Fix another case of live_in at irreducible loop entry.

GVN was implicitly extending the liveness of an instruction across
an irreducible loop.

Fix this problem by clearing the value set at loop entries that contain
an irreducible loop.

bug:28252896

(cherry picked from commit 77ce6430af2709432b22344ed656edd8ec80581b)

Change-Id: Ie0121e83b2dfe47bcd184b90a69c0194d13fce54

1 files changed, 7 insertions, 0 deletions

diff --git a/compiler/optimizing/nodes.h b/compiler/optimizing/nodes.h
index 934d355e82..12ea059d3f 100644
--- a/compiler/optimizing/nodes.h
+++ b/compiler/optimizing/nodes.h
@@ -650,6 +650,7 @@ class HLoopInformation : public ArenaObject<kArenaAllocLoopInfo> {
       : header_(header),
         suspend_check_(nullptr),
         irreducible_(false),
+        contains_irreducible_loop_(false),
         back_edges_(graph->GetArena()->Adapter(kArenaAllocLoopInfoBackEdges)),
         // Make bit vector growable, as the number of blocks may change.
         blocks_(graph->GetArena(), graph->GetBlocks().size(), true, kArenaAllocLoopInfoBackEdges) {
@@ -657,6 +658,7 @@ class HLoopInformation : public ArenaObject<kArenaAllocLoopInfo> {
   }
 
   bool IsIrreducible() const { return irreducible_; }
+  bool ContainsIrreducibleLoop() const { return contains_irreducible_loop_; }
 
   void Dump(std::ostream& os);
 
@@ -727,6 +729,10 @@ class HLoopInformation : public ArenaObject<kArenaAllocLoopInfo> {
 
   bool HasBackEdgeNotDominatedByHeader() const;
 
+  bool IsPopulated() const {
+    return blocks_.GetHighestBitSet() != -1;
+  }
+
  private:
   // Internal recursive implementation of `Populate`.
   void PopulateRecursive(HBasicBlock* block);
@@ -735,6 +741,7 @@ class HLoopInformation : public ArenaObject<kArenaAllocLoopInfo> {
   HBasicBlock* header_;
   HSuspendCheck* suspend_check_;
   bool irreducible_;
+  bool contains_irreducible_loop_;
   ArenaVector<HBasicBlock*> back_edges_;
   ArenaBitVector blocks_;