Revert r133004 ; it's breaking nightly tests.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@133007 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 21 insertions, 4 deletions

diff --git a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
index 161afba..187963c 100644
--- a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -1925,7 +1925,7 @@ isBlockOnlyReachableByFallthrough(const MachineBasicBlock *MBB) const {
     return false;
 
   // The predecessor has to be immediately before this block.
-  const MachineBasicBlock *Pred = *PI;
+  MachineBasicBlock *Pred = *PI;
 
   if (!Pred->isLayoutSuccessor(MBB))
     return false;
@@ -1934,9 +1934,26 @@ isBlockOnlyReachableByFallthrough(const MachineBasicBlock *MBB) const {
   if (Pred->empty())
     return true;
 
-  // Otherwise, check the last instruction.
-  const MachineInstr &LastInst = Pred->back();
-  return !LastInst.getDesc().isBarrier();
+  // Check the terminators in the previous blocks
+  for (MachineBasicBlock::iterator II = Pred->getFirstTerminator(),
+         IE = Pred->end(); II != IE; ++II) {
+    MachineInstr &MI = *II;
+
+    // If it is not a simple branch, we are in a table somewhere.
+    if (!MI.getDesc().isBranch() || MI.getDesc().isIndirectBranch())
+      return false;
+
+    // If we are the operands of one of the branches, this is not
+    // a fall through.
+    for (MachineInstr::mop_iterator OI = MI.operands_begin(),
+           OE = MI.operands_end(); OI != OE; ++OI) {
+      const MachineOperand& OP = *OI;
+      if (OP.isMBB() && OP.getMBB() == MBB)
+        return false;
+    }
+  }
+
+  return true;
 }