[turbofan] Introduce NumberFloor simplified operator.

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 120d7926d541bbc5feab7f5627d5aa8c1dbc7540..48aca9729e0393b1a9ba8db7a07c52b75581a841 100644
--- a/src/compiler/simplified-operator-reducer.cc
+++ b/src/compiler/simplified-operator-reducer.cc
@@ -9,14 +9,14 @@
 #include "src/compiler/node-matchers.h"
 #include "src/compiler/operator-properties.h"
 #include "src/conversions-inl.h"
+#include "src/type-cache.h"
 
 namespace v8 {
 namespace internal {
 namespace compiler {
 
 SimplifiedOperatorReducer::SimplifiedOperatorReducer(JSGraph* jsgraph)
-    : jsgraph_(jsgraph) {}
-
+    : jsgraph_(jsgraph), type_cache_(TypeCache::Get()) {}
 
 SimplifiedOperatorReducer::~SimplifiedOperatorReducer() {}
 
@@ -89,6 +89,8 @@ Reduction SimplifiedOperatorReducer::Reduce(Node* node) {
       if (m.HasValue()) return ReplaceNumber(FastUI2D(m.Value()));
       break;
     }
+    case IrOpcode::kNumberFloor:
+      return ReduceNumberFloor(node);
     case IrOpcode::kReferenceEqual:
       return ReduceReferenceEqual(node);
     default:
@@ -97,6 +99,15 @@ Reduction SimplifiedOperatorReducer::Reduce(Node* node) {
   return NoChange();
 }
 
+Reduction SimplifiedOperatorReducer::ReduceNumberFloor(Node* node) {
+  DCHECK_EQ(IrOpcode::kNumberFloor, node->opcode());
+  Node* const input = NodeProperties::GetValueInput(node, 0);
+  Type* const input_type = NodeProperties::GetType(input);
+  if (input_type->Is(type_cache_.kIntegerOrMinusZeroOrNaN)) {
+    return Replace(input);
+  }
+  return NoChange();
+}
 
 Reduction SimplifiedOperatorReducer::ReduceReferenceEqual(Node* node) {
   DCHECK_EQ(IrOpcode::kReferenceEqual, node->opcode());