Reviewers: Sven Panne,
Message:
It improves the array.join by 30% for short cases and less than 1%
regression
for long cases.
Micros
function foo() {
var fruits = ["Banana", "Orange", "Apple", "Mango"];
var energy = fruits.join();
return energy;
}
function fooLong() {
var fruits = ["BananaBananaBananaBananaBanana",
"OrangeOrangeOrangeOrangeOrange", "AppleAppleAppleAppleAppleAppleApple",
"MangoMangoMangoMangoMangoMangoMango"];
var energy = fruits.join();
return energy;
}
Description:
Refine CopyBytes macro instruction in IA32
Use DWORD copy for more short cases
BUG=
Please review this at https://codereview.chromium.org/66073003/
SVN Base: git://github.com/v8/v8.git@master
Affected files (+25, -7 lines):
M src/ia32/macro-assembler-ia32.cc
Index: src/ia32/macro-assembler-ia32.cc
diff --git a/src/ia32/macro-assembler-ia32.cc
b/src/ia32/macro-assembler-ia32.cc
index
8414f85d656eb7b9b67029d628eceb43b6e1e3b1..6b38801d4122e7b120b40171389b3f9d6fec6305
100644
--- a/src/ia32/macro-assembler-ia32.cc
+++ b/src/ia32/macro-assembler-ia32.cc
@@ -1986,30 +1986,48 @@ void MacroAssembler::CopyBytes(Register source,
Register destination,
Register length,
Register scratch) {
- Label loop, done, short_string, short_loop;
- // Experimentation shows that the short string loop is faster if length
< 10.
- cmp(length, Immediate(10));
- j(less_equal, &short_string);
-
+ Label short_loop, len4, len8, len12, done, short_string;
ASSERT(source.is(esi));
ASSERT(destination.is(edi));
ASSERT(length.is(ecx));
+ cmp(length, Immediate(4));
+ j(below_equal, &short_string, Label::kNear);
// Because source is 4-byte aligned in our uses of this function,
// we keep source aligned for the rep_movs call by copying the odd bytes
// at the end of the ranges.
mov(scratch, Operand(source, length, times_1, -4));
mov(Operand(destination, length, times_1, -4), scratch);
+
+ cmp(length, Immediate(8));
+ j(below_equal, &len4, Label::kNear);
+ cmp(length, Immediate(12));
+ j(below_equal, &len8, Label::kNear);
+ cmp(length, Immediate(16));
+ j(below_equal, &len12, Label::kNear);
+
mov(scratch, ecx);
shr(ecx, 2);
rep_movs();
and_(scratch, Immediate(0x3));
add(destination, scratch);
- jmp(&done);
+ jmp(&done, Label::kNear);
+
+ bind(&len12);
+ mov(scratch, Operand(source, 8));
+ mov(Operand(destination, 8), scratch);
+ bind(&len8);
+ mov(scratch, Operand(source, 4));
+ mov(Operand(destination, 4), scratch);
+ bind(&len4);
+ mov(scratch, Operand(source, 0));
+ mov(Operand(destination, 0), scratch);
+ add(destination, length);
+ jmp(&done, Label::kNear);
bind(&short_string);
test(length, length);
- j(zero, &done);
+ j(zero, &done, Label::kNear);
bind(&short_loop);
mov_b(scratch, Operand(source, 0));
--
--
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