Turns out AnalyzeBranch can modify the mbb being analyzed. This is a nasty

suprise to some callers, e.g. register coalescer. For now, add an parameter
that tells AnalyzeBranch whether it's safe to modify the mbb. A better
solution is out there, but I don't have time to deal with it right now.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@64124 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/PowerPC/PPCInstrInfo.cpp

@@ -204,7 +204,8 @@ void PPCInstrInfo::insertNoop(MachineBasicBlock &MBB,
 // Branch analysis.
 bool PPCInstrInfo::AnalyzeBranch(MachineBasicBlock &MBB,MachineBasicBlock *&TBB,
                                  MachineBasicBlock *&FBB,
-                                 SmallVectorImpl<MachineOperand> &Cond) const {
+                                 SmallVectorImpl<MachineOperand> &Cond,
+                                 bool AllowModify) const {
   // If the block has no terminators, it just falls into the block after it.
   MachineBasicBlock::iterator I = MBB.end();
   if (I == MBB.begin() || !isUnpredicatedTerminator(--I))
@@ -253,7 +254,8 @@ bool PPCInstrInfo::AnalyzeBranch(MachineBasicBlock &MBB,MachineBasicBlock *&TBB,
       LastInst->getOpcode() == PPC::B) {
     TBB = SecondLastInst->getOperand(0).getMBB();
     I = LastInst;
-    I->eraseFromParent();
+    if (AllowModify)
+      I->eraseFromParent();
     return false;
   }