[MIPS] BuildCondBr should preserve MO flags

While simplifying branches in the MachineInstr representation, the
routine BuildCondBr must preserve flags on register MachineOperands. In
particular, it must preserve the <undef> flag.

This fixes a bug that is unlikely to occur in any real scenario, but
which bugpoint is likely to introduce.

Patch By Nick Johnson!

Reviewers: ahatanak, sdardis

Differential Revision: https://reviews.llvm.org/D34041

llvm-svn: 305290

1 files changed, 3 insertions, 6 deletions

diff --git a/llvm/lib/Target/Mips/MipsInstrInfo.cpp b/llvm/lib/Target/Mips/MipsInstrInfo.cpp
index df62c66b75a..4adf77f8d9a 100644
--- a/llvm/lib/Target/Mips/MipsInstrInfo.cpp
+++ b/llvm/lib/Target/Mips/MipsInstrInfo.cpp
@@ -103,12 +103,9 @@ void MipsInstrInfo::BuildCondBr(MachineBasicBlock &MBB, MachineBasicBlock *TBB,
   MachineInstrBuilder MIB = BuildMI(&MBB, DL, MCID);
 
   for (unsigned i = 1; i < Cond.size(); ++i) {
-    if (Cond[i].isReg())
-      MIB.addReg(Cond[i].getReg());
-    else if (Cond[i].isImm())
-      MIB.addImm(Cond[i].getImm());
-    else
-       assert(false && "Cannot copy operand");
+    assert((Cond[i].isImm() || Cond[i].isReg()) &&
+           "Cannot copy operand for conditional branch!");
+    MIB.add(Cond[i]);
   }
   MIB.addMBB(TBB);
 }