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Unified Diff: src/ia32/full-codegen-ia32.cc

Issue 6148007: Speed up FastAsciiArrayJoin on ia32 by improving hand-written assembly code. (Closed) Base URL: http://v8.googlecode.com/svn/branches/bleeding_edge/
Patch Set: '' Created 9 years, 11 months ago
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Index: src/ia32/full-codegen-ia32.cc
===================================================================
--- src/ia32/full-codegen-ia32.cc (revision 6301)
+++ src/ia32/full-codegen-ia32.cc (working copy)
@@ -3351,39 +3351,37 @@
void FullCodeGenerator::EmitFastAsciiArrayJoin(ZoneList<Expression*>* args) {
- Label bailout;
- Label done;
+ Label bailout, done, one_char_separator, long_separator,
+ non_trivial_array, not_size_one_array, loop, loop_condition,
+ loop_1, loop_1_condition, loop_2, loop_2_entry, loop_3, loop_3_entry;
ASSERT(args->length() == 2);
// We will leave the separator on the stack until the end of the function.
VisitForStackValue(args->at(1));
// Load this to eax (= array)
VisitForAccumulatorValue(args->at(0));
-
// All aliases of the same register have disjoint lifetimes.
Register array = eax;
- Register result_pos = no_reg;
+ Register elements = no_reg; // Will be eax.
- Register index = edi;
+ Register index = edx;
- Register current_string_length = ecx; // Will be ecx when live.
+ Register string_length = ecx;
- Register current_string = edx;
+ Register string = esi;
Register scratch = ebx;
- Register scratch_2 = esi;
- Register new_padding_chars = scratch_2;
+ Register array_length = edi;
+ Register result_pos = no_reg; // Will be edi.
- Operand separator = Operand(esp, 4 * kPointerSize); // Already pushed.
- Operand elements = Operand(esp, 3 * kPointerSize);
- Operand result = Operand(esp, 2 * kPointerSize);
- Operand padding_chars = Operand(esp, 1 * kPointerSize);
- Operand array_length = Operand(esp, 0);
- __ sub(Operand(esp), Immediate(4 * kPointerSize));
-
-
- // Check that eax is a JSArray
+ // Separator operand is already pushed.
+ Operand separator_operand = Operand(esp, 2 * kPointerSize);
+ Operand result_operand = Operand(esp, 1 * kPointerSize);
+ Operand array_length_operand = Operand(esp, 0);
+ __ sub(Operand(esp), Immediate(2 * kPointerSize));
+ __ cld();
+ // Check that the array is a JSArray
__ test(array, Immediate(kSmiTagMask));
__ j(zero, &bailout);
__ CmpObjectType(array, JS_ARRAY_TYPE, scratch);
@@ -3394,140 +3392,226 @@
1 << Map::kHasFastElements);
__ j(zero, &bailout);
- // If the array is empty, return the empty string.
- __ mov(scratch, FieldOperand(array, JSArray::kLengthOffset));
- __ sar(scratch, 1);
- Label non_trivial;
- __ j(not_zero, &non_trivial);
- __ mov(result, Factory::empty_string());
+ // If the array has length zero, return the empty string.
+ __ mov(array_length, FieldOperand(array, JSArray::kLengthOffset));
+ __ sar(array_length, 1);
+ __ j(not_zero, &non_trivial_array);
+ __ mov(result_operand, Factory::empty_string());
__ jmp(&done);
- __ bind(&non_trivial);
- __ mov(array_length, scratch);
+ // Save the array length.
+ __ bind(&non_trivial_array);
+ __ mov(array_length_operand, array_length);
- __ mov(scratch, FieldOperand(array, JSArray::kElementsOffset));
- __ mov(elements, scratch);
-
+ // Save the FixedArray containing array's elements.
// End of array's live range.
- result_pos = array;
+ elements = array;
+ __ mov(elements, FieldOperand(array, JSArray::kElementsOffset));
array = no_reg;
- // Check that the separator is a flat ascii string.
- __ mov(current_string, separator);
- __ test(current_string, Immediate(kSmiTagMask));
+ // Check that all array elements are sequential ASCII strings, and
+ // accumulate the sum of their lengths, as a smi-encoded value.
+ __ Set(index, Immediate(0));
+ __ Set(string_length, Immediate(0));
+ // Loop condition: while (index < length).
+ // Live loop registers: index, array_length, string,
+ // scratch, string_length, elements.
+ __ jmp(&loop_condition);
+ __ bind(&loop);
+ __ cmp(index, Operand(array_length));
+ __ j(greater_equal, &done);
+
+ __ mov(string, FieldOperand(elements, index,
+ times_pointer_size,
+ FixedArray::kHeaderSize));
+ __ test(string, Immediate(kSmiTagMask));
__ j(zero, &bailout);
- __ mov(scratch, FieldOperand(current_string, HeapObject::kMapOffset));
- __ mov_b(scratch, FieldOperand(scratch, Map::kInstanceTypeOffset));
+ __ mov(scratch, FieldOperand(string, HeapObject::kMapOffset));
+ __ movzx_b(scratch, FieldOperand(scratch, Map::kInstanceTypeOffset));
__ and_(scratch, Immediate(
kIsNotStringMask | kStringEncodingMask | kStringRepresentationMask));
__ cmp(scratch, kStringTag | kAsciiStringTag | kSeqStringTag);
__ j(not_equal, &bailout);
- // If the separator is the empty string, replace it with NULL.
- // The test for NULL is quicker than the empty string test, in a loop.
- __ cmp(FieldOperand(current_string, SeqAsciiString::kLengthOffset),
- Immediate(0));
- Label separator_checked;
- __ j(not_zero, &separator_checked);
- __ mov(separator, Immediate(0));
- __ bind(&separator_checked);
+ __ add(string_length,
+ FieldOperand(string, SeqAsciiString::kLengthOffset));
+ __ j(overflow, &bailout);
+ __ add(Operand(index), Immediate(1));
+ __ bind(&loop_condition);
+ __ cmp(index, Operand(array_length));
+ __ j(less, &loop);
- // Check that elements[0] is a flat ascii string, and copy it in new space.
- __ mov(scratch, elements);
- __ mov(current_string, FieldOperand(scratch, FixedArray::kHeaderSize));
- __ test(current_string, Immediate(kSmiTagMask));
+ // If array_length is 1, return elements[0], a string.
+ __ cmp(array_length, 1);
+ __ j(not_equal, &not_size_one_array);
+ __ mov(scratch, FieldOperand(elements, FixedArray::kHeaderSize));
+ __ mov(result_operand, scratch);
+ __ jmp(&done);
+
+ __ bind(&not_size_one_array);
+
+ // End of array_length live range.
+ result_pos = array_length;
+ array_length = no_reg;
+
+ // Live registers:
+ // string_length: Sum of string lengths, as a smi.
+ // elements: FixedArray of strings.
+
+ // Check that the separator is a flat ASCII string.
+ __ mov(string, separator_operand);
+ __ test(string, Immediate(kSmiTagMask));
__ j(zero, &bailout);
- __ mov(scratch, FieldOperand(current_string, HeapObject::kMapOffset));
- __ mov_b(scratch, FieldOperand(scratch, Map::kInstanceTypeOffset));
+ __ mov(scratch, FieldOperand(string, HeapObject::kMapOffset));
+ __ movzx_b(scratch, FieldOperand(scratch, Map::kInstanceTypeOffset));
__ and_(scratch, Immediate(
kIsNotStringMask | kStringEncodingMask | kStringRepresentationMask));
__ cmp(scratch, kStringTag | kAsciiStringTag | kSeqStringTag);
__ j(not_equal, &bailout);
- // Allocate space to copy it. Round up the size to the alignment granularity.
- __ mov(current_string_length,
- FieldOperand(current_string, String::kLengthOffset));
- __ shr(current_string_length, 1);
+ // Add (separator length times array_length) - separator length
+ // to string_length.
+ __ mov(scratch, separator_operand);
+ __ mov(scratch, FieldOperand(scratch, SeqAsciiString::kLengthOffset));
+ __ sub(string_length, Operand(scratch)); // May be negative, temporarily.
+ __ imul(scratch, array_length_operand);
+ __ j(overflow, &bailout);
+ __ add(string_length, Operand(scratch));
+ __ j(overflow, &bailout);
+ __ shr(string_length, 1);
// Live registers and stack values:
- // current_string_length: length of elements[0].
+ // string_length
+ // elements
+ __ AllocateAsciiString(result_pos, string_length, scratch,
+ index, string, &bailout);
+ __ mov(result_operand, result_pos);
+ __ lea(result_pos, FieldOperand(result_pos, SeqAsciiString::kHeaderSize));
- // New string result in new space = elements[0]
- __ AllocateAsciiString(result_pos, current_string_length, scratch_2,
- index, no_reg, &bailout);
- __ mov(result, result_pos);
- // Adjust current_string_length to include padding bytes at end of string.
- // Keep track of the number of padding bytes.
- __ mov(new_padding_chars, current_string_length);
- __ add(Operand(current_string_length), Immediate(kObjectAlignmentMask));
- __ and_(Operand(current_string_length), Immediate(~kObjectAlignmentMask));
- __ sub(new_padding_chars, Operand(current_string_length));
- __ neg(new_padding_chars);
- __ mov(padding_chars, new_padding_chars);
+ __ mov(string, separator_operand);
+ __ cmp(FieldOperand(string, SeqAsciiString::kLengthOffset),
+ Immediate(Smi::FromInt(1)));
+ __ j(equal, &one_char_separator);
+ __ j(greater, &long_separator);
- Label copy_loop_1_done;
- Label copy_loop_1;
- __ test(current_string_length, Operand(current_string_length));
- __ j(zero, &copy_loop_1_done);
- __ bind(&copy_loop_1);
- __ sub(Operand(current_string_length), Immediate(kPointerSize));
- __ mov(scratch, FieldOperand(current_string, current_string_length,
- times_1, SeqAsciiString::kHeaderSize));
- __ mov(FieldOperand(result_pos, current_string_length,
- times_1, SeqAsciiString::kHeaderSize),
- scratch);
- __ j(not_zero, &copy_loop_1);
- __ bind(&copy_loop_1_done);
- __ mov(index, Immediate(1));
+ // Empty separator case
+ __ mov(index, Immediate(0));
+ __ jmp(&loop_1_condition);
// Loop condition: while (index < length).
- Label loop;
- __ bind(&loop);
- __ cmp(index, array_length);
- __ j(greater_equal, &done);
+ __ bind(&loop_1);
+ // Each iteration of the loop concatenates one string to the result.
+ // Live values in registers:
+ // index: which element of the elements array we are adding to the result.
+ // result_pos: the position to which we are currently copying characters.
+ // elements: the FixedArray of strings we are joining.
- // If the separator is the empty string, signalled by NULL, skip it.
- Label separator_done;
- __ mov(current_string, separator);
- __ test(current_string, Operand(current_string));
- __ j(zero, &separator_done);
+ // Get string = array[index].
+ __ mov(string, FieldOperand(elements, index,
+ times_pointer_size,
+ FixedArray::kHeaderSize));
+ __ mov(string_length,
+ FieldOperand(string, String::kLengthOffset));
+ __ shr(string_length, 1);
+ __ lea(string,
+ FieldOperand(string, SeqAsciiString::kHeaderSize));
+ __ CopyBytes(string, result_pos, string_length, scratch);
+ __ add(Operand(index), Immediate(1));
+ __ bind(&loop_1_condition);
+ __ cmp(index, array_length_operand);
+ __ j(less, &loop_1); // End while (index < length).
+ __ jmp(&done);
- // Append separator to result. It is known to be a flat ascii string.
- __ AppendStringToTopOfNewSpace(current_string, current_string_length,
- result_pos, scratch, scratch_2, result,
- padding_chars, &bailout);
- __ bind(&separator_done);
- // Add next element of array to the end of the result.
- // Get current_string = array[index].
- __ mov(scratch, elements);
- __ mov(current_string, FieldOperand(scratch, index,
- times_pointer_size,
- FixedArray::kHeaderSize));
- // If current != flat ascii string drop result, return undefined.
- __ test(current_string, Immediate(kSmiTagMask));
- __ j(zero, &bailout);
- __ mov(scratch, FieldOperand(current_string, HeapObject::kMapOffset));
- __ mov_b(scratch, FieldOperand(scratch, Map::kInstanceTypeOffset));
- __ and_(scratch, Immediate(
- kIsNotStringMask | kStringEncodingMask | kStringRepresentationMask));
- __ cmp(scratch, kStringTag | kAsciiStringTag | kSeqStringTag);
- __ j(not_equal, &bailout);
- // Append current to the result.
- __ AppendStringToTopOfNewSpace(current_string, current_string_length,
- result_pos, scratch, scratch_2, result,
- padding_chars, &bailout);
+ // One-character separator case
+ __ bind(&one_char_separator);
+ // Replace separator with its ascii character value.
+ __ mov_b(scratch, FieldOperand(string, SeqAsciiString::kHeaderSize));
+ __ mov_b(separator_operand, scratch);
+
+ __ Set(index, Immediate(0));
+ // Jump into the loop after the code that copies the separator, so the first
+ // element is not preceded by a separator
+ __ jmp(&loop_2_entry);
+ // Loop condition: while (index < length).
+ __ bind(&loop_2);
+ // Each iteration of the loop concatenates one string to the result.
+ // Live values in registers:
+ // index: which element of the elements array we are adding to the result.
+ // result_pos: the position to which we are currently copying characters.
+
+ // Copy the separator character to the result.
+ __ mov_b(scratch, separator_operand);
+ __ mov_b(Operand(result_pos, 0), scratch);
+ __ inc(result_pos);
+
+ __ bind(&loop_2_entry);
+ // Get string = array[index].
+ __ mov(string, FieldOperand(elements, index,
+ times_pointer_size,
+ FixedArray::kHeaderSize));
+ __ mov(string_length,
+ FieldOperand(string, String::kLengthOffset));
+ __ shr(string_length, 1);
+ __ lea(string,
+ FieldOperand(string, SeqAsciiString::kHeaderSize));
+ __ CopyBytes(string, result_pos, string_length, scratch);
__ add(Operand(index), Immediate(1));
- __ jmp(&loop); // End while (index < length).
+ __ cmp(index, array_length_operand);
+ __ j(less, &loop_2); // End while (index < length).
+ __ jmp(&done);
+
+
+ // Long separator case (separator is more than one character).
+ __ bind(&long_separator);
+
+ __ Set(index, Immediate(0));
+ // Jump into the loop after the code that copies the separator, so the first
+ // element is not preceded by a separator
+ __ jmp(&loop_3_entry);
+ // Loop condition: while (index < length).
+ __ bind(&loop_3);
+ // Each iteration of the loop concatenates one string to the result.
+ // Live values in registers:
+ // index: which element of the elements array we are adding to the result.
+ // result_pos: the position to which we are currently copying characters.
+
+ // Copy the separator to the result.
+ __ mov(string, separator_operand);
+ __ mov(string_length,
+ FieldOperand(string, String::kLengthOffset));
+ __ shr(string_length, 1);
+ __ lea(string,
+ FieldOperand(string, SeqAsciiString::kHeaderSize));
+ __ CopyBytes(string, result_pos, string_length, scratch);
+
+ __ bind(&loop_3_entry);
+ // Get string = array[index].
+ __ mov(string, FieldOperand(elements, index,
+ times_pointer_size,
+ FixedArray::kHeaderSize));
+ __ mov(string_length,
+ FieldOperand(string, String::kLengthOffset));
+ __ shr(string_length, 1);
+ __ lea(string,
+ FieldOperand(string, SeqAsciiString::kHeaderSize));
+ __ CopyBytes(string, result_pos, string_length, scratch);
+ __ add(Operand(index), Immediate(1));
+
+ __ cmp(index, array_length_operand);
+ __ j(less, &loop_3); // End while (index < length).
+ __ jmp(&done);
+
+
__ bind(&bailout);
- __ mov(result, Factory::undefined_value());
+ __ mov(result_operand, Factory::undefined_value());
__ bind(&done);
- __ mov(eax, result);
+ __ mov(eax, result_operand);
// Drop temp values from the stack, and restore context register.
- __ add(Operand(esp), Immediate(5 * kPointerSize));
+ __ add(Operand(esp), Immediate(3 * kPointerSize));
__ mov(esi, Operand(ebp, StandardFrameConstants::kContextOffset));
context()->Plug(eax);

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