[MachineVerify] Verify property of atomic G_LOAD/STORE variants

[reames]

Summary

More or less directly copied from IR/Verifier.cpp.

[arsenm]

Should have test in test/MachineVerifier

lib/CodeGen/MachineVerifier.cpp

1036–1037

IMO we should remove alignment 0 from all points in the IR and MIR

[arsenm]

lib/CodeGen/MachineVerifier.cpp

1036–1037

On second thought, I'm not sure this is necessary. The MIRParser won't ever produce a 0 base alignment MMO. This can probably be replaced with an assert in the MMO constructor

[reames]

Pending refresh w/suggested changes.

lib/CodeGen/MachineVerifier.cpp

1036–1037

This is a good idea. I will do so.

[arsenm]

lib/CodeGen/MachineVerifier.cpp

1036–1037

I'm not sure the MIParser rejects 0, it just doesn't default to 0. It would be a good idea to make sure that happens also

[reames]

It turns out the MachineMemOperand constructor already asserts on a zero alignment. The vector check is potentially useful, but given this doesn't cover SelectionDAG anyway (where I'm currently focused), I'm deferring it until a future point.

lib/CodeGen/MachineVerifier.cpp

if (!MI->hasOneMemOperand()) {
           report("Generic extload must have a narrower memory type", MI);
       } else if (MI->getOpcode() == TargetOpcode::G_LOAD) {
         if (MMO.getSize() > ValTy.getSizeInBytes())
           report("load memory size cannot exceed result size", MI);
       } else if (MI->getOpcode() == TargetOpcode::G_STORE) {
         if (ValTy.getSizeInBytes() < MMO.getSize())
           report("store memory size cannot exceed value size", MI);
       }
+
+      if (MMO.isAtomic()) {
+        if (MMO.getAlignment() == 0)
+          report("Atomics must have explicit alignment", MI);
+        if (ValTy.isVector())
+          report("atomic operations can't have vector type", MI);
+      }
     }
 
     break;
   }
   case TargetOpcode::G_PHI: {
     LLT DstTy = MRI->getType(MI->getOperand(0).getReg());
     if (!DstTy.isValid() ||
         !std::all_of(MI->operands_begin() + 1, MI->operands_end(),