[stubs] Port SubStringStub to TurboFan

src/mips/code-stubs-mips.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_MIPS
 
 #include "src/code-stubs.h"
 #include "src/api-arguments.h"
 #include "src/base/bits.h"
 #include "src/bootstrapper.h"
@@ skipping 2250 matching lines @@
   __ lbu(scratch, MemOperand(src));
   __ Addu(src, src, Operand(1));
   __ sb(scratch, MemOperand(dest));
   __ Addu(dest, dest, Operand(1));
   __ bind(&loop_entry);
   __ Branch(&loop, lt, dest, Operand(limit));
 
   __ bind(&done);
 }
 
-
-void SubStringStub::Generate(MacroAssembler* masm) {
-  Label runtime;
-  // Stack frame on entry.
-  //  ra: return address
-  //  sp[0]: to
-  //  sp[4]: from
-  //  sp[8]: string
-
-  // This stub is called from the native-call %_SubString(...), so
-  // nothing can be assumed about the arguments. It is tested that:
-  //  "string" is a sequential string,
-  //  both "from" and "to" are smis, and
-  //  0 <= from <= to <= string.length.
-  // If any of these assumptions fail, we call the runtime system.
-
-  const int kToOffset = 0 * kPointerSize;
-  const int kFromOffset = 1 * kPointerSize;
-  const int kStringOffset = 2 * kPointerSize;
-
-  __ lw(a2, MemOperand(sp, kToOffset));
-  __ lw(a3, MemOperand(sp, kFromOffset));
-  STATIC_ASSERT(kFromOffset == kToOffset + 4);
-  STATIC_ASSERT(kSmiTag == 0);
-  STATIC_ASSERT(kSmiTagSize + kSmiShiftSize == 1);
-
-  // Utilize delay slots. SmiUntag doesn't emit a jump, everything else is
-  // safe in this case.
-  __ UntagAndJumpIfNotSmi(a2, a2, &runtime);
-  __ UntagAndJumpIfNotSmi(a3, a3, &runtime);
-  // Both a2 and a3 are untagged integers.
-
-  __ Branch(&runtime, lt, a3, Operand(zero_reg));  // From < 0.
-
-  __ Branch(&runtime, gt, a3, Operand(a2));  // Fail if from > to.
-  __ Subu(a2, a2, a3);
-
-  // Make sure first argument is a string.
-  __ lw(v0, MemOperand(sp, kStringOffset));
-  __ JumpIfSmi(v0, &runtime);
-  __ lw(a1, FieldMemOperand(v0, HeapObject::kMapOffset));
-  __ lbu(a1, FieldMemOperand(a1, Map::kInstanceTypeOffset));
-  __ And(t0, a1, Operand(kIsNotStringMask));
-
-  __ Branch(&runtime, ne, t0, Operand(zero_reg));
-
-  Label single_char;
-  __ Branch(&single_char, eq, a2, Operand(1));
-
-  // Short-cut for the case of trivial substring.
-  Label return_v0;
-  // v0: original string
-  // a2: result string length
-  __ lw(t0, FieldMemOperand(v0, String::kLengthOffset));
-  __ sra(t0, t0, 1);
-  // Return original string.
-  __ Branch(&return_v0, eq, a2, Operand(t0));
-  // Longer than original string's length or negative: unsafe arguments.
-  __ Branch(&runtime, hi, a2, Operand(t0));
-  // Shorter than original string's length: an actual substring.
-
-  // Deal with different string types: update the index if necessary
-  // and put the underlying string into t1.
-  // v0: original string
-  // a1: instance type
-  // a2: length
-  // a3: from index (untagged)
-  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);
-  __ And(t0, a1, Operand(kIsIndirectStringMask));
-  __ Branch(USE_DELAY_SLOT, &seq_or_external_string, eq, t0, Operand(zero_reg));
-  // t0 is used as a scratch register and can be overwritten in either case.
-  __ And(t0, a1, Operand(kSlicedNotConsMask));
-  __ Branch(&sliced_string, ne, t0, Operand(zero_reg));
-  // Cons string.  Check whether it is flat, then fetch first part.
-  __ lw(t1, FieldMemOperand(v0, ConsString::kSecondOffset));
-  __ LoadRoot(t0, Heap::kempty_stringRootIndex);
-  __ Branch(&runtime, ne, t1, Operand(t0));
-  __ lw(t1, FieldMemOperand(v0, ConsString::kFirstOffset));
-  // Update instance type.
-  __ lw(a1, FieldMemOperand(t1, HeapObject::kMapOffset));
-  __ lbu(a1, FieldMemOperand(a1, Map::kInstanceTypeOffset));
-  __ jmp(&underlying_unpacked);
-
-  __ bind(&sliced_string);
-  // Sliced string.  Fetch parent and correct start index by offset.
-  __ lw(t1, FieldMemOperand(v0, SlicedString::kParentOffset));
-  __ lw(t0, FieldMemOperand(v0, SlicedString::kOffsetOffset));
-  __ sra(t0, t0, 1);  // Add offset to index.
-  __ Addu(a3, a3, t0);
-  // Update instance type.
-  __ lw(a1, FieldMemOperand(t1, HeapObject::kMapOffset));
-  __ lbu(a1, FieldMemOperand(a1, Map::kInstanceTypeOffset));
-  __ jmp(&underlying_unpacked);
-
-  __ bind(&seq_or_external_string);
-  // Sequential or external string.  Just move string to the expected register.
-  __ mov(t1, v0);
-
-  __ bind(&underlying_unpacked);
-
-  if (FLAG_string_slices) {
-    Label copy_routine;
-    // t1: underlying subject string
-    // a1: instance type of underlying subject string
-    // a2: length
-    // a3: adjusted start index (untagged)
-    // Short slice.  Copy instead of slicing.
-    __ Branch(&copy_routine, lt, a2, Operand(SlicedString::kMinLength));
-    // 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);
-    __ And(t0, a1, Operand(kStringEncodingMask));
-    __ Branch(&two_byte_slice, eq, t0, Operand(zero_reg));
-    __ AllocateOneByteSlicedString(v0, a2, t2, t3, &runtime);
-    __ jmp(&set_slice_header);
-    __ bind(&two_byte_slice);
-    __ AllocateTwoByteSlicedString(v0, a2, t2, t3, &runtime);
-    __ bind(&set_slice_header);
-    __ sll(a3, a3, 1);
-    __ sw(t1, FieldMemOperand(v0, SlicedString::kParentOffset));
-    __ sw(a3, FieldMemOperand(v0, SlicedString::kOffsetOffset));
-    __ jmp(&return_v0);
-
-    __ bind(&copy_routine);
-  }
-
-  // t1: underlying subject string
-  // a1: instance type of underlying subject string
-  // a2: length
-  // a3: adjusted start index (untagged)
-  Label two_byte_sequential, sequential_string, allocate_result;
-  STATIC_ASSERT(kExternalStringTag != 0);
-  STATIC_ASSERT(kSeqStringTag == 0);
-  __ And(t0, a1, Operand(kExternalStringTag));
-  __ Branch(&sequential_string, eq, t0, Operand(zero_reg));
-
-  // Handle external string.
-  // Rule out short external strings.
-  STATIC_ASSERT(kShortExternalStringTag != 0);
-  __ And(t0, a1, Operand(kShortExternalStringTag));
-  __ Branch(&runtime, ne, t0, Operand(zero_reg));
-  __ lw(t1, FieldMemOperand(t1, ExternalString::kResourceDataOffset));
-  // t1 already points to the first character of underlying string.
-  __ jmp(&allocate_result);
-
-  __ bind(&sequential_string);
-  // Locate first character of underlying subject string.
-  STATIC_ASSERT(SeqTwoByteString::kHeaderSize == SeqOneByteString::kHeaderSize);
-  __ Addu(t1, t1, Operand(SeqOneByteString::kHeaderSize - kHeapObjectTag));
-
-  __ bind(&allocate_result);
-  // Sequential acii string.  Allocate the result.
-  STATIC_ASSERT((kOneByteStringTag & kStringEncodingMask) != 0);
-  __ And(t0, a1, Operand(kStringEncodingMask));
-  __ Branch(&two_byte_sequential, eq, t0, Operand(zero_reg));
-
-  // Allocate and copy the resulting ASCII string.
-  __ AllocateOneByteString(v0, a2, t0, t2, t3, &runtime);
-
-  // Locate first character of substring to copy.
-  __ Addu(t1, t1, a3);
-
-  // Locate first character of result.
-  __ Addu(a1, v0, Operand(SeqOneByteString::kHeaderSize - kHeapObjectTag));
-
-  // v0: result string
-  // a1: first character of result string
-  // a2: result string length
-  // t1: first character of substring to copy
-  STATIC_ASSERT((SeqOneByteString::kHeaderSize & kObjectAlignmentMask) == 0);
-  StringHelper::GenerateCopyCharacters(
-      masm, a1, t1, a2, a3, String::ONE_BYTE_ENCODING);
-  __ jmp(&return_v0);
-
-  // Allocate and copy the resulting two-byte string.
-  __ bind(&two_byte_sequential);
-  __ AllocateTwoByteString(v0, a2, t0, t2, t3, &runtime);
-
-  // Locate first character of substring to copy.
-  STATIC_ASSERT(kSmiTagSize == 1 && kSmiTag == 0);
-  __ Lsa(t1, t1, a3, 1);
-  // Locate first character of result.
-  __ Addu(a1, v0, Operand(SeqTwoByteString::kHeaderSize - kHeapObjectTag));
-
-  // v0: result string.
-  // a1: first character of result.
-  // a2: result length.
-  // t1: first character of substring to copy.
-  STATIC_ASSERT((SeqTwoByteString::kHeaderSize & kObjectAlignmentMask) == 0);
-  StringHelper::GenerateCopyCharacters(
-      masm, a1, t1, a2, a3, String::TWO_BYTE_ENCODING);
-
-  __ bind(&return_v0);
-  Counters* counters = isolate()->counters();
-  __ IncrementCounter(counters->sub_string_native(), 1, a3, t0);
-  __ DropAndRet(3);
-
-  // Just jump to runtime to create the sub string.
-  __ bind(&runtime);
-  __ TailCallRuntime(Runtime::kSubString);
-
-  __ bind(&single_char);
-  // v0: original string
-  // a1: instance type
-  // a2: length
-  // a3: from index (untagged)
-  __ SmiTag(a3, a3);
-  StringCharAtGenerator generator(v0, a3, a2, v0, &runtime, &runtime, &runtime,
-                                  RECEIVER_IS_STRING);
-  generator.GenerateFast(masm);
-  __ DropAndRet(3);
-  generator.SkipSlow(masm, &runtime);
-}
-
-
 void ToStringStub::Generate(MacroAssembler* masm) {
   // The ToString stub takes on argument in a0.
   Label is_number;
   __ JumpIfSmi(a0, &is_number);
 
   Label not_string;
   __ GetObjectType(a0, a1, a1);
   // a0: receiver
   // a1: receiver instance type
   __ Branch(&not_string, ge, a1, Operand(FIRST_NONSTRING_TYPE));
@@ skipping 2860 matching lines @@
                            kStackUnwindSpace, kInvalidStackOffset,
                            return_value_operand, NULL);
 }
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_MIPS