/slang-ir-insts.h b/source/slang/slang-ir-insts.h
index c342039a5..fcafe4bc6 100644
--- a/source/slang/slang-ir-insts.h
+++ b/source/slang/slang-ir-insts.h
@@ -515,6 +515,17 @@ struct IRNVAPISlotDecoration : IRDecoration
     UnownedStringSlice getSpaceName() { return getSpaceNameOperand()->getStringSlice(); }
 };
 
+struct IRMaxTessFactorDecoration : IRDecoration
+{
+    enum
+    {
+        kOp = kIROp_MaxTessFactorDecoration
+    };
+    IR_LEAF_ISA(MaxTessFactorDecoration)
+
+    IRFloatLit* getMaxTessFactor() { return cast<IRFloatLit>(getOperand(0)); }
+};
+
 struct IROutputControlPointsDecoration : IRDecoration
 {
     enum
@@ -3656,6 +3667,7 @@ public:
     IRBasicType* getUInt64Type();
     IRBasicType* getUInt16Type();
     IRBasicType* getUInt8Type();
+    IRBasicType* getFloatType();
     IRBasicType* getCharType();
     IRStringType* getStringType();
     IRNativeStringType* getNativeStringType();
diff --git a/source/slang/slang-ir.cpp b/source/slang/slang-ir.cpp
index 6a7564e67..3314567f1 100644
--- a/source/slang/slang-ir.cpp
+++ b/source/slang/slang-ir.cpp
@@ -2678,6 +2678,11 @@ IRBasicType* IRBuilder::getUInt8Type()
     return (IRBasicType*)getType(kIROp_UInt8Type);
 }
 
+IRBasicType* IRBuilder::getFloatType()
+{
+    return (IRBasicType*)getType(kIROp_FloatType);
+}
+
 IRBasicType* IRBuilder::getCharType()
 {
     return (IRBasicType*)getType(kIROp_CharType);
diff --git a/source/slang/slang-lower-to-ir.cpp b/source/slang/slang-lower-to-ir.cpp
index a966189a0..cac157f9b 100644
--- a/source/slang/slang-lower-to-ir.cpp
+++ b/source/slang/slang-lower-to-ir.cpp
@@ -9986,6 +9986,24 @@ struct DeclLoweringVisitor : DeclVisitor<DeclLoweringVisitor, LoweredValInfo>
         }
     }
 
+    IRFloatLit* _getFloatFromAttribute(IRBuilder* builder, Attribute* attrib, Index index = 0)
+    {
+        SLANG_ASSERT(attrib->args.getCount() > index);
+        Expr* expr = attrib->args[index];
+
+        if (auto floatLitExpr = as<FloatingPointLiteralExpr>(expr))
+        {
+            return as<IRFloatLit>(
+                builder->getFloatValue(builder->getFloatType(), floatLitExpr->value));
+        }
+
+        auto intLitExpr = as<IntegerLiteralExpr>(expr);
+        SLANG_ASSERT(intLitExpr);
+        return as<IRFloatLit>(builder->getFloatValue(
+            builder->getFloatType(),
+            (IRFloatingPointValue)(intLitExpr->value)));
+    }
+
     IRIntLit* _getIntLitFromAttribute(IRBuilder* builder, Attribute* attrib, Index index = 0)
     {
         SLANG_ASSERT(attrib->args.getCount() > index);
@@ -10520,6 +10538,11 @@ struct DeclLoweringVisitor : DeclVisitor<DeclLoweringVisitor, LoweredValInfo>
                 IRStringLit* stringLit = _getStringLitFromAttribute(getBuilder(), outputTopAttr);
                 getBuilder()->addDecoration(irFunc, kIROp_OutputTopologyDecoration, stringLit);
             }
+            else if (auto maxTessFactortAttr = as<MaxTessFactorAttribute>(modifier))
+            {
+                IRFloatLit* floatLit = _getFloatFromAttribute(getBuilder(), maxTessFactortAttr);
+                getBuilder()->addDecoration(irFunc, kIROp_MaxTessFactorDecoration, floatLit);
+            }
             else if (auto outputCtrlPtAttr = as<OutputControlPointsAttribute>(modifier))
             {
                 IRIntLit* intLit = _getIntLitFromAttribute(getBuilder(), outputCtrlPtAttr);