Re-apply r80926, with fixes: keep the domtree informed of new blocks

that get created during loop unswitching, and fix SplitBlockPredecessors'
LCSSA updating code to create new PHIs instead of trying to just move
existing ones.

Also, optimize Loop::verifyLoop, since it gets called a lot. Use
searches on a sorted list of blocks instead of calling the "contains"
function, as is done in other places in the Loop class, since "contains"
does a linear search. Also, don't call verifyLoop from LoopSimplify or
LCSSA, as the PassManager is already calling verifyLoop as part of
LoopInfo's verifyAnalysis.

llvm-svn: 81221

1 files changed, 10 insertions, 0 deletions

diff --git a/llvm/lib/Analysis/LoopInfo.cpp b/llvm/lib/Analysis/LoopInfo.cpp
index b240579..665e53d 100644
--- a/llvm/lib/Analysis/LoopInfo.cpp
+++ b/llvm/lib/Analysis/LoopInfo.cpp
@@ -300,6 +300,9 @@ bool Loop::isLoopSimplifyForm() const {
 ///
 void
 Loop::getUniqueExitBlocks(SmallVectorImpl<BasicBlock *> &ExitBlocks) const {
+  assert(isLoopSimplifyForm() &&
+         "getUniqueExitBlocks assumes the loop is in canonical form!");
+
   // Sort the blocks vector so that we can use binary search to do quick
   // lookups.
   SmallVector<BasicBlock *, 128> LoopBBs(block_begin(), block_end());
@@ -371,6 +374,13 @@ bool LoopInfo::runOnFunction(Function &) {
   return false;
 }
 
+void LoopInfo::verifyAnalysis() const {
+  for (iterator I = begin(), E = end(); I != E; ++I) {
+    assert(!(*I)->getParentLoop() && "Top-level loop has a parent!");
+    (*I)->verifyLoopNest();
+  }
+}
+
 void LoopInfo::getAnalysisUsage(AnalysisUsage &AU) const {
   AU.setPreservesAll();
   AU.addRequired<DominatorTree>();