From: Joern Rennecke <amylaar@cygnus.co.uk>
To: rth@cygnus.com
Cc: egcs@cygnus.com
Subject: Re: alpha regression on 920625-1
Date: Mon, 27 Apr 1998 11:10:00 -0000 [thread overview]
Message-ID: <199804271603.RAA06176@phal.cygnus.co.uk> (raw)
In-Reply-To: <19980426215614.41398@dot.cygnus.com>
> typedef struct{double x,y;}point;
> point pts[]={{1.0,2.0},{3.0,4.0},{5.0,6.0},{7.0,8.0}};
> static int va1(int nargs,...)
> {
> va_list args;
> int i;
> point pi;
> va_start(args,nargs);
> for(i=0;i<nargs;i++){
> pi=va_arg(args,point);
> if(pts[i].x!=pi.x||pts[i].y!=pi.y)abort();
> }
> va_end(args);
> }
>
> `pi' is initially allocated to a TImode register, and when comes reload
> time, we find that we must drop the register to memory. It so happens
> that the copy from varargs is done in DImode, while the comparison must
> of course be done in DFmode.
>
> The problem arose with jfc's recent mode-dependant aliasing changes.
> Because the memory block created for the TImode register is not marked
> as a structure, and we have two different modes manipulating the memory,
> the DFmode load gets scheduled before the DImode store.
Everything that gets read via varargs should be treated as part of a
structure; this is already necessary to treat the writing to the varargs
area properly.
You can archive this with a suitable definitions of va_arg.
next prev parent reply other threads:[~1998-04-27 11:10 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
1998-04-27 0:33 Richard Henderson
1998-04-27 11:10 ` Joern Rennecke [this message]
1998-04-27 13:59 ` Richard Henderson
1998-04-28 19:14 ` Jim Wilson
1998-04-28 21:59 ` Richard Henderson
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