[stubs] Port SubStringStub to TurboFan

src/arm/code-stubs-arm.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_ARM
 
 #include "src/code-stubs.h"
 #include "src/api-arguments.h"
 #include "src/base/bits.h"
 #include "src/bootstrapper.h"
@@ skipping 2106 matching lines @@
   __ bind(&loop);
   __ ldrb(scratch, MemOperand(src, 1, PostIndex), lt);
   __ strb(scratch, MemOperand(dest, 1, PostIndex));
   __ bind(&loop_entry);
   __ cmp(dest, Operand(limit));
   __ b(lt, &loop);
 
   __ bind(&done);
 }
 
-
-void SubStringStub::Generate(MacroAssembler* masm) {
-  Label runtime;
-
-  // Stack frame on entry.
-  //  lr: 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;
-
-  __ Ldrd(r2, r3, MemOperand(sp, kToOffset));
-  STATIC_ASSERT(kFromOffset == kToOffset + 4);
-  STATIC_ASSERT(kSmiTag == 0);
-  STATIC_ASSERT(kSmiTagSize + kSmiShiftSize == 1);
-
-  // Arithmetic shift right by one un-smi-tags. In this case we rotate right
-  // instead because we bail out on non-smi values: ROR and ASR are equivalent
-  // for smis but they set the flags in a way that's easier to optimize.
-  __ mov(r2, Operand(r2, ROR, 1), SetCC);
-  __ mov(r3, Operand(r3, ROR, 1), SetCC, cc);
-  // If either to or from had the smi tag bit set, then C is set now, and N
-  // has the same value: we rotated by 1, so the bottom bit is now the top bit.
-  // We want to bailout to runtime here if From is negative.  In that case, the
-  // next instruction is not executed and we fall through to bailing out to
-  // runtime.
-  // Executed if both r2 and r3 are untagged integers.
-  __ sub(r2, r2, Operand(r3), SetCC, cc);
-  // One of the above un-smis or the above SUB could have set N==1.
-  __ b(mi, &runtime);  // Either "from" or "to" is not an smi, or from > to.
-
-  // Make sure first argument is a string.
-  __ ldr(r0, MemOperand(sp, kStringOffset));
-  __ JumpIfSmi(r0, &runtime);
-  Condition is_string = masm->IsObjectStringType(r0, r1);
-  __ b(NegateCondition(is_string), &runtime);
-
-  Label single_char;
-  __ cmp(r2, Operand(1));
-  __ b(eq, &single_char);
-
-  // Short-cut for the case of trivial substring.
-  Label return_r0;
-  // r0: original string
-  // r2: result string length
-  __ ldr(r4, FieldMemOperand(r0, String::kLengthOffset));
-  __ cmp(r2, Operand(r4, ASR, 1));
-  // Return original string.
-  __ b(eq, &return_r0);
-  // Longer than original string's length or negative: unsafe arguments.
-  __ b(hi, &runtime);
-  // 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 r5.
-  // r0: original string
-  // r1: instance type
-  // r2: length
-  // r3: 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);
-  __ tst(r1, Operand(kIsIndirectStringMask));
-  __ b(eq, &seq_or_external_string);
-
-  __ tst(r1, Operand(kSlicedNotConsMask));
-  __ b(ne, &sliced_string);
-  // Cons string.  Check whether it is flat, then fetch first part.
-  __ ldr(r5, FieldMemOperand(r0, ConsString::kSecondOffset));
-  __ CompareRoot(r5, Heap::kempty_stringRootIndex);
-  __ b(ne, &runtime);
-  __ ldr(r5, FieldMemOperand(r0, ConsString::kFirstOffset));
-  // Update instance type.
-  __ ldr(r1, FieldMemOperand(r5, HeapObject::kMapOffset));
-  __ ldrb(r1, FieldMemOperand(r1, Map::kInstanceTypeOffset));
-  __ jmp(&underlying_unpacked);
-
-  __ bind(&sliced_string);
-  // Sliced string.  Fetch parent and correct start index by offset.
-  __ ldr(r5, FieldMemOperand(r0, SlicedString::kParentOffset));
-  __ ldr(r4, FieldMemOperand(r0, SlicedString::kOffsetOffset));
-  __ add(r3, r3, Operand(r4, ASR, 1));  // Add offset to index.
-  // Update instance type.
-  __ ldr(r1, FieldMemOperand(r5, HeapObject::kMapOffset));
-  __ ldrb(r1, FieldMemOperand(r1, Map::kInstanceTypeOffset));
-  __ jmp(&underlying_unpacked);
-
-  __ bind(&seq_or_external_string);
-  // Sequential or external string.  Just move string to the expected register.
-  __ mov(r5, r0);
-
-  __ bind(&underlying_unpacked);
-
-  if (FLAG_string_slices) {
-    Label copy_routine;
-    // r5: underlying subject string
-    // r1: instance type of underlying subject string
-    // r2: length
-    // r3: adjusted start index (untagged)
-    __ cmp(r2, Operand(SlicedString::kMinLength));
-    // Short slice.  Copy instead of slicing.
-    __ b(lt, &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);
-    __ tst(r1, Operand(kStringEncodingMask));
-    __ b(eq, &two_byte_slice);
-    __ AllocateOneByteSlicedString(r0, r2, r6, r4, &runtime);
-    __ jmp(&set_slice_header);
-    __ bind(&two_byte_slice);
-    __ AllocateTwoByteSlicedString(r0, r2, r6, r4, &runtime);
-    __ bind(&set_slice_header);
-    __ mov(r3, Operand(r3, LSL, 1));
-    __ str(r5, FieldMemOperand(r0, SlicedString::kParentOffset));
-    __ str(r3, FieldMemOperand(r0, SlicedString::kOffsetOffset));
-    __ jmp(&return_r0);
-
-    __ bind(&copy_routine);
-  }
-
-  // r5: underlying subject string
-  // r1: instance type of underlying subject string
-  // r2: length
-  // r3: adjusted start index (untagged)
-  Label two_byte_sequential, sequential_string, allocate_result;
-  STATIC_ASSERT(kExternalStringTag != 0);
-  STATIC_ASSERT(kSeqStringTag == 0);
-  __ tst(r1, Operand(kExternalStringTag));
-  __ b(eq, &sequential_string);
-
-  // Handle external string.
-  // Rule out short external strings.
-  STATIC_ASSERT(kShortExternalStringTag != 0);
-  __ tst(r1, Operand(kShortExternalStringTag));
-  __ b(ne, &runtime);
-  __ ldr(r5, FieldMemOperand(r5, ExternalString::kResourceDataOffset));
-  // r5 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);
-  __ add(r5, r5, Operand(SeqOneByteString::kHeaderSize - kHeapObjectTag));
-
-  __ bind(&allocate_result);
-  // Sequential acii string.  Allocate the result.
-  STATIC_ASSERT((kOneByteStringTag & kStringEncodingMask) != 0);
-  __ tst(r1, Operand(kStringEncodingMask));
-  __ b(eq, &two_byte_sequential);
-
-  // Allocate and copy the resulting one-byte string.
-  __ AllocateOneByteString(r0, r2, r4, r6, r1, &runtime);
-
-  // Locate first character of substring to copy.
-  __ add(r5, r5, r3);
-  // Locate first character of result.
-  __ add(r1, r0, Operand(SeqOneByteString::kHeaderSize - kHeapObjectTag));
-
-  // r0: result string
-  // r1: first character of result string
-  // r2: result string length
-  // r5: first character of substring to copy
-  STATIC_ASSERT((SeqOneByteString::kHeaderSize & kObjectAlignmentMask) == 0);
-  StringHelper::GenerateCopyCharacters(
-      masm, r1, r5, r2, r3, String::ONE_BYTE_ENCODING);
-  __ jmp(&return_r0);
-
-  // Allocate and copy the resulting two-byte string.
-  __ bind(&two_byte_sequential);
-  __ AllocateTwoByteString(r0, r2, r4, r6, r1, &runtime);
-
-  // Locate first character of substring to copy.
-  STATIC_ASSERT(kSmiTagSize == 1 && kSmiTag == 0);
-  __ add(r5, r5, Operand(r3, LSL, 1));
-  // Locate first character of result.
-  __ add(r1, r0, Operand(SeqTwoByteString::kHeaderSize - kHeapObjectTag));
-
-  // r0: result string.
-  // r1: first character of result.
-  // r2: result length.
-  // r5: first character of substring to copy.
-  STATIC_ASSERT((SeqTwoByteString::kHeaderSize & kObjectAlignmentMask) == 0);
-  StringHelper::GenerateCopyCharacters(
-      masm, r1, r5, r2, r3, String::TWO_BYTE_ENCODING);
-
-  __ bind(&return_r0);
-  Counters* counters = isolate()->counters();
-  __ IncrementCounter(counters->sub_string_native(), 1, r3, r4);
-  __ Drop(3);
-  __ Ret();
-
-  // Just jump to runtime to create the sub string.
-  __ bind(&runtime);
-  __ TailCallRuntime(Runtime::kSubString);
-
-  __ bind(&single_char);
-  // r0: original string
-  // r1: instance type
-  // r2: length
-  // r3: from index (untagged)
-  __ SmiTag(r3, r3);
-  StringCharAtGenerator generator(r0, r3, r2, r0, &runtime, &runtime, &runtime,
-                                  RECEIVER_IS_STRING);
-  generator.GenerateFast(masm);
-  __ Drop(3);
-  __ Ret();
-  generator.SkipSlow(masm, &runtime);
-}
-
 void ToStringStub::Generate(MacroAssembler* masm) {
   // The ToString stub takes one argument in r0.
   Label is_number;
   __ JumpIfSmi(r0, &is_number);
 
   __ CompareObjectType(r0, r1, r1, FIRST_NONSTRING_TYPE);
   // r0: receiver
   // r1: receiver instance type
   __ Ret(lo);
 
@@ skipping 2805 matching lines @@
   CallApiFunctionAndReturn(masm, api_function_address, thunk_ref,
                            kStackUnwindSpace, NULL, return_value_operand, NULL);
 }
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_ARM