[fullcodegen] Remove the hacky %_FastOneByteArrayJoin intrinsic.

src/full-codegen/arm64/full-codegen-arm64.cc

Index: src/full-codegen/arm64/full-codegen-arm64.cc
diff --git a/src/full-codegen/arm64/full-codegen-arm64.cc b/src/full-codegen/arm64/full-codegen-arm64.cc
index 7f3a970c12010b90c761c806287c6e3930e72fa0..87624af18c90ed68963aba50cbe7c1bff1446eb6 100644
--- a/src/full-codegen/arm64/full-codegen-arm64.cc
+++ b/src/full-codegen/arm64/full-codegen-arm64.cc
@@ -3243,226 +3243,6 @@ void FullCodeGenerator::EmitGetSuperConstructor(CallRuntime* expr) {
 }
 
 
-void FullCodeGenerator::EmitFastOneByteArrayJoin(CallRuntime* expr) {
-  ASM_LOCATION("FullCodeGenerator::EmitFastOneByteArrayJoin");
-
-  ZoneList<Expression*>* args = expr->arguments();
-  DCHECK(args->length() == 2);
-  VisitForStackValue(args->at(1));
-  VisitForAccumulatorValue(args->at(0));
-
-  Register array = x0;
-  Register result = x0;
-  Register elements = x1;
-  Register element = x2;
-  Register separator = x3;
-  Register array_length = x4;
-  Register result_pos = x5;
-  Register map = x6;
-  Register string_length = x10;
-  Register elements_end = x11;
-  Register string = x12;
-  Register scratch1 = x13;
-  Register scratch2 = x14;
-  Register scratch3 = x7;
-  Register separator_length = x15;
-
-  Label bailout, done, one_char_separator, long_separator,
-      non_trivial_array, not_size_one_array, loop,
-      empty_separator_loop, one_char_separator_loop,
-      one_char_separator_loop_entry, long_separator_loop;
-
-  // The separator operand is on the stack.
-  __ Pop(separator);
-
-  // Check that the array is a JSArray.
-  __ JumpIfSmi(array, &bailout);
-  __ JumpIfNotObjectType(array, map, scratch1, JS_ARRAY_TYPE, &bailout);
-
-  // Check that the array has fast elements.
-  __ CheckFastElements(map, scratch1, &bailout);
-
-  // If the array has length zero, return the empty string.
-  // Load and untag the length of the array.
-  // It is an unsigned value, so we can skip sign extension.
-  // We assume little endianness.
-  __ Ldrsw(array_length,
-           UntagSmiFieldMemOperand(array, JSArray::kLengthOffset));
-  __ Cbnz(array_length, &non_trivial_array);
-  __ LoadRoot(result, Heap::kempty_stringRootIndex);
-  __ B(&done);
-
-  __ Bind(&non_trivial_array);
-  // Get the FixedArray containing array's elements.
-  __ Ldr(elements, FieldMemOperand(array, JSArray::kElementsOffset));
-
-  // Check that all array elements are sequential one-byte strings, and
-  // accumulate the sum of their lengths.
-  __ Mov(string_length, 0);
-  __ Add(element, elements, FixedArray::kHeaderSize - kHeapObjectTag);
-  __ Add(elements_end, element, Operand(array_length, LSL, kPointerSizeLog2));
-  // Loop condition: while (element < elements_end).
-  // Live values in registers:
-  //   elements: Fixed array of strings.
-  //   array_length: Length of the fixed array of strings (not smi)
-  //   separator: Separator string
-  //   string_length: Accumulated sum of string lengths (not smi).
-  //   element: Current array element.
-  //   elements_end: Array end.
-  if (FLAG_debug_code) {
-    __ Cmp(array_length, 0);
-    __ Assert(gt, kNoEmptyArraysHereInEmitFastOneByteArrayJoin);
-  }
-  __ Bind(&loop);
-  __ Ldr(string, MemOperand(element, kPointerSize, PostIndex));
-  __ JumpIfSmi(string, &bailout);
-  __ Ldr(scratch1, FieldMemOperand(string, HeapObject::kMapOffset));
-  __ Ldrb(scratch1, FieldMemOperand(scratch1, Map::kInstanceTypeOffset));
-  __ JumpIfInstanceTypeIsNotSequentialOneByte(scratch1, scratch2, &bailout);
-  __ Ldrsw(scratch1,
-           UntagSmiFieldMemOperand(string, SeqOneByteString::kLengthOffset));
-  __ Adds(string_length, string_length, scratch1);
-  __ B(vs, &bailout);
-  __ Cmp(element, elements_end);
-  __ B(lt, &loop);
-
-  // If array_length is 1, return elements[0], a string.
-  __ Cmp(array_length, 1);
-  __ B(ne, &not_size_one_array);
-  __ Ldr(result, FieldMemOperand(elements, FixedArray::kHeaderSize));
-  __ B(&done);
-
-  __ Bind(&not_size_one_array);
-
-  // Live values in registers:
-  //   separator: Separator string
-  //   array_length: Length of the array (not smi).
-  //   string_length: Sum of string lengths (not smi).
-  //   elements: FixedArray of strings.
-
-  // Check that the separator is a flat one-byte string.
-  __ JumpIfSmi(separator, &bailout);
-  __ Ldr(scratch1, FieldMemOperand(separator, HeapObject::kMapOffset));
-  __ Ldrb(scratch1, FieldMemOperand(scratch1, Map::kInstanceTypeOffset));
-  __ JumpIfInstanceTypeIsNotSequentialOneByte(scratch1, scratch2, &bailout);
-
-  // Add (separator length times array_length) - separator length to the
-  // string_length to get the length of the result string.
-  // Load the separator length as untagged.
-  // We assume little endianness, and that the length is positive.
-  __ Ldrsw(separator_length,
-           UntagSmiFieldMemOperand(separator,
-                                   SeqOneByteString::kLengthOffset));
-  __ Sub(string_length, string_length, separator_length);
-  __ Umaddl(string_length, array_length.W(), separator_length.W(),
-            string_length);
-
-  // Bailout for large object allocations.
-  __ Cmp(string_length, Page::kMaxRegularHeapObjectSize);
-  __ B(gt, &bailout);
-
-  // Get first element in the array.
-  __ Add(element, elements, FixedArray::kHeaderSize - kHeapObjectTag);
-  // Live values in registers:
-  //   element: First array element
-  //   separator: Separator string
-  //   string_length: Length of result string (not smi)
-  //   array_length: Length of the array (not smi).
-  __ AllocateOneByteString(result, string_length, scratch1, scratch2, scratch3,
-                           &bailout);
-
-  // Prepare for looping. Set up elements_end to end of the array. Set
-  // result_pos to the position of the result where to write the first
-  // character.
-  // TODO(all): useless unless AllocateOneByteString trashes the register.
-  __ Add(elements_end, element, Operand(array_length, LSL, kPointerSizeLog2));
-  __ Add(result_pos, result, SeqOneByteString::kHeaderSize - kHeapObjectTag);
-
-  // Check the length of the separator.
-  __ Cmp(separator_length, 1);
-  __ B(eq, &one_char_separator);
-  __ B(gt, &long_separator);
-
-  // Empty separator case
-  __ Bind(&empty_separator_loop);
-  // Live values in registers:
-  //   result_pos: the position to which we are currently copying characters.
-  //   element: Current array element.
-  //   elements_end: Array end.
-
-  // Copy next array element to the result.
-  __ Ldr(string, MemOperand(element, kPointerSize, PostIndex));
-  __ Ldrsw(string_length,
-           UntagSmiFieldMemOperand(string, String::kLengthOffset));
-  __ Add(string, string, SeqOneByteString::kHeaderSize - kHeapObjectTag);
-  __ CopyBytes(result_pos, string, string_length, scratch1);
-  __ Cmp(element, elements_end);
-  __ B(lt, &empty_separator_loop);  // End while (element < elements_end).
-  __ B(&done);
-
-  // One-character separator case
-  __ Bind(&one_char_separator);
-  // Replace separator with its one-byte character value.
-  __ Ldrb(separator, FieldMemOperand(separator, SeqOneByteString::kHeaderSize));
-  // Jump into the loop after the code that copies the separator, so the first
-  // element is not preceded by a separator
-  __ B(&one_char_separator_loop_entry);
-
-  __ Bind(&one_char_separator_loop);
-  // Live values in registers:
-  //   result_pos: the position to which we are currently copying characters.
-  //   element: Current array element.
-  //   elements_end: Array end.
-  //   separator: Single separator one-byte char (in lower byte).
-
-  // Copy the separator character to the result.
-  __ Strb(separator, MemOperand(result_pos, 1, PostIndex));
-
-  // Copy next array element to the result.
-  __ Bind(&one_char_separator_loop_entry);
-  __ Ldr(string, MemOperand(element, kPointerSize, PostIndex));
-  __ Ldrsw(string_length,
-           UntagSmiFieldMemOperand(string, String::kLengthOffset));
-  __ Add(string, string, SeqOneByteString::kHeaderSize - kHeapObjectTag);
-  __ CopyBytes(result_pos, string, string_length, scratch1);
-  __ Cmp(element, elements_end);
-  __ B(lt, &one_char_separator_loop);  // End while (element < elements_end).
-  __ B(&done);
-
-  // Long separator case (separator is more than one character). Entry is at the
-  // label long_separator below.
-  __ Bind(&long_separator_loop);
-  // Live values in registers:
-  //   result_pos: the position to which we are currently copying characters.
-  //   element: Current array element.
-  //   elements_end: Array end.
-  //   separator: Separator string.
-
-  // Copy the separator to the result.
-  // TODO(all): hoist next two instructions.
-  __ Ldrsw(string_length,
-           UntagSmiFieldMemOperand(separator, String::kLengthOffset));
-  __ Add(string, separator, SeqOneByteString::kHeaderSize - kHeapObjectTag);
-  __ CopyBytes(result_pos, string, string_length, scratch1);
-
-  __ Bind(&long_separator);
-  __ Ldr(string, MemOperand(element, kPointerSize, PostIndex));
-  __ Ldrsw(string_length,
-           UntagSmiFieldMemOperand(string, String::kLengthOffset));
-  __ Add(string, string, SeqOneByteString::kHeaderSize - kHeapObjectTag);
-  __ CopyBytes(result_pos, string, string_length, scratch1);
-  __ Cmp(element, elements_end);
-  __ B(lt, &long_separator_loop);  // End while (element < elements_end).
-  __ B(&done);
-
-  __ Bind(&bailout);
-  // Returning undefined will force slower code to handle it.
-  __ LoadRoot(result, Heap::kUndefinedValueRootIndex);
-  __ Bind(&done);
-  context()->Plug(result);
-}
-
-
 void FullCodeGenerator::EmitDebugIsActive(CallRuntime* expr) {
   DCHECK(expr->arguments()->length() == 0);
   ExternalReference debug_is_active =