Revert of [fullcodegen] Remove the hacky %_FastOneByteArrayJoin intrinsic.

src/full-codegen/x87/full-codegen-x87.cc

Index: src/full-codegen/x87/full-codegen-x87.cc
diff --git a/src/full-codegen/x87/full-codegen-x87.cc b/src/full-codegen/x87/full-codegen-x87.cc
index 9d68852a8306270a8719236b2ded6ba81c95e21e..74d307eec4e14d56303a321ec2618e36032d04a2 100644
--- a/src/full-codegen/x87/full-codegen-x87.cc
+++ b/src/full-codegen/x87/full-codegen-x87.cc
@@ -3314,6 +3314,275 @@
   __ AssertFunction(eax);
   __ mov(eax, FieldOperand(eax, HeapObject::kMapOffset));
   __ mov(eax, FieldOperand(eax, Map::kPrototypeOffset));
+  context()->Plug(eax);
+}
+
+
+void FullCodeGenerator::EmitFastOneByteArrayJoin(CallRuntime* expr) {
+  Label bailout, done, one_char_separator, long_separator,
+      non_trivial_array, not_size_one_array, loop,
+      loop_1, loop_1_condition, loop_2, loop_2_entry, loop_3, loop_3_entry;
+
+  ZoneList<Expression*>* args = expr->arguments();
+  DCHECK(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.
+
+  Register index = edx;
+
+  Register string_length = ecx;
+
+  Register string = esi;
+
+  Register scratch = ebx;
+
+  Register array_length = edi;
+  Register result_pos = no_reg;  // Will be edi.
+
+  // Separator operand is already pushed.
+  Operand separator_operand = Operand(esp, 2 * kPointerSize);
+  Operand result_operand = Operand(esp, 1 * kPointerSize);
+  Operand array_length_operand = Operand(esp, 0);
+  __ sub(esp, Immediate(2 * kPointerSize));
+  __ cld();
+  // Check that the array is a JSArray
+  __ JumpIfSmi(array, &bailout);
+  __ CmpObjectType(array, JS_ARRAY_TYPE, scratch);
+  __ j(not_equal, &bailout);
+
+  // Check that the array has fast elements.
+  __ CheckFastElements(scratch, &bailout);
+
+  // If the array has length zero, return the empty string.
+  __ mov(array_length, FieldOperand(array, JSArray::kLengthOffset));
+  __ SmiUntag(array_length);
+  __ j(not_zero, &non_trivial_array);
+  __ mov(result_operand, isolate()->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 one-byte strings, and
+  // accumulate the sum of their lengths, as a smi-encoded value.
+  __ Move(index, Immediate(0));
+  __ Move(string_length, Immediate(0));
+  // Loop condition: while (index < length).
+  // Live loop registers: index, array_length, string,
+  //                      scratch, string_length, elements.
+  if (generate_debug_code_) {
+    __ cmp(index, array_length);
+    __ Assert(less, kNoEmptyArraysHereInEmitFastOneByteArrayJoin);
+  }
+  __ bind(&loop);
+  __ mov(string, FieldOperand(elements,
+                              index,
+                              times_pointer_size,
+                              FixedArray::kHeaderSize));
+  __ JumpIfSmi(string, &bailout);
+  __ mov(scratch, FieldOperand(string, HeapObject::kMapOffset));
+  __ movzx_b(scratch, FieldOperand(scratch, Map::kInstanceTypeOffset));
+  __ and_(scratch, Immediate(
+      kIsNotStringMask | kStringEncodingMask | kStringRepresentationMask));
+  __ cmp(scratch, kStringTag | kOneByteStringTag | kSeqStringTag);
+  __ j(not_equal, &bailout);
+  __ add(string_length,
+         FieldOperand(string, SeqOneByteString::kLengthOffset));
+  __ j(overflow, &bailout);
+  __ add(index, Immediate(1));
+  __ cmp(index, 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);
+
+  __ bind(&not_size_one_array);
+
+  // End of array_length live range.
+  result_pos = array_length;
+  array_length = no_reg;
+
+  // Live registers:
+  // string_length: Sum of string lengths, as a smi.
+  // elements: FixedArray of strings.
+
+  // Check that the separator is a flat one-byte string.
+  __ mov(string, separator_operand);
+  __ JumpIfSmi(string, &bailout);
+  __ mov(scratch, FieldOperand(string, HeapObject::kMapOffset));
+  __ movzx_b(scratch, FieldOperand(scratch, Map::kInstanceTypeOffset));
+  __ and_(scratch, Immediate(
+      kIsNotStringMask | kStringEncodingMask | kStringRepresentationMask));
+  __ cmp(scratch, kStringTag | kOneByteStringTag | kSeqStringTag);
+  __ j(not_equal, &bailout);
+
+  // Add (separator length times array_length) - separator length
+  // to string_length.
+  __ mov(scratch, separator_operand);
+  __ mov(scratch, FieldOperand(scratch, SeqOneByteString::kLengthOffset));
+  __ sub(string_length, scratch);  // May be negative, temporarily.
+  __ imul(scratch, array_length_operand);
+  __ j(overflow, &bailout);
+  __ add(string_length, scratch);
+  __ j(overflow, &bailout);
+
+  __ shr(string_length, 1);
+
+  // Bailout for large object allocations.
+  __ cmp(string_length, Page::kMaxRegularHeapObjectSize);
+  __ j(greater, &bailout);
+
+  // Live registers and stack values:
+  //   string_length
+  //   elements
+  __ AllocateOneByteString(result_pos, string_length, scratch, index, string,
+                           &bailout);
+  __ mov(result_operand, result_pos);
+  __ lea(result_pos, FieldOperand(result_pos, SeqOneByteString::kHeaderSize));
+
+
+  __ mov(string, separator_operand);
+  __ cmp(FieldOperand(string, SeqOneByteString::kLengthOffset),
+         Immediate(Smi::FromInt(1)));
+  __ j(equal, &one_char_separator);
+  __ j(greater, &long_separator);
+
+
+  // Empty separator case
+  __ mov(index, Immediate(0));
+  __ jmp(&loop_1_condition);
+  // Loop condition: while (index < length).
+  __ bind(&loop_1);
+  // Each iteration of the loop concatenates one string to the result.
+  // Live values in registers:
+  //   index: which element of the elements array we are adding to the result.
+  //   result_pos: the position to which we are currently copying characters.
+  //   elements: the FixedArray of strings we are joining.
+
+  // Get string = array[index].
+  __ mov(string, FieldOperand(elements, index,
+                              times_pointer_size,
+                              FixedArray::kHeaderSize));
+  __ mov(string_length,
+         FieldOperand(string, String::kLengthOffset));
+  __ shr(string_length, 1);
+  __ lea(string,
+         FieldOperand(string, SeqOneByteString::kHeaderSize));
+  __ CopyBytes(string, result_pos, string_length, scratch);
+  __ add(index, Immediate(1));
+  __ bind(&loop_1_condition);
+  __ cmp(index, array_length_operand);
+  __ j(less, &loop_1);  // End while (index < length).
+  __ jmp(&done);
+
+
+
+  // One-character separator case
+  __ bind(&one_char_separator);
+  // Replace separator with its one-byte character value.
+  __ mov_b(scratch, FieldOperand(string, SeqOneByteString::kHeaderSize));
+  __ mov_b(separator_operand, scratch);
+
+  __ Move(index, Immediate(0));
+  // Jump into the loop after the code that copies the separator, so the first
+  // element is not preceded by a separator
+  __ jmp(&loop_2_entry);
+  // Loop condition: while (index < length).
+  __ bind(&loop_2);
+  // Each iteration of the loop concatenates one string to the result.
+  // Live values in registers:
+  //   index: which element of the elements array we are adding to the result.
+  //   result_pos: the position to which we are currently copying characters.
+
+  // Copy the separator character to the result.
+  __ mov_b(scratch, separator_operand);
+  __ mov_b(Operand(result_pos, 0), scratch);
+  __ inc(result_pos);
+
+  __ bind(&loop_2_entry);
+  // Get string = array[index].
+  __ mov(string, FieldOperand(elements, index,
+                              times_pointer_size,
+                              FixedArray::kHeaderSize));
+  __ mov(string_length,
+         FieldOperand(string, String::kLengthOffset));
+  __ shr(string_length, 1);
+  __ lea(string,
+         FieldOperand(string, SeqOneByteString::kHeaderSize));
+  __ CopyBytes(string, result_pos, string_length, scratch);
+  __ add(index, Immediate(1));
+
+  __ cmp(index, array_length_operand);
+  __ j(less, &loop_2);  // End while (index < length).
+  __ jmp(&done);
+
+
+  // Long separator case (separator is more than one character).
+  __ bind(&long_separator);
+
+  __ Move(index, Immediate(0));
+  // Jump into the loop after the code that copies the separator, so the first
+  // element is not preceded by a separator
+  __ jmp(&loop_3_entry);
+  // Loop condition: while (index < length).
+  __ bind(&loop_3);
+  // Each iteration of the loop concatenates one string to the result.
+  // Live values in registers:
+  //   index: which element of the elements array we are adding to the result.
+  //   result_pos: the position to which we are currently copying characters.
+
+  // Copy the separator to the result.
+  __ mov(string, separator_operand);
+  __ mov(string_length,
+         FieldOperand(string, String::kLengthOffset));
+  __ shr(string_length, 1);
+  __ lea(string,
+         FieldOperand(string, SeqOneByteString::kHeaderSize));
+  __ CopyBytes(string, result_pos, string_length, scratch);
+
+  __ bind(&loop_3_entry);
+  // Get string = array[index].
+  __ mov(string, FieldOperand(elements, index,
+                              times_pointer_size,
+                              FixedArray::kHeaderSize));
+  __ mov(string_length,
+         FieldOperand(string, String::kLengthOffset));
+  __ shr(string_length, 1);
+  __ lea(string,
+         FieldOperand(string, SeqOneByteString::kHeaderSize));
+  __ CopyBytes(string, result_pos, string_length, scratch);
+  __ add(index, Immediate(1));
+
+  __ cmp(index, array_length_operand);
+  __ j(less, &loop_3);  // End while (index < length).
+  __ jmp(&done);
+
+
+  __ bind(&bailout);
+  __ mov(result_operand, isolate()->factory()->undefined_value());
+  __ bind(&done);
+  __ mov(eax, result_operand);
+  // Drop temp values from the stack, and restore context register.
+  __ add(esp, Immediate(3 * kPointerSize));
+
+  __ mov(esi, Operand(ebp, StandardFrameConstants::kContextOffset));
   context()->Plug(eax);
 }