[PowerPC] Added an assert to make sure that the MBBI iterator is valid.

The function createTailCallBranchInstr assumes that the iterator MBBI is valid.
However, only one use of MBBI is guarded in the function.
Fix this by adding an assert.

Differential Revision: https://reviews.llvm.org/D41358

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@321205 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/PowerPC/PPCFrameLowering.cpp b/lib/Target/PowerPC/PPCFrameLowering.cpp
index c870a22..7902da2 100644 (file)
--- a/lib/Target/PowerPC/PPCFrameLowering.cpp
+++ b/lib/Target/PowerPC/PPCFrameLowering.cpp
@@ -1531,11 +1531,11 @@ void PPCFrameLowering::emitEpilogue(MachineFunction &MF,
 
 void PPCFrameLowering::createTailCallBranchInstr(MachineBasicBlock &MBB) const {
   MachineBasicBlock::iterator MBBI = MBB.getFirstTerminator();
-  DebugLoc dl;
 
-  if (MBBI != MBB.end())
-    dl = MBBI->getDebugLoc();
+  // If we got this far a first terminator should exist.
+  assert(MBBI != MBB.end() && "Failed to find the first terminator.");
 
+  DebugLoc dl = MBBI->getDebugLoc();
   const PPCInstrInfo &TII = *Subtarget.getInstrInfo();
 
   // Create branch instruction for pseudo tail call return instruction