From: Egon Elbre <egonelbre@gmail.com>
Date: Tue, 25 Aug 2020 07:38:50 +0000 (+0300)
Subject: doc/asm: add BP is callee-save paragraph
X-Git-Tag: go1.16beta1~1152
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=d7a6a44deb3a56aa3f94b75f7ab4ffa1a0fa8cef;p=gostls13.git

doc/asm: add BP is callee-save paragraph

Change-Id: Id38e639c66a42acf0b1c4488cdfd0b7b6cf71c78
Reviewed-on: https://go-review.googlesource.com/c/go/+/250397
Reviewed-by: Keith Randall <khr@golang.org>
---

diff --git a/doc/asm.html b/doc/asm.html
index dbbe8f2cd1..cc8598aeff 100644
--- a/doc/asm.html
+++ b/doc/asm.html
@@ -687,6 +687,13 @@ MOVQ	g(CX), AX     // Move g into AX.
 MOVQ	g_m(AX), BX   // Move g.m into BX.
 </pre>
 
+<p>
+Register <code>BP</code> is callee-save.
+The assembler automatically inserts <code>BP</code> save/restore when frame size is larger than zero.
+Using <code>BP</code> as a general purpose register is allowed,
+however it can interfere with sampling-based profiling.
+</p>
+
 <h3 id="arm">ARM</h3>
 
 <p>