[GPU] Document memexport/resolve formats with more details

src/xenia/gpu/dxbc_shader_translator_memexport.cc

@@ -15,6 +15,14 @@ namespace xe {
 namespace gpu {
 using namespace ucode;
 
+// TODO(Triang3l): Support sub-dword memexports (like k_8 in 58410B86). This
+// would require four 128 MB R8_UINT UAVs due to the Nvidia addressing limit.
+// Need to be careful with resource binding tiers, however. Resource binding
+// tier 1 on feature level 11_0 allows only 8 UAVs _across all stages_.
+// RWByteAddressBuffer + 4 typed buffers is 5 per stage already, would need 10
+// for both VS and PS, or even 11 with the eDRAM ROV. Need to drop draw commands
+// doing memexport in both VS and PS on FL 11_0 resource binding tier 1.
+
 void DxbcShaderTranslator::ExportToMemory_PackFixed32(
     const uint32_t* eM_temps, uint32_t eM_count, const uint32_t bits[4],
     const dxbc::Src& is_integer, const dxbc::Src& is_signed) {