From 318e23e7fe4c09f316891a2b7803f360f4834f57 Mon Sep 17 00:00:00 2001
From: Chris Lattner <sabre@nondot.org>
Date: Mon, 5 Feb 2007 06:30:51 +0000
Subject: [PATCH] add a note

llvm-svn: 33904
---
 docs/ProgrammersManual.html | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/docs/ProgrammersManual.html b/docs/ProgrammersManual.html
index 1d5ad0e82c0..c4fedbf5d7b 100644
--- a/docs/ProgrammersManual.html
+++ b/docs/ProgrammersManual.html
@@ -797,6 +797,33 @@ rarely be a benefit) or if you will be allocating many instances of the vector
 itself (which would waste space for elements that aren't in the container).
 vector is also useful when interfacing with code that expects vectors :).
 </p>
+
+<p>One worthwhile note about std::vector: avoid code like this:</p>
+
+<div class="doc_code">
+<pre>
+for ( ... ) {
+   std::vector<foo> V;
+   use V;
+}
+</pre>
+</div>
+
+<p>Instead, write this as:</p>
+
+<div class="doc_code">
+<pre>
+std::vector<foo> V;
+for ( ... ) {
+   use V;
+   V.clear();
+}
+</pre>
+</div>
+
+<p>Doing so will save (at least) one heap allocation and free per iteration of
+the loop.</p>
+
 </div>
 
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