call lowering may not know register's type

Author: VyacheslavLevytskyy

llvm/lib/Target/SPIRV/SPIRVCallLowering.cpp

@@ -545,13 +545,23 @@ bool SPIRVCallLowering::lowerCall(MachineIRBuilder &MIRBuilder,
       Register ArgReg = Arg.Regs[0];
       ArgVRegs.push_back(ArgReg);
       SPIRVType *SpvType = GR->getSPIRVTypeForVReg(ArgReg);
-      if (!SpvType) {
+      // If Arg.Ty is an untyped pointer (i.e., ptr [addrspace(...)]) we should
+      // wait with setting the type for the virtual register until pre-legalizer
+      // step when we access @llvm.spv.assign.ptr.type.p...(...)'s info.
+      if (!SpvType && !isUntypedPointerTy(Arg.Ty)) {
         SpvType = GR->getOrCreateSPIRVType(Arg.Ty, MIRBuilder);
         GR->assignSPIRVTypeToVReg(SpvType, ArgReg, MF);
       }
       if (!MRI->getRegClassOrNull(ArgReg)) {
-        MRI->setRegClass(ArgReg, GR->getRegClass(SpvType));
-        MRI->setType(ArgReg, GR->getRegType(SpvType));
+        // Either we have SpvType created, or Arg.Ty is an untyped pointer and
+        // we know its virtual register's class and type.
+        MRI->setRegClass(ArgReg, SpvType ? GR->getRegClass(SpvType)
+                                         : &SPIRV::pIDRegClass);
+        MRI->setType(
+            ArgReg,
+            SpvType ? GR->getRegType(SpvType)
+                    : LLT::pointer(cast<PointerType>(Arg.Ty)->getAddressSpace(),
+                                   GR->getPointerSize()));
       }
     }
     auto instructionSet = canUseOpenCL ? SPIRV::InstructionSet::OpenCL_std