Intrinsify StringBase.isEmpty and inline StringBase.get:length.

runtime/vm/intrinsifier_ia32.cc

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 //
 // The intrinsic code below is executed before a method has built its frame.
 // The return address is on the stack and the arguments below it.
 // Registers EDX (arguments descriptor) and ECX (function) must be preserved.
 // Each intrinsification method returns true if the corresponding
 // Dart method was intrinsified.
 
@@ skipping 60 matching lines @@
   V(GrowableObjectArray, [], GrowableArray_getIndexed)                         \
   V(ImmutableArray, [], Array_getIndexed)                                      \
   V(ImmutableArray, get:length, Array_getLength)                               \
   V(Math, sqrt, Math_sqrt)                                                     \
   V(Object, ==, Object_equal)                                                  \
   V(FixedSizeArrayIterator, next, FixedSizeArrayIterator_next)                 \
   V(FixedSizeArrayIterator, hasNext, FixedSizeArrayIterator_hasNext)           \
   V(StringBase, get:length, String_getLength)                                  \
   V(StringBase, charCodeAt, String_charCodeAt)                                 \
   V(StringBase, hashCode, String_hashCode)                                     \
+  V(StringBase, isEmpty, String_isEmpty)                                       \
 
 #define __ assembler->
 
 static bool ObjectArray_Allocate(Assembler* assembler) {
   // This snippet of inlined code uses the following registers:
   // EAX, EBX, EDI
   // and the newly allocated object is returned in EAX.
   const intptr_t kTypeArgumentsOffset = 2 * kWordSize;
   const intptr_t kArrayLengthOffset = 1 * kWordSize;
   Label fall_through;
@@ skipping 847 matching lines @@
   __ movl(EAX, Address(ESP, + 1 * kWordSize));  // String object.
   __ movl(EAX, FieldAddress(EAX, String::hash_offset()));
   __ cmpl(EAX, Immediate(0));
   __ j(EQUAL, &fall_through, Assembler::kNearJump);
   __ ret();
   __ Bind(&fall_through);
   // Hash not yet computed.
   return false;
 }
 
+
+static bool String_isEmpty(Assembler* assembler) {
+  Label is_true;
+  const Bool& bool_true = Bool::ZoneHandle(Bool::True());
+  const Bool& bool_false = Bool::ZoneHandle(Bool::False());
+  // Get length.
+  __ movl(EAX, Address(ESP, + 1 * kWordSize));  // String object.
+  __ movl(EAX, FieldAddress(EAX, String::length_offset()));
+  __ cmpl(EAX, Immediate(Smi::RawValue(0)));
+  __ j(EQUAL, &is_true, Assembler::kNearJump);
+  __ LoadObject(EAX, bool_false);
+  __ ret();
+  __ Bind(&is_true);
+  __ LoadObject(EAX, bool_true);
+  __ ret();
+  return true;
+}
+
 #undef __
 
 
 bool Intrinsifier::Intrinsify(const Function& function, Assembler* assembler) {
   if (!FLAG_intrinsify) return false;
   const char* function_name = String::Handle(function.name()).ToCString();
   const Class& function_class = Class::Handle(function.owner());
   const char* class_name = String::Handle(function_class.Name()).ToCString();
 #define FIND_INTRINSICS(test_class_name, test_function_name, destination)      \
   if ((strcmp(#test_function_name, function_name) == 0) &&                     \
       (strcmp(#test_class_name, class_name) == 0)) {                           \
     return destination(assembler);                                             \
   }                                                                            \
 
 INTRINSIC_LIST(FIND_INTRINSICS);
 #undef FIND_INTRINSICS
   return false;
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_IA32