Recommit "[GVN] Preserve loop related analysis/canonical forms."

This fixes some pipeline tests.
This reverts commit d0b6f42936bfb6d56d325c732ae79400c9c6016a.

llvm-svn: 367401

1 files changed, 9 insertions, 2 deletions

diff --git a/llvm/lib/Analysis/CFG.cpp b/llvm/lib/Analysis/CFG.cpp
index 18b83d6838c..8215b4ecbb0 100644
--- a/llvm/lib/Analysis/CFG.cpp
+++ b/llvm/lib/Analysis/CFG.cpp
@@ -87,11 +87,18 @@ unsigned llvm::GetSuccessorNumber(const BasicBlock *BB,
 /// with multiple predecessors.
 bool llvm::isCriticalEdge(const Instruction *TI, unsigned SuccNum,
                           bool AllowIdenticalEdges) {
-  assert(TI->isTerminator() && "Must be a terminator to have successors!");
   assert(SuccNum < TI->getNumSuccessors() && "Illegal edge specification!");
+  return isCriticalEdge(TI, TI->getSuccessor(SuccNum), AllowIdenticalEdges);
+}
+
+bool llvm::isCriticalEdge(const Instruction *TI, const BasicBlock *Dest,
+                          bool AllowIdenticalEdges) {
+  assert(TI->isTerminator() && "Must be a terminator to have successors!");
   if (TI->getNumSuccessors() == 1) return false;
 
-  const BasicBlock *Dest = TI->getSuccessor(SuccNum);
+  assert(find(predecessors(Dest), TI->getParent()) != pred_end(Dest) &&
+         "No edge between TI's block and Dest.");
+
   const_pred_iterator I = pred_begin(Dest), E = pred_end(Dest);
 
   // If there is more than one predecessor, this is a critical edge...