adding default flag to frontend root signature

Author: joaosaffran

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

@@ -131,6 +131,8 @@ struct StaticSampler {
   float MaxLOD = std::numeric_limits<float>::max();
   uint32_t Space = 0;
   dxbc::ShaderVisibility Visibility = dxbc::ShaderVisibility::All;
+  // Flags added in Root Signature 1.2
+  dxbc::StaticSamplerFlags Flags = dxbc::StaticSamplerFlags::None;
 };
 
 /// Models RootElement : RootFlags | RootConstants | RootParam

llvm/lib/Frontend/HLSL/RootSignatureMetadata.cpp

@@ -212,7 +212,7 @@ MDNode *MetadataBuilder::BuildStaticSampler(const StaticSampler &Sampler) {
       ConstantAsMetadata::get(Builder.getInt32(Sampler.Space)),
       ConstantAsMetadata::get(
           Builder.getInt32(to_underlying(Sampler.Visibility))),
-      ConstantAsMetadata::get(Builder.getInt32(0)),
+      ConstantAsMetadata::get(Sampler.Flags),
   };
   return MDNode::get(Ctx, Operands);
 }