[src/trunk]: src/doc note the -fno-tree-vrp hack for amd64.

[mrg <mrg%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/89145d30be0d
branches:  trunk
changeset: 344948:89145d30be0d
user:      mrg <mrg%NetBSD.org@localhost>
date:      Thu Apr 28 21:18:23 2016 +0000

description:
note the -fno-tree-vrp hack for amd64.

diffstat:

 doc/HACKS |  10 +++++++++-
 1 files changed, 9 insertions(+), 1 deletions(-)

diffs (24 lines):

diff -r 33a07143213f -r 89145d30be0d doc/HACKS
--- a/doc/HACKS Thu Apr 28 19:52:43 2016 +0000
+++ b/doc/HACKS Thu Apr 28 21:18:23 2016 +0000
@@ -1,4 +1,4 @@
-# $NetBSD: HACKS,v 1.164 2016/01/12 23:03:33 christos Exp $
+# $NetBSD: HACKS,v 1.165 2016/04/28 21:18:23 mrg Exp $
 #
 # This file is intended to document workarounds for currently unsolved
 # (mostly) compiler bugs.
@@ -783,6 +783,14 @@
                out which option is causing this.
        hcah
 
+       hack    turn off -ftree-vrp for ufs_lookup.c
+       who     mrg
+       file    src/sys/arch/amd64/conf/Makefile.amd64 : 1.54
+       descr
+               with -ftree-vrp enabled in ufs_lookup.c sometimes bad dir
+               panicks are see.  see PR 51094.
+       hcah
+
 port   powerpc
 
        hack    avoid using __builtin_return_address(0) because it fails in