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Generated code for substring slices in x64 and arm.

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Review URL: http://codereview.chromium.org/7795018

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@9111 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This commit is contained in:
yangguo@chromium.org 2011-09-01 15:24:26 +00:00
parent 4e049d4619
commit 1be99a9627
14 changed files with 380 additions and 94 deletions
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197
src/arm/code-stubs-arm.cc
View File

@ -4894,7 +4894,8 @@ void StringCharCodeAtGenerator::GenerateFast(MacroAssembler* masm) {
// Check for 1-byte or 2-byte string.
__ bind(&flat_string);
STATIC_ASSERT(kAsciiStringTag != 0);
STATIC_ASSERT((kStringEncodingMask & kAsciiStringTag) != 0);
STATIC_ASSERT((kStringEncodingMask & kTwoByteStringTag) == 0);
__ tst(result_, Operand(kStringEncodingMask));
__ b(ne, &ascii_string);
@ -5468,11 +5469,6 @@ void SubStringStub::Generate(MacroAssembler* masm) {
Register to = r6;
Register from = r7;
if (FLAG_string_slices) {
__ nop(0); // Jumping as first instruction would crash the code generation.
__ jmp(&runtime);
}
__ Ldrd(to, from, MemOperand(sp, kToOffset));
STATIC_ASSERT(kFromOffset == kToOffset + 4);
STATIC_ASSERT(kSmiTag == 0);
@ -5490,64 +5486,79 @@ void SubStringStub::Generate(MacroAssembler* masm) {
__ b(mi, &runtime); // Fail if from > to.
// Special handling of sub-strings of length 1 and 2. One character strings
// are handled in the runtime system (looked up in the single character
// cache). Two character strings are looked for in the symbol cache.
// cache). Two character strings are looked for in the symbol cache in
// generated code.
__ cmp(r2, Operand(2));
__ b(lt, &runtime);
// r2: length
// r3: from index (untaged smi)
// r2: result string length
// r3: from index (untagged smi)
// r6 (a.k.a. to): to (smi)
// r7 (a.k.a. from): from offset (smi)
// Make sure first argument is a sequential (or flat) string.
__ ldr(r5, MemOperand(sp, kStringOffset));
__ ldr(r0, MemOperand(sp, kStringOffset));
STATIC_ASSERT(kSmiTag == 0);
__ JumpIfSmi(r5, &runtime);
Condition is_string = masm->IsObjectStringType(r5, r1);
__ JumpIfSmi(r0, &runtime);
Condition is_string = masm->IsObjectStringType(r0, r1);
__ b(NegateCondition(is_string), &runtime);
// 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));
__ b(eq, &return_r0);
Label create_slice;
if (FLAG_string_slices) {
__ cmp(r2, Operand(SlicedString::kMinLength));
__ b(ge, &create_slice);
}
// r0: original string
// r1: instance type
// r2: length
// r2: result string length
// r3: from index (untagged smi)
// r5: string
// r6 (a.k.a. to): to (smi)
// r7 (a.k.a. from): from offset (smi)
Label seq_string;
__ and_(r4, r1, Operand(kStringRepresentationMask));
STATIC_ASSERT(kSeqStringTag < kConsStringTag);
STATIC_ASSERT(kConsStringTag < kExternalStringTag);
STATIC_ASSERT(kConsStringTag < kSlicedStringTag);
__ cmp(r4, Operand(kConsStringTag));
__ b(gt, &runtime); // External strings go to runtime.
__ b(gt, &runtime); // Slices and external strings go to runtime.
__ b(lt, &seq_string); // Sequential strings are handled directly.
// Cons string. Try to recurse (once) on the first substring.
// (This adds a little more generality than necessary to handle flattened
// cons strings, but not much).
__ ldr(r5, FieldMemOperand(r5, ConsString::kFirstOffset));
__ ldr(r4, FieldMemOperand(r5, HeapObject::kMapOffset));
__ ldr(r0, FieldMemOperand(r0, ConsString::kFirstOffset));
__ ldr(r4, FieldMemOperand(r0, HeapObject::kMapOffset));
__ ldrb(r1, FieldMemOperand(r4, Map::kInstanceTypeOffset));
__ tst(r1, Operand(kStringRepresentationMask));
STATIC_ASSERT(kSeqStringTag == 0);
__ b(ne, &runtime); // Cons and External strings go to runtime.
__ b(ne, &runtime); // Cons, slices and external strings go to runtime.
// Definitly a sequential string.
__ bind(&seq_string);
// r1: instance type.
// r2: length
// r3: from index (untaged smi)
// r5: string
// r0: original string
// r1: instance type
// r2: result string length
// r3: from index (untagged smi)
// r6 (a.k.a. to): to (smi)
// r7 (a.k.a. from): from offset (smi)
__ ldr(r4, FieldMemOperand(r5, String::kLengthOffset));
__ ldr(r4, FieldMemOperand(r0, String::kLengthOffset));
__ cmp(r4, Operand(to));
__ b(lt, &runtime); // Fail if to > length.
to = no_reg;
// r1: instance type.
// r2: result string length.
// r3: from index (untaged smi)
// r5: string.
// r0: original string or left hand side of the original cons string.
// r1: instance type
// r2: result string length
// r3: from index (untagged smi)
// r7 (a.k.a. from): from offset (smi)
// Check for flat ASCII string.
Label non_ascii_flat;
@ -5561,82 +5572,146 @@ void SubStringStub::Generate(MacroAssembler* masm) {
// Sub string of length 2 requested.
// Get the two characters forming the sub string.
__ add(r5, r5, Operand(r3));
__ ldrb(r3, FieldMemOperand(r5, SeqAsciiString::kHeaderSize));
__ ldrb(r4, FieldMemOperand(r5, SeqAsciiString::kHeaderSize + 1));
__ add(r0, r0, Operand(r3));
__ ldrb(r3, FieldMemOperand(r0, SeqAsciiString::kHeaderSize));
__ ldrb(r4, FieldMemOperand(r0, SeqAsciiString::kHeaderSize + 1));
// Try to lookup two character string in symbol table.
Label make_two_character_string;
StringHelper::GenerateTwoCharacterSymbolTableProbe(
masm, r3, r4, r1, r5, r6, r7, r9, &make_two_character_string);
Counters* counters = masm->isolate()->counters();
__ IncrementCounter(counters->sub_string_native(), 1, r3, r4);
__ add(sp, sp, Operand(3 * kPointerSize));
__ Ret();
__ jmp(&return_r0);
// r2: result string length.
// r3: two characters combined into halfword in little endian byte order.
__ bind(&make_two_character_string);
__ AllocateAsciiString(r0, r2, r4, r5, r9, &runtime);
__ strh(r3, FieldMemOperand(r0, SeqAsciiString::kHeaderSize));
__ IncrementCounter(counters->sub_string_native(), 1, r3, r4);
__ add(sp, sp, Operand(3 * kPointerSize));
__ Ret();
__ jmp(&return_r0);
__ bind(&result_longer_than_two);
// Locate 'from' character of string.
__ add(r5, r0, Operand(SeqAsciiString::kHeaderSize - kHeapObjectTag));
__ add(r5, r5, Operand(from, ASR, 1));
// Allocate the result.
__ AllocateAsciiString(r0, r2, r3, r4, r1, &runtime);
// r0: result string.
// r2: result string length.
// r5: string.
// r0: result string
// r2: result string length
// r5: first character of substring to copy
// r7 (a.k.a. from): from offset (smi)
// Locate first character of result.
__ add(r1, r0, Operand(SeqAsciiString::kHeaderSize - kHeapObjectTag));
// Locate 'from' character of string.
__ add(r5, r5, Operand(SeqAsciiString::kHeaderSize - kHeapObjectTag));
__ add(r5, r5, Operand(from, ASR, 1));
// r0: result string.
// r1: first character of result string.
// r2: result string length.
// r5: first character of sub string to copy.
// r0: result string
// r1: first character of result string
// r2: result string length
// r5: first character of substring to copy
STATIC_ASSERT((SeqAsciiString::kHeaderSize & kObjectAlignmentMask) == 0);
StringHelper::GenerateCopyCharactersLong(masm, r1, r5, r2, r3, r4, r6, r7, r9,
COPY_ASCII | DEST_ALWAYS_ALIGNED);
__ IncrementCounter(counters->sub_string_native(), 1, r3, r4);
__ add(sp, sp, Operand(3 * kPointerSize));
__ Ret();
__ jmp(&return_r0);
__ bind(&non_ascii_flat);
// r2: result string length.
// r5: string.
// r0: original string
// r2: result string length
// r7 (a.k.a. from): from offset (smi)
// Check for flat two byte string.
// Locate 'from' character of string.
__ add(r5, r0, Operand(SeqTwoByteString::kHeaderSize - kHeapObjectTag));
// As "from" is a smi it is 2 times the value which matches the size of a two
// byte character.
STATIC_ASSERT(kSmiTagSize == 1 && kSmiTag == 0);
__ add(r5, r5, Operand(from));
// Allocate the result.
__ AllocateTwoByteString(r0, r2, r1, r3, r4, &runtime);
// r0: result string.
// r2: result string length.
// r5: string.
// r0: result string
// r2: result string length
// r5: first character of substring to copy
// Locate first character of result.
__ add(r1, r0, Operand(SeqTwoByteString::kHeaderSize - kHeapObjectTag));
// Locate 'from' character of string.
__ add(r5, r5, Operand(SeqTwoByteString::kHeaderSize - kHeapObjectTag));
// As "from" is a smi it is 2 times the value which matches the size of a two
// byte character.
__ add(r5, r5, Operand(from));
from = no_reg;
// r0: result string.
// r1: first character of result.
// r2: result length.
// r5: first character of string to copy.
// r5: first character of substring to copy.
STATIC_ASSERT((SeqTwoByteString::kHeaderSize & kObjectAlignmentMask) == 0);
StringHelper::GenerateCopyCharactersLong(
masm, r1, r5, r2, r3, r4, r6, r7, r9, DEST_ALWAYS_ALIGNED);
__ jmp(&return_r0);
if (FLAG_string_slices) {
__ bind(&create_slice);
// r0: original string
// r1: instance type
// r2: length
// r3: from index (untagged smi)
// r6 (a.k.a. to): to (smi)
// r7 (a.k.a. from): from offset (smi)
Label allocate_slice, sliced_string, seq_string;
STATIC_ASSERT(kSeqStringTag == 0);
__ tst(r1, Operand(kStringRepresentationMask));
__ b(eq, &seq_string);
STATIC_ASSERT(kIsIndirectStringMask == (kSlicedStringTag & kConsStringTag));
STATIC_ASSERT(kIsIndirectStringMask != 0);
__ tst(r1, Operand(kIsIndirectStringMask));
// External string. Jump to runtime.
__ b(eq, &runtime);
__ 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));
__ LoadRoot(r9, Heap::kEmptyStringRootIndex);
__ cmp(r5, r9);
__ b(ne, &runtime);
__ ldr(r5, FieldMemOperand(r0, ConsString::kFirstOffset));
__ jmp(&allocate_slice);
__ bind(&sliced_string);
// Sliced string. Fetch parent and correct start index by offset.
__ ldr(r5, FieldMemOperand(r0, SlicedString::kOffsetOffset));
__ add(r7, r7, r5);
__ ldr(r5, FieldMemOperand(r0, SlicedString::kParentOffset));
__ jmp(&allocate_slice);
__ bind(&seq_string);
// Sequential string. Just move string to the right register.
__ mov(r5, r0);
__ bind(&allocate_slice);
// r1: instance type of original string
// r2: length
// r5: underlying subject string
// r7 (a.k.a. from): from offset (smi)
// 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 & kAsciiStringTag) != 0);
STATIC_ASSERT((kStringEncodingMask & kTwoByteStringTag) == 0);
__ tst(r1, Operand(kStringEncodingMask));
__ b(eq, &two_byte_slice);
__ AllocateAsciiSlicedString(r0, r2, r3, r4, &runtime);
__ jmp(&set_slice_header);
__ bind(&two_byte_slice);
__ AllocateTwoByteSlicedString(r0, r2, r3, r4, &runtime);
__ bind(&set_slice_header);
__ str(r7, FieldMemOperand(r0, SlicedString::kOffsetOffset));
__ str(r5, FieldMemOperand(r0, SlicedString::kParentOffset));
}
__ bind(&return_r0);
__ IncrementCounter(counters->sub_string_native(), 1, r3, r4);
__ add(sp, sp, Operand(3 * kPointerSize));
__ Ret();

3
src/arm/lithium-codegen-arm.cc
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@ -3509,7 +3509,8 @@ void LCodeGen::DoStringCharCodeAt(LStringCharCodeAt* instr) {
// Dispatch on the encoding: ASCII or two-byte.
Label ascii_string;
STATIC_ASSERT(kAsciiStringTag != 0);
STATIC_ASSERT((kStringEncodingMask & kAsciiStringTag) != 0);
STATIC_ASSERT((kStringEncodingMask & kTwoByteStringTag) == 0);
__ tst(result, Operand(kStringEncodingMask));
__ b(ne, &ascii_string);

40
src/arm/macro-assembler-arm.cc
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@ -1725,6 +1725,46 @@ void MacroAssembler::AllocateAsciiConsString(Register result,
}
void MacroAssembler::AllocateTwoByteSlicedString(Register result,
Register length,
Register scratch1,
Register scratch2,
Label* gc_required) {
AllocateInNewSpace(SlicedString::kSize,
result,
scratch1,
scratch2,
gc_required,
TAG_OBJECT);
InitializeNewString(result,
length,
Heap::kSlicedStringMapRootIndex,
scratch1,
scratch2);
}
void MacroAssembler::AllocateAsciiSlicedString(Register result,
Register length,
Register scratch1,
Register scratch2,
Label* gc_required) {
AllocateInNewSpace(SlicedString::kSize,
result,
scratch1,
scratch2,
gc_required,
TAG_OBJECT);
InitializeNewString(result,
length,
Heap::kSlicedAsciiStringMapRootIndex,
scratch1,
scratch2);
}
void MacroAssembler::CompareObjectType(Register object,
Register map,
Register type_reg,

10
src/arm/macro-assembler-arm.h
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@ -532,6 +532,16 @@ class MacroAssembler: public Assembler {
Register scratch1,
Register scratch2,
Label* gc_required);
void AllocateTwoByteSlicedString(Register result,
Register length,
Register scratch1,
Register scratch2,
Label* gc_required);
void AllocateAsciiSlicedString(Register result,
Register length,
Register scratch1,
Register scratch2,
Label* gc_required);
// Allocates a heap number or jumps to the gc_required label if the young
// space is full and a scavenge is needed. All registers are clobbered also

26
src/ia32/code-stubs-ia32.cc
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@ -4907,7 +4907,8 @@ void StringCharCodeAtGenerator::GenerateFast(MacroAssembler* masm) {
// Check for 1-byte or 2-byte string.
__ bind(&flat_string);
STATIC_ASSERT(kAsciiStringTag != 0);
STATIC_ASSERT((kStringEncodingMask & kAsciiStringTag) != 0);
STATIC_ASSERT((kStringEncodingMask & kTwoByteStringTag) == 0);
__ test(result_, Immediate(kStringEncodingMask));
__ j(not_zero, &ascii_string, Label::kNear);
@ -5178,8 +5179,9 @@ void StringAddStub::Generate(MacroAssembler* masm) {
__ mov(edi, FieldOperand(edx, HeapObject::kMapOffset));
__ movzx_b(edi, FieldOperand(edi, Map::kInstanceTypeOffset));
__ and_(ecx, Operand(edi));
STATIC_ASSERT(kStringEncodingMask == kAsciiStringTag);
__ test(ecx, Immediate(kAsciiStringTag));
STATIC_ASSERT((kStringEncodingMask & kAsciiStringTag) != 0);
STATIC_ASSERT((kStringEncodingMask & kTwoByteStringTag) == 0);
__ test(ecx, Immediate(kStringEncodingMask));
__ j(zero, &non_ascii);
__ bind(&ascii_data);
// Allocate an acsii cons string.
@ -5210,7 +5212,7 @@ void StringAddStub::Generate(MacroAssembler* masm) {
__ cmp(edi, kAsciiStringTag | kAsciiDataHintTag);
__ j(equal, &ascii_data);
// Allocate a two byte cons string.
__ AllocateConsString(ecx, edi, no_reg, &string_add_runtime);
__ AllocateTwoByteConsString(ecx, edi, no_reg, &string_add_runtime);
__ jmp(&allocated);
// Handle creating a flat result. First check that both strings are not
@ -5236,12 +5238,13 @@ void StringAddStub::Generate(MacroAssembler* masm) {
// ebx: length of resulting flat string as a smi
// edx: second string
Label non_ascii_string_add_flat_result;
STATIC_ASSERT(kStringEncodingMask == kAsciiStringTag);
STATIC_ASSERT((kStringEncodingMask & kAsciiStringTag) != 0);
STATIC_ASSERT((kStringEncodingMask & kTwoByteStringTag) == 0);
__ mov(ecx, FieldOperand(eax, HeapObject::kMapOffset));
__ test_b(FieldOperand(ecx, Map::kInstanceTypeOffset), kAsciiStringTag);
__ test_b(FieldOperand(ecx, Map::kInstanceTypeOffset), kStringEncodingMask);
__ j(zero, &non_ascii_string_add_flat_result);
__ mov(ecx, FieldOperand(edx, HeapObject::kMapOffset));
__ test_b(FieldOperand(ecx, Map::kInstanceTypeOffset), kAsciiStringTag);
__ test_b(FieldOperand(ecx, Map::kInstanceTypeOffset), kStringEncodingMask);
__ j(zero, &string_add_runtime);
// Both strings are ascii strings. As they are short they are both flat.
@ -5281,7 +5284,7 @@ void StringAddStub::Generate(MacroAssembler* masm) {
// edx: second string
__ bind(&non_ascii_string_add_flat_result);
__ mov(ecx, FieldOperand(edx, HeapObject::kMapOffset));
__ test_b(FieldOperand(ecx, Map::kInstanceTypeOffset), kAsciiStringTag);
__ test_b(FieldOperand(ecx, Map::kInstanceTypeOffset), kStringEncodingMask);
__ j(not_zero, &string_add_runtime);
// Both strings are two byte strings. As they are short they are both
// flat.
@ -5759,13 +5762,14 @@ void SubStringStub::Generate(MacroAssembler* masm) {
// 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(kAsciiStringTag != 0);
__ test(ebx, Immediate(kAsciiStringTag));
STATIC_ASSERT((kStringEncodingMask & kAsciiStringTag) != 0);
STATIC_ASSERT((kStringEncodingMask & kTwoByteStringTag) == 0);
__ test(ebx, Immediate(kStringEncodingMask));
__ j(zero, &two_byte_slice, Label::kNear);
__ AllocateAsciiSlicedString(eax, ebx, no_reg, &runtime);
__ jmp(&set_slice_header, Label::kNear);
__ bind(&two_byte_slice);
__ AllocateSlicedString(eax, ebx, no_reg, &runtime);
__ AllocateTwoByteSlicedString(eax, ebx, no_reg, &runtime);
__ bind(&set_slice_header);
__ mov(FieldOperand(eax, SlicedString::kOffsetOffset), edx);
__ SmiTag(ecx);

3
src/ia32/lithium-codegen-ia32.cc
View File

@ -3269,7 +3269,8 @@ void LCodeGen::DoStringCharCodeAt(LStringCharCodeAt* instr) {
// Dispatch on the encoding: ASCII or two-byte.
Label ascii_string;
STATIC_ASSERT(kAsciiStringTag != 0);
STATIC_ASSERT((kStringEncodingMask & kAsciiStringTag) != 0);
STATIC_ASSERT((kStringEncodingMask & kTwoByteStringTag) == 0);
__ test(result, Immediate(kStringEncodingMask));
__ j(not_zero, &ascii_string, Label::kNear);

4
src/ia32/macro-assembler-ia32.cc
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@ -1172,7 +1172,7 @@ void MacroAssembler::AllocateAsciiString(Register result,
}
void MacroAssembler::AllocateConsString(Register result,
void MacroAssembler::AllocateTwoByteConsString(Register result,
Register scratch1,
Register scratch2,
Label* gc_required) {
@ -1208,7 +1208,7 @@ void MacroAssembler::AllocateAsciiConsString(Register result,
}
void MacroAssembler::AllocateSlicedString(Register result,
void MacroAssembler::AllocateTwoByteSlicedString(Register result,
Register scratch1,
Register scratch2,
Label* gc_required) {

4
src/ia32/macro-assembler-ia32.h
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@ -437,7 +437,7 @@ class MacroAssembler: public Assembler {
// Allocate a raw cons string object. Only the map field of the result is
// initialized.
void AllocateConsString(Register result,
void AllocateTwoByteConsString(Register result,
Register scratch1,
Register scratch2,
Label* gc_required);
@ -448,7 +448,7 @@ class MacroAssembler: public Assembler {
// Allocate a raw sliced string object. Only the map field of the result is
// initialized.
void AllocateSlicedString(Register result,
void AllocateTwoByteSlicedString(Register result,
Register scratch1,
Register scratch2,
Label* gc_required);

3
src/mips/code-stubs-mips.cc
View File

@ -5079,7 +5079,8 @@ void StringCharCodeAtGenerator::GenerateFast(MacroAssembler* masm) {
// Check for 1-byte or 2-byte string.
__ bind(&flat_string);
STATIC_ASSERT(kAsciiStringTag != 0);
STATIC_ASSERT((kStringEncodingMask & kAsciiStringTag) != 0);
STATIC_ASSERT((kStringEncodingMask & kTwoByteStringTag) == 0);
__ And(t0, result_, Operand(kStringEncodingMask));
__ Branch(&ascii_string, ne, t0, Operand(zero_reg));

101
src/x64/code-stubs-x64.cc
View File

@ -3938,7 +3938,8 @@ void StringCharCodeAtGenerator::GenerateFast(MacroAssembler* masm) {
// Check for 1-byte or 2-byte string.
__ bind(&flat_string);
STATIC_ASSERT(kAsciiStringTag != 0);
STATIC_ASSERT((kStringEncodingMask & kAsciiStringTag) != 0);
STATIC_ASSERT((kStringEncodingMask & kTwoByteStringTag) == 0);
__ testb(result_, Immediate(kStringEncodingMask));
__ j(not_zero, &ascii_string);
@ -4195,8 +4196,9 @@ void StringAddStub::Generate(MacroAssembler* masm) {
Label non_ascii, allocated, ascii_data;
__ movl(rcx, r8);
__ and_(rcx, r9);
STATIC_ASSERT(kStringEncodingMask == kAsciiStringTag);
__ testl(rcx, Immediate(kAsciiStringTag));
STATIC_ASSERT((kStringEncodingMask & kAsciiStringTag) != 0);
STATIC_ASSERT((kStringEncodingMask & kTwoByteStringTag) == 0);
__ testl(rcx, Immediate(kStringEncodingMask));
__ j(zero, &non_ascii);
__ bind(&ascii_data);
// Allocate an acsii cons string.
@ -4225,7 +4227,7 @@ void StringAddStub::Generate(MacroAssembler* masm) {
__ cmpb(r8, Immediate(kAsciiStringTag | kAsciiDataHintTag));
__ j(equal, &ascii_data);
// Allocate a two byte cons string.
__ AllocateConsString(rcx, rdi, no_reg, &string_add_runtime);
__ AllocateTwoByteConsString(rcx, rdi, no_reg, &string_add_runtime);
__ jmp(&allocated);
// Handle creating a flat result. First check that both strings are not
@ -4254,10 +4256,11 @@ void StringAddStub::Generate(MacroAssembler* masm) {
// r8: instance type of first string
// r9: instance type of second string
Label non_ascii_string_add_flat_result;
STATIC_ASSERT(kStringEncodingMask == kAsciiStringTag);
__ testl(r8, Immediate(kAsciiStringTag));
STATIC_ASSERT((kStringEncodingMask & kAsciiStringTag) != 0);
STATIC_ASSERT((kStringEncodingMask & kTwoByteStringTag) == 0);
__ testl(r8, Immediate(kStringEncodingMask));
__ j(zero, &non_ascii_string_add_flat_result);
__ testl(r9, Immediate(kAsciiStringTag));
__ testl(r9, Immediate(kStringEncodingMask));
__ j(zero, &string_add_runtime);
__ bind(&make_flat_ascii_string);
@ -4295,7 +4298,9 @@ void StringAddStub::Generate(MacroAssembler* masm) {
// r8: instance type of first string
// r9: instance type of first string
__ bind(&non_ascii_string_add_flat_result);
__ and_(r9, Immediate(kAsciiStringTag));
STATIC_ASSERT((kStringEncodingMask & kAsciiStringTag) != 0);
STATIC_ASSERT((kStringEncodingMask & kTwoByteStringTag) == 0);
__ and_(r9, Immediate(kStringEncodingMask));
__ j(not_zero, &string_add_runtime);
// Both strings are two byte strings. As they are short they are both
// flat.
@ -4639,9 +4644,6 @@ void StringHelper::GenerateHashGetHash(MacroAssembler* masm,
void SubStringStub::Generate(MacroAssembler* masm) {
Label runtime;
if (FLAG_string_slices) {
__ jmp(&runtime);
}
// Stack frame on entry.
// rsp[0]: return address
// rsp[8]: to
@ -4707,7 +4709,82 @@ void SubStringStub::Generate(MacroAssembler* masm) {
__ movzxbl(rbx, FieldOperand(rbx, Map::kInstanceTypeOffset));
__ Set(rcx, 2);
__ bind(&result_longer_than_two);
if (FLAG_string_slices) {
Label copy_routine;
// If coming from the make_two_character_string path, the string
// is too short to be sliced anyways.
STATIC_ASSERT(2 < SlicedString::kMinLength);
__ jmp(&copy_routine);
__ bind(&result_longer_than_two);
// rax: string
// rbx: instance type
// rcx: sub string length
// rdx: from index (smi)
Label allocate_slice, sliced_string, seq_string;
__ cmpq(rcx, Immediate(SlicedString::kMinLength));
// Short slice. Copy instead of slicing.
__ j(less, &copy_routine);
STATIC_ASSERT(kSeqStringTag == 0);
__ testb(rbx, Immediate(kStringRepresentationMask));
__ j(zero, &seq_string, Label::kNear);
STATIC_ASSERT(kIsIndirectStringMask == (kSlicedStringTag & kConsStringTag));
STATIC_ASSERT(kIsIndirectStringMask != 0);
__ testb(rbx, Immediate(kIsIndirectStringMask));
// External string. Jump to runtime.
__ j(zero, &runtime);
__ testb(rbx, Immediate(kSlicedNotConsMask));
__ j(not_zero, &sliced_string, Label::kNear);
// Cons string. Check whether it is flat, then fetch first part.
__ CompareRoot(FieldOperand(rax, ConsString::kSecondOffset),
Heap::kEmptyStringRootIndex);
__ j(not_equal, &runtime);
__ movq(rdi, FieldOperand(rax, ConsString::kFirstOffset));
__ jmp(&allocate_slice, Label::kNear);
__ bind(&sliced_string);
// Sliced string. Fetch parent and correct start index by offset.
__ addq(rdx, FieldOperand(rax, SlicedString::kOffsetOffset));
__ movq(rdi, FieldOperand(rax, SlicedString::kParentOffset));
__ jmp(&allocate_slice, Label::kNear);
__ bind(&seq_string);
// Sequential string. Just move string to the right register.
__ movq(rdi, rax);
__ bind(&allocate_slice);
// edi: underlying subject string
// ebx: instance type of original subject string
// edx: offset
// ecx: length
// 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 & kAsciiStringTag) != 0);
STATIC_ASSERT((kStringEncodingMask & kTwoByteStringTag) == 0);
__ testb(rbx, Immediate(kStringEncodingMask));
__ j(zero, &two_byte_slice, Label::kNear);
__ AllocateAsciiSlicedString(rax, rbx, no_reg, &runtime);
__ jmp(&set_slice_header, Label::kNear);
__ bind(&two_byte_slice);
__ AllocateTwoByteSlicedString(rax, rbx, no_reg, &runtime);
__ bind(&set_slice_header);
__ movq(FieldOperand(rax, SlicedString::kOffsetOffset), rdx);
__ Integer32ToSmi(rcx, rcx);
__ movq(FieldOperand(rax, SlicedString::kLengthOffset), rcx);
__ movq(FieldOperand(rax, SlicedString::kParentOffset), rdi);
__ movq(FieldOperand(rax, SlicedString::kHashFieldOffset),
Immediate(String::kEmptyHashField));
__ jmp(&return_rax);
__ bind(&copy_routine);
} else {
__ bind(&result_longer_than_two);
}
// rax: string
// rbx: instance type

3
src/x64/lithium-codegen-x64.cc
View File

@ -3251,7 +3251,8 @@ void LCodeGen::DoStringCharCodeAt(LStringCharCodeAt* instr) {
// Dispatch on the encoding: ASCII or two-byte.
Label ascii_string;
STATIC_ASSERT(kAsciiStringTag != 0);
STATIC_ASSERT((kStringEncodingMask & kAsciiStringTag) != 0);
STATIC_ASSERT((kStringEncodingMask & kTwoByteStringTag) == 0);
__ testb(result, Immediate(kStringEncodingMask));
__ j(not_zero, &ascii_string, Label::kNear);

38
src/x64/macro-assembler-x64.cc
View File

@ -3623,7 +3623,7 @@ void MacroAssembler::AllocateAsciiString(Register result,
}
void MacroAssembler::AllocateConsString(Register result,
void MacroAssembler::AllocateTwoByteConsString(Register result,
Register scratch1,
Register scratch2,
Label* gc_required) {
@ -3659,6 +3659,42 @@ void MacroAssembler::AllocateAsciiConsString(Register result,
}
void MacroAssembler::AllocateTwoByteSlicedString(Register result,
Register scratch1,
Register scratch2,
Label* gc_required) {
// Allocate heap number in new space.
AllocateInNewSpace(SlicedString::kSize,
result,
scratch1,
scratch2,
gc_required,
TAG_OBJECT);
// Set the map. The other fields are left uninitialized.
LoadRoot(kScratchRegister, Heap::kSlicedStringMapRootIndex);
movq(FieldOperand(result, HeapObject::kMapOffset), kScratchRegister);
}
void MacroAssembler::AllocateAsciiSlicedString(Register result,
Register scratch1,
Register scratch2,
Label* gc_required) {
// Allocate heap number in new space.
AllocateInNewSpace(SlicedString::kSize,
result,
scratch1,
scratch2,
gc_required,
TAG_OBJECT);
// Set the map. The other fields are left uninitialized.
LoadRoot(kScratchRegister, Heap::kSlicedAsciiStringMapRootIndex);
movq(FieldOperand(result, HeapObject::kMapOffset), kScratchRegister);
}
// Copy memory, byte-by-byte, from source to destination. Not optimized for
// long or aligned copies. The contents of scratch and length are destroyed.
// Destination is incremented by length, source, length and scratch are

13
src/x64/macro-assembler-x64.h
View File

@ -921,7 +921,7 @@ class MacroAssembler: public Assembler {
// Allocate a raw cons string object. Only the map field of the result is
// initialized.
void AllocateConsString(Register result,
void AllocateTwoByteConsString(Register result,
Register scratch1,
Register scratch2,
Label* gc_required);
@ -930,6 +930,17 @@ class MacroAssembler: public Assembler {
Register scratch2,
Label* gc_required);
// Allocate a raw sliced string object. Only the map field of the result is
// initialized.
void AllocateTwoByteSlicedString(Register result,
Register scratch1,
Register scratch2,
Label* gc_required);
void AllocateAsciiSlicedString(Register result,
Register scratch1,
Register scratch2,
Label* gc_required);
// ---------------------------------------------------------------------------
// Support functions.

29
test/cctest/test-strings.cc
View File

@ -529,3 +529,32 @@ TEST(TrivialSlice) {
CHECK(string->IsSlicedString());
CHECK_EQ("bcdefghijklmnopqrstuvwxy", *(string->ToCString()));
}
TEST(SliceFromSlice) {
// This tests whether a slice that contains the entire parent string
// actually creates a new string (it should not).
FLAG_string_slices = true;
InitializeVM();
HandleScope scope;
v8::Local<v8::Value> result;
Handle<String> string;
const char* init = "var str = 'abcdefghijklmnopqrstuvwxyz';";
const char* slice = "var slice = str.slice(1,-1); slice";
const char* slice_from_slice = "slice.slice(1,-1);";
CompileRun(init);
result = CompileRun(slice);
CHECK(result->IsString());
string = v8::Utils::OpenHandle(v8::String::Cast(*result));
CHECK(string->IsSlicedString());
CHECK(SlicedString::cast(*string)->parent()->IsSeqString());
CHECK_EQ("bcdefghijklmnopqrstuvwxy", *(string->ToCString()));
result = CompileRun(slice_from_slice);
CHECK(result->IsString());
string = v8::Utils::OpenHandle(v8::String::Cast(*result));
CHECK(string->IsSlicedString());
CHECK(SlicedString::cast(*string)->parent()->IsSeqString());
CHECK_EQ("cdefghijklmnopqrstuvwx", *(string->ToCString()));
}