We've made v8 even faster! nc 35.198.159.246 1337

Difficulty: hard

Chromium v8 patch:

diff --git a/src/compiler/redundancy-elimination.cc b/src/compiler/redundancy-elimination.cc
index 3a40e8d..cb51acc 100644
--- a/src/compiler/redundancy-elimination.cc
+++ b/src/compiler/redundancy-elimination.cc
@@ -5,6 +5,8 @@
 #include "src/compiler/redundancy-elimination.h"
 
 #include "src/compiler/node-properties.h"
+#include "src/compiler/simplified-operator.h"
+#include "src/objects-inl.h"
 
 namespace v8 {
 namespace internal {
@@ -23,6 +25,7 @@ Reduction RedundancyElimination::Reduce(Node* node) {
     case IrOpcode::kCheckHeapObject:
     case IrOpcode::kCheckIf:
     case IrOpcode::kCheckInternalizedString:
+    case IrOpcode::kCheckMaps:
     case IrOpcode::kCheckNumber:
     case IrOpcode::kCheckReceiver:
     case IrOpcode::kCheckSmi:
@@ -129,6 +132,14 @@ bool IsCompatibleCheck(Node const* a, Node const* b) {
     if (a->opcode() == IrOpcode::kCheckInternalizedString &&
         b->opcode() == IrOpcode::kCheckString) {
       // CheckInternalizedString(node) implies CheckString(node)
+    } else if (a->opcode() == IrOpcode::kCheckMaps &&
+               b->opcode() == IrOpcode::kCheckMaps) {
+      // CheckMaps are compatible if the first checks a subset of the second.
+      ZoneHandleSet<Map> const& a_maps = CheckMapsParametersOf(a->op()).maps();
+      ZoneHandleSet<Map> const& b_maps = CheckMapsParametersOf(b->op()).maps();
+      if (!b_maps.contains(a_maps)) {
+        return false;
+      }
     } else {
       return false;
     }