Add a verifyAnalysis to LoopInfo, LoopSimplify, and LCSSA form that verify

that these passes are properly preserved.

Fix several transformation passes that claimed to preserve LoopSimplify
form but weren't.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@80926 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 81 insertions, 12 deletions

diff --git a/include/llvm/Analysis/LoopInfo.h b/include/llvm/Analysis/LoopInfo.h
index b803176..1892bc7 100644
--- a/include/llvm/Analysis/LoopInfo.h
+++ b/include/llvm/Analysis/LoopInfo.h
@@ -376,11 +376,73 @@ public:
   /// verifyLoop - Verify loop structure
   void verifyLoop() const {
 #ifndef NDEBUG
-    assert (getHeader() && "Loop header is missing");
-    assert (getLoopPreheader() && "Loop preheader is missing");
-    assert (getLoopLatch() && "Loop latch is missing");
-    for (iterator I = SubLoops.begin(), E = SubLoops.end(); I != E; ++I)
+    assert(!Blocks.empty() && "Loop header is missing");
+    assert(getHeader() && "Loop header is missing");
+
+    // Verify the individual blocks.
+    for (block_iterator I = block_begin(), E = block_end(); I != E; ++I) {
+      BlockT *BB = *I;
+      bool HasInsideLoopSuccs = false;
+      bool HasInsideLoopPreds = false;
+      SmallVector<BlockT *, 2> OutsideLoopPreds;
+
+      typedef GraphTraits<BlockT*> BlockTraits;
+      for (typename BlockTraits::ChildIteratorType SI =
+           BlockTraits::child_begin(BB), SE = BlockTraits::child_end(BB);
+           SI != SE; ++SI)
+        if (contains(*SI))
+          HasInsideLoopSuccs = true;
+      typedef GraphTraits<Inverse<BlockT*> > InvBlockTraits;
+      for (typename InvBlockTraits::ChildIteratorType PI =
+           InvBlockTraits::child_begin(BB), PE = InvBlockTraits::child_end(BB);
+           PI != PE; ++PI) {
+        if (contains(*PI))
+          HasInsideLoopPreds = true;
+        else
+          OutsideLoopPreds.push_back(*PI);
+      }
+
+      if (BB == getHeader()) {
+        assert(!OutsideLoopPreds.empty() && "Loop is unreachable!");
+      } else if (!OutsideLoopPreds.empty()) {
+        // A non-header loop shouldn't be reachable from outside the loop,
+        // though it is permitted if the predecessor is not itself actually
+        // reachable.
+        BlockT *EntryBB = BB->getParent()->begin();
+        for (df_iterator<BlockT *> NI = df_begin(EntryBB),
+             NE = df_end(EntryBB); NI != NE; ++NI)
+          for (unsigned i = 0, e = OutsideLoopPreds.size(); i != e; ++i)
+            assert(*NI != OutsideLoopPreds[i] &&
+                   "Loop has multiple entry points!");
+      }
+      assert(HasInsideLoopPreds && "Loop block has no in-loop predecessors!");
+      assert(HasInsideLoopSuccs && "Loop block has no in-loop successors!");
+      assert(BB != getHeader()->getParent()->begin() &&
+             "Loop contains function entry block!");
+    }
+
+    // Verify the subloops.
+    for (iterator I = begin(), E = end(); I != E; ++I) {
+      // Each block in each subloop should be contained within this loop.
+      for (block_iterator BI = (*I)->block_begin(), BE = (*I)->block_end();
+           BI != BE; ++BI) {
+        assert(contains(*BI) &&
+               "Loop does not contain all the blocks of a subloop!");
+      }
+      // Recursively check the subloop.
       (*I)->verifyLoop();
+    }
+
+    // Verify the parent loop.
+    if (ParentLoop) {
+      bool FoundSelf = false;
+      for (iterator I = ParentLoop->begin(), E = ParentLoop->end(); I != E; ++I)
+        if (*I == this) {
+          FoundSelf = true;
+          break;
+        }
+      assert(FoundSelf && "Loop is not a subloop of its parent!");
+    }
 #endif
   }
 
@@ -873,6 +935,8 @@ public:
   ///
   virtual bool runOnFunction(Function &F);
 
+  virtual void verifyAnalysis() const;
+
   virtual void releaseMemory() { LI.releaseMemory(); }
 
   virtual void print(raw_ostream &O, const Module* M = 0) const;
diff --git a/include/llvm/Transforms/Utils/BasicBlockUtils.h b/include/llvm/Transforms/Utils/BasicBlockUtils.h
index 95ffa46..e766d72 100644
--- a/include/llvm/Transforms/Utils/BasicBlockUtils.h
+++ b/include/llvm/Transforms/Utils/BasicBlockUtils.h
@@ -126,10 +126,10 @@ bool isCriticalEdge(const TerminatorInst *TI, unsigned SuccNum,
 /// dest go to one block instead of each going to a different block, but isn't 
 /// the standard definition of a "critical edge".
 ///
-bool SplitCriticalEdge(TerminatorInst *TI, unsigned SuccNum, Pass *P = 0,
-                       bool MergeIdenticalEdges = false);
+BasicBlock *SplitCriticalEdge(TerminatorInst *TI, unsigned SuccNum,
+                              Pass *P = 0, bool MergeIdenticalEdges = false);
 
-inline bool SplitCriticalEdge(BasicBlock *BB, succ_iterator SI, Pass *P = 0) {
+inline BasicBlock *SplitCriticalEdge(BasicBlock *BB, succ_iterator SI, Pass *P = 0) {
   return SplitCriticalEdge(BB->getTerminator(), SI.getSuccessorIndex(), P);
 }
 
@@ -143,7 +143,7 @@ inline bool SplitCriticalEdge(BasicBlock *Succ, pred_iterator PI, Pass *P = 0) {
   TerminatorInst *TI = (*PI)->getTerminator();
   for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
     if (TI->getSuccessor(i) == Succ)
-      MadeChange |= SplitCriticalEdge(TI, i, P);
+      MadeChange |= !!SplitCriticalEdge(TI, i, P);
   return MadeChange;
 }
 
@@ -151,8 +151,9 @@ inline bool SplitCriticalEdge(BasicBlock *Succ, pred_iterator PI, Pass *P = 0) {
 /// and return true, otherwise return false.  This method requires that there be
 /// an edge between the two blocks.  If P is specified, it updates the analyses
 /// described above.
-inline bool SplitCriticalEdge(BasicBlock *Src, BasicBlock *Dst, Pass *P = 0,
-                              bool MergeIdenticalEdges = false) {
+inline BasicBlock *SplitCriticalEdge(BasicBlock *Src, BasicBlock *Dst,
+                                     Pass *P = 0,
+                                     bool MergeIdenticalEdges = false) {
   TerminatorInst *TI = Src->getTerminator();
   unsigned i = 0;
   while (1) {
@@ -180,8 +181,12 @@ BasicBlock *SplitBlock(BasicBlock *Old, Instruction *SplitPt, Pass *P);
 /// Preds array, which has NumPreds elements in it.  The new block is given a
 /// suffix of 'Suffix'.  This function returns the new block.
 ///
-/// This currently updates the LLVM IR, AliasAnalysis, DominatorTree and
-/// DominanceFrontier, but no other analyses.
+/// This currently updates the LLVM IR, AliasAnalysis, DominatorTree,
+/// DominanceFrontier, LoopInfo, and LCCSA but no other analyses.
+/// In particular, it does not preserve LoopSimplify (because it's
+/// complicated to handle the case where one of the edges being split
+/// is an exit of a loop with other exits).
+///
 BasicBlock *SplitBlockPredecessors(BasicBlock *BB, BasicBlock *const *Preds,
                                    unsigned NumPreds, const char *Suffix,
                                    Pass *P = 0);