Revision: 3843
Author: [email protected]
Date: Fri Feb 12 03:55:04 2010
Log: Optimize string plus smi
When adding a string with a smi value the number string cache is checked in
generated code. If the there is a string value in the number string cache
the resulting string is produced in generated code.
Review URL: http://codereview.chromium.org/596082
http://code.google.com/p/v8/source/detail?r=3843
Modified:
/branches/bleeding_edge/src/ia32/assembler-ia32.h
/branches/bleeding_edge/src/ia32/codegen-ia32.cc
/branches/bleeding_edge/src/v8-counters.h
=======================================
--- /branches/bleeding_edge/src/ia32/assembler-ia32.h Thu Feb 4 13:32:02
2010
+++ /branches/bleeding_edge/src/ia32/assembler-ia32.h Fri Feb 12 03:55:04
2010
@@ -231,7 +231,8 @@
times_8 = 3,
times_int_size = times_4,
times_half_pointer_size = times_2,
- times_pointer_size = times_4
+ times_pointer_size = times_4,
+ times_twice_pointer_size = times_8
};
=======================================
--- /branches/bleeding_edge/src/ia32/codegen-ia32.cc Fri Feb 12 03:43:00
2010
+++ /branches/bleeding_edge/src/ia32/codegen-ia32.cc Fri Feb 12 03:55:04
2010
@@ -7639,7 +7639,7 @@
switch (op_) {
case Token::ADD: {
// Test for string arguments before calling runtime.
- Label not_strings, not_string1, string1;
+ Label not_strings, not_string1, string1, string1_smi2;
Result answer;
__ test(edx, Immediate(kSmiTagMask));
__ j(zero, ¬_string1);
@@ -7648,15 +7648,56 @@
// First argument is a string, test second.
__ test(eax, Immediate(kSmiTagMask));
- __ j(zero, &string1);
+ __ j(zero, &string1_smi2);
__ CmpObjectType(eax, FIRST_NONSTRING_TYPE, ecx);
__ j(above_equal, &string1);
// First and second argument are strings. Jump to the string add
stub.
- StringAddStub stub(NO_STRING_CHECK_IN_STUB);
- __ TailCallStub(&stub);
-
- // Only first argument is a string.
+ StringAddStub string_add_stub(NO_STRING_CHECK_IN_STUB);
+ __ TailCallStub(&string_add_stub);
+
+ __ bind(&string1_smi2);
+ // First argument is a string, second is a smi. Try to lookup the
number
+ // string for the smi in the number string cache.
+ // Load the number string cache.
+ ExternalReference roots_address = ExternalReference::roots_address();
+ __ mov(ecx, Immediate(Heap::kNumberStringCacheRootIndex));
+ __ mov(ebx,
+ Operand::StaticArray(ecx, times_pointer_size, roots_address));
+ // Make the hash mask from the length of the number string cache. It
+ // contains two elements (number and string) for each cache entry.
+ __ mov(ecx, FieldOperand(ebx, FixedArray::kLengthOffset));
+ __ shr(ecx, 1); // Divide length by two (length is not a smi).
+ __ sub(Operand(ecx), Immediate(1)); // Make mask.
+ // Calculate the entry in the number string cache. The hash value in
the
+ // number string cache for smis is just the smi value.
+ __ mov(edi, eax);
+ __ SmiUntag(edi);
+ __ and_(edi, Operand(ecx));
+ // Check if the entry is the smi we are looking for.
+ __ cmp(eax,
+ FieldOperand(ebx,
+ edi,
+ times_twice_pointer_size,
+ FixedArray::kHeaderSize));
+ __ IncrementCounter(equal, &Counters::string_plus_smi_hit, 1);
+ __ IncrementCounter(not_equal, &Counters::string_plus_smi_miss, 1);
+ __ j(not_equal, &string1);
+
+ // Get the string from the cache and call the string add stub to
make the
+ // result.
+ __ mov(edi,
+ FieldOperand(ebx,
+ edi,
+ times_twice_pointer_size,
+ FixedArray::kHeaderSize + kPointerSize));
+ __ EnterInternalFrame();
+ __ push(edx); // Original first argument.
+ __ push(edi); // Number to string result for second argument.
+ __ CallStub(&string_add_stub);
+ __ LeaveInternalFrame();
+ __ ret(2 * kPointerSize);
+
__ bind(&string1);
__ InvokeBuiltin(
HasArgsReversed() ?
=======================================
--- /branches/bleeding_edge/src/v8-counters.h Tue Feb 9 08:14:14 2010
+++ /branches/bleeding_edge/src/v8-counters.h Fri Feb 12 03:55:04 2010
@@ -167,7 +167,9 @@
SC(string_compare_native, V8.StringCompareNative) \
SC(string_compare_runtime, V8.StringCompareRuntime) \
SC(regexp_entry_runtime, V8.RegExpEntryRuntime) \
- SC(regexp_entry_native, V8.RegExpEntryNative)
+ SC(regexp_entry_native, V8.RegExpEntryNative) \
+ SC(string_plus_smi_hit, V8.StringPlusSmiHit) \
+ SC(string_plus_smi_miss, V8.StringPlusSmiMiss)
// This file contains all the v8 counters that are in use.
class Counters : AllStatic {
--
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