Re: linux-2.1.103 crashes egcs-19980517 on i586

Jeffrey A Law (law@hurl.cygnus.com)
Thu, 21 May 1998 23:19:07 -0600

In message <199805212117.OAA27882@penguin.transmeta.com>you write:
> The asm is surrounded by
>
> cli();
> .. asm ..
> restore_flags();
>
> and both of those are either defined to be volatile asm's (for UP case)
> or to be function calls (for SMP). In either case gcc is _not_ legally
> supposed to move the __asm__ with the lcall around them: the lcall asm
> is has a "memory" modifier to mark that it can change memory.
Adding the volatile is just a band-aid, it is not a fix. I would
expect HJ to know that. The compiler shouldn't be core dumping
in that manner no matter what input it receives.

> nervous. And it makes me irritated that people _continue_ to patch the
> kernel instead of trying to fix the compiler.
Can't argue with that. I have to deal with it on a regular basis
myself. I'd much rather be fixing problems than symptoms!

It turned out to be a bug introduced in our alias code a short while
ago. This bug does not effect the egcs-1.0.x releases.

* alias.c (rtx_equal_for_memref_p): Handle SCRATCH as a memory
address.

Index: alias.c
===================================================================
RCS file: /egcs/carton/cvsfiles/egcs/./gcc/alias.c,v
retrieving revision 1.31
retrieving revision 1.32
diff -c -r1.31 -r1.32
*** alias.c 1998/05/17 13:47:28 1.31
--- alias.c 1998/05/21 22:12:04 1.32
***************
*** 467,472 ****
--- 467,476 ----
return 0;
break;

+ /* This can happen for an asm which clobbers memory. */
+ case '0':
+ break;
+
/* It is believed that rtx's at this level will never
contain anything but integers and other rtx's,
except for within LABEL_REFs and SYMBOL_REFs. */

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