Re: asm constraint rule change

[Horst von Brand <vonbrand at sleipnir dot valparaiso dot cl>]

Andi Kleen <ak@muc.de> said:
> In article <17150.908609572@hurl.cygnus.com>,
> Jeffrey A Law <law@cygnus.com> writes:
> >   In message <19981016193609.A4141@dot.cygnus.com>you write:
> >> The recent asm checking patches have tightened the rules such that output
> >> constraints like "r=" are no longer valid.  The problem is that there is
> >> a largish body of code that writes things that way.  More to the point,
> >> despite all the examples running about the documentation, it does not ever
> >> come out and specify this as a rule.  It merely says 
> >> 
> >> ... all output operands' constraints must use `='.
> >> 
> >> So this change is gonna piss some folks off, and with reason.
> >> 
> >> I suggest we adopt the following patch to loosen this rule again.

> >> * stmt.c (expand_asm_operands): Accept `=' or `+' at any position.

> > How about let's make it a warning instead of a hard error.

> > I wouldn't be suprised if some code handles them wrong if the '=' or
> > '+' are not first.  We need to get folks to fix their code.

> Richard's patch moves them automagically to the beginning (with the bcopy).
> Don't you think that is enough, why bother the programmer with another
> warning if the compiler can fix it without problems? Also the requirement
> wasn't documented.

Better force people to do it _right_ than add "just another tiny special
case fix" to gcc.  Note that many people are turned away from gcc as it
stands, claiming it's just a gigantic mess.

Just my 2 cents.
-- 
Horst von Brand                             vonbrand@sleipnir.valparaiso.cl
Casilla 9G, Viņa del Mar, Chile                               +56 32 672616