From 7006aafdcd3be55d13e987dc9008425111bc7850 Mon Sep 17 00:00:00 2001
From: Russ Cox <rsc@golang.org>
Date: Sat, 30 Aug 2014 14:18:41 -0400
Subject: [PATCH] runtime: preallocate panic errors for index and slice

This avoids allocating at the panic sites.

LGTM=r, khr
R=golang-codereviews, r, khr
CC=dvyukov, golang-codereviews, iant, khr
https://golang.org/cl/136020043
---
 src/pkg/runtime/panic.go | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/pkg/runtime/panic.go b/src/pkg/runtime/panic.go
index ac0c6b77ee..9b95f49673 100644
--- a/src/pkg/runtime/panic.go
+++ b/src/pkg/runtime/panic.go
@@ -4,10 +4,14 @@
 
 package runtime
 
+var indexError = error(errorString("index out of range"))
+
 func panicindex() {
-	panic(errorString("index out of range"))
+	panic(indexError)
 }
 
+var sliceError = error(errorString("slice bounds out of range"))
+
 func panicslice() {
-	panic(errorString("slice bounds out of range"))
+	panic(sliceError)
 }