GlobalISel: Verify G_GEP

[paquette]

LGTM

[arsenm]

r353209

lib/CodeGen/MachineVerifier.cpp

if (MI->getOpcode() == TargetOpcode::G_INTTOPTR) {
       else {
         if (SrcTy.getAddressSpace() == DstTy.getAddressSpace())
           report("addrspacecast must convert different address spaces", MI);
       }
     }
 
     break;
   }
+  case TargetOpcode::G_GEP: {
+    LLT DstTy = MRI->getType(MI->getOperand(0).getReg());
+    LLT PtrTy = MRI->getType(MI->getOperand(1).getReg());
+    LLT OffsetTy = MRI->getType(MI->getOperand(2).getReg());
+    if (!DstTy.isValid() || !PtrTy.isValid() || !OffsetTy.isValid())
+      break;
+
+    if (!PtrTy.getScalarType().isPointer())
+      report("gep first operand must be a pointer", MI);
+
+    if (OffsetTy.getScalarType().isPointer())
+      report("gep offset operand must not be a pointer", MI);
+
+    // TODO: Is the offset allowed to be a scalar with a vector?
+    break;
+  }
   case TargetOpcode::G_SEXT:
   case TargetOpcode::G_ZEXT:
   case TargetOpcode::G_ANYEXT:
   case TargetOpcode::G_TRUNC:
   case TargetOpcode::G_FPEXT:
   case TargetOpcode::G_FPTRUNC: {
     // Number of operands and presense of types is already checked (and
     // reported in case of any issues), so no need to report them again. As

test/Verifier/test_g_gep.mir

+#RUN: not llc -o -  -run-pass=none -verify-machineinstrs %s 2>&1 | FileCheck %s
+# REQUIRES: global-isel, aarch64-registered-target
+
+---
+name:            test_gep
+legalized:       true
+regBankSelected: false
+selected:        false
+tracksRegLiveness: true
+liveins:
+body:             |
+  bb.0:
+
+    %0:_(p0) = G_IMPLICIT_DEF
+    %1:_(s64) = G_IMPLICIT_DEF
+
+    ; CHECK:  Bad machine code: Type mismatch in generic instruction
+    %2:_(s64) = G_GEP %0, %1
+
+    ; CHECK:  Bad machine code: Type mismatch in generic instruction
+    %3:_(p0) = G_GEP %1, %1
+
+    ; CHECK: Bad machine code: gep offset operand must not be a pointer
+    %4:_(p0) = G_GEP %0, %0
+
+    ; CHECK: Bad machine code: Type mismatch in generic instruction
+    %5:_(p1) = G_GEP %0, %1
+
+    ; CHECK: Bad machine code: gep first operand must be a pointer
+    %6:_(s64) = G_GEP %1, %1
+
+...