Re-apply bottom-up fast-isel, with fixes. Be very careful to avoid emitting
a DBG_VALUE after a terminator, or emitting any instructions before an EH_LABEL.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@107943 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/InstrEmitter.cpp b/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
index d7d63d3..40fb3a4 100644
--- a/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
+++ b/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
@@ -734,8 +734,13 @@
   if (II.usesCustomInsertionHook()) {
     // Insert this instruction into the basic block using a target
     // specific inserter which may returns a new basic block.
-    MBB = TLI->EmitInstrWithCustomInserter(MI, MBB);
-    InsertPos = MBB->end();
+    bool AtEnd = InsertPos == MBB->end();
+    MachineBasicBlock *NewMBB = TLI->EmitInstrWithCustomInserter(MI, MBB);
+    if (NewMBB != MBB) {
+      if (AtEnd)
+        InsertPos = NewMBB->end();
+      MBB = NewMBB;
+    }
     return;
   }