[dxbc] Implement geometry shader instancing

Required for Frostpunk (see #385).

src/dxbc/dxbc_compiler.cpp

@@ -277,6 +277,9 @@ namespace dxvk {
       case DxbcOpcode::DclThreadGroup:
         return this->emitDclThreadGroup(ins);
       
+      case DxbcOpcode::DclGsInstanceCount:
+        return this->emitDclGsInstanceCount(ins);
+      
       default:
         Logger::warn(
           str::format("DxbcCompiler: Unhandled opcode: ",
@@ -545,6 +548,14 @@ namespace dxvk {
         // output arrays, so there's nothing left to do.
       } break;
       
+      case DxbcOperandType::InputGsInstanceId: {
+        m_gs.builtinInvocationId = emitNewBuiltinVariable({
+          { DxbcScalarType::Uint32, 1, 0 },
+          spv::StorageClassInput },
+          spv::BuiltInInvocationId,
+          "vInstanceID");
+      } break;
+      
       default:
         Logger::err(str::format(
           "DxbcCompiler: Unsupported operand type declaration: ",
@@ -1219,6 +1230,13 @@ namespace dxvk {
   }
   
   
+  void DxbcCompiler::emitDclGsInstanceCount(const DxbcShaderInstruction& ins) {
+    // dcl_gs_instance_count has one operand:
+    //    (imm0) Number of geometry shader invocations
+    m_module.setInvocations(m_entryPointId, ins.imm[0].u32);
+  }
+  
+  
   uint32_t DxbcCompiler::emitDclUavCounter(uint32_t regId) {
     // Declare a structure type which holds the UAV counter
     if (m_uavCtrStructType == 0) {
@@ -4282,6 +4300,11 @@ namespace dxvk {
         return DxbcRegisterPointer {
           { DxbcScalarType::Uint32, 1 },
           getCurrentHsForkJoinPhase()->instanceIdPtr };
+      
+      case DxbcOperandType::InputGsInstanceId:
+        return DxbcRegisterPointer {
+          { DxbcScalarType::Uint32, 1 },
+          m_gs.builtinInvocationId };
         
       default:
         throw DxvkError(str::format(

src/dxbc/dxbc_compiler.h

@@ -120,6 +120,7 @@ namespace dxvk {
     
     uint32_t builtinLayer         = 0;
     uint32_t builtinViewportId    = 0;
+    uint32_t builtinInvocationId  = 0;
   };
   
   
@@ -514,6 +515,9 @@ namespace dxvk {
     void emitDclThreadGroup(
       const DxbcShaderInstruction&  ins);
     
+    void emitDclGsInstanceCount(
+      const DxbcShaderInstruction&  ins);
+    
     uint32_t emitDclUavCounter(
             uint32_t                regId);
     

src/dxbc/dxbc_defs.cpp

@@ -999,7 +999,9 @@ namespace dxvk {
       { DxbcOperandKind::SrcReg, DxbcScalarType::Float32 },
     } },
     /* DclGsInstanceCount                   */
-    { },
+    { 1, DxbcInstClass::Declaration, {
+      { DxbcOperandKind::Imm32, DxbcScalarType::Uint32 },
+    } },
   }};
   
   

src/spirv/spirv_module.cpp

@@ -92,6 +92,16 @@ namespace dxvk {
   }
   
   
+  void SpirvModule::setInvocations(
+          uint32_t                entryPointId,
+          uint32_t                invocations) {
+    m_execModeInfo.putIns  (spv::OpExecutionMode, 4);
+    m_execModeInfo.putWord (entryPointId);
+    m_execModeInfo.putWord (spv::ExecutionModeInvocations);
+    m_execModeInfo.putInt32(invocations);
+  }
+  
+  
   void SpirvModule::setLocalSize(
           uint32_t                entryPointId,
           uint32_t                x,

src/spirv/spirv_module.h

@@ -79,6 +79,10 @@ namespace dxvk {
             uint32_t                entryPointId,
             spv::ExecutionMode      executionMode);
     
+    void setInvocations(
+            uint32_t                entryPointId,
+            uint32_t                invocations);
+    
     void setLocalSize(
             uint32_t                entryPointId,
             uint32_t                x,