Don't use getNextOperandForReg().

This way of using getNextOperandForReg() was unlikely to work as
intended. We don't give any guarantees about the order of operands in
the use-def chains, so looking only at operands following a given
operand in the chain doesn't make sense.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161542 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/PowerPC/PPCCTRLoops.cpp b/lib/Target/PowerPC/PPCCTRLoops.cpp
index f50f9b5..2a2abb1 100644
--- a/lib/Target/PowerPC/PPCCTRLoops.cpp
+++ b/lib/Target/PowerPC/PPCCTRLoops.cpp
@@ -337,7 +337,10 @@
     // can get a useful trip count.  The trip count can
     // be either a register or an immediate.  The location
     // of the value depends upon the type (reg or imm).
-    while ((IV_Opnd = IV_Opnd->getNextOperandForReg())) {
+    for (MachineRegisterInfo::reg_iterator
+         RI = MRI->reg_begin(IV_Opnd->getReg()), RE = MRI->reg_end();
+         RI != RE; ++RI) {
+      IV_Opnd = &RI.getOperand();
       bool SignedCmp;
       MachineInstr *MI = IV_Opnd->getParent();
       if (L->contains(MI) && isCompareEqualsImm(MI, SignedCmp) &&