From mboxrd@z Thu Jan  1 00:00:00 1970
From: Richard Earnshaw <rearnsha@arm.com>
To: Alexandre Oliva <aoliva@redhat.com>
Cc: Joern Rennecke <amylaar@redhat.com>, wilson@cygnus.com (Jim Wilson), gcc@gcc.gnu.org, gcc-patches@gcc.gnu.org, gdb@sources.redhat.com, Richard.Earnshaw@arm.com
Subject: Re: C++ ptrmemfun break if FUNCTION_BOUNDARY < 2 * BITS_PER_UNIT 
Date: Wed, 18 Apr 2001 05:48:00 -0000
Message-id: <200104181247.NAA23421@cam-mail2.cambridge.arm.com>
References: <orn19pu921.fsf@guarana.lsd.ic.unicamp.br>
X-SW-Source: 2001-04/msg00862.html

aoliva@redhat.com said:
> I don't want to extract a bit.  I want to extract the remaining bits.
> The delta was shifted left (or multiplied by 2) to make room for the
> vbit; now I want the delta back.  It's a signed offset.  

This is OK, provided that you can guarantee that the left shift won't 
cause the "sign" bit to change value.  That is

	((X << 1) MOD size) >> 1 == X

for all interesting values of X.

R.