Revert of [stubs] Port SubStringStub to TurboFan

src/x87/code-stubs-x87.cc

 // Copyright 2012 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.
 
 #if V8_TARGET_ARCH_X87
 
 #include "src/code-stubs.h"
 #include "src/api-arguments.h"
 #include "src/base/bits.h"
 #include "src/bootstrapper.h"
@@ skipping 1889 matching lines @@
   __ mov_b(scratch, Operand(src, 0));
   __ mov_b(Operand(dest, 0), scratch);
   __ inc(src);
   __ inc(dest);
   __ dec(count);
   __ j(not_zero, &loop);
 
   __ bind(&done);
 }
 
+
+void SubStringStub::Generate(MacroAssembler* masm) {
+  Label runtime;
+
+  // Stack frame on entry.
+  //  esp[0]: return address
+  //  esp[4]: to
+  //  esp[8]: from
+  //  esp[12]: string
+
+  // Make sure first argument is a string.
+  __ mov(eax, Operand(esp, 3 * kPointerSize));
+  STATIC_ASSERT(kSmiTag == 0);
+  __ JumpIfSmi(eax, &runtime);
+  Condition is_string = masm->IsObjectStringType(eax, ebx, ebx);
+  __ j(NegateCondition(is_string), &runtime);
+
+  // eax: string
+  // ebx: instance type
+
+  // Calculate length of sub string using the smi values.
+  __ mov(ecx, Operand(esp, 1 * kPointerSize));  // To index.
+  __ JumpIfNotSmi(ecx, &runtime);
+  __ mov(edx, Operand(esp, 2 * kPointerSize));  // From index.
+  __ JumpIfNotSmi(edx, &runtime);
+  __ sub(ecx, edx);
+  __ cmp(ecx, FieldOperand(eax, String::kLengthOffset));
+  Label not_original_string;
+  // Shorter than original string's length: an actual substring.
+  __ j(below, &not_original_string, Label::kNear);
+  // Longer than original string's length or negative: unsafe arguments.
+  __ j(above, &runtime);
+  // Return original string.
+  Counters* counters = isolate()->counters();
+  __ IncrementCounter(counters->sub_string_native(), 1);
+  __ ret(3 * kPointerSize);
+  __ bind(&not_original_string);
+
+  Label single_char;
+  __ cmp(ecx, Immediate(Smi::FromInt(1)));
+  __ j(equal, &single_char);
+
+  // eax: string
+  // ebx: instance type
+  // ecx: sub string length (smi)
+  // edx: from index (smi)
+  // Deal with different string types: update the index if necessary
+  // and put the underlying string into edi.
+  Label underlying_unpacked, sliced_string, seq_or_external_string;
+  // If the string is not indirect, it can only be sequential or external.
+  STATIC_ASSERT(kIsIndirectStringMask == (kSlicedStringTag & kConsStringTag));
+  STATIC_ASSERT(kIsIndirectStringMask != 0);
+  __ test(ebx, Immediate(kIsIndirectStringMask));
+  __ j(zero, &seq_or_external_string, Label::kNear);
+
+  Factory* factory = isolate()->factory();
+  __ test(ebx, Immediate(kSlicedNotConsMask));
+  __ j(not_zero, &sliced_string, Label::kNear);
+  // Cons string.  Check whether it is flat, then fetch first part.
+  // Flat cons strings have an empty second part.
+  __ cmp(FieldOperand(eax, ConsString::kSecondOffset),
+         factory->empty_string());
+  __ j(not_equal, &runtime);
+  __ mov(edi, FieldOperand(eax, ConsString::kFirstOffset));
+  // Update instance type.
+  __ mov(ebx, FieldOperand(edi, HeapObject::kMapOffset));
+  __ movzx_b(ebx, FieldOperand(ebx, Map::kInstanceTypeOffset));
+  __ jmp(&underlying_unpacked, Label::kNear);
+
+  __ bind(&sliced_string);
+  // Sliced string.  Fetch parent and adjust start index by offset.
+  __ add(edx, FieldOperand(eax, SlicedString::kOffsetOffset));
+  __ mov(edi, FieldOperand(eax, SlicedString::kParentOffset));
+  // Update instance type.
+  __ mov(ebx, FieldOperand(edi, HeapObject::kMapOffset));
+  __ movzx_b(ebx, FieldOperand(ebx, Map::kInstanceTypeOffset));
+  __ jmp(&underlying_unpacked, Label::kNear);
+
+  __ bind(&seq_or_external_string);
+  // Sequential or external string.  Just move string to the expected register.
+  __ mov(edi, eax);
+
+  __ bind(&underlying_unpacked);
+
+  if (FLAG_string_slices) {
+    Label copy_routine;
+    // edi: underlying subject string
+    // ebx: instance type of underlying subject string
+    // edx: adjusted start index (smi)
+    // ecx: length (smi)
+    __ cmp(ecx, Immediate(Smi::FromInt(SlicedString::kMinLength)));
+    // Short slice.  Copy instead of slicing.
+    __ j(less, &copy_routine);
+    // Allocate new sliced string.  At this point we do not reload the instance
+    // type including the string encoding because we simply rely on the info
+    // provided by the original string.  It does not matter if the original
+    // string's encoding is wrong because we always have to recheck encoding of
+    // the newly created string's parent anyways due to externalized strings.
+    Label two_byte_slice, set_slice_header;
+    STATIC_ASSERT((kStringEncodingMask & kOneByteStringTag) != 0);
+    STATIC_ASSERT((kStringEncodingMask & kTwoByteStringTag) == 0);
+    __ test(ebx, Immediate(kStringEncodingMask));
+    __ j(zero, &two_byte_slice, Label::kNear);
+    __ AllocateOneByteSlicedString(eax, ebx, no_reg, &runtime);
+    __ jmp(&set_slice_header, Label::kNear);
+    __ bind(&two_byte_slice);
+    __ AllocateTwoByteSlicedString(eax, ebx, no_reg, &runtime);
+    __ bind(&set_slice_header);
+    __ mov(FieldOperand(eax, SlicedString::kLengthOffset), ecx);
+    __ mov(FieldOperand(eax, SlicedString::kHashFieldOffset),
+           Immediate(String::kEmptyHashField));
+    __ mov(FieldOperand(eax, SlicedString::kParentOffset), edi);
+    __ mov(FieldOperand(eax, SlicedString::kOffsetOffset), edx);
+    __ IncrementCounter(counters->sub_string_native(), 1);
+    __ ret(3 * kPointerSize);
+
+    __ bind(&copy_routine);
+  }
+
+  // edi: underlying subject string
+  // ebx: instance type of underlying subject string
+  // edx: adjusted start index (smi)
+  // ecx: length (smi)
+  // The subject string can only be external or sequential string of either
+  // encoding at this point.
+  Label two_byte_sequential, runtime_drop_two, sequential_string;
+  STATIC_ASSERT(kExternalStringTag != 0);
+  STATIC_ASSERT(kSeqStringTag == 0);
+  __ test_b(ebx, Immediate(kExternalStringTag));
+  __ j(zero, &sequential_string);
+
+  // Handle external string.
+  // Rule out short external strings.
+  STATIC_ASSERT(kShortExternalStringTag != 0);
+  __ test_b(ebx, Immediate(kShortExternalStringMask));
+  __ j(not_zero, &runtime);
+  __ mov(edi, FieldOperand(edi, ExternalString::kResourceDataOffset));
+  // Move the pointer so that offset-wise, it looks like a sequential string.
+  STATIC_ASSERT(SeqTwoByteString::kHeaderSize == SeqOneByteString::kHeaderSize);
+  __ sub(edi, Immediate(SeqTwoByteString::kHeaderSize - kHeapObjectTag));
+
+  __ bind(&sequential_string);
+  // Stash away (adjusted) index and (underlying) string.
+  __ push(edx);
+  __ push(edi);
+  __ SmiUntag(ecx);
+  STATIC_ASSERT((kOneByteStringTag & kStringEncodingMask) != 0);
+  __ test_b(ebx, Immediate(kStringEncodingMask));
+  __ j(zero, &two_byte_sequential);
+
+  // Sequential one byte string.  Allocate the result.
+  __ AllocateOneByteString(eax, ecx, ebx, edx, edi, &runtime_drop_two);
+
+  // eax: result string
+  // ecx: result string length
+  // Locate first character of result.
+  __ mov(edi, eax);
+  __ add(edi, Immediate(SeqOneByteString::kHeaderSize - kHeapObjectTag));
+  // Load string argument and locate character of sub string start.
+  __ pop(edx);
+  __ pop(ebx);
+  __ SmiUntag(ebx);
+  __ lea(edx, FieldOperand(edx, ebx, times_1, SeqOneByteString::kHeaderSize));
+
+  // eax: result string
+  // ecx: result length
+  // edi: first character of result
+  // edx: character of sub string start
+  StringHelper::GenerateCopyCharacters(
+      masm, edi, edx, ecx, ebx, String::ONE_BYTE_ENCODING);
+  __ IncrementCounter(counters->sub_string_native(), 1);
+  __ ret(3 * kPointerSize);
+
+  __ bind(&two_byte_sequential);
+  // Sequential two-byte string.  Allocate the result.
+  __ AllocateTwoByteString(eax, ecx, ebx, edx, edi, &runtime_drop_two);
+
+  // eax: result string
+  // ecx: result string length
+  // Locate first character of result.
+  __ mov(edi, eax);
+  __ add(edi,
+         Immediate(SeqTwoByteString::kHeaderSize - kHeapObjectTag));
+  // Load string argument and locate character of sub string start.
+  __ pop(edx);
+  __ pop(ebx);
+  // As from is a smi it is 2 times the value which matches the size of a two
+  // byte character.
+  STATIC_ASSERT(kSmiTag == 0);
+  STATIC_ASSERT(kSmiTagSize + kSmiShiftSize == 1);
+  __ lea(edx, FieldOperand(edx, ebx, times_1, SeqTwoByteString::kHeaderSize));
+
+  // eax: result string
+  // ecx: result length
+  // edi: first character of result
+  // edx: character of sub string start
+  StringHelper::GenerateCopyCharacters(
+      masm, edi, edx, ecx, ebx, String::TWO_BYTE_ENCODING);
+  __ IncrementCounter(counters->sub_string_native(), 1);
+  __ ret(3 * kPointerSize);
+
+  // Drop pushed values on the stack before tail call.
+  __ bind(&runtime_drop_two);
+  __ Drop(2);
+
+  // Just jump to runtime to create the sub string.
+  __ bind(&runtime);
+  __ TailCallRuntime(Runtime::kSubString);
+
+  __ bind(&single_char);
+  // eax: string
+  // ebx: instance type
+  // ecx: sub string length (smi)
+  // edx: from index (smi)
+  StringCharAtGenerator generator(eax, edx, ecx, eax, &runtime, &runtime,
+                                  &runtime, RECEIVER_IS_STRING);
+  generator.GenerateFast(masm);
+  __ ret(3 * kPointerSize);
+  generator.SkipSlow(masm, &runtime);
+}
+
 void ToStringStub::Generate(MacroAssembler* masm) {
   // The ToString stub takes one argument in eax.
   Label is_number;
   __ JumpIfSmi(eax, &is_number, Label::kNear);
 
   Label not_string;
   __ CmpObjectType(eax, FIRST_NONSTRING_TYPE, edi);
   // eax: receiver
   // edi: receiver map
   __ j(above_equal, &not_string, Label::kNear);
@@ skipping 3162 matching lines @@
                            kStackUnwindSpace, nullptr, return_value_operand,
                            NULL);
 }
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_X87