[regexp] Avoid runtime call on OOB lastIndex values

src/code-stub-assembler.cc

 // Copyright 2016 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 #include "src/code-stub-assembler.h"
 #include "src/code-factory.h"
 #include "src/frames-inl.h"
 #include "src/frames.h"
 
 namespace v8 {
 namespace internal {
@@ skipping 3323 matching lines @@
   GotoIf(Float64GreaterThan(value, smi_max), &out);
   GotoIfNot(Float64Equal(value, value), &out);  // NaN.
 
   var_result.Bind(Int32Constant(0));
   Goto(&out);
 
   BIND(&out);
   return var_result.value();
 }
 
+Node* CodeStubAssembler::IsNumberPositive(Node* number) {
+  CSA_ASSERT(this, IsNumber(number));
+  Node* const float_zero = Float64Constant(0.);
+  return Select(TaggedIsSmi(number),
+                [=] { return TaggedIsPositiveSmi(number); },
+                [=] {
+                  Node* v = LoadHeapNumberValue(number);
+                  return Float64GreaterThanOrEqual(v, float_zero);
+                },
+                MachineRepresentation::kWord32);
+}
+
 Node* CodeStubAssembler::StringCharCodeAt(Node* string, Node* index,
                                           ParameterMode parameter_mode) {
   if (parameter_mode == SMI_PARAMETERS) CSA_ASSERT(this, TaggedIsSmi(index));
   CSA_ASSERT(this, IsString(string));
 
   // Translate the {index} into a Word.
   Node* const int_index = ParameterToWord(index, parameter_mode);
   CSA_ASSERT(this, IntPtrGreaterThanOrEqual(int_index, IntPtrConstant(0)));
 
   VARIABLE(var_result, MachineRepresentation::kWord32);
@@ skipping 5532 matching lines @@
         formatted.c_str(), TENURED);
     CallRuntime(Runtime::kGlobalPrint, NoContextConstant(),
                 HeapConstant(string));
   }
   CallRuntime(Runtime::kDebugPrint, NoContextConstant(), tagged_value);
 #endif
 }
 
 }  // namespace internal
 }  // namespace v8