Index: llvm/test/TableGen/GlobalISelEmitter-multiple-output.td
===================================================================
--- llvm/test/TableGen/GlobalISelEmitter-multiple-output.td
+++ llvm/test/TableGen/GlobalISelEmitter-multiple-output.td
@@ -10,6 +10,7 @@
 
 // Verify that patterns with multiple outputs are translated
 
+//-----------------------------------------------------------------------------
 // Test where only the opcode is mutated during ISel
 
 let Constraints = "$ptr_out = $addr" in
@@ -46,6 +47,7 @@
 // CHECK-NEXT: GIR_MutateOpcode, /*InsnID*/0, /*RecycleInsnID*/0, /*Opcode*/MyTarget::LDPost,
 // CHECK-NEXT: GIR_ConstrainSelectedInstOperands, /*InsnID*/0,
 
+//-----------------------------------------------------------------------------
 // Test where a whole new MIR instruction is created during ISel
 
 def TWO_INS : I<(outs GPR32:$out1, GPR32:$out2), (ins GPR32:$in1, GPR32:$in2), []>;
@@ -84,3 +86,34 @@
 // CHECK-NEXT: GIR_Copy, /*NewInsnID*/0, /*OldInsnID*/0, /*OpIdx*/2, // i1
 // CHECK-NEXT: GIR_EraseFromParent, /*InsnID*/0,
 // CHECK-NEXT: GIR_ConstrainSelectedInstOperands, /*InsnID*/0,
+
+//-----------------------------------------------------------------------------
+// Test where implicit defs are added using Defs.
+
+let Defs = [R0] in
+def ImplicitDefInstr : I<(outs GPR32:$dst), (ins GPR32:$src), []>;
+def OtherInstr : I<(outs GPR32:$dst), (ins GPR32:$src), []>;
+
+def : Pat<(i32 (add i32:$src, i32:$src)),
+  (OtherInstr (ImplicitDefInstr GPR32:$src))>;
+
+// CHECK: GIM_CheckOpcode, /*MI*/0, TargetOpcode::G_ADD,
+// CHECK-NEXT: // MIs[0] dst
+// CHECK-NEXT: GIM_CheckType, /*MI*/0, /*Op*/0, /*Type*/GILLT_s32,
+// CHECK-NEXT: GIM_CheckRegBankForClass, /*MI*/0, /*Op*/0, /*RC*/MyTarget::GPR32RegClassID,
+// CHECK-NEXT: // MIs[0] src
+// CHECK-NEXT: GIM_CheckType, /*MI*/0, /*Op*/1, /*Type*/GILLT_s32,
+// CHECK-NEXT: // MIs[0] src
+// CHECK-NEXT: GIM_CheckIsSameOperand, /*MI*/0, /*OpIdx*/2, /*OtherMI*/0, /*OtherOpIdx*/1,
+// CHECK-NEXT: // (add:{ *:[i32] } i32:{ *:[i32] }:$src, i32:{ *:[i32] }:$src)  =>  (OtherInstr:{ *:[i32] } (ImplicitDefInstr:{ *:[i32] }:{ *:[i32] } GPR32:{ *:[i32] }:$src))
+// CHECK-NEXT: GIR_MakeTempReg, /*TempRegID*/0, /*TypeID*/GILLT_s32,
+// CHECK-NEXT: GIR_BuildMI, /*InsnID*/1, /*Opcode*/MyTarget::ImplicitDefInstr,
+// CHECK-NEXT: GIR_AddTempRegister, /*InsnID*/1, /*TempRegID*/0, /*TempRegFlags*/RegState::Define,
+// CHECK-NEXT: GIR_Copy, /*NewInsnID*/1, /*OldInsnID*/0, /*OpIdx*/1, // src
+// CHECK-NEXT: GIR_SetImplicitDefDead, /*InsnID*/1, /*OpIdx for MyTarget::R0*/0,
+// CHECK-NEXT: GIR_ConstrainSelectedInstOperands, /*InsnID*/1,
+// CHECK-NEXT: GIR_BuildMI, /*InsnID*/0, /*Opcode*/MyTarget::OtherInstr,
+// CHECK-NEXT: GIR_Copy, /*NewInsnID*/0, /*OldInsnID*/0, /*OpIdx*/0, // dst
+// CHECK-NEXT: GIR_AddTempRegister, /*InsnID*/0, /*TempRegID*/0, /*TempRegFlags*/0,
+// CHECK-NEXT: GIR_EraseFromParent, /*InsnID*/0,
+// CHECK-NEXT: GIR_ConstrainSelectedInstOperands, /*InsnID*/0,
Index: llvm/utils/TableGen/GlobalISelEmitter.cpp
===================================================================
--- llvm/utils/TableGen/GlobalISelEmitter.cpp
+++ llvm/utils/TableGen/GlobalISelEmitter.cpp
@@ -286,9 +286,11 @@
 
 static Expected<LLTCodeGen> getInstResultType(const TreePatternNode *Dst) {
   ArrayRef<TypeSetByHwMode> ChildTypes = Dst->getExtTypes();
-  if (ChildTypes.size() != 1)
-    return failedImport("Dst pattern child has multiple results");
+  if (ChildTypes.size() < 1)
+    return failedImport("Dst pattern child has no result");
 
+  // If there are multiple results, just take the first one (this is how
+  // SelectionDAG does it).
   std::optional<LLTCodeGen> MaybeOpTy;
   if (ChildTypes.front().isMachineValueType()) {
     MaybeOpTy = MVTToLLT(ChildTypes.front().getMachineValueType().SimpleTy);
@@ -1776,10 +1778,11 @@
     return getRegClassFromLeaf(N);
 
   // We don't have a leaf node, so we have to try and infer something. Check
-  // that we have an instruction that we an infer something from.
+  // that we have an instruction that we can infer something from.
 
-  // Only handle things that produce a single type.
-  if (N->getNumTypes() != 1)
+  // Only handle things that produce at least one value (if multiple values,
+  // just take the first one).
+  if (N->getNumTypes() < 1)
     return std::nullopt;
   Record *OpRec = N->getOperator();