SDAG: Make sure we use an allocatable reg class when we create this vreg

As per the discussion on r280783, if constrainRegClass fails we need
to call getAllocatableClass like we did before that commit.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@285467 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/SelectionDAG/InstrEmitter.cpp b/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
index d760a70b1f368fdc7fc6e44e5c101d58ab9b796c..3b91e58879b49e6d09ebc55c4be0ead8174d2560 100644 (file)
--- a/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
+++ b/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
@@ -338,6 +338,8 @@ InstrEmitter::AddRegisterOperand(MachineInstrBuilder &MIB,
       const TargetRegisterClass *ConstrainedRC
         = MRI->constrainRegClass(VReg, OpRC, MinRCSize);
       if (!ConstrainedRC) {
+        OpRC = TRI->getAllocatableClass(OpRC);
+        assert(OpRC && "Constraints cannot be fulfilled for allocation");
         unsigned NewVReg = MRI->createVirtualRegister(OpRC);
         BuildMI(*MBB, InsertPos, Op.getNode()->getDebugLoc(),
                 TII->get(TargetOpcode::COPY), NewVReg).addReg(VReg);