Revert r133607. This is causing failures in the Clang gccTestSuite.

Specifically, gcc.c-torture/compile/pr21356.c.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@133646 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/TailDuplication.cpp b/lib/CodeGen/TailDuplication.cpp
index 6e832d99ef928c91b5e0e96508020e2ff4f17ac2..d16369a4ca66cf036a1b460d97d28bdb74b69f8a 100644 (file)
--- a/lib/CodeGen/TailDuplication.cpp
+++ b/lib/CodeGen/TailDuplication.cpp
@@ -568,9 +568,9 @@ bool
 TailDuplicatePass::isSimpleBB(MachineBasicBlock *TailBB) {
   if (TailBB->succ_size() != 1)
     return false;
-  MachineBasicBlock::iterator I = TailBB->begin();
+  MachineBasicBlock::iterator I = TailBB->getFirstNonPHI();
   MachineBasicBlock::iterator E = TailBB->end();
-  while (I != E && I->isDebugValue())
+  while (I->isDebugValue() && I != E)
     ++I;
   if (I == E)
     return true;
@@ -712,7 +712,7 @@ TailDuplicatePass::TailDuplicate(MachineBasicBlock *TailBB, MachineFunction &MF,
   DenseSet<unsigned> UsedByPhi;
   getRegsUsedByPHIs(*TailBB, &UsedByPhi);
 
-  if (isSimpleBB(TailBB))
+  if (0 && isSimpleBB(TailBB))
     return duplicateSimpleBB(TailBB, TDBBs, UsedByPhi, Copies);
 
   // Iterate through all the unique predecessors and tail-duplicate this