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

Issue 5122005: Add a fast case to Array.join when all the elements and the separator are fla... (Closed) Base URL: http://v8.googlecode.com/svn/branches/bleeding_edge/
Patch Set: '' Created 10 years, 1 month ago
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Index: src/ia32/full-codegen-ia32.cc
===================================================================
--- src/ia32/full-codegen-ia32.cc (revision 5857)
+++ src/ia32/full-codegen-ia32.cc (working copy)
@@ -3084,6 +3084,190 @@
}
+void FullCodeGenerator::EmitFastAsciiArrayJoin(ZoneList<Expression*>* args) {
+ Label bailout;
+ Label done;
+
+ 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 index = edi;
+
+ Register current_string_length = ecx; // Will be ecx when live.
+
+ Register current_string = edx;
+
+ Register scratch = ebx;
+
+ Register scratch_2 = esi;
+ Register new_padding_chars = scratch_2;
+
+ 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
+ __ test(array, Immediate(kSmiTagMask));
+ __ j(zero, &bailout);
+ __ CmpObjectType(array, JS_ARRAY_TYPE, scratch);
+ __ j(not_equal, &bailout);
+
+ // Check that the array has fast elements.
+ __ test_b(FieldOperand(scratch, Map::kBitField2Offset),
+ 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());
+ __ jmp(&done);
+
+ __ bind(&non_trivial);
+ __ mov(array_length, scratch);
+
+ __ mov(scratch, FieldOperand(array, JSArray::kElementsOffset));
+ __ mov(elements, scratch);
+
+ // End of array's live range.
+ result_pos = array;
+ array = no_reg;
+
+
+ // Check that the separator is a flat ascii string.
+ __ mov(current_string, separator);
+ __ 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);
+ // 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);
+
+ // 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));
+ __ 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);
+
+ // 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);
+
+ // Live registers and stack values:
+ // current_string_length: length of elements[0].
+
+ // 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);
+
+ 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));
+ // Loop condition: while (index < length).
+ Label loop;
+ __ bind(&loop);
+ __ cmp(index, array_length);
+ __ j(greater_equal, &done);
+
+ // 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);
+
+ // 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);
+ __ add(Operand(index), Immediate(1));
+ __ jmp(&loop); // End while (index < length).
+
+ __ bind(&bailout);
+ __ mov(result, Factory::undefined_value());
+ __ bind(&done);
+ __ mov(eax, result);
+ // Drop temp values from the stack, and restore context register.
+ __ add(Operand(esp), Immediate(5 * kPointerSize));
+
+ __ mov(esi, Operand(ebp, StandardFrameConstants::kContextOffset));
+ context()->Plug(eax);
+}
+
+
void FullCodeGenerator::VisitCallRuntime(CallRuntime* expr) {
Handle<String> name = expr->name();
if (name->length() > 0 && name->Get(0) == '_') {
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