Minor change to FullCodeGenerator::EmitFastAsciiArrayJoin...

src/ia32/full-codegen-ia32.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 3399 matching lines @@
 
   __ mov(eax, FieldOperand(eax, String::kHashFieldOffset));
   __ IndexFromHash(eax, eax);
 
   context()->Plug(eax);
 }
 
 
 void FullCodeGenerator::EmitFastAsciiArrayJoin(ZoneList<Expression*>* args) {
   Label bailout, done, one_char_separator, long_separator,
-      non_trivial_array, not_size_one_array, loop, loop_condition,
+      non_trivial_array, not_size_one_array, loop,
       loop_1, loop_1_condition, loop_2, loop_2_entry, loop_3, loop_3_entry;
 
   ASSERT(args->length() == 2);
   // We will leave the separator on the stack until the end of the function.
   VisitForStackValue(args->at(1));
   // Load this to eax (= array)
   VisitForAccumulatorValue(args->at(0));
   // All aliases of the same register have disjoint lifetimes.
   Register array = eax;
   Register elements = no_reg;  // Will be eax.
@@ skipping 21 matching lines @@
   __ CmpObjectType(array, JS_ARRAY_TYPE, scratch);
   __ j(not_equal, &bailout);
 
   // Check that the array has fast elements.
   __ test_b(FieldOperand(scratch, Map::kBitField2Offset),
             1 << Map::kHasFastElements);
   __ j(zero, &bailout);
 
   // If the array has length zero, return the empty string.
   __ mov(array_length, FieldOperand(array, JSArray::kLengthOffset));
-  __ sar(array_length, 1);
+  __ SmiUntag(array_length);
   __ j(not_zero, &non_trivial_array);
   __ mov(result_operand, Factory::empty_string());
   __ jmp(&done);
 
   // Save the array length.
   __ bind(&non_trivial_array);
   __ mov(array_length_operand, array_length);
 
   // Save the FixedArray containing array's elements.
   // End of array's live range.
   elements = array;
   __ mov(elements, FieldOperand(array, JSArray::kElementsOffset));
   array = no_reg;
 
 
   // Check that all array elements are sequential ASCII strings, and
   // accumulate the sum of their lengths, as a smi-encoded value.
   __ Set(index, Immediate(0));
   __ Set(string_length, Immediate(0));
   // Loop condition: while (index < length).
   // Live loop registers: index, array_length, string,
   //                      scratch, string_length, elements.
-  __ jmp(&loop_condition);
+  if (FLAG_debug_code) {
+    __ cmp(index, Operand(array_length));
+    __ Assert(less, "No empty arrays here in EmitFastAsciiArrayJoin");
+  }
   __ bind(&loop);
-  __ cmp(index, Operand(array_length));
-  __ j(greater_equal, &done);
-
-  __ mov(string, FieldOperand(elements, index,
-                                      times_pointer_size,
-                                      FixedArray::kHeaderSize));
+  __ mov(string, FieldOperand(elements,
+                              index,
+                              times_pointer_size,
+                              FixedArray::kHeaderSize));
   __ test(string, Immediate(kSmiTagMask));
   __ j(zero, &bailout);
   __ mov(scratch, FieldOperand(string, HeapObject::kMapOffset));
   __ movzx_b(scratch, FieldOperand(scratch, Map::kInstanceTypeOffset));
   __ and_(scratch, Immediate(
       kIsNotStringMask | kStringEncodingMask | kStringRepresentationMask));
   __ cmp(scratch, kStringTag | kAsciiStringTag | kSeqStringTag);
   __ j(not_equal, &bailout);
   __ add(string_length,
          FieldOperand(string, SeqAsciiString::kLengthOffset));
   __ j(overflow, &bailout);
   __ add(Operand(index), Immediate(1));
-  __ bind(&loop_condition);
   __ cmp(index, Operand(array_length));
   __ j(less, &loop);
 
   // If array_length is 1, return elements[0], a string.
   __ cmp(array_length, 1);
   __ j(not_equal, &not_size_one_array);
   __ mov(scratch, FieldOperand(elements, FixedArray::kHeaderSize));
   __ mov(result_operand, scratch);
   __ jmp(&done);
 
@@ skipping 919 matching lines @@
   // And return.
   __ ret(0);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32