Add r134057 back, but splice the predecessor after the successors phi

nodes.

Original message:
Let simplify cfg simplify bb with only debug and lifetime intrinsics.

llvm-svn: 134182

1 files changed, 20 insertions, 0 deletions

diff --git a/llvm/lib/VMCore/BasicBlock.cpp b/llvm/lib/VMCore/BasicBlock.cpp
index 7d470440aff..70265c899d7 100644
--- a/llvm/lib/VMCore/BasicBlock.cpp
+++ b/llvm/lib/VMCore/BasicBlock.cpp
@@ -147,6 +147,26 @@ Instruction* BasicBlock::getFirstNonPHIOrDbg() {
   return &*i;
 }
 
+Instruction* BasicBlock::getFirstNonPHIOrDbgOrLifetime() {
+  // All valid basic blocks should have a terminator,
+  // which is not a PHINode. If we have an invalid basic
+  // block we'll get an assertion failure when dereferencing
+  // a past-the-end iterator.
+  BasicBlock::iterator i = begin();
+  for (;; ++i) {
+    if (isa<PHINode>(i) || isa<DbgInfoIntrinsic>(i))
+      continue;
+
+    const IntrinsicInst *II = dyn_cast<IntrinsicInst>(i);
+    if (!II)
+      break;
+    if (II->getIntrinsicID() != Intrinsic::lifetime_start &&
+        II->getIntrinsicID() != Intrinsic::lifetime_end)
+      break;
+  }
+  return &*i;
+}
+
 void BasicBlock::dropAllReferences() {
   for(iterator I = begin(), E = end(); I != E; ++I)
     I->dropAllReferences();