Reviewers: fschneider,
Message:
Please take a look.
Math.min and Math.max are almost always used with two arguments only. By
handling this case separately and not calling built-in functions to get the
arguments, we gain some performance.
Description:
Improve performance of Math.min and Math.max for the case of two arguments.
BUG=v8:1325
TEST=
Please review this at http://codereview.chromium.org/9065008/
SVN Base: https://v8.googlecode.com/svn/branches/bleeding_edge
Affected files:
M src/math.js
Index: src/math.js
diff --git a/src/math.js b/src/math.js
index
18492aa050c0245cd078202cbb01780d189702d6..e078ced6c0e74b225ea5a6a01b23ba2f6f761e58
100644
--- a/src/math.js
+++ b/src/math.js
@@ -119,6 +119,19 @@ function MathLog(x) {
// ECMA 262 - 15.8.2.11
function MathMax(arg1, arg2) { // length == 2
var length = %_ArgumentsLength();
+ if (length == 2) {
+ if (!IS_NUMBER(arg1)) arg1 = NonNumberToNumber(arg1);
+ if (!IS_NUMBER(arg2)) arg2 = NonNumberToNumber(arg2);
+ if (arg2 > arg1) return arg2;
+ if (arg1 > arg2) return arg1;
+ if (arg1 == arg2) {
+ // Make sure -0 is considered less than +0. -0 is never a Smi, +0
can be
+ // a Smi or a heap number.
+ return (arg1 === 0 && !%_IsSmi(arg1) && 1 / arg1 < 0) ? arg2 : arg1;
+ }
+ // All comparisons failed, one of the arguments must be NaN.
+ return 0/0; // Compiler constant-folds this to NaN.
+ }
if (length == 0) {
return -1/0; // Compiler constant-folds this to -Infinity.
}
@@ -139,6 +152,19 @@ function MathMax(arg1, arg2) { // length == 2
// ECMA 262 - 15.8.2.12
function MathMin(arg1, arg2) { // length == 2
var length = %_ArgumentsLength();
+ if (length == 2) {
+ if (!IS_NUMBER(arg1)) arg1 = NonNumberToNumber(arg1);
+ if (!IS_NUMBER(arg2)) arg2 = NonNumberToNumber(arg2);
+ if (arg2 > arg1) return arg1;
+ if (arg1 > arg2) return arg2;
+ if (arg1 == arg2) {
+ // Make sure -0 is considered less than +0. -0 is never a Smi, +0
can be
+ // a Smi or a heap number.
+ return (arg1 === 0 && !%_IsSmi(arg1) && 1 / arg1 < 0) ? arg1 : arg2;
+ }
+ // All comparisons failed, one of the arguments must be NaN.
+ return 0/0; // Compiler constant-folds this to NaN.
+ }
if (length == 0) {
return 1/0; // Compiler constant-folds this to Infinity.
}
@@ -149,7 +175,7 @@ function MathMin(arg1, arg2) { // length == 2
var n = %_Arguments(i);
if (!IS_NUMBER(n)) n = NonNumberToNumber(n);
if (NUMBER_IS_NAN(n)) return n;
- // Make sure -0 is considered less than +0. -0 is never a Smi, +0 can
b a
+ // Make sure -0 is considered less than +0. -0 is never a Smi, +0 can
be a
// Smi or a heap number.
if (n < r || (r === 0 && n === 0 && !%_IsSmi(n) && 1 / n < 0)) r = n;
}
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