[turbofan] Eliminate typed array bounds checks if both key and length are constant.

src/compiler/simplified-operator-reducer.cc

Index: src/compiler/simplified-operator-reducer.cc
diff --git a/src/compiler/simplified-operator-reducer.cc b/src/compiler/simplified-operator-reducer.cc
index f6181ea988ffca2e432ce7afd0847578ace1e8e2..49b87b22a1aa036f15ccaee3028d6b90131f910c 100644
--- a/src/compiler/simplified-operator-reducer.cc
+++ b/src/compiler/simplified-operator-reducer.cc
@@ -12,6 +12,10 @@ namespace v8 {
 namespace internal {
 namespace compiler {
 
+SimplifiedOperatorReducer::SimplifiedOperatorReducer(JSGraph* jsgraph)
+    : jsgraph_(jsgraph), simplified_(jsgraph->zone()) {}
+
+
 SimplifiedOperatorReducer::~SimplifiedOperatorReducer() {}
 
 
@@ -95,6 +99,38 @@ Reduction SimplifiedOperatorReducer::Reduce(Node* node) {
       if (m.HasValue()) return ReplaceNumber(FastUI2D(m.Value()));
       break;
     }
+    case IrOpcode::kLoadElement: {
+      ElementAccess access = ElementAccessOf(node->op());
+      if (access.bounds_check == kTypedArrayBoundsCheck) {
+        NumericValueMatcher mkey(node->InputAt(1));
+        NumericValueMatcher mlength(node->InputAt(2));
+        if (mkey.HasValue() && mlength.HasValue()) {
+          // Skip the typed array bounds check if key and length are constant.
+          if (mkey.Value() < mlength.Value()) {
+            access.bounds_check = kNoBoundsCheck;
+            node->set_op(simplified()->LoadElement(access));
+            return Changed(node);
+          }
+        }
+      }
+      break;
+    }
+    case IrOpcode::kStoreElement: {
+      ElementAccess access = ElementAccessOf(node->op());
+      if (access.bounds_check == kTypedArrayBoundsCheck) {
+        NumericValueMatcher mkey(node->InputAt(1));
+        NumericValueMatcher mlength(node->InputAt(2));
+        if (mkey.HasValue() && mlength.HasValue()) {
+          // Skip the typed array bounds check if key and length are constant.
+          if (mkey.Value() < mlength.Value()) {
+            access.bounds_check = kNoBoundsCheck;
+            node->set_op(simplified()->StoreElement(access));
+            return Changed(node);
+          }
+        }
+      }
+      break;
+    }
     default:
       break;
   }