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Re: hppa-linux regressions and 3.2.2 release
On Sunday 02 February 2003 16:55, Eric Botcazou wrote:
> > #9492 is causing the hppa-linux kernel to be miscompiled. We have a
> > workaround in place, but I think there may be more silently miscompiled
> > cases that we have not yet discovered. No one has identified what
> > causes this yet, but it seems to be a generic scheduling problem
> > rather than an hppa specific one?
>
> I think so.
>
> There are actually two bugs:
>
> struct termios {
> tcflag_t c_iflag;
> tcflag_t c_oflag;
> tcflag_t c_cflag;
> tcflag_t c_lflag;
> cc_t c_line;
> cc_t c_cc[19];
> };
>
> struct tty_driver {
> int magic;
> const char *driver_name;
> const char *name;
> int name_base;
> short major;
> short minor_start;
> short num;
> short type;
> short subtype;
> struct termios init_termios;
> int flags;
> int *refcount;
> };
>
> int main(void) {
> ...
> pty_driver.init_termios = tty_std_termios;
> ...
> }
>
>
> struct init_termios is reported by the front-end as having a size of 8
> (instead of 36) for the copy-assignment operation. This causes the alias
> analysis to think that c_lflag (offset 12) is not clobbered by the
> copy-assignment. Interestingly, c_cflag (offset 8) is detected as being
> clobbered, although it is outside the first 8 bytes.
>
> On first inspection (.sched log file), both errors fixed on the 3.3 branch.
>
> The latter error is fixed by:
>
> 2002-06-03 Dan Nicolaescu <dann@godzilla.ics.uci.edu>
>
> * alias.c (nonoverlapping_memrefs_p): Fix off by one error.
>
>
> The former problem comes from expand_assignment() that uses a hack with
> set_mem_offset() in order to adjust the offset. It is (supposedly) fixed
> by:
>
> 2002-07-29 Richard Henderson <rth@redhat.com>
>
> * emit-rtl.c (set_mem_attributes_minus_bitpos): Rename from
> set_mem_attributes and add BITPOS argument. Subtract it from
> OFFSET when same is adjusted.
> (set_mem_attributes): New wrapper function.
> * expr.c (expand_assignment): Use set_mem_attributes_minus_bitpos;
> remove offset adjustment hack.
> * expr.h (set_mem_attributes_minus_bitpos): Declare.
>
> which relies on:
>
> 2002-07-25 Richard Henderson <rth@redhat.com>
>
> * emit-rtl.c (set_mem_attributes): Fix size and alignment thinkos
> in ARRAY_REF of DECL_P case.
>
> and
>
> 2002-07-21 Richard Henderson <rth@redhat.com>
>
> * emit-rtl.c (set_mem_attributes): Preserve indirection of PARM_DECL
> when flag_argument_noalias == 2.
> * alias.c (nonoverlapping_memrefs_p): Handle that.
> * print-rtl.c (print_mem_expr): Likewise.
>
>
> As David Edelsohn would say, a nice string :-)
Yeah, and I think you missed a few more fixes to
set_mem_attributes_minus_bitpos. I've applied these to my gcc-3_2-branch
testing tree and started a build for powerpc-linux-gnu. I will report
tomorrow.
These are the patches I applied:
cvs diff -r1.172 -r1.173 alias.c |patch
cvs diff -r1.177 -r1.178 alias.c |patch
cvs diff -r1.285 -r1.288 emit-rtl.c |patch
cvs diff -r1.291 -r1.292 emit-rtl.c |patch
cvs diff -r1.294 -r1.295 emit-rtl.c |patch
cvs diff -r1.85 -r1.86 print-rtl.c |patch
cvs diff -r1.471 -r1.472 expr.c |patch
cvs diff -r1.118 -r1.119 expr.h |patch
Hopefully I didn't miss something and the tree is buildable :-).
Franz.
irc://irc.freenode.net/#gcc