[turbofan] Fix non-termination in RedundancyElimination.

A pointer comparison on the effect path states is not sufficient to
guarantee termination; we really need to check the actual nodes to
make sure we terminate properly, similar to what BranchElimination
does.

R=jarin@chromium.org
BUG=v8:5161

Review-Url: https://codereview.chromium.org/2112463002
Cr-Commit-Position: refs/heads/master@{#37389}

src/compiler/redundancy-elimination.cc

@@ -55,6 +55,19 @@ RedundancyElimination::EffectPathChecks::Empty(Zone* zone) {
   return new (zone->New(sizeof(EffectPathChecks))) EffectPathChecks(nullptr, 0);
 }
 
+bool RedundancyElimination::EffectPathChecks::Equals(
+    EffectPathChecks const* that) const {
+  if (this->size_ != that->size_) return false;
+  Check* this_head = this->head_;
+  Check* that_head = that->head_;
+  while (this_head != that_head) {
+    if (this_head->node != that_head->node) return false;
+    this_head = this_head->next;
+    that_head = that_head->next;
+  }
+  return true;
+}
+
 void RedundancyElimination::EffectPathChecks::Merge(
     EffectPathChecks const* that) {
   // Change the current check list to a longest common tail of this check
@@ -207,8 +220,10 @@ Reduction RedundancyElimination::UpdateChecks(Node* node,
   // Only signal that the {node} has Changed, if the information about {checks}
   // has changed wrt. the {original}.
   if (checks != original) {
-    node_checks_.Set(node, checks);
-    return Changed(node);
+    if (original == nullptr || !checks->Equals(original)) {
+      node_checks_.Set(node, checks);
+      return Changed(node);
+    }
   }
   return NoChange();
 }

src/compiler/redundancy-elimination.h

@@ -29,6 +29,7 @@ class RedundancyElimination final : public AdvancedReducer {
    public:
     static EffectPathChecks* Copy(Zone* zone, EffectPathChecks const* checks);
     static EffectPathChecks const* Empty(Zone* zone);
+    bool Equals(EffectPathChecks const* that) const;
     void Merge(EffectPathChecks const* that);
 
     EffectPathChecks const* AddCheck(Zone* zone, Node* node) const;

test/cctest/cctest.status

@@ -123,9 +123,6 @@
   'test-cpu-profiler/DeoptAtSecondLevelInlinedSource': [PASS, NO_VARIANTS],
   'test-cpu-profiler/DeoptUntrackedFunction': [PASS, NO_VARIANTS],
 
-  # BUG(v8:5161): Flaky with turbofan.
-  'test-thread-termination/TerminateAndReenterFromThreadItself': [PASS, ['system == macos', NO_VARIANTS]],
-
   ############################################################################
   # Slow tests.
   'test-api/Threading1': [PASS, ['mode == debug', SLOW]],

test/mjsunit/mjsunit.status

@@ -278,10 +278,6 @@
   'unicodelctest': [PASS, NO_VARIANTS],
   'unicodelctest-no-optimization': [PASS, NO_VARIANTS],
 
-  # BUG(v8:5161): Flaky with turbofan.
-  'regress/regress-201': [PASS, NO_VARIANTS],
-  'regress/regress-91008': [PASS, NO_VARIANTS],
-
   ############################################################################
   # Ignition