[globalisel][tblgen] Add support for ComplexPatterns

Summary:
Adds a new kind of MachineOperand: MO_Placeholder.
This operand must not appear in the MIR and only exists as a way of
creating an 'uninitialized' operand until a matcher function overwrites it.

Depends on D30046, D29712

Reviewers: t.p.northover, ab, rovka, aditya_nandakumar, javed.absar, qcolombet

Reviewed By: qcolombet

Subscribers: dberris, kristof.beyls, llvm-commits

Differential Revision: https://reviews.llvm.org/D30089

llvm-svn: 297782

1 files changed, 8 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/MachineInstr.cpp b/llvm/lib/CodeGen/MachineInstr.cpp
index 20ae830818a..7039aecc219 100644
--- a/llvm/lib/CodeGen/MachineInstr.cpp
+++ b/llvm/lib/CodeGen/MachineInstr.cpp
@@ -287,6 +287,8 @@ bool MachineOperand::isIdenticalTo(const MachineOperand &Other) const {
     return getIntrinsicID() == Other.getIntrinsicID();
   case MachineOperand::MO_Predicate:
     return getPredicate() == Other.getPredicate();
+  case MachineOperand::MO_Placeholder:
+    return true;
   }
   llvm_unreachable("Invalid machine operand type");
 }
@@ -335,6 +337,8 @@ hash_code llvm::hash_value(const MachineOperand &MO) {
     return hash_combine(MO.getType(), MO.getTargetFlags(), MO.getIntrinsicID());
   case MachineOperand::MO_Predicate:
     return hash_combine(MO.getType(), MO.getTargetFlags(), MO.getPredicate());
+  case MachineOperand::MO_Placeholder:
+    return hash_combine();
   }
   llvm_unreachable("Invalid machine operand type");
 }
@@ -504,7 +508,11 @@ void MachineOperand::print(raw_ostream &OS, ModuleSlotTracker &MST,
     auto Pred = static_cast<CmpInst::Predicate>(getPredicate());
     OS << '<' << (CmpInst::isIntPredicate(Pred) ? "intpred" : "floatpred")
        << CmpInst::getPredicateName(Pred) << '>';
+    break;
   }
+  case MachineOperand::MO_Placeholder:
+    OS << "<placeholder>";
+    break;
   }
   if (unsigned TF = getTargetFlags())
     OS << "[TF=" << TF << ']';