GlobalISel: Fix invoke lowering creating invalid type registers

[arsenm]

Summary

Unlike the call handling, this wasn't checking for void results and
creating a register with the invalid LLT.

[aemerson]

Is there a reasonably sized test?

[arsenm]

In D60339#1456892, @aemerson wrote:

Is there a reasonably sized test?

I don’t think this actually broke anything other than wasting a register. The assert I added is hit for at least one invoke in the current tests

[arsenm]

r358110

include/llvm/CodeGen/GlobalISel/CallLowering.h

public:
   struct ArgInfo {
     unsigned Reg;
     Type *Ty;
     ISD::ArgFlagsTy Flags;
     bool IsFixed;
 
     ArgInfo(unsigned Reg, Type *Ty, ISD::ArgFlagsTy Flags = ISD::ArgFlagsTy{},
             bool IsFixed = true)
-        : Reg(Reg), Ty(Ty), Flags(Flags), IsFixed(IsFixed) {}
+      : Reg(Reg), Ty(Ty), Flags(Flags), IsFixed(IsFixed) {
+      assert((Ty->isVoidTy() == (Reg == 0)) &&
+             "only void types should have no register");
+    }
   };
 
   /// Argument handling is mostly uniform between the four places that
   /// make these decisions: function formal arguments, call
   /// instruction args, call instruction returns and function
   /// returns. However, once a decision has been made on where an
   /// arugment should go, exactly what happens can vary slightly. This
   /// class abstracts the differences.

lib/CodeGen/GlobalISel/IRTranslator.cpp

bool IRTranslator::translateInvoke(const User &U,
   if (!isa<LandingPadInst>(EHPadBB->front()))
     return false;
 
   // Emit the actual call, bracketed by EH_LABELs so that the MF knows about
   // the region covered by the try.
   MCSymbol *BeginSymbol = Context.createTempSymbol();
   MIRBuilder.buildInstr(TargetOpcode::EH_LABEL).addSym(BeginSymbol);
 
-  unsigned Res =
-        MRI->createGenericVirtualRegister(getLLTForType(*I.getType(), *DL));
+  unsigned Res = 0;
+  if (!I.getType()->isVoidTy())
+    Res = MRI->createGenericVirtualRegister(getLLTForType(*I.getType(), *DL));
   SmallVector<unsigned, 8> Args;
   for (auto &Arg: I.arg_operands())
     Args.push_back(packRegs(*Arg, MIRBuilder));
 
   if (!CLI->lowerCall(MIRBuilder, &I, Res, Args,
                       [&]() { return getOrCreateVReg(*I.getCalledValue()); }))
     return false;