recompiler: proper VS inputs initialization

src/shader_recompiler/backend/spirv/emit_spirv_context_get_set.cpp

@@ -131,6 +131,13 @@ Id EmitReadConstBufferU32(EmitContext& ctx, u32 handle, Id index) {
     return ctx.OpBitcast(ctx.U32[1], EmitReadConstBuffer(ctx, handle, index));
 }
 
+Id EmitReadStepRate(EmitContext& ctx, int rate_idx) {
+    return ctx.OpLoad(
+        ctx.U32[1], ctx.OpAccessChain(ctx.TypePointer(spv::StorageClass::PushConstant, ctx.U32[1]),
+                                      ctx.instance_step_rates,
+                                      rate_idx == 0 ? ctx.u32_zero_value : ctx.u32_one_value));
+}
+
 Id EmitGetAttribute(EmitContext& ctx, IR::Attribute attr, u32 comp) {
     if (IR::IsParam(attr)) {
         const u32 index{u32(attr) - u32(IR::Attribute::Param0)};
@@ -149,11 +156,7 @@ Id EmitGetAttribute(EmitContext& ctx, IR::Attribute attr, u32 comp) {
                 return ctx.OpLoad(param.component_type, param.id);
             }
         } else {
-            const auto rate_idx = param.id.value == 0 ? ctx.u32_zero_value : ctx.u32_one_value;
-            const auto step_rate = ctx.OpLoad(
-                ctx.U32[1],
-                ctx.OpAccessChain(ctx.TypePointer(spv::StorageClass::PushConstant, ctx.U32[1]),
-                                  ctx.instance_step_rates, rate_idx));
+            const auto step_rate = EmitReadStepRate(ctx, param.id.value);
             const auto offset = ctx.OpIAdd(
                 ctx.U32[1],
                 ctx.OpIMul(
@@ -182,6 +185,12 @@ Id EmitGetAttributeU32(EmitContext& ctx, IR::Attribute attr, u32 comp) {
     switch (attr) {
     case IR::Attribute::VertexId:
         return ctx.OpLoad(ctx.U32[1], ctx.vertex_index);
+    case IR::Attribute::InstanceId:
+        return ctx.OpLoad(ctx.U32[1], ctx.instance_id);
+    case IR::Attribute::InstanceId0:
+        return EmitReadStepRate(ctx, 0);
+    case IR::Attribute::InstanceId1:
+        return EmitReadStepRate(ctx, 1);
     case IR::Attribute::WorkgroupId:
         return ctx.OpCompositeExtract(ctx.U32[1], ctx.OpLoad(ctx.U32[3], ctx.workgroup_id), comp);
     case IR::Attribute::LocalInvocationId:

src/shader_recompiler/frontend/translate/translate.cpp

@@ -35,10 +35,20 @@ void Translator::EmitPrologue() {
     IR::VectorReg dst_vreg = IR::VectorReg::V0;
     switch (info.stage) {
     case Stage::Vertex:
-        // https://github.com/chaotic-cx/mesa-mirror/blob/72326e15/src/amd/vulkan/radv_shader_args.c#L146C1-L146C23
+        // v0: vertex ID, always present
         ir.SetVectorReg(dst_vreg++, ir.GetAttributeU32(IR::Attribute::VertexId));
-        ir.SetVectorReg(dst_vreg++, ir.GetAttributeU32(IR::Attribute::InstanceId));
-        ir.SetVectorReg(dst_vreg++, ir.GetAttributeU32(IR::Attribute::PrimitiveId));
+        // v1: instance ID, step rate 0
+        if (info.num_input_vgprs > 0) {
+            ir.SetVectorReg(dst_vreg++, ir.GetAttributeU32(IR::Attribute::InstanceId0));
+        }
+        // v2: instance ID, step rate 1
+        if (info.num_input_vgprs > 1) {
+            ir.SetVectorReg(dst_vreg++, ir.GetAttributeU32(IR::Attribute::InstanceId1));
+        }
+        // v3: instance ID, plain
+        if (info.num_input_vgprs > 2) {
+            ir.SetVectorReg(dst_vreg++, ir.GetAttributeU32(IR::Attribute::InstanceId));
+        }
         break;
     case Stage::Fragment:
         // https://github.com/chaotic-cx/mesa-mirror/blob/72326e15/src/amd/vulkan/radv_shader_args.c#L258

src/shader_recompiler/ir/attribute.h

@@ -72,6 +72,8 @@ enum class Attribute : u64 {
     LocalInvocationId = 75,
     LocalInvocationIndex = 76,
     FragCoord = 77,
+    InstanceId0 = 78, // step rate 0
+    InstanceId1 = 79, // step rate 1
     Max,
 };
 

src/shader_recompiler/runtime_info.h

@@ -163,6 +163,7 @@ struct Info {
     std::array<u32, 3> workgroup_size{};
 
     u32 num_user_data;
+    u32 num_input_vgprs;
     std::span<const u32> user_data;
     Stage stage;
 

src/video_core/amdgpu/liverpool.h

@@ -80,6 +80,7 @@ struct Liverpool {
         union {
             BitField<0, 6, u64> num_vgprs;
             BitField<6, 4, u64> num_sgprs;
+            BitField<24, 2, u64> vgpr_comp_cnt; // SPI provided per-thread inputs
             BitField<33, 5, u64> num_user_regs;
         } settings;
         UserData user_data;

src/video_core/renderer_vulkan/vk_pipeline_cache.cpp

@@ -72,6 +72,7 @@ Shader::Info MakeShaderInfo(Shader::Stage stage, std::span<const u32, 16> user_d
     switch (stage) {
     case Shader::Stage::Vertex: {
         info.num_user_data = regs.vs_program.settings.num_user_regs;
+        info.num_input_vgprs = regs.vs_program.settings.vgpr_comp_cnt;
         BuildVsOutputs(info, regs.vs_output_control);
         break;
     }