From db6b6a7f0c951c6b11b68605ede0aacbbda4bb2a Mon Sep 17 00:00:00 2001
From: Justin Bogner <mail@justinbogner.com>
Date: Fri, 28 Oct 2016 22:42:54 +0000
Subject: [PATCH] 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.

llvm-svn: 285467
---
 llvm/lib/CodeGen/SelectionDAG/InstrEmitter.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/llvm/lib/CodeGen/SelectionDAG/InstrEmitter.cpp b/llvm/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
index d760a70b1f36..3b91e58879b4 100644
--- a/llvm/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
+++ b/llvm/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);